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| Subject Categories: Signal Transduction | Microbiology & Pathogens |
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| The EMBO Journal
(2003) 22, 4709–4718, doi:10.1093/emboj/cdg458 |
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| Transmembrane modulator-dependent bacterial tyrosine kinase activates UDP-glucose dehydrogenases |
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| Ivan Mijakovic1, Sandrine Poncet1, Grégory Boël1, Alain Mazé1, Sylvie Gillet2, Emmanuel Jamet1, Paulette Decottignies2, Christophe Grangeasse3, Patricia Doublet3, Pierre Le Maréchal2 and Josef Deutscher1 |
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1 Laboratoire de Génétique des Microorganismes, CNRS/INRA/INA-PG UMR2585, 78850 Thiverval-Grignon, France 2 Institut de Biochimie et Biophysique Moléculaire et Cellulaire, CNRS UMR8619, Université de Paris-Sud, 91405 Orsay, France 3 Institut de Biologie et Chimie des Protéines, CNRS/UCB Lyon I, UMR5086, 69367 Lyon, France To whom correspondence should be addressed Josef Deutscher, jdeu@grignon.inra.fr Received 5 December 2002; Revised 23 July 2003; Accepted 24 July 2003. |
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| Abstract |
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| Protein-tyrosine kinases regulating bacterial exopolysaccharide synthesis autophosphorylate on tyrosines located in a conserved C-terminal region. So far no other substrates have been identified for these kinases. Here we demonstrate that Bacillus subtilis YwqD not only autophosphorylates at Tyr-228, but that it also phosphorylates the two UDP-glucose dehydrogenases (UDP-glucose DHs) YwqF and TuaD at a tyrosine residue. However, phosphorylation of YwqF and TuaD occurs only in the presence of the transmembrane protein YwqC. The presumed intracellular C-terminal part of YwqC (last 50 amino acids) seems to interact with the tyrosine-kinase and to allow YwqD-catalysed phosphorylation of the two UDP-glucose DHs, which are key enzymes for the synthesis of acidic polysaccharides. However, only when phosphorylated by YwqD do the two enzymes exhibit detectable UDP-glucose DH activity. Dephosphorylation of P-Tyr-YwqF and P-Tyr-TuaD by the P-Tyr-protein phosphatase YwqE switched off their UDP-glucose DH activity. YwqE, which is encoded by the fourth gene of the B.subtilis ywqCDEF operon, also dephosphorylates P-Tyr-YwqD. |
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| Keywords: P-tyrosine phosphatase, polysaccharide synthesis, protein phosphorylation, tyrosine-kinase, UDP-glucose dehydrogenase |
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