title: Las17p-Vrp1p but not Las17p-Arp2/3 interaction is important for actin patch polarization in yeast.
abstract: The actin cytoskeleton plays a central role in many important cellular processes such as cell polarization, cell division and endocytosis. The dynamic changes to the actin cytoskeleton that accompany these processes are regulated by actin-associated proteins Wiskott-Aldrich Syndrome Protein (WASP) (known as Las17p in yeast) and WASP-Interacting Protein (WIP) (known as Vrp1p in yeast). Both yeast and human WASP bind to and stimulate the Arp2/3 complex which in turn nucleates assembly of actin monomers into filaments at polarized sites at the cortex. WASP-WIP interaction in yeast and humans are important for Arp2/3 complex stimulation in vitro. It has been proposed that these interactions are also important for polarized actin assembly in vivo. However, the redundancy of actin-associated proteins has made it difficult to test this hypothesis. We have identified two point mutations (L80T and H94L) in yeast WASP that in combination abolish WASP-WIP interaction in yeast. We also identify an N-terminal fragment of Las17p (N-Las17p1-368) able to interact with Vrp1p but not Arp2/3. Using these mutant and truncated forms of yeast WASP we provide novel evidence that WASP interaction with WIP is more important than interaction with Arp2/3 for polarized actin assembly and endocytosis in yeast.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore.
authors.forename: Rajamuthiah
authors.initials: R
authors.lastname: Rajmohan
authors.forename: Ming Hwa
authors.initials: MH
authors.lastname: Wong
authors.forename: Lei
authors.initials: L
authors.lastname: Meng
authors.forename: Alan L
authors.initials: AL
authors.lastname: Munn
authors.forename: Thirumaran
authors.initials: T
authors.lastname: Thanabalu
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D006801:Humans; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; C480361:LAS17 protein, S cerevisiae; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C090350:VRP1 protein, S cerevisiae; D051316:Wiskott-Aldrich Syndrome Protein