cycling of etk and etp phosphorylation states is involved in formation of group 4 capsule by escherichia coli自行车etk和etp磷酸化状态参与形成的4组由大肠杆菌胶囊.pdf

Cycling of Etk and Etp Phosphorylation States Is Involved in Formation of Group 4 Capsule by Escherichia coli 1 1 1 2 2 Chen Nadler , Simi Koby , Adi Peleg , Austin C. Johnson , Krishna C. Suddala , 2¤ 3 3 1 Karthik Sathiyamoorthy , Bennett E. Smith , Mark A. Saper *, Ilan Rosenshine * 1 Department of Microbiology and Molecular Genetics, The Hebrew University-Hadassah Medical School, Jerusalem, Israel, 2 Program in Biophysics, University of Michigan, Ann Arbor, Michigan, United States of America, 3 Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America Abstract Capsules frequently play a key role in bacterial interactions with their environment. Escherichia coli capsules were categorized as groups 1 through 4, each produced by a distinct mechanism. Etk and Etp are members of protein families required for the production of group 1 and group 4 capsules. These members function as a protein tyrosine kinase and protein tyrosine phosphatase, respectively. We show that Etp dephosphorylates Etk in vivo, and mutations rendering Etk or Etp catalytically inactive result in loss of group 4 capsule production, supporting the notion that cyclic phosphorylation and dephosphorylation of Etk is required for capsule formation. Notably, Etp also becomes tyrosine phosphorylated in vivo and catalyzes rapid auto-dephosphorylation. Further analysis identified Tyr121 as the phosphorylated residue of Etp. Etp containing Phe, Glu or Ala in place of Tyr121 retained phosphatase activity and catalyzed dephosphorylation of Etp and Etk.