A monomeric myosin VI with a large working stroke.
Myosin VI is involved in a wide variety of intracellular processes such as endocytosis, secretion and cell migration. Unlike almost all other myosins so far studied, it moves towards the minus end of actin filaments and is therefore likely to have unique cellular properties. However, its mechanism of force production and movement is not understood. Under our experimental conditions, both expressed full-length and native myosin VI are monomeric. Electron microscopy using negative staining revealed that the addition of ATP induces a large conformational change in the neck/tail region of the expressed molecule. Using an optical tweezers-based force transducer we found that expressed myosin VI is nonprocessive and produces a large working stroke of 18 nm. Since the neck region of myosin VI is short (it contains only a single IQ motif), it is difficult to reconcile the 18 nm working stroke with the classical 'lever arm mechanism', unless other structures in the molecule contribute to the effective lever. A possible model to explain the large working stroke of myosin VI is presented.
Lister
Ida
I
MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK.
Schmitz
Stephan
S
Walker
Matthew
M
Trinick
John
J
Buss
Folma
F
Veigel
Claudia
C
Kendrick-Jones
John
J
D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002645:Chickens; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents / Q000494:pharmacology; D006801:Humans; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D016415:Sequence Alignment; D018411:Spodoptera; D013395:Sucrose / Q000494:pharmacology
D000199:Actins; D003432:Cross-Linking Reagents; C089785:myosin VI; D013395:Sucrose; D000255:Adenosine Triphosphate; D018995:Myosin Heavy Chains