Class VI myosin moves processively along actin filaments backward with large steps.
Among a superfamily of myosin, class VI myosin moves actin filaments backwards. Here we show that myosin VI moves processively on actin filaments backwards with large ( approximately 36 nm) steps, nevertheless it has an extremely short neck domain. Myosin V also moves processively with large ( approximately 36 nm) steps and it is believed that myosin V strides along the actin helical repeat with its elongated neck domain that is critical for its processive movement with large steps. Myosin VI having a short neck cannot take this scenario. We found by electron microscopy that myosin VI cooperatively binds to an actin filament at approximately 36 nm intervals in the presence of ATP, raising a hypothesis that the binding of myosin VI evokes "hot spots" on actin filaments that attract myosin heads. Myosin VI may step on these "hot spots" on actin filaments in every helical pitch, thus producing processive movement with 36 nm steps.
Nishikawa
So
S
Single Molecule Process Project, ICORP, JST, 2-4-14, Senba-Higashi, Mino, Osaka 562-0035, Japan.
Homma
Kazuaki
K
Komori
Yasunori
Y
Iwaki
Mitsuhiro
M
Wazawa
Tetsuichi
T
Hikikoshi Iwane
Atsuko
A
Saito
Junya
J
Ikebe
Reiko
R
Katayama
Eisaku
E
Yanagida
Toshio
T
Ikebe
Mitsuo
M
D000199:Actins / Q000737:chemistry* / Q000648:ultrastructure; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D049452:Green Fluorescent Proteins; D007313:Insecta; D008164:Luminescent Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000737:chemistry* / Q000648:ultrastructure; D024701:Myosin Type V / Q000737:chemistry; D011485:Protein Binding; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus
D000199:Actins; D018076:DNA, Complementary; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C089785:myosin VI; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D024701:Myosin Type V; D018995:Myosin Heavy Chains