Among the protein kinases, an absolutely conserved lysine in subdomain II is required for high catalytic activity. This lysine is known to interact with the substrate ATP, but otherwise its role is not well understood. We have used biochemical and structural methods to investigate the function of this lysine (K52) in phosphoryl transfer reactions catalyzed by the MAP kinase ERK2 ...
Among the protein kinases, an absolutely conserved lysine in subdomain II is required for high catalytic activity. This lysine is known to interact with the substrate ATP, but otherwise its role is not well understood. We have used biochemical and structural methods to investigate the function of this lysine (K52) in phosphoryl transfer reactions catalyzed by the MAP kinase ERK2. The kinetic properties of activated wild-type ERK2 and K52 mutants were examined using the oncoprotein TAL2, myelin basic protein, and a designed synthetic peptide as substrates. The catalytic activities of K52R and K52A ERK2 were lower than that of wild-type ERK2, primarily as a consequence of reductions in kcat. Further, there was little difference in Km for ATP, but the Km,app for peptide substrate was higher for the K52 mutants. The three-dimensional structure of unphosphorylated K52R ERK2 in the absence and presence of bound ATP was determined and compared with the structure of unphosphorylated wild-type ERK2. ATP adopted a well-defined but distinct binding mode in K52R ERK2 compared to the binding mode in the wild-type enzyme. The structural and kinetic data show that mutation of K52 created a nonproductive binding mode for ATP and suggest that K52 is essential for orienting ATP for catalysis.
Related Citations:
Activity of the Map Kinase Erk2 is Controlled by a Flexible Surface Loop Zhang, J., Zhang, F., Ebert, D., Cobb, M.H., Goldsmith, E.J. (1995) Structure 3: 299
Atomic Structure of the Map Kinase Erk2 at 2.3 A Resolution Zhang, F., Strand, A., Robbins, D., Cobb, M.H., Goldsmith, E.J. (1994) Nature 367: 704
Crystallization and Preliminary X-Ray Studies of Extracellular Signal-Regulated Kinase-2/Map Kinase with an Incorporated His-Tag Zhang, F., Robbins, D.J., Cobb, M.H., Goldsmith, E.J. (1993) J Mol Biol 233: 550
Organizational Affiliation:
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
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