Differential actin binding along the PEVK domain of skeletal muscle titin

J Cell Sci. 2004 Nov 15;117(Pt 24):5781-9. doi: 10.1242/jcs.01501. Epub 2004 Oct 26.

Abstract

Parts of the PEVK (Pro-Glu-Val-Lys) domain of the skeletal muscle isoform of the giant intrasarcomeric protein titin have been shown to bind F-actin. However, the mechanisms and physiological function of this are poorly understood. To test for actin binding along PEVK, we expressed contiguous N-terminal (PEVKI), middle (PEVKII), and C-terminal (PEVKIII) PEVK segments of the human soleus muscle isoform. We found a differential actin binding along PEVK in solid-state binding, cross-linking and in vitro motility assays. The order of apparent affinity is PEVKII>PEVKI>PEVKIII. To explore which sequence motifs convey the actin-binding property, we cloned and expressed PEVK fragments with different motif structure: PPAK, polyE-rich and pure polyE fragments. The polyE-containing fragments had a stronger apparent actin binding, suggesting that a local preponderance of polyE motifs conveys an enhanced local actin-binding property to PEVK. The actin binding of PEVK may serve as a viscous bumper mechanism that limits the velocity of unloaded muscle shortening towards short sarcomere lengths. Variations in the motif structure of PEVK might be a method of regulating the magnitude of the viscous drag.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / chemistry
  • Actins / metabolism*
  • Adenosine Triphosphatases / chemistry
  • Amino Acid Motifs
  • Animals
  • Calcium / chemistry
  • Cell Movement
  • Connectin
  • DNA, Complementary / metabolism
  • Dose-Response Relationship, Drug
  • Gene Library
  • Humans
  • Muscle Proteins / physiology*
  • Muscle, Skeletal / cytology*
  • Muscle, Skeletal / metabolism
  • Myofibrils / metabolism
  • Potassium Chloride / chemistry
  • Protein Binding
  • Protein Isoforms
  • Protein Kinases / physiology*
  • Protein Structure, Tertiary
  • Time Factors

Substances

  • Actins
  • Connectin
  • DNA, Complementary
  • Muscle Proteins
  • Protein Isoforms
  • TTN protein, human
  • Potassium Chloride
  • Protein Kinases
  • Adenosine Triphosphatases
  • Calcium