Ribonucleoprotein-dependent localization of the yeast class V myosin Myo4p.
Class V myosins are motor proteins with functions in vesicle transport, organelle segregation, and RNA localization. Although they have been extensively studied, only little is known about the regulation of their spatial distribution. Here we demonstrate that a GFP fusion protein of the budding yeast class V myosin Myo4p accumulates at the bud cortex and is a component of highly dynamic cortical particles. Bud-specific enrichment depends on Myo4p's association with its cargo, a ribonucleoprotein complex containing the RNA-binding protein She2p. Cortical accumulation of Myo4p at the bud tip can be explained by a transient retention mechanism that requires SHE2 and, apparently, localized mRNAs bound to She2p. A mutant She2 protein that is unable to recognize its cognate target mRNA, ASH1, fails to localize Myo4p. Mutant She2p accumulates inside the nucleus, indicating that She2p shuttles between the nucleus and cytoplasm and is exported in an RNA-dependent manner. Consistently, inhibition of nuclear mRNA export results in nuclear accumulation of She2p and cytoplasmic Myo4p mislocalization. Loss of She2p can be complemented by direct targeting of a heterologous lacZ mRNA to a complex of Myo4p and its associated adaptor She3p, suggesting that She2p's function in Myo4p targeting is to link an mRNA to the motor complex.
Kruse
Claudia
C
Zentrum für Molekulare Biologie, Universität Heidelberg, D-69120 Heidelberg, Germany.
Jaedicke
Andreas
A
Beaudouin
Joel
J
Bohl
Florian
F
Ferring
Dunja
D
Guttler
Thomas
T
Ellenberg
Jan
J
Jansen
Ralf-Peter
RP
D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005838:Genotype; D049452:Green Fluorescent Proteins; D007700:Kinetics; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
D008164:Luminescent Proteins; C098732:Myo4 protein, S cerevisiae; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C471175:SHE2 protein, S cerevisiae; C471176:SHE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D012313:RNA; D024701:Myosin Type V; D018995:Myosin Heavy Chains