Kinetic characterization of the ATPase and actin-activated ATPase activities of Acanthamoeba castellanii myosin-2.
J Biol Chem
; 288(37): 26709-20, 2013 Sep 13.
Article
em En
| MEDLINE
| ID: mdl-23897814
ABSTRACT
Phosphorylation of Ser-639 in loop-2 of the catalytic motor domain of the heavy chain of Acanthamoeba castellanii myosin-2 and the phosphomimetic mutation S639D have been shown previously to down-regulate the actin-activated ATPase activity of both the full-length myosin and single-headed subfragment-1 (Liu, X., Lee, D. Y., Cai, S., Yu, S., Shu, S., Levine, R. L., and Korn, E. D. (2013) Proc. Natl. Acad. Sci. U.S.A. 110, E23-E32). In the present study we determined the kinetic constants for each step in the myosin and actomyosin ATPase cycles of recombinant wild-type S1 and S1-S639D. The kinetic parameter predominantly affected by the S639D mutation is the actin-activated release of inorganic phosphate from the acto myosin·ADP·Pi complex, which is the rate-limiting step in the steady-state actomyosin ATPase cycle. As consequence of this change, the duty ratio of this conventional myosin decreases. We speculate on the effect of Ser-639 phosphorylation on the processive behavior of myosin-2 filaments.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Actinas
/
Miosinas
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Adenosina Trifosfatases
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Acanthamoeba castellanii
Limite:
Animals
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article