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  • The EMBO Journal (2003) 22, 4709 - 4718
  • doi:10.1093/emboj/cdg458

Transmembrane modulator-dependent bacterial tyrosine kinase activates UDP-glucose dehydrogenases

Ivan Mijakovic1, Sandrine Poncet1, Grégory Boël1, Alain Mazé1, Sylvie Gillet2, Emmanuel Jamet1, Paulette Decottignies2, Christophe Grangeasse3, Patricia Doublet3, Pierre Le Maréchal2 and Josef Deutscher1

  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

Correspondence to:

Josef Deutscher, E-mail: jdeu@grignon.inra.fr

Received 5 December 2002; Accepted 24 July 2003; Revised 23 July 2003

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.

  • Keywords:

    • P-tyrosine phosphatase,
    • polysaccharide synthesis,
    • protein phosphorylation,
    • tyrosine-kinase,
    • UDP-glucose dehydrogenase