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Bacillus subtilis StoA Is a Thiol-Disulfide Oxidoreductase Important for Spore Cortex Synthesis. L, 2004.Bacillus subtilis is an endospore-forming bacterium . There are indications that protein disulfide linkages occur in spores,but the role of thiol-disulfide chemistry in spore synthesisis not understood . Thiol-disulfide oxidoreductases catalyzeformation or breakage of disulfide bonds in proteins . CcdA isthe only B . subtilis thiol-disulfide oxidoreductase that haspreviously been shown to play some role in endospore biogenesis.In this work we show that lack of the StoA [YkvV] protein resultsin spores sensitive to heat, lysozyme, and chloroform . Comparedto CcdA deficiency, StoA deficiency results in a 100-fold-strongernegative effect on sporulation efficiency . StoA is a membrane-boundprotein with a predicted thioredoxin-like domain probably localizedin the intermembrane space of the forespore . Electron microscopyof spores of CcdA- and StoA-deficient strains showed that thespore cortex is absent in both cases . The BdbD protein catalyzesformation of disulfide bonds in proteins on the outer side ofthe cytoplasmic membrane but is not required for sporulation.Inactivation of bdbD was found to suppress the sporulation defectof a strain deficient in StoA . Our results indicate that StoAis a thiol-disulfide oxidoreductase that is involved in breakingdisulfide bonds in cortex components or in proteins importantfor cortex synthesis. Substitutions at Methionine 220 in the 14  -Sterol Demethylase (Cyp51A) of Aspergillus fumigatus Are Responsible for Resistance In Vitro to Azole Antifungal Drugs.E. Mellado, 2004.Five clinical isolates of Aspergillus fumigatus that exhibited similar patterns of reduced susceptibility to itraconazole and other triazole drugs were analyzed . Sequence analysis of genes (cyp51A and cyp51B) encoding the 14 -sterol demethylases revealed that all five strains harbored mutations in cyp51A resulting in the replacement of methionine at residue 220 by valine, lysine, or threonine . When the mutated cyp51A genes were introduced into an A . fumigatus wild-type strain, the transformants exhibited reduced susceptibility to all triazole agents, confirming that the mutations were responsible for the resistance phenotype .
Analysis of the Heat Shock Response of Neisseria meningitidis with cDNA- and Oligonucleotide-Based DNA Microarrays. Matthias Guckenberger, 2002.Oligonucleotide- and cDNA-based microarrays comprising a subset of Neisseria meningitidis genes were assessed for study of the meningococcal heat shock response and found to be highly suitable for transcriptional profiling of N . meningitidis . Employing oligonucleotide arrays encompassing the entire genome of N . meningitidis, we analyzed the meningococcal heat shock response on a global scale and identified 55 heat shock-deregulated open reading frames (34 induced and 21 repressed) . A New Heat Shock Gene, agsA, Which Encodes a Small Chaperone Involved in Suppressing Protein Aggregation in Salmonella enterica Serovar Typhimurium. Toshifumi Tomoyasu, 2003.We discovered a novel small heat shock protein (sHsp) named AgsA (aggregation-suppressing protein) in the thermally aggregated fraction from a Salmonella enterica serovar Typhimurium dnaK-null strain . The -10 and -35 regions upstream of the transcriptional start site of the agsA gene are characteristic of  32- and
72-dependent promoters . AgsA was strongly induced by high temperatures . The similarity between AgsA and the other two sHsps of Salmonella serovar Typhimurium, IbpA and IbpB, is rather low (around 30% amino acid sequence identity) . Phylogenetic analysis suggested that AgsA arose from an ancient gene duplication or amplification at an early evolutionary stage of gram-negative bacteria . Here we show that overproduction of AgsA partially complements the
 dnaK52 thermosensitive phenotype and reduces the amount of heat-aggregated proteins in both
dnaK52 and
rpoH mutants of Escherichia coli . These data suggest that AgsA is an effective chaperone capable of preventing aggregation of nonnative proteins and maintaining them in a state competent for refolding in Salmonella serovar Typhimurium at high temperatures .
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