Functions of Vrp1p in cytokinesis and actin patches are distinct and neither requires a WH2/V domain.
Vrp1 (verprolin, End5) is a Saccharomyces cerevisiae actin-associated protein and is related to mammalian Wiskott-Aldrich syndrome protein (WASP)-interacting protein (WIP). Vrp1-deficient (vrp1 Delta) cells are inviable at high temperature, have partially depolarized cortical actin patches and have defects in both actomyosin ring-dependent and Hof1 (Cyk2)-dependent pathways of cytokinesis. We demonstrate here that N-Vrp1(1-364) and C-Vrp1(364-817) are each sufficient to restore viability, actomyosin ring constriction and Hof1 localization at 37 degrees C to vrp1 Delta. C-Vrp1, like Vrp1, partially co-localizes with cortical actin patches and restores actin patch polarization to vrp1 Delta. Cortical localization of C-Vrp1, but not Vrp1, requires Las17. N-Vrp1 exhibits diffuse cytoplasmic localization and functions in cytokinesis without efficiently restoring polarization of cortical actin patches. N-Vrp1 function is not abolished by mutations affecting the WASP homology 2 (WH2) [verprolin homology (V)] actin-binding domain. N-Vrp1 may function through the type I myosins and actin, while C-Vrp1 may function through both Las17 (Bee1) and type I myosins. The functions of Vrp1 in viability at 37 degrees C and cytokinesis do not require efficient localization to, and function in, the cortical actin cytoskeleton.
Thanabalu
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Institute of Molecular Agrobiology, 1 Research Link, The National University of Singapore, Singapore 117604, Republic of Singapore.
Munn
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D000199:Actins / Q000737:chemistry / Q000502:physiology*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology*; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins / Q000737:chemistry / Q000502:physiology*; D006358:Hot Temperature; D008840:Microfilament Proteins / Q000737:chemistry / Q000502:physiology*; D008869:Microtubule-Associated Proteins; D009218:Myosins / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D051316:Wiskott-Aldrich Syndrome Protein
D000199:Actins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; C116847:HOF1 protein, S cerevisiae; C480361:LAS17 protein, S cerevisiae; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C090350:VRP1 protein, S cerevisiae; D051316:Wiskott-Aldrich Syndrome Protein; D009218:Myosins