1
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Sever AIM, Alderson TR, Rennella E, Aramini JM, Liu ZH, Harkness RW, Kay LE. Activation of caspase-9 on the apoptosome as studied by methyl-TROSY NMR. Proc Natl Acad Sci U S A 2023; 120:e2310944120. [PMID: 38085782 PMCID: PMC10743466 DOI: 10.1073/pnas.2310944120] [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: 06/28/2023] [Accepted: 10/23/2023] [Indexed: 12/18/2023] Open
Abstract
Mitochondrial apoptotic signaling cascades lead to the formation of the apoptosome, a 1.1-MDa heptameric protein scaffold that recruits and activates the caspase-9 protease. Once activated, caspase-9 cleaves and activates downstream effector caspases, triggering the onset of cell death through caspase-mediated proteolysis of cellular proteins. Failure to activate caspase-9 enables the evasion of programmed cell death, which occurs in various forms of cancer. Despite the critical apoptotic function of caspase-9, the structural mechanism by which it is activated on the apoptosome has remained elusive. Here, we used a combination of methyl-transverse relaxation-optimized NMR spectroscopy, protein engineering, and biochemical assays to study the activation of caspase-9 bound to the apoptosome. In the absence of peptide substrate, we observed that both caspase-9 and its isolated protease domain (PD) only very weakly dimerize with dissociation constants in the millimolar range. Methyl-NMR spectra of isotope-labeled caspase-9, within the 1.3-MDa native apoptosome complex or an engineered 480-kDa apoptosome mimic, reveal that the caspase-9 PD remains monomeric after recruitment to the scaffold. Binding to the apoptosome, therefore, organizes caspase-9 PDs so that they can rapidly and extensively dimerize only when substrate is present, providing an important layer in the regulation of caspase-9 activation. Our work highlights the unique role of NMR spectroscopy to structurally characterize protein domains that are flexibly tethered to large scaffolds, even in cases where the molecular targets are in excess of 1 MDa, as in the present example.
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Affiliation(s)
- Alexander I. M. Sever
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ONM5G 0A4, Canada
| | - T. Reid Alderson
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
| | - Enrico Rennella
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
| | - James M. Aramini
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
| | - Zi Hao Liu
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ONM5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
| | - Robert W. Harkness
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ONM5G 0A4, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
| | - Lewis E. Kay
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ONM5G 0A4, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
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2
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Guo S, Hoeprich GJ, Magliozzi JO, Gelles J, Goode BL. Dynamic remodeling of actin networks by cyclase-associated protein and CAP-Abp1 complexes. Curr Biol 2023; 33:4484-4495.e5. [PMID: 37797614 DOI: 10.1016/j.cub.2023.09.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/20/2023] [Accepted: 09/13/2023] [Indexed: 10/07/2023]
Abstract
How actin filaments are spatially organized and remodeled into diverse higher-order networks in vivo is still not well understood. Here, we report an unexpected F-actin "coalescence" activity driven by cyclase-associated protein (CAP) and enhanced by its interactions with actin-binding protein 1 (Abp1). We directly observe S. cerevisiae CAP and Abp1 rapidly transforming branched or linear actin networks by bundling and sliding filaments past each other, maximizing filament overlap, and promoting compaction into bundles. This activity does not require ATP and is conserved, as similar behaviors are observed for the mammalian homologs of CAP and Abp1. Coalescence depends on the CAP oligomerization domain but not the helical folded domain (HFD) that mediates its functions in F-actin severing and depolymerization. Coalescence by CAP-Abp1 further depends on interactions between CAP and Abp1 and interactions between Abp1 and F-actin. Our results are consistent with a mechanism in which the formation of energetically favorable sliding CAP and CAP-Abp1 crosslinks drives F-actin bundle compaction. Roles for CAP and CAP-Abp1 in actin remodeling in vivo are supported by strong phenotypes arising from deletion of the CAP oligomerization domain and by genetic interactions between sac6Δ and an srv2-301 mutant that does not bind Abp1. Together, these observations identify a new actin filament remodeling function for CAP, which is further enhanced by its direct interactions with Abp1.
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Affiliation(s)
- Siyang Guo
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Gregory J Hoeprich
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Joseph O Magliozzi
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
| | - Bruce L Goode
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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3
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Rennella E, Sahtoe DD, Baker D, Kay LE. Exploiting conformational dynamics to modulate the function of designed proteins. Proc Natl Acad Sci U S A 2023; 120:e2303149120. [PMID: 37094170 PMCID: PMC10161014 DOI: 10.1073/pnas.2303149120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 03/22/2023] [Indexed: 04/26/2023] Open
Abstract
With the recent success in calculating protein structures from amino acid sequences using artificial intelligence-based algorithms, an important next step is to decipher how dynamics is encoded by the primary protein sequence so as to better predict function. Such dynamics information is critical for protein design, where strategies could then focus not only on sequences that fold into particular structures that perform a given task, but would also include low-lying excited protein states that could influence the function of the designed protein. Herein, we illustrate the importance of dynamics in modulating the function of C34, a designed α/β protein that captures β-strands of target ligands and is a member of a family of proteins designed to sequester β-strands and β hairpins of aggregation-prone molecules that lead to a variety of pathologies. Using a strategy to "see" regions of apo C34 that are invisible to NMR spectroscopy as a result of pervasive conformational exchange, as well as a mutagenesis approach whereby C34 molecules are stabilized into a single conformer, we determine the structures of the predominant conformations that are sampled by C34 and show that these attenuate the affinity for cognate peptide. Subsequently, the observed motion is exploited to develop an allosterically regulated peptide binder whose binding affinity can be controlled through the addition of a second molecule. Our study emphasizes the unique role that NMR can play in directing the design process and in the construction of new molecules with more complex functionality.
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Affiliation(s)
- Enrico Rennella
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
| | - Danny D. Sahtoe
- Department of Biochemistry, University of Washington, Seattle, WA98195
- Institute for Protein Design, University of Washington, Seattle, WA98195
- HHMI, University of Washington, Seattle, WA98195
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA98195
- Institute for Protein Design, University of Washington, Seattle, WA98195
- HHMI, University of Washington, Seattle, WA98195
| | - Lewis E. Kay
- Department of Molecular Genetics, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ONM5S 1A8, Canada
- Department of Chemistry, University of Toronto, Toronto, ONM5S 3H6, Canada
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ONM5G 0A4, Canada
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4
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Jaramillo-Martinez V, Dominguez MJ, Bell GM, Souness ME, Carhart AH, Cuibus MA, Masoumzadeh E, Lantz BJ, Adkins AJ, Latham MP, Ball KA, Stollar EJ. How a highly acidic SH3 domain folds in the absence of its charged peptide target. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.21.532811. [PMID: 36993259 PMCID: PMC10055188 DOI: 10.1101/2023.03.21.532811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Charged residues on the surface of proteins are critical for both protein stability and interactions. However, many proteins contain binding regions with a high net-charge that may destabilize the protein but are useful for binding to oppositely charged targets. We hypothesized that these domains would be marginally stable, as electrostatic repulsion would compete with favorable hydrophobic collapse during folding. Furthermore, by increasing the salt concentration we predict that these protein folds would be stabilized by mimicking some of the favorable electrostatic interactions that take place during target binding. We varied the salt and urea concentrations to probe the contributions of electrostatic and hydrophobic interactions for the folding of the 60-residue yeast SH3 domain found in Abp1p. The SH3 domain was significantly stabilized with increased salt concentrations according to the Debye-Huckel limiting law. Molecular dynamics and NMR show that sodium ions interact with all 15 acidic residues but do little to change backbone dynamics or overall structure. Folding kinetics experiments show that the addition of urea or salt primarily affects the folding rate, indicating that almost all the hydrophobic collapse and electrostatic repulsion occurs in the transition state. After the transition state formation, modest yet favorable short-range salt-bridges are formed along with hydrogen bonds, as the native state fully folds. Thus, hydrophobic collapse offsets electrostatic repulsion to ensure this highly charged binding domain can still fold and be ready to bind to its charged peptide targets, a property that is likely evolutionarily conserved over one billion years. Statement for broader audience Some protein domains are highly charged because they are adapted to bind oppositely charged proteins and nucleic acids. However, it is unknown how these highly charged domains fold as during folding there will be significant repulsion between like-charges. We investigate how one of these highly charged domains folds in the presence of salt, which can screen the charge repulsion and make folding easier, allowing us to understand how folding occurs despite the protein’s high charge. Supplementary material Supplementary material document containing additional details on protein expression methods, thermodynamics and kinetics equations, and the effect of urea on electrostatic interactions, as well as 4 supplemental figures and 4 supplemental data tables. ( Supplementary_Material.docx ), 15 pages Supplemental excel file containing covariation data across AbpSH3 orthologs ( FileS1.xlsx ).
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Discovering molecular features of intrinsically disordered regions by using evolution for contrastive learning. PLoS Comput Biol 2022; 18:e1010238. [PMID: 35767567 PMCID: PMC9275697 DOI: 10.1371/journal.pcbi.1010238] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 07/12/2022] [Accepted: 05/23/2022] [Indexed: 02/07/2023] Open
Abstract
A major challenge to the characterization of intrinsically disordered regions (IDRs), which are widespread in the proteome, but relatively poorly understood, is the identification of molecular features that mediate functions of these regions, such as short motifs, amino acid repeats and physicochemical properties. Here, we introduce a proteome-scale feature discovery approach for IDRs. Our approach, which we call “reverse homology”, exploits the principle that important functional features are conserved over evolution. We use this as a contrastive learning signal for deep learning: given a set of homologous IDRs, the neural network has to correctly choose a held-out homolog from another set of IDRs sampled randomly from the proteome. We pair reverse homology with a simple architecture and standard interpretation techniques, and show that the network learns conserved features of IDRs that can be interpreted as motifs, repeats, or bulk features like charge or amino acid propensities. We also show that our model can be used to produce visualizations of what residues and regions are most important to IDR function, generating hypotheses for uncharacterized IDRs. Our results suggest that feature discovery using unsupervised neural networks is a promising avenue to gain systematic insight into poorly understood protein sequences. Intrinsically disordered regions (IDRs) are widespread in proteins but are poorly understood on a systematic level because they evolve too rapidly for classic bioinformatics methods to be effective. We designed a neural network that learns what features (for example, electrostatic charge, or the presence of certain motifs) might be important to the function of IDRs, even when we don’t have prior knowledge of function. Our neural network learns by exploiting principles of evolution. Important features tend to be conserved over species, so guessing what sequences evolved from the same common ancestor helps the neural network identify these features. Importantly, training a neural network this way can be defined as a fully automatic operation, so no manual effort is required. After our neural network is trained, we can apply interpretation techniques to understand what kinds of features are important to IDRs globally in the proteome, and to form hypotheses about specific IDRs. We show that many of the features our neural network learns are consistent with features we already know to be important to IDRs. We hope that our neural network can be applied to help biologists form hypotheses about poorly characterized IDRs.
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6
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Alcantara J, Stix R, Huang K, Connor A, East R, Jaramillo-Martinez V, Stollar EJ, Ball KA. An Unbound Proline-Rich Signaling Peptide Frequently Samples Cis Conformations in Gaussian Accelerated Molecular Dynamics Simulations. Front Mol Biosci 2021; 8:734169. [PMID: 34869581 PMCID: PMC8634643 DOI: 10.3389/fmolb.2021.734169] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/27/2021] [Indexed: 11/13/2022] Open
Abstract
Disordered proline-rich motifs are common across the proteomes of many species and are often involved in protein-protein interactions. Proline is a unique amino acid due to the covalent bond between the backbone nitrogen and the proline side chain. The resulting five-membered ring allows proline to sample the cis state about its peptide bond, which other residues cannot do as readily. Because proline-rich disordered sequences exist as ensembles that likely include structures with the proline peptide bond in cis, a robust methodology to accurately account for these conformations in the overall ensemble is crucial. Observing the cis conformations of proline in a disordered sequence is challenging both experimentally and computationally. Nitrogen-hydrogen NMR spectroscopy cannot directly observe proline residues, which lack an amide bond, and computational methods struggle to overcome the large kinetic barrier between the cis and trans states, since isomerization usually occurs on the order of seconds. In the current work, Gaussian accelerated molecular dynamics was used to overcome this free energy barrier and simulate proline isomerization in a tetrapeptide (KPTP) and in the 12-residue proline-rich SH3 binding peptide, ArkA. We found that Gaussian accelerated molecular dynamics, when combined with a lowered peptide bond dihedral angle potential energy barrier (15 kcal/mol), allowed sufficient sampling of the proline cis and trans states on a microsecond timescale. All ArkA prolines spend a significant fraction of time in cis, leading to a more compact ensemble with less polyproline II helix structure than an ArkA ensemble with all peptide bonds in trans. The ensemble containing cis prolines also matches more closely to in vitro circular dichroism data than the all-trans ensemble. The ability of the ArkA prolines to isomerize likely affects the peptide's ability to bind its partner SH3 domain, and should be studied further. This is the first molecular dynamics simulation study of proline isomerization in a biologically relevant proline-rich sequence that we know of, and a similar protocol could be applied to study multi-proline isomerization in other proline-containing proteins to improve conformational diversity and agreement with in vitro data.
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Affiliation(s)
- Juan Alcantara
- Department of Chemistry, Skidmore College, Saratoga Springs, NY, United States
| | - Robyn Stix
- Department of Chemistry, Skidmore College, Saratoga Springs, NY, United States
| | - Katherine Huang
- Department of Chemistry, Skidmore College, Saratoga Springs, NY, United States
| | - Acadia Connor
- Department of Chemistry, Skidmore College, Saratoga Springs, NY, United States
| | - Ray East
- Department of Chemistry, Skidmore College, Saratoga Springs, NY, United States
| | - Valeria Jaramillo-Martinez
- Department of Neuroscience and Pharmacology, Texas Teach University Health Science Center, Lubbock, TX, United States
| | - Elliott J Stollar
- School of Life Sciences, University of Liverpool, Liverpool, United Kingdom
| | - K Aurelia Ball
- Department of Chemistry, Skidmore College, Saratoga Springs, NY, United States
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7
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Protein context shapes the specificity of SH3 domain-mediated interactions in vivo. Nat Commun 2021; 12:1597. [PMID: 33712617 PMCID: PMC7954794 DOI: 10.1038/s41467-021-21873-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
Protein–protein interactions (PPIs) between modular binding domains and their target peptide motifs are thought to largely depend on the intrinsic binding specificities of the domains. The large family of SRC Homology 3 (SH3) domains contribute to cellular processes via their ability to support such PPIs. While the intrinsic binding specificities of SH3 domains have been studied in vitro, whether each domain is necessary and sufficient to define PPI specificity in vivo is largely unknown. Here, by combining deletion, mutation, swapping and shuffling of SH3 domains and measurements of their impact on protein interactions in yeast, we find that most SH3s do not dictate PPI specificity independently from their host protein in vivo. We show that the identity of the host protein and the position of the SH3 domains within their host are critical for PPI specificity, for cellular functions and for key biophysical processes such as phase separation. Our work demonstrates the importance of the interplay between a modular PPI domain such as SH3 and its host protein in establishing specificity to wire PPI networks. These findings will aid understanding how protein networks are rewired during evolution and in the context of mutation-driven diseases such as cancer. The SRC Homology 3 (SH3) domains mediate protein–protein interactions (PPIs). Here, the authors assess the SH3-mediated PPIs in yeast, and show that the identity of the protein itself and the position of the SH3 both affect the interaction specificity and thus the PPI-dependent cellular functions.
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8
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Gerlach GJ, Carrock R, Stix R, Stollar EJ, Ball KA. A disordered encounter complex is central to the yeast Abp1p SH3 domain binding pathway. PLoS Comput Biol 2020; 16:e1007815. [PMID: 32925900 PMCID: PMC7514057 DOI: 10.1371/journal.pcbi.1007815] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 09/24/2020] [Accepted: 08/15/2020] [Indexed: 12/20/2022] Open
Abstract
Protein-protein interactions are involved in a wide range of cellular processes. These interactions often involve intrinsically disordered proteins (IDPs) and protein binding domains. However, the details of IDP binding pathways are hard to characterize using experimental approaches, which can rarely capture intermediate states present at low populations. SH3 domains are common protein interaction domains that typically bind proline-rich disordered segments and are involved in cell signaling, regulation, and assembly. We hypothesized, given the flexibility of SH3 binding peptides, that their binding pathways include multiple steps important for function. Molecular dynamics simulations were used to characterize the steps of binding between the yeast Abp1p SH3 domain (AbpSH3) and a proline-rich IDP, ArkA. Before binding, the N-terminal segment 1 of ArkA is pre-structured and adopts a polyproline II helix, while segment 2 of ArkA (C-terminal) adopts a 310 helix, but is far less structured than segment 1. As segment 2 interacts with AbpSH3, it becomes more structured, but retains flexibility even in the fully engaged state. Binding simulations reveal that ArkA enters a flexible encounter complex before forming the fully engaged bound complex. In the encounter complex, transient nonspecific hydrophobic and long-range electrostatic contacts form between ArkA and the binding surface of SH3. The encounter complex ensemble includes conformations with segment 1 in both the forward and reverse orientation, suggesting that segment 2 may play a role in stabilizing the correct binding orientation. While the encounter complex forms quickly, the slow step of binding is the transition from the disordered encounter ensemble to the fully engaged state. In this transition, ArkA makes specific contacts with AbpSH3 and buries more hydrophobic surface. Simulating the binding between ApbSH3 and ArkA provides insight into the role of encounter complex intermediates and nonnative hydrophobic interactions for other SH3 domains and IDPs in general.
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Affiliation(s)
- Gabriella J. Gerlach
- Department of Chemistry, Skidmore College, Saratoga Springs, New York, United States
| | - Rachel Carrock
- Department of Chemistry, Skidmore College, Saratoga Springs, New York, United States
| | - Robyn Stix
- Department of Chemistry, Skidmore College, Saratoga Springs, New York, United States
| | - Elliott J. Stollar
- School of Life Sciences, University of Liverpool, Liverpool, United Kingdom
| | - K. Aurelia Ball
- Department of Chemistry, Skidmore College, Saratoga Springs, New York, United States
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9
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Phage tail fibre assembly proteins employ a modular structure to drive the correct folding of diverse fibres. Nat Microbiol 2019; 4:1645-1653. [DOI: 10.1038/s41564-019-0477-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 05/01/2019] [Indexed: 12/18/2022]
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10
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Li L, Zhang S, Liu X, Yu R, Li X, Liu M, Zhang H, Zheng X, Wang P, Zhang Z. Magnaporthe oryzae Abp1, a MoArk1 Kinase-Interacting Actin Binding Protein, Links Actin Cytoskeleton Regulation to Growth, Endocytosis, and Pathogenesis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:437-451. [PMID: 30451565 DOI: 10.1094/mpmi-10-18-0281-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The actin cytoskeleton and actin-coupled endocytosis are conserved cellular processes required for the normal growth and pathogenesis of the rice blast fungus Magnaporthe oryzae. We have previously shown that actin regulating kinase MoArk1 regulates actin dynamics and endocytosis to play a key role in virulence of the fungus. To understand the underlying mechanism, we have characterized the actin-binding protein MoAbp1 that interacts with MoArk1 from M. oryzae. The ΔMoabp1 mutant exhibited delayed endocytosis and defects in growth, host penetration, and invasive growth. Consistent with its putative function associated with actin-binding, MoAbp1 regulates the localization of actin patches and plays a role in MoArk1 phosphorylation. In addition, MoAbp1 interacts with MoCap (adenylyl cyclase-associated protein) affecting its normal patch localization pattern and the actin protein MoAct1 through its conserved domains. Taken together, our results support a notion that MoAbp1 functions as a protein scaffold linking MoArk1, MoCap1, and MoAct1 to regulate actin cytoskeleton dynamics critical in growth and pathogenicity of the blast fungus.
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Affiliation(s)
- Lianwei Li
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Shengpei Zhang
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Xinyu Liu
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Rui Yu
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Xinrui Li
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Muxing Liu
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Haifeng Zhang
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Xiaobo Zheng
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
| | - Ping Wang
- 2 Departments of Pediatrics, and Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, U.S.A
| | - Zhengguang Zhang
- 1 Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China; and
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11
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A multi-column plate adapter provides an economical and versatile high-throughput protein purification system. Protein Expr Purif 2018; 152:84-91. [PMID: 30041031 DOI: 10.1016/j.pep.2018.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/20/2018] [Accepted: 07/20/2018] [Indexed: 11/21/2022]
Abstract
Protein purification is essential in the study of protein structure and function, and the development of novel therapeutics. Many studies require purifying multiple proteins at once, increasing the demand for improved purification methods. We hypothesized that multiple chromatography columns could be interfaced with a multi-well collection plate for rapid and convenient protein purification without the need of expensive instrumentation. As such, we developed a multi-column plate adapter (MCPA), which provides an economical yet versatile and time efficient, high-throughput protein purification system. The MCPA system simultaneously purified milligrams of different proteins under gravity or under vacuum for faster purification. The MCPA handles up to twenty-four 12 mL columns and multiple MCPA's in sequence allow milligram-scale purification of 96 different samples with relative ease. We also used the MCPA system for large scale affinity purification of four proteins, providing sufficient yields and purity for protein crystallization and biophysical characterization. The MCPA system is ideal for optimizing resin type and volume or any other purification parameter by customizing individual columns during the same purification. The high-throughput and versatile nature of this system should prove to be useful in obtaining adequate amounts of protein for subsequent analyses in any laboratory setting.
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12
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Brown T, Brown N, Stollar EJ. Most yeast SH3 domains bind peptide targets with high intrinsic specificity. PLoS One 2018; 13:e0193128. [PMID: 29470497 PMCID: PMC5823434 DOI: 10.1371/journal.pone.0193128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 02/04/2018] [Indexed: 01/07/2023] Open
Abstract
A need exists to develop bioinformatics for predicting differences in protein function, especially for members of a domain family who share a common fold, yet are found in a diverse array of proteins. Many domain families have been conserved over large evolutionary spans and representative genomic data during these periods are now available. This allows a simple method for grouping domain sequences to reveal common and unique/specific binding residues. As such, we hypothesize that sequence alignment analysis of the yeast SH3 domain family across ancestral species in the fungal kingdom can determine whether each member encodes specific information to bind unique peptide targets. With this approach, we identify important specific residues for a given domain as those that show little conservation within an alignment of yeast domain family members (paralogs) but are conserved in an alignment of its direct relatives (orthologs). We find most of the yeast SH3 domain family members have maintained unique amino acid conservation patterns that suggest they bind peptide targets with high intrinsic specificity through varying degrees of non-canonical recognition. For a minority of domains, we predict a less diverse binding surface, likely requiring additional factors to bind targets specifically. We observe that our predictions are consistent with high throughput binding data, which suggests our approach can probe intrinsic binding specificity in any other interaction domain family that is maintained during evolution.
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Affiliation(s)
- Tom Brown
- Math and Computer Science Department, Eastern New Mexico University, Portales, NM, United States of America
| | - Nick Brown
- Portales High School, Portales, NM, United States of America
| | - Elliott J. Stollar
- Physical Sciences Department, Eastern New Mexico University, Portales, NM, United States of America
- * E-mail:
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13
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Charlier C, Bouvignies G, Pelupessy P, Walrant A, Marquant R, Kozlov M, De Ioannes P, Bolik-Coulon N, Sagan S, Cortes P, Aggarwal AK, Carlier L, Ferrage F. Structure and Dynamics of an Intrinsically Disordered Protein Region That Partially Folds upon Binding by Chemical-Exchange NMR. J Am Chem Soc 2017; 139:12219-12227. [PMID: 28780862 DOI: 10.1021/jacs.7b05823] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many intrinsically disordered proteins (IDPs) and protein regions (IDRs) engage in transient, yet specific, interactions with a variety of protein partners. Often, if not always, interactions with a protein partner lead to partial folding of the IDR. Characterizing the conformational space of such complexes is challenging: in solution-state NMR, signals of the IDR in the interacting region become broad, weak, and often invisible, while X-ray crystallography only provides information on fully ordered regions. There is thus a need for a simple method to characterize both fully and partially ordered regions in the bound state of IDPs. Here, we introduce an approach based on monitoring chemical exchange by NMR to investigate the state of an IDR that folds upon binding through the observation of the free state of the protein. Structural constraints for the bound state are obtained from chemical shifts, and site-specific dynamics of the bound state are characterized by relaxation rates. The conformation of the interacting part of the IDR was determined and subsequently docked onto the structure of the folded partner. We apply the method to investigate the interaction between the disordered C-terminal region of Artemis and the DNA binding domain of Ligase IV. We show that we can accurately reproduce the structure of the core of the complex determined by X-ray crystallography and identify a broader interface. The method is widely applicable to the biophysical investigation of complexes of disordered proteins and folded proteins.
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Affiliation(s)
- Cyril Charlier
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Guillaume Bouvignies
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Philippe Pelupessy
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Astrid Walrant
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Rodrigue Marquant
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Mikhail Kozlov
- Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai , 1425 Madison Avenue, New York, New York 10029, United States
| | - Pablo De Ioannes
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai , 1425 Madison Avenue, New York, New York 10029, United States
| | - Nicolas Bolik-Coulon
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Sandrine Sagan
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Patricia Cortes
- Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai , 1425 Madison Avenue, New York, New York 10029, United States.,Department of Molecular, Cellular and Biomedical Science, CUNY School of Medicine, City College of New York , 160 Convent Avenue, New York, New York 10031, United States
| | - Aneel K Aggarwal
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai , 1425 Madison Avenue, New York, New York 10029, United States
| | - Ludovic Carlier
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
| | - Fabien Ferrage
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Université Paris 06, CNRS, PSL Research University , 24 rue Lhomond, Paris 75005, France.,Sorbonne Universités, UPMC Université Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules (LBM) , Paris 75005, France
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14
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Kelil A, Dubreuil B, Levy ED, Michnick SW. Exhaustive search of linear information encoding protein-peptide recognition. PLoS Comput Biol 2017; 13:e1005499. [PMID: 28426660 PMCID: PMC5417721 DOI: 10.1371/journal.pcbi.1005499] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 05/04/2017] [Accepted: 04/04/2017] [Indexed: 11/24/2022] Open
Abstract
High-throughput in vitro methods have been extensively applied to identify linear information that encodes peptide recognition. However, these methods are limited in number of peptides, sequence variation, and length of peptides that can be explored, and often produce solutions that are not found in the cell. Despite the large number of methods developed to attempt addressing these issues, the exhaustive search of linear information encoding protein-peptide recognition has been so far physically unfeasible. Here, we describe a strategy, called DALEL, for the exhaustive search of linear sequence information encoded in proteins that bind to a common partner. We applied DALEL to explore binding specificity of SH3 domains in the budding yeast Saccharomyces cerevisiae. Using only the polypeptide sequences of SH3 domain binding proteins, we succeeded in identifying the majority of known SH3 binding sites previously discovered either in vitro or in vivo. Moreover, we discovered a number of sites with both non-canonical sequences and distinct properties that may serve ancillary roles in peptide recognition. We compared DALEL to a variety of state-of-the-art algorithms in the blind identification of known binding sites of the human Grb2 SH3 domain. We also benchmarked DALEL on curated biological motifs derived from the ELM database to evaluate the effect of increasing/decreasing the enrichment of the motifs. Our strategy can be applied in conjunction with experimental data of proteins interacting with a common partner to identify binding sites among them. Yet, our strategy can also be applied to any group of proteins of interest to identify enriched linear motifs or to exhaustively explore the space of linear information encoded in a polypeptide sequence. Finally, we have developed a webserver located at http://michnick.bcm.umontreal.ca/dalel, offering user-friendly interface and providing different scenarios utilizing DALEL. Here we describe the first strategy for the exhaustive search of the linear information encoding protein-peptide recognition; an approach that has previously been physically unfeasible because the combinatorial space of polypeptide sequences is too vast. The search covers the entire space of sequences with no restriction on motif length or composition, and includes all possible combinations of amino acids at distinct positions of each sequence, as well as positions with correlated preferences for amino acids.
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Affiliation(s)
- Abdellali Kelil
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Benjamin Dubreuil
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Emmanuel D. Levy
- Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, Canada
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Stephen W. Michnick
- Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, Quebec, Canada
- * E-mail:
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15
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Wang Q, Waterhouse N, Feyijinmi O, Dominguez MJ, Martinez LM, Sharp Z, Service R, Bothe JR, Stollar EJ. Development and Application of a High Throughput Protein Unfolding Kinetic Assay. PLoS One 2016; 11:e0146232. [PMID: 26745729 PMCID: PMC4706425 DOI: 10.1371/journal.pone.0146232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 12/15/2015] [Indexed: 11/18/2022] Open
Abstract
The kinetics of folding and unfolding underlie protein stability and quantification of these rates provides important insights into the folding process. Here, we present a simple high throughput protein unfolding kinetic assay using a plate reader that is applicable to the studies of the majority of 2-state folding proteins. We validate the assay by measuring kinetic unfolding data for the SH3 (Src Homology 3) domain from Actin Binding Protein 1 (AbpSH3) and its stabilized mutants. The results of our approach are in excellent agreement with published values. We further combine our kinetic assay with a plate reader equilibrium assay, to obtain indirect estimates of folding rates and use these approaches to characterize an AbpSH3-peptide hybrid. Our high throughput protein unfolding kinetic assays allow accurate screening of libraries of mutants by providing both kinetic and equilibrium measurements and provide a means for in-depth ϕ-value analyses.
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Affiliation(s)
- Qiang Wang
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Nicklas Waterhouse
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Olusegun Feyijinmi
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Matthew J. Dominguez
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Lisa M. Martinez
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Zoey Sharp
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Rachel Service
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
| | - Jameson R. Bothe
- NMRFAM, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Elliott J. Stollar
- Department of Physical Sciences, Eastern New Mexico University, Portales, New Mexico, United States of America
- * E-mail:
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16
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Vulic K, Shoichet MS. Affinity-Based Drug Delivery Systems for Tissue Repair and Regeneration. Biomacromolecules 2014; 15:3867-80. [DOI: 10.1021/bm501084u] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Katarina Vulic
- Department of Chemistry, ‡Department of Chemical
Engineering and Applied Chemistry, §Institute of Biomaterials
and Biomedical Engineering, Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S3E1, Canada
| | - Molly S. Shoichet
- Department of Chemistry, ‡Department of Chemical
Engineering and Applied Chemistry, §Institute of Biomaterials
and Biomedical Engineering, Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario M5S3E1, Canada
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17
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Kelil A, Dubreuil B, Levy ED, Michnick SW. Fast and accurate discovery of degenerate linear motifs in protein sequences. PLoS One 2014; 9:e106081. [PMID: 25207816 PMCID: PMC4160167 DOI: 10.1371/journal.pone.0106081] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 08/01/2014] [Indexed: 11/20/2022] Open
Abstract
Linear motifs mediate a wide variety of cellular functions, which makes their characterization in protein sequences crucial to understanding cellular systems. However, the short length and degenerate nature of linear motifs make their discovery a difficult problem. Here, we introduce MotifHound, an algorithm particularly suited for the discovery of small and degenerate linear motifs. MotifHound performs an exact and exhaustive enumeration of all motifs present in proteins of interest, including all of their degenerate forms, and scores the overrepresentation of each motif based on its occurrence in proteins of interest relative to a background (e.g., proteome) using the hypergeometric distribution. To assess MotifHound, we benchmarked it together with state-of-the-art algorithms. The benchmark consists of 11,880 sets of proteins from S. cerevisiae; in each set, we artificially spiked-in one motif varying in terms of three key parameters, (i) number of occurrences, (ii) length and (iii) the number of degenerate or “wildcard” positions. The benchmark enabled the evaluation of the impact of these three properties on the performance of the different algorithms. The results showed that MotifHound and SLiMFinder were the most accurate in detecting degenerate linear motifs. Interestingly, MotifHound was 15 to 20 times faster at comparable accuracy and performed best in the discovery of highly degenerate motifs. We complemented the benchmark by an analysis of proteins experimentally shown to bind the FUS1 SH3 domain from S. cerevisiae. Using the full-length protein partners as sole information, MotifHound recapitulated most experimentally determined motifs binding to the FUS1 SH3 domain. Moreover, these motifs exhibited properties typical of SH3 binding peptides, e.g., high intrinsic disorder and evolutionary conservation, despite the fact that none of these properties were used as prior information. MotifHound is available (http://michnick.bcm.umontreal.ca or http://tinyurl.com/motifhound) together with the benchmark that can be used as a reference to assess future developments in motif discovery.
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Affiliation(s)
- Abdellali Kelil
- Département de Biochimie and Centre Robert-Cedergren, Bio-Informatique et Génomique, Université de Montréal, Succursale Centre-Ville, Montreal, Quebec, Canada
| | - Benjamin Dubreuil
- Département de Biochimie and Centre Robert-Cedergren, Bio-Informatique et Génomique, Université de Montréal, Succursale Centre-Ville, Montreal, Quebec, Canada
| | - Emmanuel D. Levy
- Département de Biochimie and Centre Robert-Cedergren, Bio-Informatique et Génomique, Université de Montréal, Succursale Centre-Ville, Montreal, Quebec, Canada
- * E-mail: (EDL); (SWM)
| | - Stephen W. Michnick
- Département de Biochimie and Centre Robert-Cedergren, Bio-Informatique et Génomique, Université de Montréal, Succursale Centre-Ville, Montreal, Quebec, Canada
- * E-mail: (EDL); (SWM)
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18
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McGraw J, Tatipelli VK, Feyijinmi O, Traore MC, Eangoor P, Lane S, Stollar EJ. A semi-automated method for purification of milligram quantities of proteins on the QIAcube. Protein Expr Purif 2014; 96:48-53. [PMID: 24508590 DOI: 10.1016/j.pep.2014.01.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/16/2014] [Accepted: 01/27/2014] [Indexed: 11/17/2022]
Abstract
A growing number of studies require the purification of multiple proteins simultaneously and the development of simple economical high-throughput purification methods is essential. We have tested the purification of two related proteins in a variety of conditions to benchmark the semi-automated affinity chromatography method for the QIAcube that we have developed. We find that this new QIAcube method can successfully purify milligram quantities of proteins with minimal user involvement and performs as well as methods based on gravity. The method could easily be adapted to other chromatography resins and should prove to be a versatile method for optimizing protein expression or purification conditions for multiple proteins while obtaining sufficient amounts for subsequent biochemical analyses.
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Affiliation(s)
- J McGraw
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States
| | - V K Tatipelli
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States
| | - O Feyijinmi
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States
| | - M C Traore
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States
| | - P Eangoor
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States
| | - S Lane
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States
| | - E J Stollar
- Eastern New Mexico University, Department of Physical Sciences, Station #33, Portales, NM 88130, United States.
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19
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Structural basis for recognition of the third SH3 domain of full-length R85 (R85FL)/ponsin by ataxin-7. FEBS Lett 2013; 587:2905-11. [PMID: 23892081 DOI: 10.1016/j.febslet.2013.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 06/01/2013] [Accepted: 07/04/2013] [Indexed: 11/22/2022]
Abstract
Ataxin-7 (Atx7) is a component of the nuclear transcription co-activator complex; its polyglutamine (polyQ) expansion may cause nuclear accumulation and recruit numerous proteins to the intranuclear inclusion bodies. Full-length R85 (R85FL) is such a protein sequestered by polyQ-expanded Atx7. Here, we report that Atx7 specifically interacts with the third SH3 domain (SH3C) of R85FL through its second portion of proline-rich region (PRR). NMR structural analysis of the SH3C domain and its complex with PRR revealed that SH3C contains a large negatively charged surface for binding with the RRTR motif of Atx7. Microscopy imaging demonstrated that sequestration of R85FL by the polyQ-expanded Atx7 in cell is mediated by this specific SH3C-PRR interaction, which is implicated in the pathogenesis of spinocerebellar ataxia 7.
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20
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Pakulska MM, Vulic K, Shoichet MS. Affinity-based release of chondroitinase ABC from a modified methylcellulose hydrogel. J Control Release 2013; 171:11-6. [PMID: 23831055 DOI: 10.1016/j.jconrel.2013.06.029] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 06/19/2013] [Accepted: 06/20/2013] [Indexed: 11/25/2022]
Abstract
Chondroitinase ABC (ChABC) is a promising therapeutic for spinal cord injury as it can degrade the glial scar that is detrimental to regrowth and repair. However, the sustained delivery of bioactive ChABC is a challenge requiring highly invasive methods such as intra-spinal injections, insertion of intrathecal catheters, or implantation of delivery vehicles directly into the tissue. ChABC is thermally unstable, further complicating its delivery. Moreover, there are no commercial antibodies available for its detection. To achieve controlled release, we designed an affinity-based system that sustained the release of bioactive ChABC for at least 7days. ChABC was recombinantly expressed as a fusion protein with Src homology domain 3 (SH3) with an N-terminal histidine (HIS) tag and a C-terminal FLAG tag (ChABC-SH3). Protein purification was achieved using a nickel affinity column and, for the first time, direct quantification of ChABC down to 0.1nM was attained using an in-house HIS/FLAG double tag ELISA. The release of active ChABC-SH3 was sustained from a methylcellulose hydrogel covalently modified with an SH3 binding peptide. The rate of release was tunable by varying either the binding strength of the SH3-protein/SH3-peptide pair or the SH3-peptide to SH3-protein ratio. This innovative system has the potential to be used as a platform technology for the release and detection of other proteins that can be expressed using a similar construct.
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Affiliation(s)
- Malgosia M Pakulska
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 1A1, Canada
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21
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Yang Y, de la Roche M, Crawley SW, Li Z, Furmaniak-Kazmierczak E, Côté GP. PakB binds to the SH3 domain of Dictyostelium Abp1 and regulates its effects on cell polarity and early development. Mol Biol Cell 2013; 24:2216-27. [PMID: 23699396 PMCID: PMC3708727 DOI: 10.1091/mbc.e12-12-0883] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Dictyostelium p21-activated kinase B (PakB) phosphorylates and activates class I myosins. PakB colocalizes with myosin I to actin-rich regions of the cell, including macropinocytic and phagocytic cups and the leading edge of migrating cells. Here we show that residues 1-180 mediate the cellular localization of PakB. Yeast two-hybrid and pull-down experiments identify two proline-rich motifs in PakB-1-180 that directly interact with the SH3 domain of Dictyostelium actin-binding protein 1 (dAbp1). dAbp1 colocalizes with PakB to actin-rich regions in the cell. The loss of dAbp1 does not affect the cellular distribution of PakB, whereas the loss of PakB causes dAbp1 to adopt a diffuse cytosolic distribution. Cosedimentation studies show that the N-terminal region of PakB (residues 1-70) binds directly to actin filaments, whereas dAbp1 exhibits only a low affinity for filamentous actin. PakB-1-180 significantly enhances the binding of dAbp1 to actin filaments. When overexpressed in PakB-null cells, dAbp1 completely blocks early development at the aggregation stage, prevents cell polarization, and significantly reduces chemotaxis rates. The inhibitory effects are abrogated by the introduction of a function-blocking mutation into the dAbp1 SH3 domain. We conclude that PakB plays a critical role in regulating the cellular functions of dAbp1, which are mediated largely by its SH3 domain.
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Affiliation(s)
- Yidai Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
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22
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Stollar EJ, Lin H, Davidson AR, Forman-Kay JD. Differential dynamic engagement within 24 SH3 domain: peptide complexes revealed by co-linear chemical shift perturbation analysis. PLoS One 2012; 7:e51282. [PMID: 23251481 PMCID: PMC3520974 DOI: 10.1371/journal.pone.0051282] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/31/2012] [Indexed: 11/18/2022] Open
Abstract
There is increasing evidence for the functional importance of multiple dynamically populated states within single proteins. However, peptide binding by protein-protein interaction domains, such as the SH3 domain, has generally been considered to involve the full engagement of peptide to the binding surface with minimal dynamics and simple methods to determine dynamics at the binding surface for multiple related complexes have not been described. We have used NMR spectroscopy combined with isothermal titration calorimetry to comprehensively examine the extent of engagement to the yeast Abp1p SH3 domain for 24 different peptides. Over one quarter of the domain residues display co-linear chemical shift perturbation (CCSP) behavior, in which the position of a given chemical shift in a complex is co-linear with the same chemical shift in the other complexes, providing evidence that each complex exists as a unique dynamic rapidly inter-converting ensemble. The extent the specificity determining sub-surface of AbpSH3 is engaged as judged by CCSP analysis correlates with structural and thermodynamic measurements as well as with functional data, revealing the basis for significant structural and functional diversity amongst the related complexes. Thus, CCSP analysis can distinguish peptide complexes that may appear identical in terms of general structure and percent peptide occupancy but have significant local binding differences across the interface, affecting their ability to transmit conformational change across the domain and resulting in functional differences.
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Affiliation(s)
- Elliott J. Stollar
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (EJS); (JFK)
| | - Hong Lin
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Alan R. Davidson
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Julie D. Forman-Kay
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (EJS); (JFK)
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23
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The importance of conserved features of yeast actin-binding protein 1 (Abp1p): the conditional nature of essentiality. Genetics 2012; 191:1199-211. [PMID: 22661326 DOI: 10.1534/genetics.112.141739] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Saccharomyces cerevisiae Actin-Binding Protein 1 (Abp1p) is a member of the Abp1 family of proteins, which are in diverse organisms including fungi, nematodes, flies, and mammals. All proteins in this family possess an N-terminal Actin Depolymerizing Factor Homology (ADF-H) domain, a central Proline-Rich Region (PRR), and a C-terminal SH3 domain. In this study, we employed sequence analysis to identify additional conserved features of the family, including sequences rich in proline, glutamic acid, serine, and threonine amino acids (PEST), which are found in all family members examined, and two motifs, Conserved Fungal Motifs 1 and 2 (CFM1 and CFM2), that are conserved in fungi. We also discovered that, similar to its mammalian homologs, Abp1p is phosphorylated in its PRR. This phosphorylation is mediated by the Cdc28p and Pho85p kinases, and it protects Abp1p from proteolysis mediated by the conserved PEST sequences. We provide evidence for an intramolecular interaction between the PRR region and SH3 domain that may be affected by phosphorylation. Although deletion of CFM1 alone caused no detectable phenotype in any genetic backgrounds or conditions tested, deletion of this motif resulted in a significant reduction of growth when it was combined with a deletion of the ADF-H domain. Importantly, this result demonstrates that deletion of highly conserved domains on its own may produce no phenotype unless the domains are assayed in conjunction with deletions of other functionally important elements within the same protein. Detection of this type of intragenic synthetic lethality provides an important approach for understanding the function of individual protein domains or motifs.
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24
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Gorelik M, Davidson AR. Distinct peptide binding specificities of Src homology 3 (SH3) protein domains can be determined by modulation of local energetics across the binding interface. J Biol Chem 2012; 287:9168-77. [PMID: 22277653 DOI: 10.1074/jbc.m111.330753] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The yeast Nbp2p SH3 and Bem1p SH3b domains bind certain target peptides with similar high affinities, yet display vastly different affinities for other targets. To investigate this unusual behavior, we have solved the structure of the Nbp2p SH3-Ste20 peptide complex and compared it with the previously determined structure of the Bem1p SH3b bound to the same peptide. Although the Ste20 peptide interacts with both domains in a structurally similar manner, extensive in vitro studies with domain and peptide mutants revealed large variations in interaction strength across the binding interface of the two complexes. Whereas the Nbp2p SH3 made stronger contacts with the peptide core RXXPXXP motif, the Bem1p SH3b domain made stronger contacts with residues flanking the core motif. Remarkably, this modulation of local binding energetics can explain the distinct and highly nuanced binding specificities of these two domains.
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Affiliation(s)
- Maryna Gorelik
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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Smith GS, De Avila M, Paez PM, Spreuer V, Wills MK, Jones N, Boggs JM, Harauz G. Proline substitutions and threonine pseudophosphorylation of the SH3 ligand of 18.5-kDa myelin basic protein decrease its affinity for the Fyn-SH3 domain and alter process development and protein localization in oligodendrocytes. J Neurosci Res 2012; 90:28-47. [PMID: 21887699 PMCID: PMC3527418 DOI: 10.1002/jnr.22733] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/02/2011] [Accepted: 06/06/2011] [Indexed: 12/28/2022]
Abstract
The developmentally regulated myelin basic proteins (MBPs), which arise from the golli (gene of oligodendrocyte lineage) complex, are highly positively charged, intrinsically disordered, multifunctional proteins having several alternatively spliced isoforms and posttranslational modifications, and they play key roles in myelin compaction. The classic 18.5-kDa MBP isoform has a proline-rich region comprising amino acids 92-99 (murine sequence -T(92)PRTPPPS(99)-) that contains a minimal SH3 ligand domain. We have previously shown that 18.5-kDa MBP binds to several SH3 domains, including that of Fyn, a member of the Src family of tyrosine kinases involved in a number of signaling pathways during CNS development. To determine the physiological role of this binding as well as the role of phosphorylation of Thr92 and Thr95, in the current study we have produced several MBP variants specifically targeting phosphorylation sites and key structural regions of MBP's SH3 ligand domain. Using isothermal titration calorimetry, we have demonstrated that, compared with the wild-type protein, these variants have lower affinity for the SH3 domain of Fyn. Moreover, overexpression of N-terminal-tagged GFP versions in immortalized oligodendroglial N19 and N20.1 cell cultures results in aberrant elongation of membrane processes and increased branching complexity and inhibits the ability of MBP to decrease Ca(2+) influx. Phosphorylation of Thr92 can also cause MBP to traffic to the nucleus, where it may participate in additional protein-protein interactions. Coexpression of MBP with a constitutively active form of Fyn kinase resulted in membrane process elaboration, a phenomenon that was abolished by point amino acid substitutions in MBP's SH3 ligand domain. These results suggest that MBP's SH3 ligand domain plays a key role in intracellular protein interactions in vivo and may be required for proper membrane elaboration of developing oligodendrocytes and, further, that phosphorylation of Thr92 and Thr95 can regulate this function.
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Affiliation(s)
- Graham S.T. Smith
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Miguel De Avila
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Pablo M. Paez
- Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Vilma Spreuer
- Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Melanie K.B. Wills
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Joan M. Boggs
- Molecular Structure and Function, Hospital for Sick Children, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - George Harauz
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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Vulic K, Shoichet MS. Tunable growth factor delivery from injectable hydrogels for tissue engineering. J Am Chem Soc 2011; 134:882-5. [PMID: 22201513 PMCID: PMC3260740 DOI: 10.1021/ja210638x] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Current sustained delivery strategies of protein therapeutics are limited by the fragility of the protein, resulting in minimal quantities of bioactive protein delivered. In order to achieve prolonged release of bioactive protein, an affinity-based approach was designed which exploits the specific binding of the Src homology 3 (SH3) domain with short proline-rich peptides. Specifically, methyl cellulose was modified with SH3-binding peptides (MC-peptide) with either a weak affinity or strong affinity for SH3. The release profile of SH3-rhFGF2 fusion protein from hyaluronan MC-SH3 peptide (HAMC-peptide) hydrogels was investigated and compared to unmodified controls. SH3-rhFGF2 release from HAMC-peptide was extended to 10 days using peptides with different binding affinities compared to the 48 h release from unmodified HAMC. This system is capable of delivering additional proteins with tunable rates of release, while maintaining bioactivity, and thus is broadly applicable.
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Affiliation(s)
- Katarina Vulic
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
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The mammalian actin-binding protein 1 (mAbp1): a novel molecular player in leukocyte biology. Trends Cell Biol 2011; 21:247-55. [DOI: 10.1016/j.tcb.2010.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 11/21/2010] [Accepted: 12/02/2010] [Indexed: 11/18/2022]
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28
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Tonikian R, Xin X, Toret CP, Gfeller D, Landgraf C, Panni S, Paoluzi S, Castagnoli L, Currell B, Seshagiri S, Yu H, Winsor B, Vidal M, Gerstein MB, Bader GD, Volkmer R, Cesareni G, Drubin DG, Kim PM, Sidhu SS, Boone C. Bayesian modeling of the yeast SH3 domain interactome predicts spatiotemporal dynamics of endocytosis proteins. PLoS Biol 2009; 7:e1000218. [PMID: 19841731 PMCID: PMC2756588 DOI: 10.1371/journal.pbio.1000218] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 09/04/2009] [Indexed: 11/23/2022] Open
Abstract
A genome-scale specificity and interaction map for yeast SH3 domain-containing proteins reveal how family members show selective binding to target proteins and predicts the dynamic localization of new candidate endocytosis proteins. SH3 domains are peptide recognition modules that mediate the assembly of diverse biological complexes. We scanned billions of phage-displayed peptides to map the binding specificities of the SH3 domain family in the budding yeast, Saccharomyces cerevisiae. Although most of the SH3 domains fall into the canonical classes I and II, each domain utilizes distinct features of its cognate ligands to achieve binding selectivity. Furthermore, we uncovered several SH3 domains with specificity profiles that clearly deviate from the two canonical classes. In conjunction with phage display, we used yeast two-hybrid and peptide array screening to independently identify SH3 domain binding partners. The results from the three complementary techniques were integrated using a Bayesian algorithm to generate a high-confidence yeast SH3 domain interaction map. The interaction map was enriched for proteins involved in endocytosis, revealing a set of SH3-mediated interactions that underlie formation of protein complexes essential to this biological pathway. We used the SH3 domain interaction network to predict the dynamic localization of several previously uncharacterized endocytic proteins, and our analysis suggests a novel role for the SH3 domains of Lsb3p and Lsb4p as hubs that recruit and assemble several endocytic complexes. Significant diversity exists in protein structure and function, yet certain structural domains are used repeatedly across species to execute similar functions. The SH3 domain is one such common structural domain. It is found in signaling proteins and mediates protein–protein interactions by binding to short peptide sequences generally composed of proline. To investigate both the generality and selectivity of peptide binding by SH3 domains, we examined peptide specificity for almost all SH3 domains encoded within the proteome of the budding yeast, Saccharomyces cerevisiae, using a range of experimental methods. We found that although most of the intrinsic binding specificity for SH3 domains can be summarized by the two previously described canonical binding modes, each individual SH3 domain that we studied utilizes unique features of its cognate ligand to achieve binding selectivity. Moreover, some domains exhibit binding specificities that are distinct from the two canonical classes. We integrated peptide-SH3 domain binding data from three complementary screening techniques using a Bayesian statistical model to generate a protein–protein interaction network for the budding yeast SH3 domain family. This network was highly enriched in endocytosis proteins and their interactions. By examining these interactions in detail, we show that our SH3 domain network can be used to predict the temporal localization of several previously uncharacterized proteins to dynamic complexes that orchestrate the process of endocytosis.
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Affiliation(s)
- Raffi Tonikian
- Terrence Donnelly Center for Cellular and Biomolecular Research, Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Xiaofeng Xin
- Terrence Donnelly Center for Cellular and Biomolecular Research, Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Christopher P. Toret
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - David Gfeller
- Terrence Donnelly Center for Cellular and Biomolecular Research, Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Christiane Landgraf
- Institute of Medical Immunology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Simona Panni
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Department of Cell Biology, University of Calabria, Rende, Italy
| | - Serena Paoluzi
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Luisa Castagnoli
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Bridget Currell
- Department of Molecular Biology, Genentech, South San Francisco, California, United States of America
| | - Somasekar Seshagiri
- Department of Molecular Biology, Genentech, South San Francisco, California, United States of America
| | - Haiyuan Yu
- Center for Cancer Systems Biology (CCSB), Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Barbara Winsor
- CNRS et Université de Strasbourg UMR7156, Génétique moléculaire, Génomique et Microbiologie, Strasbourg, France
| | - Marc Vidal
- Center for Cancer Systems Biology (CCSB), Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mark B. Gerstein
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut, United States of America
- Department of Computer Science, Yale University, New Haven, Connecticut, United States of America
| | - Gary D. Bader
- Terrence Donnelly Center for Cellular and Biomolecular Research, Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Rudolf Volkmer
- Institute of Medical Immunology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- * E-mail: (RV); (GC); (DGD); (PMK); (SSS); (CB)
| | - Gianni Cesareni
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Research Institute “Fondazione Santa Lucia”, Rome, Italy
- * E-mail: (RV); (GC); (DGD); (PMK); (SSS); (CB)
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail: (RV); (GC); (DGD); (PMK); (SSS); (CB)
| | - Philip M. Kim
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- * E-mail: (RV); (GC); (DGD); (PMK); (SSS); (CB)
| | - Sachdev S. Sidhu
- Department of Protein Engineering, Genentech, South San Francisco, California, United States of America
- * E-mail: (RV); (GC); (DGD); (PMK); (SSS); (CB)
| | - Charles Boone
- Terrence Donnelly Center for Cellular and Biomolecular Research, Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (RV); (GC); (DGD); (PMK); (SSS); (CB)
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