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From Rings to Layers: Surprising Patterns of Protein Deposition during Bacterial Spore Assembly. Adam Driks, 2004. Evidence for Conformational Protection of Nitrogenase against Oxygen in Gluconacetobacter diazotrophicus by a Putative FeSII Protein. Alejandro Ureta, 2002.The mechanisms protecting nitrogenase in Gluconacetobacter diazotrophicus from damage by oxygen were studied . Evidence is provided suggesting that in G . diazotrophicus these mechanisms include respiratory protection as well as conformational protection in which a putative FeSII Shethna protein is involved . Demonstration that fbiC Is Required by Mycobacterium bovis BCG for Coenzyme F420 and FO Biosynthesis. Kwang-Pil Choi, 2002.Using the nitroimidazopyran-based antituberculosis drug PA-824 as a selective agent, transposon-generated Mycobacterium bovis strain BCG (M . bovis) mutants that could not make coenzyme F420 were identified . Four independent mutants that could not make F420 or the biosynthesis intermediate FO were examined more closely . These mutants contained transposons inserted in the M . bovis homologue of the Mycobacterium tuberculosis gene Rv1173, which we have named fbiC . Complementation of an M . bovis FbiC- mutant with fbiC restored the F420 phenotype . These data demonstrate that fbiC is essential for F420 production and that FbiC participates in a portion of the F420 biosynthetic pathway between pyrimidinedione and FO . Homologues of fbiC were found in all 11 microorganisms that have been fully sequenced and that are known to make F420 . Four of these homologues (all from members of the aerobic actinomycetes) coded for proteins homologous over the entire length of the M . bovis FbiC, but in seven microorganisms two separate genes were found to code for proteins homologous with either the N-terminal or C-terminal portions of the M . bovis FbiC . Histidine-tagged FbiC overexpressed in Escherichia coli produced a fusion protein of the molecular mass predicted from the M . bovis BCG sequence (  95,000 Da), as well as three other histidine-tagged proteins of significantly smaller size, which are thought to be proteolysis products of the FbiC fusion protein .
Efficient Allelic Exchange and Transposon Mutagenesis in Mycobacterium avium by Specialized Transduction. Joel Otero, 2003.Mycobacterium tuberculosis and Mycobacterium avium are pathogenic slow-growing mycobacteria that cause distinct human diseases . In contrast to recent advances in M . tuberculosis genetics and pathogenesis investigation, M . avium has remained genetically intractable and, consequently, its pathogenic strategies remain poorly understood . Here we report the successful development of efficient allelic exchange and transposon mutagenesis in an opaque clinical strain of M . avium by specialized transduction . Efforts to disrupt the leuD gene of M . avium by specialized transduction were successful but were complicated by inefficient isolation of recombinants secondary to high spontaneous antibiotic resistance . However, by using this leucine auxotroph as a genetic host and the Streptomyces coelicolor leuD gene as a selectable marker, we achieved efficient allelic exchange at the M . avium pcaA locus . A leuD-marked transposon delivered by specialized transduction mutagenized M . avium with efficiencies similar to M . tuberculosis . These results establish a system for random and directed mutagenesis of M . avium . In combination with the forthcoming M . avium genome sequence, these tools will allow the distinct physiologic and pathogenic properties of M . avium to be dissected in molecular detail .
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