RESUMO
A new Bacillus subtilis sporulation-specific gene, yhcN, has been identified, the expression of which is dependent on the forespore-specific sigma factor sigmaG and to a much lesser extent on sigmaF. A translational yhcN-lacZ fusion is expressed at a very high level in the forespore, and the protein encoded by yhcN was detected in the inner spore membrane. A yhcN mutant sporulates normally and yhcN spores have identical resistance properties to wild-type spores. However, the outgrowth of yhcN spores is slower than that of wild-type spores.
Assuntos
Bacillus subtilis/genética , Bacillus subtilis/fisiologia , Genes Bacterianos , Sequência de Aminoácidos , Bacillus subtilis/crescimento & desenvolvimento , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sequência de Bases , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Dados de Sequência Molecular , Mutagênese Insercional , Regiões Promotoras Genéticas , Fator sigma/biossíntese , Fator sigma/química , Fator sigma/genética , Fator sigma/fisiologia , Esporos Bacterianos/química , Esporos Bacterianos/genética , Fatores de Transcrição/biossíntese , Fatores de Transcrição/química , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologiaRESUMO
Most biological membranes contain one or two type I signal peptidases for the removal of signal peptides from secretory precursor proteins. In this respect, the Gram-positive bacterium Bacillus subtilis seems to be exceptional, because it contains at least four chromosomally-encoded type I signal peptidases, denoted SipS, SipT, SipU, and SipV. Here, we report the identification of the sipT and sipV genes, and the functional characterization of SipT, SipU, and SipV. The four signal peptidases have similar substrate specificities, as they can all process the same beta-lactamase precursor. Nevertheless, they seem to prefer different pre-proteins, as indicated by studies on the processing of the pre-alpha-amylase of Bacillus amyloliquefaciens in strains lacking SipS, SipT, SipU, or SipV. The sipU and sipV genes are constitutively transcribed at a low level, suggesting that they are required for processing of (pre-)proteins secreted during all growth phases. In contrast, the transcription of sipS and sipT is temporally controlled, in concert with the expression of the genes for most secretory proteins, which suggests that SipS and SipT serve to increase the secretory capacity of B. subtilis. Taken together, our findings suggest that SipS, SipT, SipU, and SipV serve different functions during the exponential and post-exponential growth phase of B. subtilis.
Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/metabolismo , Proteínas de Membrana/metabolismo , Serina Endopeptidases/metabolismo , Sequência de Aminoácidos , Bacillus subtilis/genética , Proteínas de Bactérias/química , Regulação Bacteriana da Expressão Gênica , Isoenzimas/química , Isoenzimas/metabolismo , Proteínas de Membrana/química , Dados de Sequência Molecular , Serina Endopeptidases/química , Serina Endopeptidases/genética , Especificidade por Substrato , Transcrição Gênica , alfa-Amilases/metabolismoRESUMO
A 21808 bp nucleotide sequence at 75 degrees on the genetic map of the Bacillus subtilis chromosome was determined. The sequence of this region is adjacent to the glpPFKD operon involved in glycerol utilization. Twenty-six ORFs were identified, one of which corresponds to the cspB gene, encoding a cold-shock protein. Seventeen of the deduced protein sequences of these ORFs displayed significant homology to known proteins in the data banks. One putative operon was identified, consisting of five ORFs, that is probably involved in the uptake and processing of copper. The location of cspB in this sequence does not confirm the genetic mapping data, indicating that the gene is closely linked to comK, which is located at 80 degrees on the B. subtilis chromosome.
Assuntos
Bacillus subtilis/genética , Cromossomos Bacterianos/genética , DNA Bacteriano/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Primers do DNA/genética , Genes Bacterianos , Ligação Genética , Glicerol/metabolismo , Dados de Sequência Molecular , Fases de Leitura Aberta , ÓperonRESUMO
The ATP-dependent deoxyribonuclease enzyme complex (AddAB) of Bacillus subtilis possesses two consensus ATP-binding sequences, located in the N-terminal region of both subunits. The highly conserved lysine residues in both consensus ATP-binding sequences were replaced by glycine, resulting in the mutant enzyme complexes AddAB-A-K36G (AddA*B) and AddAB-B-K14G (AddAB*). The mutation in subunit AddA reduced DNA repair and chromosomal transformation, and abolished bacteriophage PBS1-mediated transduction. This mutation also resulted in a complete loss of the ATP-dependent exonuclease and helicase activity. In contrast, the mutation in subunit AddB had only marginal effects. The recF and addAB genes are not required for transformation with plasmid DNA, but have overlapping activities in transformation with chromosomal DNA. By contrast to RecF, the AddAB enzyme is essential for PBS1-mediated transduction. However, recF has a more important function with respect to DNA repair than addAB.
