TheSaccharomyces cerevisiaeHomologue of Human Wiskott–Aldrich Syndrome Protein Las17p Interacts with the Arp2/3 Complex

Abstract

Yeast Las17 protein is homologous to the Wiskott-Aldrich Syndrome protein, which is implicated in severe immunodeficiency. Las17p/Bee1p has been shown to be important for actin patch assembly and actin polymerization. Here we show that Las17p interacts with the Arp2/3 complex. LAS17 is an allele-specific multicopy suppressor of ARP2 and ARP3 mutations; overexpression restores both actin patch organization and endocytosis defects in ARP2 temperature-sensitive (ts) cells. Six of seven ARP2 ts mutants and at least one ARP3 ts mutant are synthetically lethal with las17Delta ts confirming functional interaction with the Arp2/3 complex. Further characterization of las17Delta cells showed that receptor-mediated internalization of alpha factor by the Ste2 receptor is severely defective. The polarity of normal bipolar bud site selection is lost. Las17-gfp remains localized in cortical patches in vivo independently of polymerized actin and is required for the polarized localization of Arp2/3 as well as actin. Coimmunoprecipitation of Arp2p with Las17p indicates that Las17p interacts directly with the complex. Two hybrid results also suggest that Las17p interacts with actin, verprolin, Rvs167p and several other proteins including Src homology 3 (SH3) domain proteins, suggesting that Las17p may integrate signals from different regulatory cascades destined for the Arp2/3p complex and the actin cytoskeleton.

The WASP Homologue Las17 Activates the Novel Actin-regulatory Activity of Ysc84 to Promote Endocytosis in Yeast

“…Due to the whole genome duplication, Saccharomyces cerevisiae has two highly related genes, YSC84 and LSB3. Previous work showed that both Ysc84 (Lsb4) and Lsb3 have interactions with Las17 in two-hybrid assays (Madania et al, 1999). In our own work, we identified Ysc84 as an interactor of the endocytic adaptor protein Sla1 (Dewar This article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E08 -09 -0982) on January 21, 2009. et al, 2002).…”

“…Again this protein has been shown to localize to actin patches in vivo and interacts with both Las17 and Sla1 in two-hybrid studies (Madania et al, 1999;Dewar et al, 2002). Thus, Lsb3 might have a function that overlaps with that of Ysc84.…”

“…Las17 has been reported to interact with Ysc84 C-terminal half (amino acids 270-468) in a two-hybrid screen (Madania et al, 1999). Further details of this interaction have not been reported.…”

The Rsp5 Ubiquitin Ligase Binds to and Ubiquitinates Members of the Yeast CIN85-Endophilin Complex, Sla1-Rvs167

“…Rvs167 binds to the other yeast BAR domain protein, Rvs161, analogous to amphiphysin isoforms that dimerize through their BAR domains (1,58,59). Like endophilin, Rvs167 binds to the actin assembly regulator N-WASP (Las17) through its C-terminal SH3 domain (29,47,59,60). Unlike the amphiphysins and endophilins, Rvs167 does not carry clathrin and clathrin adaptor (AP)-binding motifs and does not appear to bind either of these proteins.…”

It's a scoop!

“…At the poster summarizing her talk, someone whipped out a mobile phone and started reading the methods to researchers in their lab. Machesky and Insall were the first to publish their findings 1 , but within months, four other papers had appeared describing similar results [2][3][4][5] .…”