The effect of Srb, a homologue of the mammalian SRP receptor alpha-subunit, on Bacillus subtilis growth and protein translocation.
To determine the signal recognition particle (SRP)-SRP receptor (Srb) system in Bacillus subtilis (Bs), we cloned the Bs srb gene, which encodes a homologue of the mammalian SRP receptor alpha-subunit [Oguro et al., DNA Res. 2 (1995) 95-100]. We sequenced a 6098-bp DNA containing srb and analyzed the gene organization. Primer extension experiment and Northern blot analysis revealed that srb constitutes an operon with two additional ORFs. A database search of known proteins revealed that one encodes a homologue of Escherichia coli RNase III [36.0% identical amino acids (aa)] and the other encodes a homologue of yeast Smc1 (26.6% identical aa). We then constructed a Bs mutant in which srb expression was induced by IPTG. The depletion of Srb caused a defect in the cell growth and the cells became filamentous and twisted. Furthermore, pulse-chase experiments using this mutant revealed that the 17% of the beta-lactamase precursor accumulated in the cell after a 4-min chase in the absence of IPTG, although almost all of the precursors were converted into the mature from after a 1-min chase in the presence of IPTG.
Oguro
A
A
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Kakeshita
H
H
Takamatsu
H
H
Nakamura
K
K
Yamane
K
K
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000254:growth & development* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D001692:Biological Transport; D004269:DNA, Bacterial; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C096754:srb protein, Bacillus subtilis