Identification and functional analysis of novel (p)ppGpp synthetase genes in Bacillus subtilis.
Bacterial alarmone (p)ppGpp, is a global regulator responsible for the stringent control. Two homologous (p)ppGpp synthetases, RelA and SpoT, have been identified and characterized in Escherichia coli, whereas Gram-positive bacteria such as Bacillus subtilis have been thought to possess only a single RelA-SpoT enzyme. We have now identified two genes, yjbM and ywaC, in B. subtilis that encode a novel type of alarmone synthetase. The predicted products of these genes are relatively small proteins ( approximately 25 kDa) that correspond to the (p)ppGpp synthetase domain of RelA-SpoT family members. A database survey revealed that genes homologous to yjbM and ywaC are conserved in certain bacteria belonging to Firmicutes or Actinobacteria phyla but not in other phyla such as Proteobacteria. We designated the proteins as small alarmone synthetases (SASs) to distinguish them from RelA-SpoT proteins. The (p)ppGpp synthetase function of YjbM and YwaC was confirmed by genetic complementation analysis and by in vitro assay of enzyme activity. Molecular genetic analysis also revealed that ywaC is induced by alkaline shock, resulting in the transient accumulation of ppGpp. The SAS proteins thus likely function in the biosynthesis of alarmone with a mode of action distinct from that of RelA-SpoT homologues.
Nanamiya
Hideaki
H
Cell-Free Science and Technology Research Center, Ehime University, Bunkyo-cho, Matsuyama 790-8577, Japan.
Kasai
Koji
K
Nozawa
Akira
A
Yun
Choong-Soo
CS
Narisawa
Takakuni
T
Murakami
Kana
K
Natori
Yousuke
Y
Kawamura
Fujio
F
Tozawa
Yuzuru
Y
D000595:Amino Acid Sequence; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D001412:Bacillus subtilis / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006159:Guanosine Tetraphosphate / Q000096:biosynthesis; D008025:Ligases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D016415:Sequence Alignment; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006159:Guanosine Tetraphosphate; C042715:argininehydroxamic acid; D001120:Arginine; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases