Type II myosin involved in cytokinesis in the fission yeast,Schizosaccharomyces pombe

✍ Scribed by May, Karen M. ;Watts, Felicity Z. ;Jones, Nic ;Hyams, Jeremy S.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 488 KB
• Volume: 38
• Category: Article
• ISSN: 0886-1544
• DOI: 10.1002/(sici)1097-0169(1997)38:4<385::aid-cm8>3.0.co;2-2

✦ Synopsis

We have cloned an unique gene encoding the heavy chain of a type II myosin in the fission yeast, Schizosaccharomyces pombe. The myo2 ϩ gene encodes a protein of 1526 amino acids with a predicted molecular weight of 177 kDa and containing consensus binding motifs for both essential and regulatory light chains. The S. pombe myo2 ϩ head domain is 45% identical to myosin IIs from Saccharomyces cerevisiae and Homo sapiens and 40% identical to Drosophila melanogaster. Structurally, myo2 ϩ most closely resembles budding yeast MYO1, the tails of both myosin IIs containing a number of proline residues that are predicted to substantially disrupt the ability of these myosins to form coiled coils. The myo2 ϩ gene is located on chromosome III, 8.3 map units from ade6 ϩ . Deletion of approximately 70% of the coding sequence of myo2 ϩ is lethal but myo2⌬ spores can acquire a suppressor mutation that allows them to form viable microcolonies consisting of filaments of branched cells with aberrant septa. Overexpression of myo2 ϩ results in the inhibition of cytokinesis; cells become elongated and multinucleate and fail to assemble a functional cytokinetic actin ring and are either aseptate or form aberrant septa. These results suggest that a contractile actinmyosin based cytokinetic mechanism appeared early in the evolution of eukaryotic cells and further emphasise the utility of fission yeast as a model organism in which to study the molecular and cellular basis of cytokinesis. Cell Motil.