PMID: 22869380

Authors:

Stiegler AL, Draheim KM, Li X, Chayen NE, Calderwood DA, Boggon TJ

Title:

Structural Basis for Paxillin Binding and Focal Adhesion Targeting of beta-Parvin.

Journal:

J Biol Chem. 2012 Sep 21;287(39):32566-77. Epub 2012 Aug 6.

Abstract:

beta-Parvin is a cytoplasmic adaptor protein that localizes to focal adhesions where it interacts with integrin-linked kinase and is involved in linking integrin receptors to the cytoskeleton. It has been reported that despite high sequence similarity to alpha-parvin, beta-parvin does not bind paxillin, suggesting distinct interactions and cellular functions for these two closely related parvins. Here, we reveal that beta-parvin binds directly and specifically to leucine-aspartic acid repeat (LD) motifs in paxillin via its C-terminal calponin homology (CH2) domain. We present the co-crystal structure of beta-parvin CH2 domain in complex with paxillin LD1 motif to 2.9 A resolution and find that the interaction is similar to that previously observed between alpha-parvin and paxillin LD1. We also present crystal structures of unbound beta-parvin CH2 domain at 2.1 A and 2.0 A resolution that show significant conformational flexibility in the N-terminal alpha-helix, suggesting an induced fit upon paxillin binding. We find that beta-parvin has specificity for the LD1, LD2, and LD4 motifs of paxillin, with K(D) values determined to 27, 42, and 73 mum, respectively, by surface plasmon resonance. Furthermore, we show that proper localization of beta-parvin to focal adhesions requires both the paxillin and integrin-linked kinase binding sites and that paxillin is important for early targeting of beta-parvin. These studies provide the first molecular details of beta-parvin binding to paxillin and help define the requirements for beta-parvin localization to focal adhesions.