title: Identification of myosin XI receptors in Arabidopsis defines a distinct class of transport vesicles.
abstract: To characterize the mechanism through which myosin XI-K attaches to its principal endomembrane cargo, a yeast two-hybrid library of Arabidopsis thaliana cDNAs was screened using the myosin cargo binding domain as bait. This screen identified two previously uncharacterized transmembrane proteins (hereinafter myosin binding proteins or MyoB1/2) that share a myosin binding, conserved domain of unknown function 593 (DUF593). Additional screens revealed that MyoB1/2 also bind myosin XI-1, whereas myosin XI-I interacts with the distantly related MyoB7. The in vivo interactions of MyoB1/2 with myosin XI-K were confirmed by immunoprecipitation and colocalization analyses. In epidermal cells, the yellow fluorescent protein-tagged MyoB1/2 localize to vesicles that traffic in a myosin XI-dependent manner. Similar to myosin XI-K, MyoB1/2 accumulate in the tip-growing domain of elongating root hairs. Gene knockout analysis demonstrated that functional cooperation between myosin XI-K and MyoB proteins is required for proper plant development. Unexpectedly, the MyoB1-containing vesicles did not correspond to brefeldin A-sensitive Golgi and post-Golgi or prevacuolar compartments and did not colocalize with known exocytic or endosomal compartments. Phylogenomic analysis suggests that DUF593 emerged in primitive land plants and founded a multigene family that is conserved in all flowering plants. Collectively, these findings indicate that MyoB are membrane-anchored myosin receptors that define a distinct, plant-specific transport vesicle compartment.
authors.affiliation: Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331.
authors.forename: Valera V
authors.initials: VV
authors.lastname: Peremyslov
authors.forename: Eva A
authors.initials: EA
authors.lastname: Morgun
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Kurth
authors.forename: Kira S
authors.initials: KS
authors.lastname: Makarova
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: Valerian V
authors.initials: VV
authors.lastname: Dolja
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002451:Cell Compartmentation; D017124:Conserved Sequence; D035264:Flowers / Q000502:physiology; D036681:Fluorescence Recovery After Photobleaching; D020868:Gene Silencing; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008954:Models, Biological; D009218:Myosins / Q000737:chemistry / Q000378:metabolism*; D010641:Phenotype; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D009218:Myosins