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Chimeric Gene (chimeric + gene)
Selected AbstractsUstilago maydis spermidine synthase is encoded by a chimeric gene, required for morphogenesis, and indispensable for survival in the hostFEMS YEAST RESEARCH, Issue 6 2009Laura Valdés-Santiago Abstract To analyze the role of spermidine in cell growth and differentiation of Ustilago maydis, the gene encoding spermidine synthase (Spe) was isolated using PCR. We found that the enzyme is encoded by a chimeric bifunctional gene (Spe-Sdh) that also encodes saccharopine dehydrogenase (Sdh), an enzyme involved in lysine biosynthesis. The gene contains a 5, region encoding Spe, followed, without a termination signal or a second initiation codon, by a 3, region encoding Sdh, and directs the synthesis of a single transcript that hybridizes with 3, or 5, regions' probes of the gene. The gene could not be disrupted in a wild-type strain, but only in a mutant defective in the gene encoding ornithine decarboxylase (Odc). Single spe-sdh mutants were isolated after sexual recombination in planta with a compatible wild-type strain. Mutants were auxotrophic for lysine and spermidine, but not for putrescine, and contained putrescine and spermidine, but not spermine. Putrescine in double mutants is probably synthesized from spermidine by the concerted action of polyamine acetyl transferase and polyamine oxidase. spe-sdh mutants were sensitive to stress, unable to carry out the yeast-to-mycelium dimorphic transition, and showed attenuated virulence to maize. These phenotypic alterations were reverted by complementation with the wild-type gene. [source] Both NUP98/TOP1 and TOP1/NUP98 transcripts are detected in a de novo AML with t(11;20)(p15;q11)GENES, CHROMOSOMES AND CANCER, Issue 1 2003Satsuki Iwase The NUP98 gene is involved in several chromosomal abnormalities associated with acute leukemia. The recurrent t(11;20)(p15;q11) chromosomal translocation results in generation of the NUP98/TOP1 chimeric gene. This abnormality has been observed primarily in therapy-related leukemias, and TOP1/NUP98 transcripts have not been demonstrated. We describe a case of de novo acute myeloid leukemia with t(11;20)(p15;q11), with no known history of exposure to chemicals. The translocation occurred in intron 13 of NUP98 and intron 7 of TOP1, as in the three previously reported cases. The breakpoint in NUP98 was exactly the same as that found in a previously reported case. In addition, a reciprocal TOP1/NUP98 transcript was detected for the first time in our patient. © 2003 Wiley-Liss, Inc. [source] A tomato mutant that shows stunting, wilting, progressive necrosis and constitutive expression of defence genes contains a recombinant Hcr9 gene encoding an autoactive proteinTHE PLANT JOURNAL, Issue 3 2006Claire L. Barker Summary The tomato Cf-9 gene confers resistance to races of the leaf mould fungus Cladosporium fulvum that carry the Avr9 avirulence gene. Cf-9 resides at a locus containing five paralogous genes and was isolated by transposon tagging using a modified maize Dissociation (Ds) element. The tagging experiment generated an allelic series of Ds -induced mutations of Cf-9, most of which were wild type in appearance. However, one mutant, designated M205, showed stunted growth, wilting, progressive leaf chlorosis and necrosis and constitutive expression of defence genes. The phenotype of M205 was caused by a semidominant, Avr9 -independent mutation that co-segregated with a Ds element insertion at the Cf-9 locus. Molecular genetic analysis indicated that the Cf-9 locus of M205 had undergone recombination, generating a chimeric gene, designated Hcr9-M205, that comprised an in-frame fusion between the 5, coding region of the Cf-9 paralogue, Hcr9-9A, and the 3, coding region of Cf-9. The presence of a possible excision footprint adjacent to the junction between Hcr9-9A and Cf-9, and a Ds insertion at the homologous position in the downstream paralogue Hcr9-9D, is consistent with recombination between Hcr9-9A and Cf-9 promoted by transposition of Ds from Cf-9 into Hcr9-9D. Agrobacterium tumefaciens -mediated transient expression of Hcr9-M205 in Nicotiana tabacum caused chlorosis and the accumulation of defence gene transcripts, indicating that the protein encoded by this novel Hcr9 gene is autoactive. [source] Role of the RUNX1-EVI1 fusion gene in leukemogenesisCANCER SCIENCE, Issue 10 2008Kazuhiro Maki RUNX1-EVI1 is a chimeric gene generated by t(3;21)(q26;q22) observed in patients with aggressive transformation of myelodysplastic syndrome or chronic myelogenous leukemia. RUNX1-EVI1 has oncogenic potentials through dominant-negative effect over wild-type RUNX1, inhibition of Jun kinase (JNK) pathway, stimulation of cell growth via AP-1, suppression of TGF-,-mediated growth inhibition and repression of C/EBP,. Runx1-EVI1 heterozygous knock-in mice die in uteri due to central nervous system (CNS) hemorrhage and severe defects in definitive hematopoiesis as Runx1,/, mice do, indicating that RUNX1-EVI1 dominantly suppresses functions of wild-type RUNX1 in vivo. Acute myelogenous leukemia is induced in mice transplanted with bone marrow cells expressing RUNX1-EVI1, and a Runx1-EVI1 knock-in chimera mouse developed acute megakaryoblastic leukemia. These results suggest that RUNX1-EVI1 plays indispensable roles in leukemogenesis of t(3;21)-positive leukemia. Major leukemogenic effect of RUNX1-EVI1 is mainly through histone deacetyltransferase recruitment via C-terminal binding protein. Histone deacetyltransferase could be a target in molecular therapy of RUNX1-EVI1-expressing leukemia. (Cancer Sci 2008; 99: 1878,1883) [source] Genetic and epigenetic factors involved in B-cell lymphomagenesisCANCER SCIENCE, Issue 9 2004Masao Seto Malignant lymphomas have been classified by the WHO into disease categories based not only on histological features, but also on cell surface markers, cytogenetic and clinical features. It is known that chromosome translocation plays an important role in lymphoma development, but it is not entirely clear yet why a given type of chromosome translocation is associated with a specific type of lymphoma. This review deals with molecular mechanisms of B-cell lymphoma development in association with chromosome translocations. The outcome of chromosome translo-cations can be categorized into three factors: enhancement of proliferation, inhibition of differentiation and anti-apoptotic activity. It is well known that chromosome translocation by itself cannot cause cells to become malignant because it is only one of the growth advantages leading to malignancy, while additional genetic and epigenetic alterations are required for cells to become fully malignant. Mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach are unique in that a majority can be cured by Helicobacter pylori eradication, although 20 to 30% remain resistant. Others as well as we have demonstrated that the presence of the API2-MALT1 chimeric gene correlates well with resistance to H. pylori eradication treatment. These characteristics have led to the speculation that the classification of MALT lymphoma falls somewhere between tumor and inflammation. Although MALT lymphoma seems to have unique features in comparison with other types of B-cell lymphomas, it shares common molecular mechanisms with B-cell lymphoma development. [source] Cloning and expression of Bacillus phytase gene (phy) in Escherichia coli and recovery of active enzyme from the inclusion bodiesJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2008D.E.C.S. Rao Abstract Aims:, To isolate, clone and express a novel phytase gene (phy) from Bacillus sp. in Escherichia coli; to recover the active enzyme from inclusion bodies; and to characterize the recombinant phytase. Methods and Results:, The molecular weight of phytase was estimated as 40 kDa on SDS-polyacrylamide gel electrophoresis. A requirement of Ca2+ ions was found essential both for refolding and activity of the enzyme. Bacillus phytase exhibited a specific activity of 16 U mg,1 protein; it also revealed broad pH and temperature ranges of 5·0 to 8·0 and 25 to 70°C, respectively. The Km value of phytase for hydrolysis of sodium phytate has been determined as 0·392 mmol l,1. The activity of enzyme has been inhibited by EDTA. The enzyme exhibited ample thermostability upon exposure to high temperatures from 75 to 95°C. After 9 h of cultivation of transformed E. coli in the bioreactor, the cell biomass reached 26·81 g wet weight (ww) per l accounting for 4289 U enzyme activity compared with 1·978 g ww per l producing 256 U activity in shake-flask cultures. In silico analysis revealed a ,-propeller structure of phytase. Conclusions:, This is the first report of its kind on the purification and successful in vitro refolding of Bacillus phytase from the inclusion bodies formed in the transformed E. coli. Significance and Impact of the Study:, Efficient and reproducible protocols for cloning, expression, purification and in vitro refolding of Bacillus phytase enzyme from the transformed E. coli have been developed. The novel phytase, with broad pH and temperature range, renaturation ability and substrate specificity, appears promising as an ideal feed supplement. Identification of site between 179th amino acid leucine and 180th amino acid asparagine offers scope for insertion of small peptides/domains for production of chimeric genes without altering enzyme activity. [source] | |||||||||||||