tyrosine phosphorylation of the udp-glucose dehydrogenase of escherichia coli is at the crossroads of colanic acid synthesis and polymyxin resistance酪氨酸磷酸化udp-glucose脱氢酶的大肠杆菌的十字路口colanic酸合成和多粘菌素抵抗.pdfVIP

Tyrosine Phosphorylation of the UDP-Glucose Dehydrogenase of Escherichia coli Is at the Crossroads of Colanic Acid Synthesis and Polymyxin Resistance 1. 1. 1 2 1 Soline Lacour , Emmanuelle Bechet , Alain J. Cozzone , Ivan Mijakovic , Christophe Grangeasse * ´ 1 Institut de Biologie et Chimie des Proteines, University of Lyon, CNRS, Lyon, France, 2 Center for Microbial Biotechnology, BioCentrum, Technical University of Denmark, Lyngby, Denmark Abstract Background: In recent years, an idiosyncratic new class of bacterial enzymes, named BY-kinases, has been shown to catalyze protein-tyrosine phosphorylation. These enzymes share no structural and functional similarities with their eukaryotic counterparts and, to date, only few substrates of BY-kinases have been characterized. BY-kinases have been shown to participate in various physiological processes. Nevertheless, we are at a very early stage of defining their importance in the bacterial cell. In Escherichia coli, two BY-kinases, Wzc and Etk, have been characterized biochemically. Wzc has been shown to phosphorylate the UDP-glucose dehydrogenase Ugd in vitro. Not only is Ugd involved in the biosynthesis of extracellular polysaccharides, but also in the production of UDP-4-amino-4-deoxy-L-arabinose, a compound that renders E. coli resistant to cationic antimicrobial peptides. Methodology/Principal Findings: Here, we studied the role of Ugd phosphorylation. We first confirmed in vivo the phosphorylation of Ugd by Wzc and we demonstrated that Ugd is also phosphorylated by Etk, the other BY-kinase identified in E. coli. Tyrosin