Type II myosin heavy chain encoded by the myo2 gene composes the contractile ring during cytokinesis in Schizosaccharomyces pombe

Chikako Kitayama, Asako Sugimoto, Masayuki Yamamoto

Research output: Contribution to journalArticlepeer-review

174 Citations (Scopus)

Abstract

We cloned the myo2 gene of Schizosaccharomyces pombe, which encodes a type II myosin heavy chain, by virtue of its ability to promote diploidization in fission yeast cells. The myo2 gene encodes 1,526 amino acids in a single open reading frame. Myo2p shows homology to the head domains and the coiled-coil tail of the conventional type II myosin heavy chain and carries putative binding sites for ATP and actin. It also carries the IQ motif, which is a presumed binding site for the myosin light chain. However, Myo2p apparently carries only one IQ motif, while its counterparts in other species have two. There are nine proline residues, which should break α-helix, in the COOH-terminal coiled-coil region of Myo2p. Thus, Myo2p is rather unusual as a type II myosin heavy chain. Disruption of myo2 inhibited cell proliferation, myo2Δ cells showed normal punctate distribution of interphase actin, but they produced irregular actin rings and septa and were impaired in cell separation. Overproduction of Myo2p was also lethal, apparently blocking actin relocation. Nuclear division proceeded without actin ring formation and cytokinesis in cells overexpressing Myo2p, giving rise to multinucleated cells with dumbbell morphology. Analysis using tagged Myo2p revealed that Myo2p colocalizes with actin in the contractile ring, suggesting that Myo2p is a component of the ring and responsible for its contraction. Furthermore, genetic evidence suggested that the acto- myosin system may interact with the Ras pathway, which regulates mating and the maintenance of cell morphology in S. pombe.

Original languageEnglish
Pages (from-to)1309-1319
Number of pages11
JournalJournal of Cell Biology
Volume137
Issue number6
DOIs
Publication statusPublished - 1997 Jun 16
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

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