title: Phosphorylation of CpgA protein enhances both its GTPase activity and its affinity for ribosome and is crucial for Bacillus subtilis growth and morphology.
abstract: In Bacillus subtilis, the ribosome-associated GTPase CpgA is crucial for growth and proper morphology and was shown to be phosphorylated in vitro by the Ser/Thr protein kinase PrkC. To further understand the function of the Escherichia coli RsgA ortholog, CpgA, we first demonstrated that its GTPase activity is stimulated by its association with the 30 S ribosomal subunit. Then the role of CpgA phosphorylation was analyzed. A single phosphorylated residue, threonine 166, was identified by mass spectrometry. Phosphoablative replacement of this residue in CpgA induces a decrease of both its affinity for the 30 S ribosomal subunit and its GTPase activity, whereas a phosphomimetic replacement has opposite effects. Furthermore, cells expressing a nonphosphorylatable CpgA protein present the morphological and growth defects similar to those of a cpgA-deleted strain. Altogether, our results suggest that CpgA phosphorylation on Thr-166 could modulate its ribosome-induced GTPase activity. Given the role of PrkC in B. subtilis spore germination, we propose that CpgA phosphorylation is a key regulatory process that is essential for B. subtilis development.
authors.affiliation: Laboratoire de Chimie Bactérienne, FR 3479, CNRS, Aix-Marseille Université, 13402 Marseille Cedex 20, France. fpompeo@ifr88.cnrs-mrs.fr
authors.forename: Frédérique
authors.initials: F
authors.lastname: Pompeo
authors.forename: Céline
authors.initials: C
authors.lastname: Freton
authors.forename: Catherine
authors.initials: C
authors.lastname: Wicker-Planquart
authors.forename: Christophe
authors.initials: C
authors.lastname: Grangeasse
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Jault
authors.forename: Anne
authors.initials: A
authors.lastname: Galinier
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D054680:Ribosome Subunits, Small, Bacterial / Q000235:genetics / Q000378:metabolism*; D013171:Spores, Bacterial / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D020558:GTP Phosphohydrolases