Contraction of reconstituted Dictyostelium cytoskeletons: An apparent role for higher order associations among myosin filaments

Carmen Aguado‐Velasco, Edward R. Kuczmarski*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

A large number of cellular functions require assembly of actin and myosin and coordinated interactions between the resulting filaments. To better understand the structure and function of one such contractile assembly, we have begun fractionation and reconstitution studies of Dictyostelium cytoskeletons. Isolated cytoskeletons rapidly contracted when mixed with Mg‐ATP, and myosin II was essential for this since myosin‐depleted (stripped) cytoskeletons failed to contract. Dictyostelium, Acanthamoeba, or skeletal muscle myosins bound to stripped cytoskeletons with equal efficiency, and the Mg‐ATPase of all three myosins was stimulated by the cytoskeleton‐associated actin. Near neutral pH, however, only the homologous system reconstituted with Dictyostelium myosin contracted, despite the fact that under the same conditions all three myosins bound to myosin‐depleted (ghost) muscle myofibrils and restored contractility. Individual Dictyostelium myosin thick filaments have a strong tendency to aggregate and associate end‐to‐end, and this may be important for functional contraction of cytoskeletons. This suggestion is supported by the observation that under conditions where individual Acanthamoeba myosin filaments aggregated, reconstituted cytoskeletons contracted. None of the solution conditions tested caused rabbit muscle myosin filaments to aggregate or to contract cytoskeletons. Thus higher order associations among individual myosin filaments may be essential for some types of cell motility. © 1993 Wiley‐Liss, Inc.

Original languageEnglish (US)
Pages (from-to)103-114
Number of pages12
JournalCell Motility and the Cytoskeleton
Volume26
Issue number2
DOIs
StatePublished - 1993

Keywords

  • actin meshwork
  • cytoskeletal contraction
  • stopped flow
  • thick filament structure

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology

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