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Phosphoinositides differentially regulate alpha-actinin flexibility and function.

Anne Marie Corgan·CoreyAyne Singleton·Cynthia B Santoso·Jeffrey A Greenwood
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Abstract

Alpha-actinin is a cell-adhesion and cytoskeletal protein that bundles actin microfilaments and links these filaments directly to integrin-adhesion receptors. Phosphoinositides bind to and regulate the interaction of a-actinin with actin filaments and integrin receptors. In the present study, we demonstrate that PtdIns(3,4,5)P3 inhibits and disrupts a-actinin-bundling activity, whereas PtdIns(4,5)P2 can only inhibit activity. In addition, a protease-sensitivity assay was developed to examine the flexibility of the linker region between the actin-binding domain and the spectrin repeats of a-actinin. Both phosphoinositides influenced the extent of proteolysis and the cleavage sites. PtdIns(4,5)P2 binding decreased the proteolysis of a-actinin, suggesting a role in stabilizing the structure of the protein. In contrast, PtdIns(3,4,5)P3 binding enhanced a-actinin proteolysis, indicating an increase in the flexibility of the protein. Furthermore, phosphoinositide binding influenced the proteolysis of the N- and C-terminal domains of a-actinin, indicating regulation of structure within both domains. These results support the hypothesis that PtdIns(4,5)P2 and PtdIns(3,4,5)P3 differentially regulate a-actinin function by modulating the structure and flexibility of the protein.

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Actin CytoskeletonActininActinsPhosphatidylinositol 4,5-DiphosphatePhosphatidylinositolsProtein Structure, SecondaryProtein Structure, TertiaryJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.

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Anne Marie Corgan, CoreyAyne Singleton, Cynthia B Santoso, Jeffrey A Greenwood. 2004-03-15. Phosphoinositides differentially regulate alpha-actinin flexibility and function.. https://doi.org/10.1042/bj20031124

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