Absalon Cédric, Obuchowski Michal, Madec Edwige, Delattre Delphine, Holland I Barry, Séror Simone J
Université Paris-Sud 11, CNRS UMR 8621, Institut de Génétique et Microbiologie, 91405 Orsay, France.
Medical University of Gdansk, Debinki 1, 80-211, Department of Medical Biotechnology, Intercollegiate Faculty of Biotechnology, Gdansk, Poland.
Microbiology (Reading). 2009 Mar;155(Pt 3):932-943. doi: 10.1099/mic.0.022475-0.
The conserved prpC, prkC, cpgA locus in Bacillus subtilis encodes respectively a Ser/Thr phosphatase, the cognate sensor kinase (containing an external PASTA domain suggested to bind peptidoglycan precursors) and CpgA, a small ribosome-associated GTPase that we have shown previously is implicated in shape determination and peptidoglycan deposition. In this study, in a search for targets of PrkC and PrpC, we showed that, in vitro, CpgA itself is phosphorylated on serine and threonine, and another GTPase, the translation factor EF-Tu, is also phosphorylated by the kinase on the conserved T384 residue. Both substrates are dephosphorylated by PrpC in vitro. In addition, we identified YezB, a 10.3 kDa polypeptide, and a component of the stressosome, as a substrate for both enzymes in vitro and apparently in vivo. We propose that the PrpC/PrkC/CpgA system constitutes an important element of a regulatory network involved in the coordination of cell wall expansion and growth in B. subtilis.
枯草芽孢杆菌中保守的prpC、prkC、cpgA基因座分别编码一种丝氨酸/苏氨酸磷酸酶、同源传感器激酶（含有一个推测可结合肽聚糖前体的外部PASTA结构域）和CpgA，CpgA是一种与核糖体相关的小GTP酶，我们之前已经证明它与细胞形态决定和肽聚糖沉积有关。在本研究中，为了寻找PrkC和PrpC的作用靶点，我们发现，在体外，CpgA自身的丝氨酸和苏氨酸会发生磷酸化，另一种GTP酶，即翻译因子EF-Tu，也会在保守的T384残基上被该激酶磷酸化。在体外，这两种底物都会被PrpC去磷酸化。此外，我们鉴定出一种10.3 kDa的多肽YezB，它是应激小体的一个组分，在体外以及显然在体内都是这两种酶的底物。我们提出，PrpC/PrkC/CpgA系统构成了一个调控网络的重要元件，该网络参与枯草芽孢杆菌细胞壁扩张与生长的协调。
