The structure of the Myo4p globular tail and its function in ASH1 mRNA localization.
Type V myosin (MyoV)-dependent transport of cargo is an essential process in eukaryotes. Studies on yeast and vertebrate MyoV showed that their globular tails mediate binding to the cargo complexes. In Saccharomyces cerevisiae, the MyoV motor Myo4p interacts with She3p to localize asymmetric synthesis of HO 1 (ASH1) mRNA into the bud of dividing cells. A recent study showed that localization of GFP-MS2-tethered ASH1 particles does not require the Myo4p globular tail, challenging the supposed role of this domain. We assessed ASH1 mRNA and Myo4p distribution more directly and found that their localization is impaired in cells expressing globular tail-lacking Myo4p. In vitro studies further show that the globular tail together with a more N-terminal linker region is required for efficient She3p binding. We also determined the x-ray structure of the Myo4p globular tail and identify a conserved surface patch important for She3p binding. The structure shows pronounced similarities to membrane-tethering complexes and indicates that Myo4p may not undergo auto-inhibition of its motor domain.
Heuck
Alexander
A
Institute of Structural Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich, Germany.
Fetka
Ingrid
I
Brewer
Daniel N
DN
Hüls
Daniela
D
Munson
Mary
M
Jansen
Ralf-Peter
RP
Niessing
Dierk
D
D001665:Binding Sites; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000737:chemistry* / Q000378:metabolism*; D024701:Myosin Type V / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*
C098733:ASH1 protein, S cerevisiae; C098732:Myo4 protein, S cerevisiae; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C471176:SHE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D024701:Myosin Type V; D018995:Myosin Heavy Chains