Calcium regulation of Myosin-I tension sensing

John H. Lewis, Michael J. Greenberg, Joseph M. Laakso, Henry Shuman, E. Michael Ostap

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Myo1b is a myosin that is exquisitely sensitive to tension. Its actin-attachment lifetime increases > 50-fold when its working stroke is opposed by 1 pN of force. The long attachment lifetime of myo1b under load raises the question: how are actin attachments that last >50 s in the presence of force regulated? Like most myosins, forces are transmitted to the myo1b motor through a light-chain binding domain that is structurally stabilized by calmodulin, a calcium-binding protein. Thus, we examined the effect of calcium on myo1b motility using ensemble and single-molecule techniques. Calcium accelerates key biochemical transitions on the ATPase pathway, decreases the working-stroke displacement, and greatly reduces the ability of myo1b to sense tension. Thus, calcium provides an effective mechanism for inhibiting motility and terminating long-duration attachments.

Original languageEnglish
Pages (from-to)2799-2807
Number of pages9
JournalBiophysical Journal
Volume102
Issue number12
DOIs
StatePublished - Jun 20 2012

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