Toward understanding actin activation of myosin ATPase: The role of myosin surface loops

Hirofumi Onishi, Sergey Mikhailenko, Manuel F. Morales

研究成果: Article

20 引用 (Scopus)

抄録

To understand the complicated interplay when a traveling myosin head reaches interaction distance with two actins in a filament we looked to three myosin loops that early on exert their influences from the "outside" of the myosin. On these we conduct, functionally test, and interpret strategically chosen mutations at sites thought from crystallography to be a patch for binding the "first" of the two actins. One loop bears a hydrophobic triplet of residues, one is the so-called "loop 2," and the third is the "cardiomyopathy" loop. So far as we know, the myosin sites that first respond are the two lysine-rich loops that produce an ionic strength-dependent weak-binding complex with actin. Subsequently, the three loops of interest bind the first actin simultaneously, and all three assist in closing the cleft in the 50-kDa domain of the myosin, a closure that results in transition from weak to strong binding and precedes rapid Pi release and motility. Mutational analysis shows that each such loop contact is distinctive in the route by which it communicates with its specific target elsewhere in myosin. The strongest contact with actin, for example, is that of the triplet-bearing loop. On the other hand, that of loop 2 (dependent on drawing close two myosin lysines and two actin aspartates) is probably responsible for opening switch I and uncovering the γ-phosphate moiety of bound ATP. Taking into account these findings, we begin to arrange in order many molecular events in muscle function.

元の言語English
ページ(範囲)6136-6141
ページ数6
ジャーナルProceedings of the National Academy of Sciences of the United States of America
103
発行部数16
DOI
出版物ステータスPublished - 2006 4 18

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Myosins
Actins
Lysine
Crystallography
Cardiomyopathies
Aspartic Acid
Osmolar Concentration
Adenosine Triphosphate
Phosphates
Muscles
Mutation

ASJC Scopus subject areas

  • Genetics
  • General

これを引用

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AU - Morales, Manuel F.

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AB - To understand the complicated interplay when a traveling myosin head reaches interaction distance with two actins in a filament we looked to three myosin loops that early on exert their influences from the "outside" of the myosin. On these we conduct, functionally test, and interpret strategically chosen mutations at sites thought from crystallography to be a patch for binding the "first" of the two actins. One loop bears a hydrophobic triplet of residues, one is the so-called "loop 2," and the third is the "cardiomyopathy" loop. So far as we know, the myosin sites that first respond are the two lysine-rich loops that produce an ionic strength-dependent weak-binding complex with actin. Subsequently, the three loops of interest bind the first actin simultaneously, and all three assist in closing the cleft in the 50-kDa domain of the myosin, a closure that results in transition from weak to strong binding and precedes rapid Pi release and motility. Mutational analysis shows that each such loop contact is distinctive in the route by which it communicates with its specific target elsewhere in myosin. The strongest contact with actin, for example, is that of the triplet-bearing loop. On the other hand, that of loop 2 (dependent on drawing close two myosin lysines and two actin aspartates) is probably responsible for opening switch I and uncovering the γ-phosphate moiety of bound ATP. Taking into account these findings, we begin to arrange in order many molecular events in muscle function.

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