Regulatory Mechanism of Dictyostelium Myosin Light Chain Kinase A

Hiroshi Tokumitsu, Naoya Hatano, Hiroyuki Inuzuka, Yumi Ishikawa, Taro Q P Uyeda, Janet L. Smith, Ryoji Kobayashi

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

In this study, we examined the activation mechanism of Dictyostelium myosin light chain kinase A (MLCK-A) using constitutively active Ca 2+/calmodulin-dependent protein kinase kinase as a surrogate MLCK-A kinase. MLCK-A was phosphorylated at Thr166 by constitutively active Ca2+/calmodulin-dependent protein kinase kinase, resulting in an ∼140-fold increase in catalytic activity, using intact Dictyostelium myosin II. Recombinant Dictyostelium myosin II regulatory light chain and Kemptamide were also readily phosphorylated by activated MLCK-A. Mass spectrometry analysis revealed that MLCK-A expressed by Escherichia coli was autophosphorylated at Thr289 and that, subsequent to Thr 166 phosphorylation, MLCK-A also underwent a slow rate of autophosphorylation at multiple Ser residues. Using site-directed mutagenesis, we show that autophosphorylation at Thr289 is required for efficient phosphorylation and activation by an upstream kinase. By performing enzyme kinetics analysis on a series of MLCK-A truncation mutants, we found that residues 283-288 function as an autoinhibitory domain and that autoinhibition is fully relieved by Thr166 phosphorylation. Simple removal of this region resulted in a significant increase in the kcat of MLCK-A; however, it did not generate maximum enzymatic activity. Together with the results of our kinetic analysis of the enzymes, these findings demonstrate that Thr166 phosphorylation of MLCK-A by an upstream kinase subsequent to autophosphorylation at Thr289 results in generation of maximum MLCK-A activity through both release of an autoinhibitory domain from its catalytic core and a further increase (15-19-fold) in the kcat of the enzyme.

Original languageEnglish
Pages (from-to)42-50
Number of pages9
JournalJournal of Biological Chemistry
Volume279
Issue number1
DOIs
Publication statusPublished - Jan 2 2004
Externally publishedYes

Fingerprint

Myosin-Light-Chain Kinase
Dictyostelium
Phosphorylation
Phosphotransferases
Myosin Type II
Calcium-Calmodulin-Dependent Protein Kinases
Surrogate Immunoglobulin Light Chains
Enzymes
Chemical activation
Enzyme kinetics
Myosin Light Chains
Mutagenesis
Site-Directed Mutagenesis
Escherichia coli
Mass spectrometry
Catalyst activity
Mass Spectrometry
Catalytic Domain

ASJC Scopus subject areas

  • Biochemistry

Cite this

Regulatory Mechanism of Dictyostelium Myosin Light Chain Kinase A. / Tokumitsu, Hiroshi; Hatano, Naoya; Inuzuka, Hiroyuki; Ishikawa, Yumi; Uyeda, Taro Q P; Smith, Janet L.; Kobayashi, Ryoji.

In: Journal of Biological Chemistry, Vol. 279, No. 1, 02.01.2004, p. 42-50.

Research output: Contribution to journalArticle

Tokumitsu, Hiroshi ; Hatano, Naoya ; Inuzuka, Hiroyuki ; Ishikawa, Yumi ; Uyeda, Taro Q P ; Smith, Janet L. ; Kobayashi, Ryoji. / Regulatory Mechanism of Dictyostelium Myosin Light Chain Kinase A. In: Journal of Biological Chemistry. 2004 ; Vol. 279, No. 1. pp. 42-50.
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