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C-terminal Deletions (c-terminal + deletion)
Selected AbstractsLevel of purposeful hand function as a marker of clinical severity in Rett syndromeDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 9 2010JENNY DOWNS Aim, We investigated relationships between hand function and genotype and aspects of phenotype in Rett syndrome. Method, Video assessment in naturalistic settings was supplemented by parent-reported data in a cross-sectional study of 144 females with a mean age of 14 years 10 months (SD 7y 10mo; range 2y,31y 10mo), 110 of whom had a mutation of the methyl CpG binding protein 2 (MECP2) gene. Ordinal logistic regression was used to assess relationships between hand function and MECP2 mutation, age, a modified Kerr score, Functional Independence Measure for Children (WeeFIM), ambulation level, and frequency of hand stereotypies. Results, Approximately two-thirds of participants demonstrated purposeful hand function, ranging from simple grasping skills to picking up and manipulating small objects. In participants with a confirmed MECP2 mutation, those with the p.R168X mutation had the poorest hand function on multivariate analysis with C-terminal deletion as the baseline (odds ratio [OR] 0.19; 95% confidence interval [CI] 0.04,0.95), whereas those with the p.R133C or p.R294X mutation had better hand function. Participants aged 19 years or older had lower hand function than those aged less than 8 years (OR 0.36; 95% CI 0.14,0.92). Factors that were associated with better hand function were lower Kerr scores for a 1-point increase in score (OR 0.77; 95% CI 0.69,0.86), higher WeeFIM scores for a 1-point increase in score (OR 1.08; 95% CI 1.04,1.12), and greater ambulation than those completely dependent on carers for mobility (OR 22.64; 95% CI 7.02,73.08). The results for participants with a confirmed pathogenic mutation were similar to results obtained when participants without a mutation were also included. Interpretation, Our novel assessment of hand function in Rett syndrome correlated well with known profiles of common MECP2 mutations and overall clinical severity. This promising assessment could measure clinical responses to therapy. [source] The C-terminal region of CHD3/ZFH interacts with the CIDD region of the Ets transcription factor ERM and represses transcription of the human presenilin 1 geneFEBS JOURNAL, Issue 6 2007Martine Pastorcic Presenilins are required for the function of ,-secretase: a multiprotein complex implicated in the development of Alzheimer's disease (AD). We analyzed expression of the presenilin 1 (PS1) gene. We show that ERM recognizes avian erythroblastosis virus E26 oncogene homolog (Ets) motifs on the PS1 promoter located at ,10, +90, +129 and +165, and activates PS1 transcription with promoter fragments containing or not the ,10 Ets site. Using yeast two-hybrid selection we identified interactions between the chromatin remodeling factor CHD3/ZFH and the C-terminal 415 amino acids of ERM used as bait. Clones contained the C-terminal region of CHD3 starting from amino acid 1676. This C-terminal fragment (amino acids 1676,2000) repressed transcription of the PS1 gene in transfection assays and PS1 protein expression from the endogenous gene in SH-SY5Y cells. In cells transfected with both CHD3 and ERM, activation of PS1 transcription by ERM was eliminated with increasing levels of CHD3. Progressive N-terminal deletions of CHD3 fragment (amino acids 1676,2000) indicated that sequences crucial for repression of PS1 and interactions with ERM in yeast two-hybrid assays are located between amino acids 1862 and 1877. This was correlated by the effect of progressive C-terminal deletions of CHD3, which indicated that sequences required for repression of PS1 lie between amino acids 1955 and 1877. Similarly, deletion to amino acid 1889 eliminated binding in yeast two-hybrid assays. Testing various shorter fragments of ERM as bait indicated that the region essential for binding CHD3/ZFH is within the amino acid region 96,349, which contains the central inhibitory DNA-binding domain (CIDD) of ERM. N-Terminal deletions of ERM showed that residues between amino acids 200 and 343 are required for binding to CHD3 (1676,2000) and C-terminal deletions of ERM indicated that amino acids 279,299 are also required. Furthermore, data from chromatin immunoprecipitation (ChIP) indicate that CHD3/ZFH interacts with the PS1 promoter in vivo. [source] Microfibril-associated glycoprotein-1 binding to tropoelastinFEBS JOURNAL, Issue 14 2004Multiple binding sites, the role of divalent cations Microfibrils and elastin are major constituents of elastic fibers, the assembly of which is dictated by multimolecular interactions. Microfibril-associated glycoprotein-1 (MAGP-1) is a microfibrillar component that interacts with the soluble elastin precursor, tropoelastin. We describe here the adaptation of a solid-phase binding assay that defines the effect of divalent cations on the interactions between MAGP-1 and tropoelastin. Using this assay, a strong calcium-dependent interaction was demonstrated, with a dissociation constant of 2.8 ± 0.3 nm, which fits a single-site binding model. Manganese and magnesium bestowed a weaker association, and copper did not facilitate the protein interactions. Three constructs spanning tropoelastin were used to quantify their relative contributions to calcium-dependent MAGP-1 binding. Binding to a construct spanning a region from the N-terminus to domain 18 followed a single-site binding model with a dissociation constant of 12.0 ± 2.2 nm, which contrasted with the complex binding behavior observed for fragments spanning domains 17,27 and domain 27 to the C-terminus. To further elucidate binding sites around the kallikrein cleavage site of domains 25/26, MAGP-1 was presented with constructs containing C-terminal deletions within the region. Construct M1659, which spans a region from the N-terminus of tropoelastin to domain 26, inclusive, bound MAGP-1 with a dissociation constant of 9.7 ± 2.0 nm, which decreased to 4.9 ± 1.0 nm following the removal of domain 26 (M155n), thus displaying only half the total capacity to bind MAGP-1. These results demonstrate that MAGP-1 is capable of cumulative binding to distinct regions on tropoelastin, with different apparent dissociation constants and different amounts of bound protein. [source] Role of the N- and C-terminal regions of the PufX protein in the structural organization of the photosynthetic core complex of Rhodobacter sphaeroidesFEBS JOURNAL, Issue 7 2002Francesco Francia The core complex of Rhodobacter sphaeroides is formed by the association of the light-harvesting antenna 1 (LH1) and the reaction center (RC). The PufX protein is essential for photosynthetic growth; it is located within the core in a 1 : 1 stoichiometry with the RC. PufX is required for a fast ubiquinol exchange between the QB site of the RC and the Qo site of the cytochrome bc1 complex. In vivo the LH1,PufX,RC complex is assembled in a dimeric form, where PufX is involved as a structural organizer. We have modified the PufX protein at the N and the C-terminus with progressive deletions. The nine mutants obtained have been characterized for their ability for photosynthetic growth, the insertion of PufX in the core LH1,RC complex, the stability of the dimers and the kinetics of flash-induced reduction of cytochrome b561 of the cytochrome bc1 complex. Deletion of 18 residues at the N-terminus destabilizes the dimer in vitro without preventing photosynthetic growth. The dimer (or a stable dimer) does not seem to be a necessary requisite for the photosynthetic phenotype. Partial C-terminal deletions impede the insertion of PufX, while the complete absence of the C-terminus leads to the insertion of a PufX protein composed of only its first 53 residues and does not affect the photosynthetic growth of the bacterium. Overall, the results point to a complex role of the N and C domains in the structural organization of the core complex; the N-terminus is suggested to be responsible mainly for dimerization, while the C-terminus is thought to be involved mainly in PufX assembly. [source] A 76-residue polypeptide of colicin E9 confers receptor specificity and inhibits the growth of vitamin B12 -dependent Escherichia coli 113/3 cellsMOLECULAR MICROBIOLOGY, Issue 3 2000Christopher N. Penfold The mechanism by which E colicins recognize and then bind to BtuB receptors in the outer membrane of Escherichia coli cells is a poorly understood first step in the process that results in cell killing. Using N- and C-terminal deletions of the N-terminal 448 residues of colicin E9, we demonstrated that the smallest polypeptide encoded by one of these constructs that retained receptor-binding activity consisted of residues 343,418. The results of the in vivo receptor-binding assay were supported by an alternative competition assay that we developed using a fusion protein consisting of residues 1,497 of colicin E9 fused to the green fluorescent protein as a fluorescent probe of binding to BtuB in E. coli cells. Using this improved assay, we demonstrated competitive inhibition of the binding of the fluorescent fusion protein by the minimal receptor-binding domain of colicin E9 and by vitamin B12. Mutations located in the minimum R domain that abolished or reduced the biological activity of colicin E9 similarly affected the competitive binding of the mutant colicin protein to BtuB. The sequence of the 76-residue R domain in colicin E9 is identical to that found in colicin E3, an RNase type E colicin. Comparative sequence analysis of colicin E3 and cloacin DF13, which is also an RNase-type colicin but uses the IutA receptor to bind to E. coli cells, revealed significant sequence homology throughout the two proteins, with the exception of a region of 92 residues that included the minimum R domain. We constructed two chimeras between cloacin DF13 and colicin E9 in which (i) the DNase domain of colicin E9 was fused onto the T+R domains of cloacin DF13; and (ii) the R domain and DNase domain of colicin E9 were fused onto the T domain of cloacin DF13. The killing activities of these two chimeric colicins against indicator strains expressing BtuB or IutA receptors support the conclusion that the 76 residues of colicin E9 confer receptor specificity. The minimum receptor-binding domain polypeptide inhibited the growth of the vitamin B12 -dependent E. coli 113/3 mutant cells, demonstrating that vitamin B12 and colicin E9 binding is mutually exclusive. [source] Brain metabolism in rett syndrome: Age, clinical, and genotype correlations,ANNALS OF NEUROLOGY, Issue 1 2009Alena Horská PhD Objective Brain metabolism, as studied by magnetic resonance spectroscopy (MRS), has been previously shown to be abnormal in Rett syndrome (RTT). This study reports the relation of MRS findings to age, disease severity, and genotype. Methods Forty RTT girls (1,14 years old) and 12 age-matched control subjects were examined. Single-voxel proton MRS of left frontal white matter was performed. Results NAA/Cr ratios decreased and myoinositol/Cr ratios increased with age in RTT patients (both p < 0.03), whereas these ratios were stable in control. The mean glutamate and glutamine/Cr ratio was 36% greater in RTT patients than in control (p = 0.043). The mean NAA/Cr ratio was 12.6% lower in RTT patients with seizures compared with those without seizures (p = 0.017). NAA/Cr ratios decreased with increasing clinical severity score (p = 0.031). Compared with patients with T158X, R255X, and R294X mutations, and C-terminal deletions, patients with the R168X mutation tended to have the greatest severity score (0.01 , p , 0.11) and the lowest NAA/Cr ratio (0.029 , p < 0.14). Interpretation Decreasing NAA/Cr and increasing myoinositol/Cr with age are suggestive of progressive axonal damage and astrocytosis in RTT, respectively, whereas increased glutamate and glutamine/Cr ratio may be secondary to increasing glutamate/glutamine cycling at the synaptic level. The relations between NAA/Cr, presence or absence of seizures, and disease severity suggest that MRS provides a noninvasive measure of cerebral involvement in RTT. Ann Neurol 2009;65:90,97 [source] | ||||||||||