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Singer A, Ramos A, Keating AE. Elaboration of the Homer1 recognition landscape reveals incomplete divergence of paralogous EVH1 domains. Protein Sci 2024; 33:e5094. [PMID: 38989636 PMCID: PMC11237882 DOI: 10.1002/pro.5094] [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: 02/26/2024] [Revised: 06/11/2024] [Accepted: 06/16/2024] [Indexed: 07/12/2024]
Abstract
Short sequences that mediate interactions with modular binding domains are ubiquitous throughout eukaryotic proteomes. Networks of short linear motifs (SLiMs) and their corresponding binding domains orchestrate many cellular processes, and the low mutational barrier to evolving novel interactions provides a way for biological systems to rapidly sample selectable phenotypes. Mapping SLiM binding specificity and the rules that govern SLiM evolution is fundamental to uncovering the pathways regulated by these networks and developing the tools to manipulate them. We used high-throughput screening of the human proteome to identify sequences that bind to the Enabled/VASP homology 1 (EVH1) domain of the postsynaptic density scaffolding protein Homer1. This expanded our understanding of the determinants of Homer EVH1 binding preferences and defined a new motif that can facilitate the discovery of additional Homer-mediated interactions. Interestingly, the Homer1 EVH1 domain preferentially binds to sequences containing an N-terminally overlapping motif that is bound by the paralogous family of Ena/VASP actin polymerases, and many of these sequences can bind to EVH1 domains from both protein families. We provide evidence from orthologous EVH1 domains in pre-metazoan organisms that the overlap in human Ena/VASP and Homer binding preferences corresponds to an incomplete divergence from a common Ena/VASP ancestor. Given this overlap in binding profiles, promiscuous sequences that can be recognized by both families either achieve specificity through extrinsic regulatory strategies or may provide functional benefits via multi-specificity. This may explain why these paralogs incompletely diverged despite the accessibility of further diverged isoforms.
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Affiliation(s)
- Avinoam Singer
- Department of BiologyMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Alejandra Ramos
- Department of BiologyMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Amy E. Keating
- Department of BiologyMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
- Koch Institute for Integrative Cancer ResearchMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
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2
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Halpin JC, Keating AE. PairK: Pairwise k-mer alignment for quantifying protein motif conservation in disordered regions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.23.604860. [PMID: 39091826 PMCID: PMC11291154 DOI: 10.1101/2024.07.23.604860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Protein-protein interactions are often mediated by a modular peptide recognition domain binding to a short linear motif (SLiM) in the disordered region of another protein. The ability to predict domain-SLiM interactions would allow researchers to map protein interaction networks, predict the effects of perturbations to those networks, and develop biologically meaningful hypotheses. Unfortunately, sequence database searches for SLiMs generally yield mostly biologically irrelevant motif matches or false positives. To improve the prediction of novel SLiM interactions, researchers employ filters to discriminate between biologically relevant and improbable motif matches. One promising criterion for identifying biologically relevant SLiMs is the sequence conservation of the motif, exploiting the fact that functional motifs are more likely to be conserved than spurious motif matches. However, the difficulty of aligning disordered regions has significantly hampered the utility of this approach. We present PairK (pairwise k-mer alignment), an MSA-free method to quantify motif conservation in disordered regions. PairK outperforms both standard MSA-based conservation scores and a modern LLM-based conservation score predictor on the task of identifying biologically important motif instances. PairK can quantify conservation over wider phylogenetic distances than MSAs, indicating that SLiMs may be more conserved than is implied by MSA-based metrics. PairK is available as open-source code at https://github.com/jacksonh1/pairk.
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Affiliation(s)
- Jackson C. Halpin
- MIT Department of Biology, 77 Massachusetts Ave., Cambridge, MA 02139
| | - Amy E. Keating
- MIT Department of Biology, 77 Massachusetts Ave., Cambridge, MA 02139
- MIT Department of Biological Engineering, 77 Massachusetts Ave., Cambridge, MA 02139
- Koch Institute for Integrative Cancer Research, 77 Massachusetts Ave., Cambridge, MA 02139
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3
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Singer A, Ramos A, Keating AE. Elaboration of the Homer1 Recognition Landscape Reveals Incomplete Divergence of Paralogous EVH1 Domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576863. [PMID: 38645240 PMCID: PMC11030225 DOI: 10.1101/2024.01.23.576863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Short sequences that mediate interactions with modular binding domains are ubiquitous throughout eukaryotic proteomes. Networks of Short Linear Motifs (SLiMs) and their corresponding binding domains orchestrate many cellular processes, and the low mutational barrier to evolving novel interactions provides a way for biological systems to rapidly sample selectable phenotypes. Mapping SLiM binding specificity and the rules that govern SLiM evolution is fundamental to uncovering the pathways regulated by these networks and developing the tools to manipulate them. We used high-throughput screening of the human proteome to identify sequences that bind to the Enabled/VASP homology 1 (EVH1) domain of the postsynaptic density scaffolding protein Homer1. In doing so, we expanded current understanding of the determinants of Homer EVH1 binding preferences and defined a new motif that can facilitate the discovery of additional Homer-mediated interactions. Interestingly, the Homer1 EVH1 domain preferentially binds to sequences containing an N-terminally overlapping motif that is bound by the paralogous family of Ena/VASP actin polymerases, and many of these sequences can bind to EVH1 domains from both protein families. We provide evidence from orthologous EVH1 domains in pre-metazoan organisms that the overlap in human Ena/VASP and Homer binding preferences corresponds to an incomplete divergence from a common Ena/VASP ancestor. Given this overlap in binding profiles, promiscuous sequences that can be recognized by both families either achieve specificity through extrinsic regulatory strategies or may provide functional benefits via multi-specificity. This may explain why these paralogs incompletely diverged despite the accessibility of further diverged isoforms.
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Affiliation(s)
- Avinoam Singer
- MIT Department of Biology, Cambridge, Massachusetts, USA
| | | | - Amy E. Keating
- MIT Department of Biology, Cambridge, Massachusetts, USA
- MIT Department of Biological Engineering, Cambridge, Massachusetts, USA
- Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, USA
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4
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Nast-Kolb T, Bleicher P, Payr M, Bausch AR. VASP localization to lipid bilayers induces polymerization driven actin bundle formation. Mol Biol Cell 2022; 33:ar91. [PMID: 35830600 PMCID: PMC9582628 DOI: 10.1091/mbc.e21-11-0577] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Actin bundles constitute important cytoskeleton structures and enable a scaffold for force transmission inside cells. Actin bundles are formed by proteins, with multiple F-actin binding domains cross-linking actin filaments to each other. Vasodilator-stimulated phosphoprotein (VASP) has mostly been reported as an actin elongator, but it has been shown to be a bundling protein as well and is found in bundled actin structures at filopodia and adhesion sites. Based on in vitro experiments, it remains unclear when and how VASP can act as an actin bundler or elongator. Here we demonstrate that VASP bound to membranes facilitates the formation of large actin bundles during polymerization. The alignment by polymerization requires the fluidity of the lipid bilayers. The mobility within the bilayer enables VASP to bind to filaments and capture and track growing barbed ends. VASP itself phase separates into a protein-enriched phase on the bilayer. This VASP-rich phase nucleates and accumulates at bundles during polymerization, which in turn leads to a reorganization of the underlying lipid bilayer. Our findings demonstrate that the nature of VASP localization is decisive for its function. The up-concentration based on VASP’s affinity to actin during polymerization enables it to simultaneously fulfill the function of an elongator and a bundler.
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Affiliation(s)
- T Nast-Kolb
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany and
| | - P Bleicher
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany and.,Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892
| | - M Payr
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany and.,Structural and Computational Biology Unit, EMBL Heidelberg, Meyerhoferstr. 1, 69117 Heidelberg, Germany
| | - A R Bausch
- Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747 Garching, Germany
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5
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Faix J, Rottner K. Ena/VASP proteins in cell edge protrusion, migration and adhesion. J Cell Sci 2022; 135:274697. [DOI: 10.1242/jcs.259226] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
ABSTRACT
The tightly coordinated, spatiotemporal control of actin filament remodeling provides the basis of fundamental cellular processes, such as cell migration and adhesion. Specific protein assemblies, composed of various actin-binding proteins, are thought to operate in these processes to nucleate and elongate new filaments, arrange them into complex three-dimensional (3D) arrays and recycle them to replenish the actin monomer pool. Actin filament assembly is not only necessary to generate pushing forces against the leading edge membrane or to propel pathogens through the cytoplasm, but also coincides with the generation of stress fibers (SFs) and focal adhesions (FAs) that generate, transmit and sense mechanical tension. The only protein families known to date that directly enhance the elongation of actin filaments are formins and the family of Ena/VASP proteins. Their mechanisms of action, however, in enhancing processive filament elongation are distinct. The aim of this Review is to summarize our current knowledge on the molecular mechanisms of Ena/VASP-mediated actin filament assembly, and to discuss recent insights into the cell biological functions of Ena/VASP proteins in cell edge protrusion, migration and adhesion.
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Affiliation(s)
- Jan Faix
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technical University Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
- Molecular Cell Biology Group, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
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Hwang T, Parker SS, Hill SM, Grant RA, Ilunga MW, Sivaraman V, Mouneimne G, Keating AE. Native proline-rich motifs exploit sequence context to target actin-remodeling Ena/VASP protein ENAH. eLife 2022; 11:70680. [PMID: 35076015 PMCID: PMC8789275 DOI: 10.7554/elife.70680] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 01/06/2022] [Indexed: 12/13/2022] Open
Abstract
The human proteome is replete with short linear motifs (SLiMs) of four to six residues that are critical for protein-protein interactions, yet the importance of the sequence surrounding such motifs is underexplored. We devised a proteomic screen to examine the influence of SLiM sequence context on protein-protein interactions. Focusing on the EVH1 domain of human ENAH, an actin regulator that is highly expressed in invasive cancers, we screened 36-residue proteome-derived peptides and discovered new interaction partners of ENAH and diverse mechanisms by which context influences binding. A pocket on the ENAH EVH1 domain that has diverged from other Ena/VASP paralogs recognizes extended SLiMs and favors motif-flanking proline residues. Many high-affinity ENAH binders that contain two proline-rich SLiMs use a noncanonical site on the EVH1 domain for binding and display a thermodynamic signature consistent with the two-motif chain engaging a single domain. We also found that photoreceptor cilium actin regulator (PCARE) uses an extended 23-residue region to obtain a higher affinity than any known ENAH EVH1-binding motif. Our screen provides a way to uncover the effects of proteomic context on motif-mediated binding, revealing diverse mechanisms of control over EVH1 interactions and establishing that SLiMs can’t be fully understood outside of their native context.
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Affiliation(s)
- Theresa Hwang
- Department of Biology, Massachusetts Institute of Technology
| | - Sara S Parker
- Department of Cellular & Molecular Medicine, University of Arizona
| | - Samantha M Hill
- Department of Cellular & Molecular Medicine, University of Arizona
| | - Robert A Grant
- Department of Biology, Massachusetts Institute of Technology
| | - Meucci W Ilunga
- Department of Biology, Massachusetts Institute of Technology
| | | | | | - Amy E Keating
- Department of Biology, Massachusetts Institute of Technology
- Department of Biological Engineering and Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology
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Hwang T, Parker SS, Hill SM, Ilunga MW, Grant RA, Mouneimne G, Keating AE. A distributed residue network permits conformational binding specificity in a conserved family of actin remodelers. eLife 2021; 10:e70601. [PMID: 34854809 PMCID: PMC8639148 DOI: 10.7554/elife.70601] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 11/08/2021] [Indexed: 11/23/2022] Open
Abstract
Metazoan proteomes contain many paralogous proteins that have evolved distinct functions. The Ena/VASP family of actin regulators consists of three members that share an EVH1 interaction domain with a 100 % conserved binding site. A proteome-wide screen revealed photoreceptor cilium actin regulator (PCARE) as a high-affinity ligand for ENAH EVH1. Here, we report the surprising observation that PCARE is ~100-fold specific for ENAH over paralogs VASP and EVL and can selectively bind ENAH and inhibit ENAH-dependent adhesion in cells. Specificity arises from a mechanism whereby PCARE stabilizes a conformation of the ENAH EVH1 domain that is inaccessible to family members VASP and EVL. Structure-based modeling rapidly identified seven residues distributed throughout EVL that are sufficient to differentiate binding by ENAH vs. EVL. By exploiting the ENAH-specific conformation, we rationally designed the tightest and most selective ENAH binder to date. Our work uncovers a conformational mechanism of interaction specificity that distinguishes highly similar paralogs and establishes tools for dissecting specific Ena/VASP functions in processes including cancer cell invasion.
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Affiliation(s)
- Theresa Hwang
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Sara S Parker
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of ArizonaTucsonUnited States
| | - Samantha M Hill
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of ArizonaTucsonUnited States
| | - Meucci W Ilunga
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Robert A Grant
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Ghassan Mouneimne
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of ArizonaTucsonUnited States
| | - Amy E Keating
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Biological Engineering and Koch Institue for Integrative Cancer Research, Massachusetts Institute of TechnologyCambridgeUnited States
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Abstract
Simple Summary Cell migration is an essential process from embryogenesis to cell death. This is tightly regulated by numerous proteins that help in proper functioning of the cell. In diseases like cancer, this process is deregulated and helps in the dissemination of tumor cells from the primary site to secondary sites initiating the process of metastasis. For metastasis to be efficient, cytoskeletal components like actin, myosin, and intermediate filaments and their associated proteins should co-ordinate in an orderly fashion leading to the formation of many cellular protrusions-like lamellipodia and filopodia and invadopodia. Knowledge of this process is the key to control metastasis of cancer cells that leads to death in 90% of the patients. The focus of this review is giving an overall understanding of these process, concentrating on the changes in protein association and regulation and how the tumor cells use it to their advantage. Since the expression of cytoskeletal proteins can be directly related to the degree of malignancy, knowledge about these proteins will provide powerful tools to improve both cancer prognosis and treatment. Abstract Successful metastasis depends on cell invasion, migration, host immune escape, extravasation, and angiogenesis. The process of cell invasion and migration relies on the dynamic changes taking place in the cytoskeletal components; actin, tubulin and intermediate filaments. This is possible due to the plasticity of the cytoskeleton and coordinated action of all the three, is crucial for the process of metastasis from the primary site. Changes in cellular architecture by internal clues will affect the cell functions leading to the formation of different protrusions like lamellipodia, filopodia, and invadopodia that help in cell migration eventually leading to metastasis, which is life threatening than the formation of neoplasms. Understanding the signaling mechanisms involved, will give a better insight of the changes during metastasis, which will eventually help targeting proteins for treatment resulting in reduced mortality and longer survival.
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Rachubik P, Piwkowska A. The role of vasodilator‐stimulated phosphoprotein in podocyte functioning. Cell Biol Int 2019; 43:1092-1101. [DOI: 10.1002/cbin.11149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 04/06/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Patrycja Rachubik
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research CentrePolish Academy of Sciences Wita Stwosza 63, 80‐308 Gdańsk Poland
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research CentrePolish Academy of Sciences Wita Stwosza 63, 80‐308 Gdańsk Poland
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Quantification of reaction cycle parameters for an essential molecular switch in an auxin-responsive transcription circuit in rice. Proc Natl Acad Sci U S A 2019; 116:2589-2594. [PMID: 30696765 DOI: 10.1073/pnas.1817038116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Protein-based molecular switches play critical roles in biological processes. The importance of the prolyl cis-trans switch is underscored by the ubiquitous presence of peptidyl prolyl isomerases such as cyclophilins that accelerate the intrinsically slow isomerization rate. In rice, a tryptophan-proline (W-P) cis-trans switch in transcription repressor protein OsIAA11 along with its associated cyclophilin LRT2 are essential components in a negative feedback gene regulation circuit that controls lateral root initiation in response to the plant hormone auxin. Importantly, no quantitative characterizations of the individual (microscopic) thermodynamic and kinetic parameters for any cyclophilin-catalyzed W-P isomerization have been reported. Here we present NMR studies that determine and independently validate these parameters for LRT2 catalysis of the W-P motif in OsIAA11, providing predictive power for understanding the role of this switch in the auxin-responsive circuit and the resulting lateral rootless phenotype in rice. We show that the observed isomerization rate is linearly dependent on LRT2 concentration but is independent of OsIAA11 concentration over a wide range, and LRT2 is optimally tuned to maintain OsIAA11 at its cis-trans equilibrium to supply the slower downstream cis-specific proteasomal degradation with maximal OsIAA11 substrate. This indicates that accelerating the LRT2-catalyzed isomerization would not accelerate OsIAA degradation, whereas decreasing this rate via targeted mutation could reveal relationships between circuit dynamics and lateral root development. Moreover, we show that sequences flanking the highly conserved Aux/IAA W-P motif do not impact LRT2 catalysis, suggesting that the parameters determined here are broadly applicable across highly conserved cyclophilins and their Aux/IAA targets.
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