The GTPase, CpgA(YloQ), a putative translation factor, is implicated in morphogenesis in Bacillus subtilis.
YloQ, from Bacillus subtilis, was identified previously as an essential nucleotide-binding protein of unknown function. YloQ was successfully over-expressed in Escherichia coli in soluble form. The purified protein displayed a low GTPase activity similar to that of other small bacterial GTPases such as Bex/Era. Based on the demonstrated GTPase activity and the unusual order of the yloQ G motifs, we now designate this protein as CpgA (circularly permuted GTPase). An unexpected property of this low abundance GTPase was the demonstration, using gel filtration and ultracentrifugation analysis, that the protein formed stable dimers, dependent upon the concentration of YloQ(CpgA), but independent of GTP. In order to investigate function, cpgA was placed under the control of the pspac promotor in the B. subtilis chromosome. When grown in E or Spizizen medium in the absence of IPTG, the rate of growth was significantly reduced. A large proportion of the cells exhibited a markedly perturbed morphology, with the formation of swollen, bent or 'curly' shapes. To confirm that this was specifically due to depleted CpgA a plasmid-borne cpgA under pxyl control was introduced. This restored normal cell shape and growth rate, even in the absence of IPTG, provided xylose was present. The crystal structure of CpgA(YloQ) suggests a role as a translation initiation factor and we discuss the possibility that CpgA is involved in the translation of a subset of proteins, including some required for shape maintenance.
Institut de Génétique et Microbiologie, Université Paris-Sud, UMR CNRS 8621, Bâtiment 409, 91405 Orsay Cedex, France.
Lionel
L
Cladière
Kassem
K
Hamze
Edwige
E
Madec
Vladimir M
VM
Levdikov
Anthony J
AJ
Wilkinson
I Barry
IB
Holland
Simone J
SJ
Séror
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism; D017124:Conserved Sequence; D019281:Dimerization; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006160:Guanosine Triphosphate / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D005810:Multigene Family; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D039662:Prokaryotic Initiation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D039662:Prokaryotic Initiation Factors; D007544:Isopropyl Thiogalactoside; D006160:Guanosine Triphosphate; D010749:Phosphoprotein Phosphatases; D020558:GTP Phosphohydrolases