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Termination Codon (termination + codon)
Kinds of Termination Codon Selected AbstractsA novel mutation in the last exon of ATRX in a patient with , -thalassemia myelodysplastic syndromeEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2006Daniel B. Costa Abstract:, We describe a patient with acquired alpha-thalassemia myelodysplastic syndrome (ATMDS). A previously healthy 66-year-old man presented with hemoglobin of 9.3 g/dL, mean corpuscular volume 59 fL, and a bone marrow aspirate with increased erythroid precursors and hypolobulated megakaryocytes. Hemoglobin H inclusions were seen in most red cells after 1% brilliant cresyl blue supravital stain of the peripheral blood. At the molecular level, we identified of a novel mutation in the most 3, exon of the ATRX gene (CGA,TGA substitution in codon 2407) resulting in a premature termination codon (p.R2407X). This case provides further evidence for a link between ATRX mutations and ATMDS, and suggests a possible role for the conserved Q-box element in ATRX function. [source] Kinetic study of sn -glycerol-1-phosphate dehydrogenase from the aerobic hyperthermophilic archaeon, Aeropyrum pernix K1FEBS JOURNAL, Issue 3 2002Jin-Suk Han A gene having high sequence homology (45,49%) with the glycerol-1-phosphate dehydrogenase gene from Methanobacterium thermoautotrophicum was cloned from the aerobic hyperthermophilic archaeon Aeropyrum pernix K1 (JCM 9820). This gene expressed in Escherichia coli with the pET vector system consists of 1113 nucleotides with an ATG initiation codon and a TAG termination codon. The molecular mass of the purified enzyme was estimated to be 38 kDa by SDS/PAGE and 72.4 kDa by gel column chromatography, indicating presence as a dimer. The optimum reaction temperature of this enzyme was observed to be 94,96 °C at near neutral pH. This enzyme was subjected to two-substrate kinetic analysis. The enzyme showed substrate specificity for NAD(P)H- dependent dihydroxyacetone phosphate reduction and NAD+ -dependent,glycerol-1-phosphate (Gro1P) oxidation. NADP+ -dependent Gro1P oxidation was not observed with this enzyme. For the production of Gro1P in A. pernix cells, NADPH is the preferred coenzyme rather than NADH. Gro1P acted as a noncompetitive inhibitor against dihydroxyacetone phosphate and NAD(P)H. However, NAD(P)+ acted as a competitive inhibitor against NAD(P)H and as a noncompetitive inhibitor against dihydroxyacetone phosphate. This kinetic data indicates that the catalytic reaction by glycerol- 1-phosphate dehydrogenase from A. pernix follows a ordered bi,bi mechanism. [source] Pleiotropic phenotypes caused by an opal nonsense mutation in an essential gene encoding HMG-CoA reductase in fission yeastGENES TO CELLS, Issue 6 2009Yue Fang Schizosaccharomyces pombe genome contains an essential gene hmg1+ encoding the sterol biosynthetic enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR). Here, we isolated an allele of the hmg1+ gene, hmg1-1/its12, as a mutant that showed sensitivities to high temperature and to FK506, a calcineurin inhibitor. The hmg1-1 allele contained an opal nonsense mutation in its N-terminal transmembrane domain, yet in spite of the mutation a full-length protein was produced, suggesting a read-through termination codon. Consistently, overexpression of the hmg1-1 mutant gene suppressed the mutant phenotypes. The hmg1-1 mutant showed hypersensitivity to pravastatin, an HMGR inhibitor, suggesting a defective HMGR activity. The mutant treated with FK506 caused dramatic morphological changes and showed defects in cell wall integrity, as well as displayed synthetic growth phenotypes with the mutant alleles of genes involved in cytokinesis and cell wall integrity. The mutant exhibited different phenotypes from those of the disruption mutants of ergosterol biosynthesis genes, and it showed normal filipin staining as well as showed normal subcellular localization of small GTPases. These data suggest that the pleiotropic phenotypes reflect the integrated effects of the reduced availability of ergosterol and various intermediates of the mevalonate pathway. [source] Calcineurin is implicated in the regulation of the septation initiation network in fission yeastGENES TO CELLS, Issue 10 2002Yabin Lu Background: In fission yeast, calcineurin has been implicated in cytokinesis because calcineurin-deleted cells form multiple septa and cell separation is impeded. However, this mechanism remains unclear. Results: We screened for mutations that confer syn-thetic lethality with calcineurin deletion and isolated a mutant, its10-1/cdc7-i10, a novel allele of the cdc7+ gene involved in the septation initiation network (SIN). The mutation created a termination codon, resulting in the truncation of Cdc7 by 162 amino acids, which is not localized in the spindle pole body. Following treatment with the immune suppressive drug FK506, cdc7-i10 and the original cdc7-24 mutant cells showed highly elongated multinuclear morphology with few visible septa, closely resembling the phenotype at the restrictive temperature. Other SIN mutants, cdc11, spg1, sid2 and mob1 showed similar phenotypes following FK506 treatment. Consistent with this, expression of the constitutively active calcineurin suppressed the growth defects and septum initiation deficiency of these SIN mutants at the restrictive temperature. Moreover, electron microscopy revealed that calcineurin-deleted cells had very thick multiple septa which were partially and ectopically formed. Conclusion: These results suggest that calcineurin is involved in the regulation of the SIN pathway, and is required for the proper formation and maturation of the septum in fission yeast. [source] Mutation analysis in nephronophthisis using a combined approach of homozygosity mapping, CEL I endonuclease cleavage, and direct sequencing,HUMAN MUTATION, Issue 3 2008Edgar A. Otto Abstract Nephronophthisis (NPHP), an autosomal recessive kidney disease, is the most frequent genetic cause of chronic renal failure in the first three decades of life. Mutations in eight genes (NPHP1,8) have been identified. We here describe a combined approach for mutation screening of NPHP1, NPHP2, NPHP3, NPHP4, and NPHP5 in a worldwide cohort of 470 unrelated patients with NPHP. First, homozygous NPHP1 deletions were detected in 97 patients (21%) by multiplex PCR. Second, 25 patients with infantile NPHP were screened for mutations in inversin (NPHP2/INVS). We detected a novel compound heterozygous frameshift mutation (p.[Q485fs]+[R687fs]), and a homozygous nonsense mutation (p.R899X). Third, 37 patients presenting with NPHP and retinitis pigmentosa (Senior-Lřken syndrome [SLS]) were screened for NPHP5/IQCB1 mutations by direct sequencing. We discovered five different (three novel) homozygous premature termination codon (PTC) mutations (p.F142fsX; p.R461X; p.R489X; p.W444X; and c.488,1G>A). The remaining 366 patients were further investigated for mutations in NPHP1, NPHP3, and NPHP4. We applied a "homozygosity only" strategy and typed three highly polymorphic microsatellite markers at the respective loci. A total of 32, eight, and 14 patients showed homozygosity, and were screened by heteroduplex crude celery extract (CEL I) endonuclease digests. The sensitivity of CEL I was established as 92%, as it detected 73 out of 79 different known mutations simply on agarose gels. A total of 10 novel PTC mutations were found in NPHP1 (p.P186fs, p.R347X, p.V492fs, p.Y509X, and c.1884+1G>A), in NPHP3 (c.3812+2T>C and p.R1259X), and in NPHP4 (p.R59X, p.T1004fs, and p.V1091fs). The combined homozygosity mapping and CEL I endonuclease mutation analysis approach allowed us to identify rare mutations in a large cohort of patients at low cost. Hum Mutat 29(3), 418,426, 2008. © 2007 Wiley-Liss, Inc. [source] A novel mutation in the ATP2C1 gene is associated with Hailey,Hailey disease in a Chinese familyINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2009Zhou Jiang Liu MD Background, A three-generation Chinese family with Hailey,Hailey disease (HHD) was identified and characterized. The proband developed HHD with severe recurrent blisters and crusted erosions involving the body folds. Skin biopsy studies showed epidermal hyperkeratosis and defects in cell-to-cell adhesion. Three other members in the family were also affected with HHD and had the same clinical manifestations. The purpose of this study was to identify the pathogenic gene or mutation in the family. Methods, All exons and exon,intron boundaries of ATP2C1 were polymerase chain reaction (PCR) amplified and sequenced with DNA samples from the proband. Restriction fragment length polymorphism (RFLP) analysis for the intron 23,exon 24 boundary of ATP2C1 was performed in all family members and in 100 normal control subjects. Results, A novel 2-bp deletion (c.2251delGT) was detected in exon 24 of the ATP2C1 gene. The mutation was present in the three other affected family members and in two asymptomatic young carriers, but not in the other normal family members or the 100 normal controls. The mutation resulted in a frameshift change and led to the formation of a premature termination codon (PTC) four amino acid residues downstream from the sixth transmembrane domain. Conclusions, Our results indicate that the novel c.2251delGT (p.V751fs) mutation in the ATP2C1 gene is responsible for HHD in this Chinese family. This study expands the spectrum of ATP2C1 mutations associated with HHD. [source] Compound heterozygosity in sibling patients with recessive dystrophic epidermolysis bullosa associated with a mild phenotypeINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 3 2006Y. Shibusawa MD We describe two cases of a 3-year-old Japanese boy and his 1-year-old sister presenting recessive dystrophic epidermolysis bullosa; a relatively mild phenotype. Blistering and scarring were limited to the acral region, and some fingernails and toenails were lost. PCR-RFLP and DNA sequencing analyses revealed compound heterozygotes for a splice-site mutation (6573 +1GtoC) and a nonsense mutation (E2857X) in the type VII collagen gene (COL7A1). Both mutations caused a premature termination codon (PTC). The mutation E2857X was located behind the candidate cleavage site within the NC-2 domain required for the assembly of anchoring fibrils. This PTC position may explain their mild phenotype. [source] Isolation and characterization of a novel copper-inducible metallothionein gene of a ciliate, Tetrahymena tropicalis lahorensisJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2010Raheela Chaudhry Abstract The two isoforms of copper metallothionein (CuMT) gene of a copper resistant ciliate, Tetrahymena tropicalis lahorensis (Ttl), have been isolated and characterized. The molecular cloning and nucleotide sequencing of cDNAs coding for the two CuMT isoforms revealed that TtlCuMT1 gene has 300, while TtlCuMT2 has 327 nucleotides, both with ATG as the initiation codon and TGA as the translational termination codon. TAG codes for glutamine in TtlCuMT2 gene which is peculiar to Tetrahymena. The deduced or translated TtlCuMT1 and TtlCuMT2 peptide sequences contain 100 and 108 amino acid residues including 28 and 32 cysteine residues, respectively. The amino acid sequences of TtlCuMT1 and TtlCuMT2 have special features of two and three CXCXXCXCXXCXC intragenic tandem repeats with a conserved structural pattern of cysteine, respectively. The predicted tertiary structures of these two isoforms indicate two domains. Domain I and the initial part of domain II showed >98% homology with other Tetrahymena CuMT. On the basis of the differences in the domain II, the metallothionein subfamily 7b can be divided into two groups, one (TtlCuMT1) comprising >100 amino acids and the other (TtlCuMT2) comprising <100 amino acids. This is a novel finding of the present study as no such report on this type of classification exists at the moment. TtlCuMT1 has 95%, while TtlCuMT2 has 97% resemblance with the previously reported CuMT genes of Tetrahymena spp. SDS-PAGE analysis using fluorescent probe as well as coomassie brilliant blue staining also confirmed the presence of metallothionein. J. Cell. Biochem. 110: 630,644, 2010. © 2010 Wiley-Liss, Inc. [source] Emerging views on tmRNA-mediated protein tagging and ribosome rescueMOLECULAR MICROBIOLOGY, Issue 4 2001Reynald Gillet Transfer- messenger RNA (tmRNA), also known as SsrA or 10Sa RNA, is a bacterial ribonucleic acid that recycles 70S ribosomes stalled on problematic messenger RNAs (mRNAs) and also contributes to the degradation of incompletely synthesized peptides. tmRNA acts initially as transfer RNA (tRNA), being aminoacylated at its 3,-end by alanyl-tRNA synthetase, to add alanine to the stalled polypeptide chain. Resumption of translation ensues not on the mRNA on which the ribosomes were stalled but at an internal position in tmRNA. Termination soon occurs, tmRNA recruiting the appropriate termination factors allowing the release of the tagged protein that is subsequently recognized and degraded by specific cytoplasmic and periplasmic proteases, and permits ribosome recycling. Recent data suggest that tmRNA tags bacterial proteins in three other instances; when ribosomes stall at internal sites; during ,readthrough' of canonical termination codons; and when ribosomes are at the termination codon of intact messages. The importance of bacterial tmRNAs for survival, growth under stress, and pathogenesis is also discussed. Recent in vivo and in vitro studies have identified novel ligands of tmRNA. Based on the available experimental evidences, an updated model of tmRNA mediated protein tagging and ribosome rescue in bacteria is presented. [source] Deletion in sortase gene of Streptococcus mutans IngbrittMOLECULAR ORAL MICROBIOLOGY, Issue 3 2004T. Igarashi Our previous studies on Streptococcus mutans have demonstrated that surface proteins containing a C-terminal sorting signal, such as surface protein antigen (PAc), glucan-binding protein C (GbpC) and dextranase (Dex), are anchored to the cell wall by a sortase (SrtA). In this study we found that, unlike other strains of S. mutans, strain Ingbritt did not exhibit cell wall-anchoring of PAc, GbpC and Dex. It is speculated that the SrtA of strain Ingbritt did not function in the cell wall-anchoring process of these surface proteins. Sequence analysis revealed a deletion of an 11-bp nucleotide sequence in the srtA gene of strain Ingbritt, resulting in the generation of a new termination codon, resulting in production of an incomplete SrtA enzyme protein. As a result, strain Ingbritt showed a localization change of PAc, GbpC and Dex in the cell, implying that strain Ingbritt loses the biological functions mediated by the cell surface-associated proteins of S. mutans. These results suggest that strain Ingbritt could be less cariogenic than other strains of S. mutans. [source] Single nucleotide polymorphism genotyping of the barley waxy gene by polymerase chain reaction with confronting two-pair primersPLANT BREEDING, Issue 3 2004E. Domon Abstract A high-throughput single nucleotide polymorphism (SNP) genotyping procedure was developed to select amylose-free barley mutants whose waxy genes had a C- to T-base substitution in exon 5, which converted Gln-89 of the wild-type gene into a termination codon. An F2 population carrying an amylose-free waxy gene was checked for segregation. Polymerase chain reaction with confronting two-pair primers (PCR-CTPP) produced allele-specific PCR products that have different sizes and are inherited in a co-dominant manner. Two alleles of the barley waxy gene with SNP were correctly identified in parental strains using the PCR-CTPP procedure. Segregation of the SNP as detected by PCR-CTPP in an F2 population fitted the expected 1:2:1 ratio. The PCR-CTPP procedure can provide a time saving and cost-effective alternative to derived cleaved amplified polymorphic sequence in marker-assisted selection. [source] Recessive dystrophic epidermolysis bullosa: Case of non-Hallopeau,Siemens variant with premature termination codons in both allelesTHE JOURNAL OF DERMATOLOGY, Issue 11 2006Nozomi YONEI ABSTRACT Dystrophic epidermolysis bullosa (DEB) is caused by mutations in the COL7A1 gene encoding collagen, the major component of anchoring fibrils. Premature termination codon (PTC) mutations in both alleles usually lead to the Hallopeau,Siemens variant that shows the most severe phenotype. We experienced a case of the non-Hallopeau,Siemens variant (nHS-RDEB), which had a mild clinical severity although it has PTC mutations in both alleles. Our patient was a compound heterozygote for a nonsense mutation (R669X) in exon 15 and a nonsense mutation (E2857X) in exon 116. But we confirmed the existence of some anchoring fibrils on electron micrograph. This suggested that a PTC close to the 3, end of COL7A1 does not completely abolish the collagen VII mRNA. We hypothesized that the truncated procollagen VII from the mutant allele with a nonsense mutation (E2857X) in exon 116 included two out of eight cysteines needed for disulfide bond formation, and hence a few functional anchoring fibrils could be formed. [source] A semi-dominant mutation in the ribosomal protein L10 gene suppresses the dwarf phenotype of the acl5 mutant in Arabidopsis thalianaTHE PLANT JOURNAL, Issue 6 2008Akihiro Imai Summary Disruption of the Arabidopsis thaliana ACAULIS5 (ACL5) gene, which has recently been shown to encode thermospermine synthase, results in a severe dwarf phenotype. A previous study showed that sac51-d, a dominant suppressor mutant of acl5-1, has a premature termination codon in an upstream open reading frame (ORF) of SAC51, which encodes a putative transcription factor, and suggested the involvement of upstream ORF-mediated translational control in ACL5 -dependent stem elongation. Here we report the identification of a gene responsible for sac52-d, another semi-dominant suppressor mutant of acl5-1. SAC52 encodes ribosomal protein L10 (RPL10A), which is highly conserved among eukaryotes and implicated in translational regulation. Transformation of acl5-1 mutants with a genomic fragment containing the sac52-d allele rescued the dwarf phenotype of acl5-1. GUS reporter activity under the control of a SAC51 promoter with its upstream ORF was higher in acl5-1 sac52-d than in acl5-1, suggesting that suppression of the acl5-1 phenotype by sac52-d is attributable, in part, to enhanced translation of certain transcripts including SAC51. We also found that a T-DNA insertion allele of SAC52/RPL10A causes lethality in the female gametophyte. [source] Repair of UV damage in plants by nucleotide excision repair: Arabidopsis UVH1 DNA repair gene is a homolog of Saccharomyces cerevisiae Rad1THE PLANT JOURNAL, Issue 6 2000Zongrang Liu Summary To analyze plant mechanisms for resistance to UV radiation, mutants of Arabidopsis that are hypersensitive to UV radiation (designated uvh and uvr) have been isolated. UVR2 and UVR3 products were previously identified as photolyases that remove UV-induced pyrimidine dimers in the presence of visible light. Plants also remove dimers in the absence of light by an as yet unidentified dark repair mechanism and uvh1 mutants are defective in this mechanism. The UVH1 locus was mapped to chromosome 5 and the position of the UVH1 gene was further delineated by Agrobacterium -mediated transformation of the uvh1-1 mutant with cosmids from this location. Cosmid NC23 complemented the UV hypersensitive phenotype and restored dimer removal in the uvh1-1 mutant. The cosmid encodes a protein similar to the S. cerevisiae RAD1 and human XPF products, components of an endonuclease that excises dimers by nucleotide excision repair (NER). The uvh1-1 mutation creates a G to A transition in intron 5 of this gene, resulting in a new 3, splice site and introducing an in-frame termination codon. These results provide evidence that the Arabidopsis UVH1/AtRAD1 product is a subunit of a repair endonuclease. The previous discovery in Lilium longiflorum of a homolog of human ERCC1 protein that comprises the second subunit of the repair endonuclease provides additional evidence for the existence of the repair endonuclease in plants. The UVH1 gene is strongly expressed in flower tissue and also in other tissues, suggesting that the repair endonuclease is widely utilized for repair of DNA damage in plant tissues. [source] Human ,2-globin nonsense-mediated mRNA decay induced by a novel , -thalassaemia frameshift mutation at codon 22BRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2006Francisco J. C. Pereira Summary We describe a novel , -thalassaemia determinant in a 3-year-old girl presenting a mild microcytic and hypochromic anaemia, and normal haemoglobin A2 level. Molecular studies revealed heterozygosity for a novel microdeletion (,C) at codon 22 of the ,2 -globin gene. As the frameshift mutation generates a premature translation termination codon at position 48/49, we investigated the effect of the nonsense codon on the ,2 -globin gene expression. Although it does not affect RNA splicing, the premature nonsense codon induces accelerated mRNA degradation. To our knowledge, this is the first time the nonsense-mediated mRNA decay has been reported to occur in human , -globin mRNA. [source] A novel deletion mutation in LIPH gene causes autosomal recessive hypotrichosis (LAH2)CLINICAL GENETICS, Issue 2 2008M Jelani Autosomal recessive hypotrichosis is a rare hereditary disorder characterized by sparse hair on scalp and rest of the body of affected subjects. Recently, three clinically similar autosomal recessive forms of hypotrichosis [localized autosomal recessive hypotrichosis (LAH)1], LAH2 and LAH3 have been mapped on chromosomes 18q12.1, 3q27.3, and 13q14.11-q21.32, respectively. For these three loci, two genes DSG4 for LAH1 and LIPH for LAH2 have been identified. To date, only five mutations in DSG4 and two in LIPH genes have been reported. In this study, we have ascertained two large unrelated consanguineous Pakistani families with autosomal recessive form of hypotrichosis. Affected individuals showed homozygosity to the microsatellite markers tightly linked to LIPH gene on chromosome 3q27. Sequence analysis of the gene in the affected subjects from both the families revealed a novel deletion mutation in exon 5 (c.659-660delTA) causing frameshift and downstream premature termination codon. All the three mutations identified in the LIPH gene, including the one in this study, are deletion mutations. [source] Novel mutations in the EXT1 gene in two consanguineous families affected with multiple hereditary exostoses (familial osteochondromatosis)CLINICAL GENETICS, Issue 2 2004M Faiyaz-Ul-Haque Multiple hereditary exostoses (HME) is an autosomal dominant developmental disorder exhibiting multiple osteocartilaginous bone tumors that generally arise near the ends of growing long bones. Here, we report two large consanguineous families from Pakistan, who display the typical features of HME. Affected individuals also show a previously unreported feature , bilateral overriding of single toes. Analysis using microsatellite markers for each of the known EXT loci, EXT1, EXT2, and EXT3 showed linkage to EXT1. In the first family, mutation analysis of the EXT1 gene revealed that affected individuals were heterozygous for an in-frame G-to-C transversion at the conserved splice donor site in intron 1. This mutation is predicted to disrupt splicing of the first intron and produce a frameshift that leads to a premature termination codon. In the second family, an insertion of an A in exon 8 is predicted to produce a frameshift at codon 555 followed by a premature termination, a further 10 codons downstream. In both families, an increased number of affected male subjects were observed. In affected females in family 2, phenotypic variability and incomplete penetrance were noted. [source] SALL1 truncated protein expression in Townes-Brocks syndrome leads to ectopic expression of downstream genes,,HUMAN MUTATION, Issue 9 2008Susan M. Kiefer Abstract Mutations in SALL1 lead to the dominant multiorgan congenital anomalies that define Townes-Brocks syndrome (TBS). The majority of these mutations result in premature termination codons that would be predicted to trigger nonsense-mediated decay (NMD) of mutant mRNA and cause haploinsufficiency. Our previous studies using a gene targeted mouse model (Sall1- ,Zn) suggested that TBS phenotypes are due to expression of a truncated mutant protein, not haploinsufficiency. In this report, we strengthen this hypothesis by showing that expression of the mutant protein alone in transgenic mice is sufficient to cause limb phenotypes that are characteristic of TBS patients. We prove that the same pathogenetic mechanism elucidated in mice is occurring in humans by demonstrating that truncated SALL1 protein is expressed in cells derived from a TBS patient. TBS mutant protein is capable of dominant negative activity that results in ectopic activation of two downstream genes, Nppa and Shox2, in the developing heart and limb. We propose a model for the pathogenesis of TBS in which truncated Sall1 protein causes derepression of Sall-responsive target genes. Hum Mutat 0,1,8, 2008. Published 2008 Wiley-Liss, Inc. [source] Expression of the muscle glycogen phosphorylase gene in patients with McArdle disease: the role of nonsense-mediated mRNA decay,HUMAN MUTATION, Issue 2 2008Gisela Nogales-Gadea Abstract Nearly 35% of all mutations identified in the muscle glycogen phosphorylase gene (PYGM) in patients with McArdle disease result in premature termination codons (PTCs), particularly the p.R50X mutation. The latter accounts for more than 50% of the mutated alleles in most Caucasian patient populations. Mutations resulting in PTC could trigger the degradation of mRNA through a mechanism known as nonsense mediated decay (NMD). To investigate if NMD affects the levels of transcripts containing PYGM mutations, 28 Spanish patients with McArdle disease, harboring 17 different mutations with PTCs in 77% of their alleles, were studied. Transcripts levels of PYGM were measured and sequenced. We assessed that 92% of patients showed NMD. The most frequent mutation (p.R50X) elicited decay in all the genotypes tested. Other PTC producing mutations resulting in NMD were: p.L5VfsX22, p.Q73HfsX7, p.E125X, p.N134KfsX161, p.W388SfsX34, p.R491AfsX7, and p.D534VfsX5. Located in the last exon, the mutation p.E797VfsX19 was not affected by NMD. Missense mutations did not appear to be affected by NMD. In the cDNA sequences they appeared as homozygous, despite being heterozygous in the genomic DNA sequences. Exceptions to the rules governing NMD were found in the mutations p.A704,V and p.K754NfsX49. Hum Mutat 29(2), 277,283, 2008. © 2007 Wiley-Liss, Inc. [source] Mutation screening of the fibrillin-1 (FBN1) gene in 76 unrelated patients with Marfan syndrome or Marfanoid features leads to the identification of 11 novel and three previously reported mutations,,HUMAN MUTATION, Issue 5 2002Kathrin Rommel Abstract Mutations in the gene encoding fibrillin-1 (FBN1) cause Marfan syndrome (MFS) and other related connective tissue disorders. In this study we performed SSCP to analyze all 65 exons of the FBN1 gene in 76 patients presenting with classical MFS or related phenotypes. We report 7 missense mutations, 3 splice site alterations, one indel mutation, one nonsense mutation and two mutations causing frameshifts: a 16bp deletion and a single nucleotide insertion. 5 of the missense mutations (Y1101C, C1806Y, T1908I, G1919D, C2251R) occur in calcium-binding Epidermal Growth Factor-like (EGFcb) domains of exons 26, 43, 46 and 55, respectively. One missense mutation (V449I) substitutes a valine residue in the non-calcium-binding epidermal growth factor like domain (EGFncb) of exon 11. One missense mutation (G880S) affects the "hybrid" motif in exon 21 by replacing glycine to serine. The 3 splice site mutations detected are: IVS1,1G>A in intron 1, IVS38-1G>A in intron 38 and IVS46+5G>A in intron 46. C628delinsK was identified in exon 15 leading to the substitution of a conserved cysteine residue. Furthermore two frameshift mutations were found in exon 15 (1904-1919del ) and exon 63 (8025insC) leading to premature termination codons (PTCs) in exon 17 and 64 respectively. Finally we identified a nonsense mutation (R429X) located in the proline rich domain in exon 10 of the FBN1 gene. Y1101C, IVS46+5G>A and R429X have been reported before. © 2002 Wiley-Liss, Inc. [source] Emerging views on tmRNA-mediated protein tagging and ribosome rescueMOLECULAR MICROBIOLOGY, Issue 4 2001Reynald Gillet Transfer- messenger RNA (tmRNA), also known as SsrA or 10Sa RNA, is a bacterial ribonucleic acid that recycles 70S ribosomes stalled on problematic messenger RNAs (mRNAs) and also contributes to the degradation of incompletely synthesized peptides. tmRNA acts initially as transfer RNA (tRNA), being aminoacylated at its 3,-end by alanyl-tRNA synthetase, to add alanine to the stalled polypeptide chain. Resumption of translation ensues not on the mRNA on which the ribosomes were stalled but at an internal position in tmRNA. Termination soon occurs, tmRNA recruiting the appropriate termination factors allowing the release of the tagged protein that is subsequently recognized and degraded by specific cytoplasmic and periplasmic proteases, and permits ribosome recycling. Recent data suggest that tmRNA tags bacterial proteins in three other instances; when ribosomes stall at internal sites; during ,readthrough' of canonical termination codons; and when ribosomes are at the termination codon of intact messages. The importance of bacterial tmRNAs for survival, growth under stress, and pathogenesis is also discussed. Recent in vivo and in vitro studies have identified novel ligands of tmRNA. Based on the available experimental evidences, an updated model of tmRNA mediated protein tagging and ribosome rescue in bacteria is presented. [source] Recessive dystrophic epidermolysis bullosa: Case of non-Hallopeau,Siemens variant with premature termination codons in both allelesTHE JOURNAL OF DERMATOLOGY, Issue 11 2006Nozomi YONEI ABSTRACT Dystrophic epidermolysis bullosa (DEB) is caused by mutations in the COL7A1 gene encoding collagen, the major component of anchoring fibrils. Premature termination codon (PTC) mutations in both alleles usually lead to the Hallopeau,Siemens variant that shows the most severe phenotype. We experienced a case of the non-Hallopeau,Siemens variant (nHS-RDEB), which had a mild clinical severity although it has PTC mutations in both alleles. Our patient was a compound heterozygote for a nonsense mutation (R669X) in exon 15 and a nonsense mutation (E2857X) in exon 116. But we confirmed the existence of some anchoring fibrils on electron micrograph. This suggested that a PTC close to the 3, end of COL7A1 does not completely abolish the collagen VII mRNA. We hypothesized that the truncated procollagen VII from the mutant allele with a nonsense mutation (E2857X) in exon 116 included two out of eight cysteines needed for disulfide bond formation, and hence a few functional anchoring fibrils could be formed. [source] Drug-induced readthrough of premature stop codons leads to the stabilization of laminin ,2 chain mRNA in CMD myotubesTHE JOURNAL OF GENE MEDICINE, Issue 2 2008Valérie Allamand Abstract Background The most common form of congenital muscular dystrophy is caused by a deficiency in the ,2 chain of laminin-211, a protein of the extracellular matrix. A wide variety of mutations, including 20 to 30% of nonsense mutations, have been identified in the corresponding gene, LAMA2. A promising approach for the treatment of genetic disorders due to premature termination codons (PTCs) is the use of drugs to force stop codon readthrough. Methods Here, we analyzed the effects of two compounds on a PTC in the LAMA2 gene that targets the mRNA to nonsense-mediated RNA decay, in vitro using a dual reporter assay, as well as ex vivo in patient-derived myotubes. Results We first showed that both gentamicin and negamycin promote significant readthrough of this PTC. We then demonstrated that the mutant mRNAs were strongly stabilized in patient-derived myotubes after administration of negamycin, but not gentamicin. Nevertheless, neither treatment allowed re-expression of the laminin ,2-chain protein, pointing to problems that may have arisen at the translational or post-translational levels. Conclusions Taken together, our results emphasize that achievement of a clinical benefit upon treatment with novel readthrough-inducing agents would require several favourable conditions including PTC nucleotide context, intrinsic and induced stability of mRNA and correct synthesis of a full-length active protein. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||