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Functional Adaptation between Yeast Actin and Its Cognate Myosin Motors
Journal article   Open access   Peer reviewed

Functional Adaptation between Yeast Actin and Its Cognate Myosin Motors

Benjamin C Stark, Kuo-Kuang Wen, John S Allingham, Peter A Rubenstein and Matthew Lord
The Journal of biological chemistry, Vol.286(35), pp.30384-30392
09/02/2011
DOI: 10.1074/jbc.M111.262899
PMCID: PMC3162397
PMID: 21757693
url
https://doi.org/10.1074/jbc.M111.262899View
Published (Version of record) Open Access

Abstract

We employed budding yeast and skeletal muscle actin to examine the contribution of the actin isoform to myosin motor function. While yeast and muscle actin are highly homologous, they exhibit different charge density at their N termini (a proposed myosin-binding interface). Muscle myosin-II actin-activated ATPase activity is significantly higher with muscle versus yeast actin. Whether this reflects inefficiency in the ability of yeast actin to activate myosin is not known. Here we optimized the isolation of two yeast myosins to assess actin function in a homogenous system. Yeast myosin-II (Myo1p) and myosin-V (Myo2p) accommodate the reduced N-terminal charge density of yeast actin, showing greater activity with yeast over muscle actin. Increasing the number of negative charges at the N terminus of yeast actin from two to four (as in muscle) had little effect on yeast myosin activity, while other substitutions of charged residues at the myosin interface of yeast actin reduced activity. Thus, yeast actin functions most effectively with its native myosins, which in part relies on associations mediated by its outer domain. Compared with yeast myosin-II and myosin-V, muscle myosin-II activity was very sensitive to salt. Collectively, our findings suggest differing degrees of reliance on electrostatic interactions during weak actomyosin binding in yeast versus muscle. Our study also highlights the importance of native actin isoforms when considering the function of myosins.
Skeletal Muscle Yeast Enzymology Actin Myosin Protein-Protein Interactions

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