Abstract

Myosin VII is an unconventional myosin widely expressed in organisms ranging from amoebae to mammals that has been shown to play vital roles in cell adhesion and phagocytosis. Here we present the first study of the mechanism of action of a myosin VII isoform. We have expressed a truncated single-headed Drosophila myosin VIIB construct in the baculovirus-Sf9 system that bound calmodulin light chains. By using steady-state and transient kinetic methods, we showed that myosin VIIB exhibits a fast release of phosphate and a slower, rate-limiting ADP release from actomyosin. As a result, myosin VIIB will be predominantly strongly bound to actin during steady-state ATP hydrolysis (its duty ratio will be at least 80%). This kinetic pattern is, in many respects, similar to that of the single-molecule vesicle transporters myosin V and VI. The enzymatic properties of myosin VIIB provide a kinetic basis for processivity upon possible dimerization via the C-terminal domains of the heavy chain. Our experiments also revealed conformational heterogeneity of the actomyosin VIIB complex in the absence of nucleotide.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Intramural Research (Z01)
Project #
1Z01HL004232-05
Application #
7158537
Study Section
(LMC)
Project Start
Project End
Budget Start
Budget End
Support Year
5
Fiscal Year
2005
Total Cost
Indirect Cost

  Institution

Name
U.S. National Heart Lung and Blood Inst
Department
Type
DUNS #
City
State
Country
United States
Zip Code

  Publications

Rehman, Atteeq U; Santos-Cortez, Regie Lyn P; Morell, Robert J et al. (2014) Mutations in TBC1D24, a gene associated with epilepsy, also cause nonsyndromic deafness DFNB86. Am J Hum Genet 94:144-52
Toepfer, Christopher; Caorsi, Valentina; Kampourakis, Thomas et al. (2013) Myosin regulatory light chain (RLC) phosphorylation change as a modulator of cardiac muscle contraction in disease. J Biol Chem 288:13446-54
Jenkinson, Emma M; Rehman, Atteeq U; Walsh, Tom et al. (2013) Perrault syndrome is caused by recessive mutations in CLPP, encoding a mitochondrial ATP-dependent chambered protease. Am J Hum Genet 92:605-13
Riazuddin, Saima; Nazli, Sabiha; Ahmed, Zubair M et al. (2008) Mutation spectrum of MYO7A and evaluation of a novel nonsyndromic deafness DFNB2 allele with residual function. Hum Mutat 29:502-11
Kempler, Karen; Toth, Judit; Yamashita, Roxanne et al. (2007) Loop 2 of limulus myosin III is phosphorylated by protein kinase A and autophosphorylation. Biochemistry 46:4280-93
Yang, Yi; Kovacs, Mihaly; Sakamoto, Takeshi et al. (2006) Dimerized Drosophila myosin VIIa: a processive motor. Proc Natl Acad Sci U S A 103:5746-51
Belyantseva, Inna A; Boger, Erich T; Naz, Sadaf et al. (2005) Myosin-XVa is required for tip localization of whirlin and differential elongation of hair-cell stereocilia. Nat Cell Biol 7:148-56
Yang, Yi; Kovacs, Mihaly; Xu, Qian et al. (2005) Myosin VIIB from Drosophila is a high duty ratio motor. J Biol Chem 280:32061-8
McNeil, E L; Tacelosky, D; Basciano, P et al. (2004) Actin-dependent motility of melanosomes from fish retinal pigment epithelial (RPE) cells investigated using in vitro motility assays. Cell Motil Cytoskeleton 58:71-82
Gillespie, P G; Albanesi, J P; Bahler, M et al. (2001) Myosin-I nomenclature. J Cell Biol 155:703-4

Showing the most recent 10 out of 14 publications