Transmembrane modulator-dependent bacterial tyrosine kinase activates UDP-glucose dehydrogenases.
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.
Mijakovic
Ivan
I
Laboratoire de Génétique des Microorganismes, CNRS/INRA/INA-PG UMR2585, 78850 Thiverval-Grignon, France.
Poncet
Sandrine
S
Boël
Grégory
G
Mazé
Alain
A
Gillet
Sylvie
S
Jamet
Emmanuel
E
Decottignies
Paulette
P
Grangeasse
Christophe
C
Doublet
Patricia
P
Le Maréchal
Pierre
P
Deutscher
Josef
J
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology*; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D004789:Enzyme Activation; D007700:Kinetics; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000737:chemistry / Q000378:metabolism*
D017931:DNA Primers; D011994:Recombinant Proteins; D010769:Phosphothreonine; D010768:Phosphoserine; D019000:Phosphotyrosine; D014533:Uridine Diphosphate Glucose Dehydrogenase; D011505:Protein-Tyrosine Kinases