Mouse myosin-19 is a plus-end-directed, high-duty ratio molecular motor.
Class XIX myosin (Myo19) is a vertebrate-specific unconventional myosin, responsible for the transport of mitochondria. To characterize biochemical properties of Myo19, we prepared recombinant mouse Myo19-truncated constructs containing the motor domain and the IQ motifs using the baculovirus/Sf9 expression system. We identified regulatory light chain (RLC) of smooth muscle/non-muscle myosin-2 as the light chain of Myo19. The actin-activated ATPase activity and the actin-gliding velocity of Myo19-truncated constructs were about one-third and one-sixth as those of myosin-5a, respectively. The apparent affinity of Myo19 to actin was about the same as that of myosin-5a. The RLCs bound to Myo19 could be phosphorylated by myosin light chain kinase, but this phosphorylation had little effect on the actin-activated ATPase activity and the actin-gliding activity of Myo19-truncated constructs. Using dual fluorescence-labeled actin filaments, we determined that Myo19 is a plus-end-directed molecular motor. We found that, similar to that of the high-duty ratio myosin, such as myosin-5a, ADP release rate was comparable with the maximal actin-activated ATPase activity of Myo19, indicating that ADP release is a rate-limiting step for the ATPase cycle of acto-Myo19. ADP strongly inhibited the actin-activated ATPase activity and actin-gliding activity of Myo19-truncated constructs. Based on the above results, we concluded that Myo19 is a high-duty ratio molecular motor moving to the plus-end of the actin filament.
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Zekuan
Z
Lu
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Xiao-Nan
XN
Ma
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Hai-Man
HM
Zhang
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Huan-Hong
HH
Ji
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Hao
H
Ding
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Jie
J
Zhang
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and.
Dan
D
Luo
the Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing 100871, China.
Yujie
Y
Sun
From the Group of Cell Motility and Muscle Contraction, National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 and lixd@ioz.ac.cn.
Xiang-Dong
XD
Li
D000199:Actins / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D007700:Kinetics; D051379:Mice; D008928:Mitochondria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism; D009218:Myosins; D016415:Sequence Alignment
D000199:Actins; C000592406:Myo19 protein, mouse; C513082:Myo5a protein, mouse; D000244:Adenosine Diphosphate; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D009218:Myosins
ATPase; Actin; Intracellular Trafficking; Mitochondria; Myosin