Autophosphorylation of the Escherichia coli Protein Kinase Wzc Regulates Tyrosine Phosphorylation of Ugd, a UDP-glucose Dehydrogenase

• Published in: The Journal of biological chemistry Vol. 278; no. 41; pp. 39323 - 39329
• Main Authors: Grangeasse, Christophe, Obadia, Brice, Mijakovic, Ivan, Deutscher, Josef, Cozzone, Alain J., Doublet, Patricia
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10-10-2003; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Bacillus subtilis - enzymology; Bacillus subtilis - genetics; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biochemistry, Molecular Biology; Catalytic Domain; Enzyme Activation; Escherichia coli - enzymology; Escherichia coli - genetics; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Genes, Bacterial; Gram-Negative Bacteria - enzymology; Gram-Negative Bacteria - genetics; Gram-Positive Bacteria - enzymology; Gram-Positive Bacteria - genetics; Life Sciences; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Models, Biological; Molecular Sequence Data; Phosphorylation; Protein-Tyrosine Kinases - chemistry; Protein-Tyrosine Kinases - genetics; Protein-Tyrosine Kinases - metabolism; Sequence Homology, Amino Acid; Substrate Specificity; Tyrosine - chemistry; Uridine Diphosphate Glucose Dehydrogenase - chemistry; Uridine Diphosphate Glucose Dehydrogenase - genetics; Uridine Diphosphate Glucose Dehydrogenase - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M305134200

Autophosphorylation of protein-tyrosine kinases (PTKs) involved in exopolysaccharide and capsular polysaccharide biosynthesis and transport has been observed in a number of Gram-negative and Gram-positive bacteria. However, besides their own phosphorylation, little is known about other substrates targeted by these protein-modifying enzymes. Here, we present evidence that the protein-tyrosine kinase Wzc of Escherichia coli is able to phosphorylate an endogenous enzyme, UDP-glucose dehydrogenase (Ugd), which participates in the synthesis of the exopolysaccharide colanic acid. The process of phosphorylation of Ugd by Wzc was shown to be stimulated by previous autophosphorylation of Wzc on tyrosine 569. The phosphorylation of Ugd was demonstrated to actually occur on tyrosine and result in a significant increase of its dehydrogenase activity. In addition, the phosphotyrosine-protein phosphatase Wzb, which is known to effectively dephosphorylate Wzc, exhibited only a low effect, if any, on the dephosphorylation of Ugd. These data were related to the recent observation that two other UDP-glucose dehydrogenases have been also shown to be phosphorylated by a PTK in the Gram-positive bacterium Bacillus subtilis. Comparative analysis of the activities of PTKs from Gram-negative and Gram-positive bacteria showed that they are regulated by different mechanisms that involve, respectively, either the autophosphorylation of kinases or their interaction with a membrane protein activator.