title: The yeast kinesin-related protein Smy1p exerts its effects on the class V myosin Myo2p via a physical interaction.
abstract: We have discovered evidence for a physical interaction between a class V myosin, Myo2p, and a kinesin-related protein, Smy1p, in budding yeast. These proteins had previously been linked by genetic and colocalization studies, but we had been unable to determine the nature of their association. We now show by two-hybrid analysis that a 69-amino acid region of the Smy1p tail interacts with the globular portion of the Myo2p tail. Deletion of this myosin-binding region of Smy1p eliminates its ability to colocalize with Myo2p and to overcome the myo2-66 mutant defects, suggesting that the interaction is necessary for these functions. Further insights about the Smy1p-Myo2p interaction have come from studies of a new mutant allele, myo2-2, which causes a loss of Myo2p localization. We report that Smy1p localization is also lost in the myo2-2 mutant, demonstrating that Smy1p localization is dependent on Myo2p. We also found that overexpression of Smy1p partially restores myo2-2p localization in a myosin-binding region-dependent manner. Thus, overexpression of Smy1p can overcome defects in both the head and tail domains of Myo2p (caused by the myo2-66 and myo2-2 alleles, respectively). We propose that Smy1p enhances some aspect of Myo2p function, perhaps delivery or docking of vesicles at the bud tip.
authors.affiliation: Department of Anatomy and Cell Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0616, USA. karen.beningo@umassmed.edu
authors.forename: K A
authors.initials: KA
authors.lastname: Beningo
authors.forename: S H
authors.initials: SH
authors.lastname: Lillie
authors.forename: S S
authors.initials: SS
authors.lastname: Brown
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001665:Binding Sites; D001692:Biological Transport; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D005656:Fungal Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005800:Genes, Fungal / Q000235:genetics / Q000502:physiology; D016547:Kinesins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D018995:Myosin Heavy Chains; D024462:Myosin Type II; D024701:Myosin Type V; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D016415:Sequence Alignment; D013489:Suppression, Genetic / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D005656:Fungal Proteins; C077512:MYO2 protein, S cerevisiae; C434211:MYO2 protein, S pombe; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D024462:Myosin Type II; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D016547:Kinesins