Functional consequences of truncating amino acid side chains located at a calmodulin-peptide interface.

Journal Article

To test the relevance of the calmodulin-peptide crystal structures to their respective calmodulin-enzyme interactions, amino acid side chains in calmodulin were altered at positions that interact with the calmodulin-binding peptide of smooth muscle myosin light chain kinase but not with the calmodulin kinase IIalpha peptide. Since shortening the side chains of Trp-800, Arg-812, and Leu-813 in smooth muscle myosin light chain kinase abrogated calmodulin-dependent activation (Bagchi, I. C., Huang, Q., and Means, A. R. (1992) J. Biol. Chem. 267, 3024-3029), substitutions were introduced at positions in calmodulin which contact residues corresponding to Arg-812 and Leu-813 in the smooth muscle myosin light chain kinase peptide. Assays of smooth muscle myosin light chain kinase with the calmodulin mutants M51A,V55A, L32A,M51A,V55A, and L32A,M51A,V55A,F68L, M71A exhibited 60%, 25%, and less than 1% of maximal activity respectively, whereas the mutants fully activated calmodulin kinase IIalpha. Alanine substitutions at positions on the smooth muscle myosin light chain kinase peptide, corresponding to Trp-800 and Arg-812 in the enzyme, produced an 8-fold increase in the enzyme inhibition constant in contrast with the abolition of calmodulin binding by similar mutations in the parent enzyme.

Full Text

Duke Authors

Cited Authors

  • Chin, D; Sloan, DJ; Quiocho, FA; Means, AR

Published Date

  • February 28, 1997

Published In

Volume / Issue

  • 272 / 9

Start / End Page

  • 5510 - 5513

PubMed ID

  • 9038155

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng

Conference Location

  • United States