Monomeric myosin V uses two binding regions for the assembly of stable translocation complexes.
Myosin-motors are conserved from yeast to human and transport a great variety of cargoes. Most plus-end directed myosins, which constitute the vast majority of all myosin motors, form stable dimers and interact constitutively with their cargo complexes. To date, little is known about regulatory mechanisms for cargo-complex assembly. In this study, we show that the type V myosin Myo4p binds to its cargo via two distinct binding regions, the C-terminal tail and a coiled-coil domain-containing fragment. Furthermore, we find that Myo4p is strictly monomeric at physiologic concentrations. Because type V myosins are thought to require dimerization for processive movement, a mechanism must be in place to ensure that oligomeric Myo4p is incorporated into cargo-translocation complexes. Indeed, we find that artificial dimerization of the Myo4p C-terminal tail promotes stabilization of myosin-cargo complexes, suggesting that full-length Myo4p dimerizes in the cocomplex as well. We also combined the Myo4p C-terminal tail with the coiled-coil region, lever arm, and motor domain from a different myosin to form constitutively dimeric motor proteins. This heterologous motor successfully translocates its cargo in vivo, suggesting that wild-type Myo4p may also function as a dimer during cargo-complex transport.
Institute of Structural Biology, GSF-National Research Center, 81377 Munich, Germany.
Alexander
A
Heuck
Tung-Gia
TG
Du
Stephan
S
Jellbauer
Klaus
K
Richter
Claudia
C
Kruse
Sigrun
S
Jaklin
Marisa
M
Müller
Johannes
J
Buchner
Ralf-Peter
RP
Jansen
Dierk
D
Niessing
D019281:Dimerization; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D024701:Myosin Type V / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
C491722:MYO3 protein, S cerevisiae; C098732:Myo4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D024701:Myosin Type V; D018995:Myosin Heavy Chains