Saccharomyces cerevisiae Bzz1p is implicated with type I myosins in actin patch polarization and is able to recruit actin-polymerizing machinery in vitro

Journal Article

In Saccharomyces cerevisiae, the WASP (Wiskott-Aldrich syndrome protein) homologue Las17p (also called Bee1p) is an important component of cortical actin patches. Las17p is part of a high-molecular-weight protein complex that regulates Arp2/3 complex-dependent actin polymerization at the cell cortex and that includes the type I myosins Myo3p and Myo5p and verprolin (Vrp1p). To identify other factors implicated with this complex in actin regulation, we isolated proteins that bind to Las17p by two-hybrid screening and affinity chromatography. Here, we report the characterization of Lsb7/Bzz1p (for Las seventeen binding protein 7), an Src homology 3 (SH3) domain protein that interacts directly with Las17p via a polyproline-SH3 interaction. Bzz1p coimmunoprecipitates in a complex with Las17p, Vrp1p, Myo3/5p, Bbc1p, Hsp70p, and actin. It colocalizes with cortical actin patches and with Las17p. This localization is dependent on Las17p, but not on F-actin. Bzz1p interacts physically and genetically with type I myosins. While deletion of BZZI shows no obvious phenotype, simultaneous deletion of the BZZ1, MY03, and MY05 genes is lethal. Overexpression of Bzz1p inhibits cell growth, and a bzz1ΔA myo5Δ double mutant is unable to restore actin polarity after NaCI stress. Finally, Bzz1p in vitro is able to recruit a functional actin polymerization machinery through its SH3 domains. Its interactions with Las17p, Vrp1p, and the type I myosins are essential for this process. This suggests that Bzz1p could be implicated in the regulation of actin polymerization.

Full Text

Duke Authors

Cited Authors

  • Soulard, A; Lechler, T; Spiridonov, V; Shevchenko, A; Shevchenko, A; Li, R; Winsor, B

Published Date

  • 2002

Published In

  • Molecular and Cellular Biology

Volume / Issue

  • 22 / 22

Start / End Page

  • 7889 - 7906

PubMed ID

  • 12391157

Digital Object Identifier (DOI)

  • 10.1128/MCB.22.22.7889-7906.2002