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Narvaez-Ortiz HY, Lynch MJ, Liu SL, Fries A, Nolen BJ. Both Las17-binding sites on Arp2/3 complex are important for branching nucleation and assembly of functional endocytic actin networks in S. cerevisiae. J Biol Chem 2024; 300:105766. [PMID: 38367669 PMCID: PMC10944109 DOI: 10.1016/j.jbc.2024.105766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 02/07/2024] [Accepted: 02/12/2024] [Indexed: 02/19/2024] Open
Abstract
Arp2/3 complex nucleates branched actin filaments that drive membrane invagination during endocytosis and leading-edge protrusion in lamellipodia. Arp2/3 complex is maximally activated in vitro by binding of a WASP family protein to two sites-one on the Arp3 subunit and one spanning Arp2 and ARPC1-but the importance of each site in the regulation of force-producing actin networks is unclear. Here, we identify mutations in budding yeast Arp2/3 complex that decrease or block engagement of Las17, the budding yeast WASP, at each site. As in the mammalian system, both sites are required for maximal activation in vitro. Dimerization of Las17 partially restores activity of mutations at both CA-binding sites. Arp2/3 complexes defective at either site assemble force-producing actin networks in a bead motility assay, but their reduced activity hinders motility by decreasing actin assembly near the bead surface and by failing to suppress actin filament bundling within the networks. While even the most defective Las17-binding site mutants assembled actin filaments at endocytic sites, they showed significant internalization defects, potentially because they lack the proper architecture to drive plasma membrane remodeling. Together, our data indicate that both Las17-binding sites are important to assemble functional endocytic actin networks in budding yeast, but Arp2/3 complex retains some activity in vitro and in vivo even with a severe defect at either Las17-binding site.
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Affiliation(s)
- Heidy Y Narvaez-Ortiz
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Michael J Lynch
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Su-Ling Liu
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Adam Fries
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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Han X, Hu Z, Surya W, Ma Q, Zhou F, Nordenskiöld L, Torres J, Lu L, Miao Y. The intrinsically disordered region of coronins fine-tunes oligomerization and actin polymerization. Cell Rep 2023; 42:112594. [PMID: 37269287 DOI: 10.1016/j.celrep.2023.112594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/21/2023] [Accepted: 05/16/2023] [Indexed: 06/05/2023] Open
Abstract
Coronins play critical roles in actin network formation. The diverse functions of coronins are regulated by the structured N-terminal β propeller and the C-terminal coiled coil (CC). However, less is known about a middle "unique region" (UR), which is an intrinsically disordered region (IDR). The UR/IDR is an evolutionarily conserved signature in the coronin family. By integrating biochemical and cell biology experiments, coarse-grained simulations, and protein engineering, we find that the IDR optimizes the biochemical activities of coronins in vivo and in vitro. The budding yeast coronin IDR plays essential roles in regulating Crn1 activity by fine-tuning CC oligomerization and maintaining Crn1 as a tetramer. The IDR-guided optimization of Crn1 oligomerization is critical for F-actin cross-linking and regulation of Arp2/3-mediated actin polymerization. The final oligomerization status and homogeneity of Crn1 are contributed by three examined factors: helix packing, the energy landscape of the CC, and the length and molecular grammar of the IDR.
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Affiliation(s)
- Xiao Han
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Zixin Hu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Wahyu Surya
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Qianqian Ma
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Feng Zhou
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Lars Nordenskiöld
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Jaume Torres
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore; Institute for Digital Molecular Analytics and Science, Nanyang Technological University, Singapore 636921, Singapore.
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Rosenbloom AD, Pollard TD. The proline-rich domain of fission yeast WASp (Wsp1p) interacts with actin filaments and inhibits actin polymerization. FEBS Lett 2023; 597:672-681. [PMID: 36650956 PMCID: PMC10023459 DOI: 10.1002/1873-3468.14571] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 12/01/2022] [Indexed: 01/19/2023]
Abstract
Members of the Wiskott-Aldrich Syndrome protein (WASp) family activate Arp2/3 complex (actin-related proteins 2 and 3 complex) to form actin filament branches. The proline-rich domain (PRD) of WASp contributes to branching nucleation, and the PRD of budding yeast Las17 binds actin filaments [Urbanek AN et al. (2013) Curr Biol 23, 196-203]. Biochemical assays showed the recombinant PRD of fission yeast Schizosaccharomyces pombe Wsp1p binds actin filaments with micromolar affinity. Recombinant PRDs of both Wsp1p and Las17p slowed the elongation of actin filaments by Mg-ATP-actin monomers by half and slowed the spontaneous polymerization of Mg-ATP-actin monomers modestly. The affinity of PRDs of WASp-family proteins for actin filaments is high enough to contribute to the reported stimulation of actin filament branching by Arp2/3 complex.
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Affiliation(s)
- Aaron D. Rosenbloom
- Department of Chemistry, Yale University, PO Box 208107, New Haven, CT 06520-8103 USA
| | - Thomas D. Pollard
- Departments of Molecular Cellular and Developmental Biology, of Molecular Biophysics and Biochemistry and of Cell Biology, Yale University, PO Box 208103, New Haven, CT 06520-8103 USA
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Liu SL, Narvaez-Ortiz HY, Miner M, Kiemel J, Oberhelman N, Watt A, Wagner AR, Luan Q, Helgeson LA, Nolen BJ. Analysis of functional surfaces on the actin nucleation promoting factor Dip1 required for Arp2/3 complex activation and endocytic actin network assembly. J Biol Chem 2022; 298:102019. [PMID: 35533728 PMCID: PMC9168731 DOI: 10.1016/j.jbc.2022.102019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 11/30/2022] Open
Abstract
Arp2/3 complex nucleates branched actin filaments that drive processes like endocytosis and lamellipodial protrusion. WISH/DIP/SPIN90 (WDS) proteins form a class of Arp2/3 complex activators or nucleation promoting factors (NPFs) that, unlike WASP family NPFs, activate Arp2/3 complex without requiring preformed actin filaments. Therefore, activation of Arp2/3 complex by WDS proteins is thought to produce the initial actin filaments that seed branching nucleation by WASP-bound Arp2/3 complexes. However, whether activation of Arp2/3 complex by WDS proteins is important for the initiation of branched actin assembly in cells has not been directly tested. Here, we used structure-based point mutations of the Schizosaccharomyces pombe WDS protein Dip1 to test the importance of its Arp2/3-activating activity in cells. Six of thirteen Dip1 mutants caused severe defects in Arp2/3 complex activation in vitro, and we found a strong correlation between the ability of mutants to activate Arp2/3 complex and to rescue endocytic actin assembly defects caused by deleting Dip1. These data support a model in which Dip1 activates Arp2/3 complex to produce actin filaments that initiate branched actin assembly at endocytic sites. Dip1 mutants that synergized with WASP in activating Arp2/3 complex in vitro showed milder defects in cells compared to those that did not, suggesting that in cells the two NPFs may coactivate Arp2/3 complex to initiate actin assembly. Finally, the mutational data reveal important complementary electrostatic contacts at the Dip1-Arp2/3 complex interface and corroborate the previously proposed wedge model, which describes how Dip1 binding triggers structural changes that activate Arp2/3 complex.
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Affiliation(s)
- Su-Ling Liu
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Heidy Y Narvaez-Ortiz
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Matt Miner
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Jack Kiemel
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Nicholas Oberhelman
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - April Watt
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Andrew R Wagner
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Qing Luan
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Luke A Helgeson
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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Tyler JJ, Smaczynska-de Rooij II, Abugharsa L, Palmer JS, Hancock LP, Allwood EG, Ayscough KR. Phosphorylation of the WH2 domain in yeast Las17/WASP regulates G-actin binding and protein function during endocytosis. Sci Rep 2021; 11:9718. [PMID: 33958621 PMCID: PMC8102491 DOI: 10.1038/s41598-021-88826-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 04/12/2021] [Indexed: 11/29/2022] Open
Abstract
Actin nucleation is the key rate limiting step in the process of actin polymerization, and tight regulation of this process is critical to ensure actin filaments form only at specific times and at defined regions of the cell. WH2 domains are short sequence motifs found in many different actin binding proteins including WASP family proteins which regulate the actin nucleating complex Arp2/3. In this study we reveal a phosphorylation site, Serine 554, within the WH2 domain of the yeast WASP homologue Las17. Both phosphorylation and a phospho-mimetic mutation reduce actin monomer binding affinity while an alanine mutation, generated to mimic the non-phosphorylated state, increases actin binding affinity. The effect of these mutations on the Las17-dependent process of endocytosis in vivo was analysed and leads us to propose that switching of Las17 phosphorylation states may allow progression through distinct phases of endocytosis from site assembly through to the final scission stage. While the study is focused on Las17, the sole WASP family protein in yeast, our results have broad implications for our understanding of how a key residue in this conserved motif can underpin the many different actin regulatory roles with which WH2 domains have been associated.
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Affiliation(s)
- J J Tyler
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK
| | - I I Smaczynska-de Rooij
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK
| | - L Abugharsa
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK
| | - J S Palmer
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK
| | - L P Hancock
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK
| | - E G Allwood
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK
| | - K R Ayscough
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, S10 2TN, UK.
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