title: Myosin V transports secretory vesicles via a Rab GTPase cascade and interaction with the exocyst complex.
abstract: Vesicle transport requires four steps: vesicle formation, movement, tethering, and fusion. In yeast, two Rab GTPases, Ypt31/32, are required for post-Golgi vesicle formation. A third Rab GTPase, Sec4, and the exocyst act in tethering and fusion of these vesicles. Vesicle production is coupled to transport via direct interaction between Ypt31/32 and the yeast myosin V, Myo2. Here we show that Myo2 interacts directly with Sec4 and the exocyst subunit Sec15. Disruption of these interactions results in compromised growth and the accumulation of secretory vesicles. We identified the Sec15-binding region on Myo2 and also identified residues on Sec15 required for interaction with Myo2. That Myo2 interacts with Sec15 uncovers additional roles for the exocyst as an adaptor for molecular motors and implies similar roles for structurally related tethering complexes. Moreover, these studies predict that for many pathways, molecular motors attach to vesicles prior to their formation and remain attached until fusion.
authors.affiliation: Life Sciences Institute, Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48109-2216, USA.
authors.forename: Yui
authors.initials: Y
authors.lastname: Jin
authors.forename: Azmiri
authors.initials: A
authors.lastname: Sultana
authors.forename: Pallavi
authors.initials: P
authors.lastname: Gandhi
authors.forename: Edward
authors.initials: E
authors.lastname: Franklin
authors.forename: Susan
authors.initials: S
authors.lastname: Hamamoto
authors.forename: Amir R
authors.initials: AR
authors.lastname: Khan
authors.forename: Mary
authors.initials: M
authors.lastname: Munson
authors.forename: Randy
authors.initials: R
authors.lastname: Schekman
authors.forename: Lois S
authors.initials: LS
authors.lastname: Weisman
mesh_terms: D019943:Amino Acid Substitution; D001665:Binding Sites; D005089:Exocytosis; D008561:Membrane Fusion; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024701:Myosin Type V / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism; D015398:Signal Transduction; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C077512:MYO2 protein, S cerevisiae; D020409:Molecular Motor Proteins; D011994:Recombinant Proteins; C060862:SEC15 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C087905:YPT31 protein, S cerevisiae; D024701:Myosin Type V; C121633:YPT32 protein, S cerevisiae; C064320:SEC4 protein, S cerevisiae; D018995:Myosin Heavy Chains; D020691:rab GTP-Binding Proteins