title: A kinetic approach towards understanding substrate interactions and the catalytic mechanism of the serine/threonine protein kinase ERK2: identifying a potential regulatory role for divalent magnesium.
abstract: We are interested in the mechanism and regulation of the extracellular regulated protein kinases, ERK1 and ERK2, due to their key roles in cellular signal transduction and disease. Both enzymes phosphorylate a large number of structurally disparate proteins upon activation by phorbol esters, serum and growth factors, and are activated through a protein kinase cascade, termed the mitogen activated protein kinase (MAPK) pathway. ERK2 catalyses the transfer of the gamma-phosphate of adenosine triphosphate to serine or threonine residues found in Ser-Pro or Thr-Pro motifs on proteins. Its catalytic mechanism is intriguing, because it appears to predominantly rely on interactions outside of the active site cleft to specify a substrate. To study ERK2, we developed a recombinant protein called EtsDelta138, which comprises residues 1-138 of the transcription factor Ets-1, an excellent substrate of ERK2. Here we review several steady-state kinetic experiments that reveal details of the ERK2 mechanism and a hitherto unknown process of ERK2 activation by free magnesium. The physiological relevance of this mechanism is discussed.
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Waas
authors.forename: Mark A
authors.initials: MA
authors.lastname: Rainey
authors.forename: Anna E
authors.initials: AE
authors.lastname: Szafranska
authors.forename: Kari
authors.initials: K
authors.lastname: Cox
authors.forename: Kevin N
authors.initials: KN
authors.lastname: Dalby
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D002413:Cations, Divalent / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D050783:Proto-Oncogene Proteins c-ets; D015398:Signal Transduction; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; C494041:ETS1 protein, human; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D014157:Transcription Factors; D000255:Adenosine Triphosphate; D019950:Mitogen-Activated Protein Kinase 1; D008274:Magnesium