title: Tyrosine phosphorylation of a membrane protein from Pseudomonas solanacearum.
abstract: We have investigated a tyrosine kinase activity from Pseudomonas solanacearum, an economically important plant pathogen. In vitro incubation of membrane fractions with [gamma-32P]ATP and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed an 85-kDa phosphoprotein. Phosphorylation of this protein on tyrosine residues was demonstrated by phosphoamino acid analysis of base hydrolysis products and by immunoanalysis of Western blots (immunoblots) with antiphosphotyrosine monoclonal antibody. In vitro incubation of membranes with ATP was not required for recognition by the antibody, indicating that the 85-kDa protein is phosphorylated in vivo. These results demonstrate that membranes from P. solanacearum exhibit a tyrosine kinase activity toward an endogenous membrane protein. This bacterium provides an opportunity to study the structure and function of a prokaryotic tyrosine kinase.
authors.affiliation: Department of Plant Pathology, University of Wisconsin, Madison 53706.
authors.forename: M
authors.initials: M
authors.lastname: Atkinson
authors.forename: C
authors.initials: C
authors.lastname: Allen
authors.forename: L
authors.initials: L
authors.lastname: Sequeira
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000302:isolation & purification; D001345:Autoradiography; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D008565:Membrane Proteins; D010750:Phosphoproteins; D010761:Phosphorus Radioisotopes; D000255:Adenosine Triphosphate; D011505:Protein-Tyrosine Kinases