QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 20, Issue 1, 358-367, January 1, 2009

This Article Full Text Full Text (PDF) All Versions of this Article: E08-07-0776v1 20/1/358    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Noguchi, T. Articles by Miller, K. G. Search for Related Content PubMed PubMed Citation Articles by Noguchi, T. Articles by Miller, K. G.

Coiled-Coil–Mediated Dimerization Is Not Required for Myosin VI to Stabilize Actin during Spermatid Individualization in Drosophila melanogaster

Tatsuhiko Noguchi^*,, Deborah J. Frank^,, Mamiko Isaji, and Kathryn G. Miller

*Center for Developmental Biology, Riken, Kobe 650-0047, Japan; and Department of Biology, Washington University, St. Louis, MO 63130

Submitted July 29, 2008; Revised October 14, 2008; Accepted November 3, 2008
Monitoring Editor: Thomas D. Pollard

Myosin VI is a pointed-end–directed actin motor that is thought to function as both a transporter of cargoes and an anchor, capable of binding cellular components to actin for long periods. Dimerization via a predicted coiled coil was hypothesized to regulate activity and motor properties. However, the importance of the coiled-coil sequence has not been tested in vivo. We used myosin VI's well-defined role in actin stabilization during Drosophila spermatid individualization to test the importance in vivo of the predicted coiled coil. If myosin VI functions as a dimer, a forced dimer should fully rescue myosin VI loss of function defects, including actin stabilization, actin cone movement, and cytoplasmic exclusion by the cones. Conversely, a molecule lacking the coiled coil should not rescue at all. Surprisingly, neither prediction was correct, because each rescued partially and the molecule lacking the coiled coil functioned better than the forced dimer. In extracts, no cross-linking into higher molecular weight forms indicative of dimerization was observed. In addition, a sequence required for altering nucleotide kinetics to make myosin VI dimers processive is not required for myosin VI's actin stabilization function. We conclude that myosin VI does not need to dimerize via the predicted coiled coil to stabilize actin in vivo.

These authors contributed equally to this work.

Address correspondence to: Kathryn G. Miller (miller{at}biology.wustl.edu).