Signaling pathways regulating Dictyostelium myosin II

J Muscle Res Cell Motil. 2002;23(7-8):703-18. doi: 10.1023/a:1024467426244.

Abstract

Dictyostelium myosin II is a conventional, two-headed myosin that consists of two copies each of a myosin heavy chain (MHC), an essential light chain (ELC) and a regulatory light chain (RLC). The MHC is comprised of an amino-terminal motor domain, a neck region that binds the RLC and ELC and a carboxyl-terminal alpha-helical coiled-coil tail. Electrostatic interactions between the tail domains mediate the self-assembly of myosin II into bipolar filaments that are capable of interacting with actin filaments to generate a contractile force. In this review we discuss the regulation of Dictyostelium myosin II by a myosin light chain kinase (MLCK-A) that phosphorylates the RLC and increases motor activity and by MHC kinases (MHCKs) that phosphorylate the tail and prevent filament assembly. Dictyostelium may express as many as four MHCKs (MHCK A-D) consisting of an atypical alpha-kinase catalytic domain and a carboxyl-terminal WD repeat domain that targets myosin II filaments. A previously reported MHCK, termed MHC-PKC, now seems more likely to be a diacylglycerol kinase (DgkA). The relationship of the MHCKs to the larger family of alpha-kinases is discussed and key features of the structure of the alpha-kinase catalytic domain are reviewed. Potential upstream regulators of myosin II are described, including DgkA, cGMP, cAMP and PAKa, a target for Rac GTPases. Recent results point to a complex network of signaling pathways responsible for controling the activity and localization of myosin II in the cell.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Calcium-Calmodulin-Dependent Protein Kinases / chemistry
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Dictyostelium / genetics
  • Dictyostelium / metabolism
  • Dictyostelium / physiology*
  • Models, Molecular
  • Myosin Light Chains / chemistry
  • Myosin Light Chains / metabolism
  • Myosin Type II / chemistry
  • Myosin Type II / genetics*
  • Myosin Type II / metabolism
  • Protein Conformation
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism
  • Signal Transduction / physiology

Substances

  • Myosin Light Chains
  • Protozoan Proteins
  • Calcium-Calmodulin-Dependent Protein Kinases
  • myosin-heavy-chain kinase
  • Myosin Type II