1
|
Marasco M, Carlomagno T. Specificity and regulation of phosphotyrosine signaling through SH2 domains. JOURNAL OF STRUCTURAL BIOLOGY-X 2020; 4:100026. [PMID: 32647828 PMCID: PMC7337045 DOI: 10.1016/j.yjsbx.2020.100026] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/14/2020] [Accepted: 05/15/2020] [Indexed: 10/26/2022]
Abstract
Phosphotyrosine (pY) signaling is instrumental to numerous cellular processes. pY recognition occurs through specialized protein modules, among which the Src-homology 2 (SH2) domain is the most common. SH2 domains are small protein modules with an invariant fold, and are present in more than a hundred proteins with different function. Here we ask the question of how such a structurally conserved, small protein domain can recognize distinct phosphopeptides with the breath of binding affinity, specificity and kinetic parameters necessary for proper control of pY-dependent signaling and rapid cellular response. We review the current knowledge on structure, thermodynamics and kinetics of SH2-phosphopeptide complexes and conclude that selective phosphopeptide recognition is governed by both structure and dynamics of the SH2 domain, as well as by the kinetics of the binding events. Further studies on the thermodynamic and kinetic properties of SH2-phosphopeptide complexes, beyond their structure, are required to understand signaling regulation.
Collapse
Affiliation(s)
- Michelangelo Marasco
- Leibniz University Hannover, Institute of Organic Chemistry and Centre for Biomolecular Drug Research, Schneiderberg 38, 30167 Hannover, Germany
| | - Teresa Carlomagno
- Leibniz University Hannover, Institute of Organic Chemistry and Centre for Biomolecular Drug Research, Schneiderberg 38, 30167 Hannover, Germany.,Helmholtz Centre for Infection Research, Group of Structural Chemistry, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| |
Collapse
|
2
|
Feng C, Roy A, Post CB. Entropic allostery dominates the phosphorylation-dependent regulation of Syk tyrosine kinase release from immunoreceptor tyrosine-based activation motifs. Protein Sci 2018; 27:1780-1796. [PMID: 30051939 PMCID: PMC6225982 DOI: 10.1002/pro.3489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/05/2018] [Accepted: 07/05/2018] [Indexed: 01/15/2023]
Abstract
Spleen tyrosine kinase (Syk) is an essential player in immune signaling through its ability to couple multiple classes of membrane immunoreceptors to intracellular signaling pathways. Ligand binding leads to the recruitment of Syk to a phosphorylated cytoplasmic region of the receptors called ITAM. Syk binds to ITAM with high-affinity (nanomolar Kd ) via its tandem pair of SH2 domains. The affinity between Syk and ITAM is allosterically regulated by phosphorylation at Y130 in a linker connecting the tandem SH2 domains; when Y130 is phosphorylated, the binding affinity decreases (micromolar Kd ). Previous equilibrium binding studies attribute the increase in the binding free energy to an intra-molecular binding (isomerization) step of the tandem SH2 and ITAM, but a physical basis for the increased free energy is unknown. Here, we provide evidence that Y130 phosphorylation imposes an entropy penalty to isomerization, but surprisingly, has negligible effect on the SH2 binding interactions with ITAM and thus on the binding enthalpy. An analysis of NMR chemical shift differences characterized conformational effects of ITAM binding, and binding thermodynamics were measured from isothermal titration calorimetry. Together the data support a previously unknown mechanism for the basis of regulating protein-protein interactions through protein phosphorylation. The decreased affinity for Syk association with immune receptor ITAMs by Y130 phosphorylation is an allosteric mechanism driven by an increased entropy penalty, likely contributed by conformational disorder in the SH2-SH2 inter-domain structure, while SH2-ITAM binding contacts are not affected, and binding enthalpy is unchanged.
Collapse
Affiliation(s)
- Chao Feng
- Department of Medicinal Chemistry and Molecular PharmacologyMarkey Center for Structural Biology, and Purdue Center for Cancer Research, Purdue UniversityWest Lafayette, Indiana, 47907
| | - Amitava Roy
- Bioinformatics and Computational Biosciences Branch, Rocky Mountain Laboratories, NIAIDNational Institutes of HealthHamilton, Montana, 59840
| | - Carol Beth Post
- Department of Medicinal Chemistry and Molecular PharmacologyMarkey Center for Structural Biology, and Purdue Center for Cancer Research, Purdue UniversityWest Lafayette, Indiana, 47907
| |
Collapse
|
3
|
Höfener M, Heinzlmeir S, Kuster B, Sewald N. Probing SH2-domains using Inhibitor Affinity Purification (IAP). Proteome Sci 2014; 12:41. [PMID: 25067910 PMCID: PMC4110944 DOI: 10.1186/1477-5956-12-41] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 07/09/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Many human diseases are correlated with the dysregulation of signal transduction processes. One of the most important protein interaction domains in the context of signal transduction is the Src homology 2 (SH2) domain that binds phosphotyrosine residues. Hence, appropriate methods for the investigation of SH2 proteins are indispensable in diagnostics and medicinal chemistry. Therefore, an affinity resin for the enrichment of all SH2 proteins in one experiment would be desirable. However, current methods are unable to address all SH2 proteins simultaneously with a single compound or a small array of compounds. RESULTS In order to overcome these limitations for the investigation of this particular protein family in future experiments, a dipeptide-derived probe has been designed, synthesized and evaluated. This probe successfully enriched 22 SH2 proteins from mixed cell lysates which contained 50 SH2 proteins. Further characterization of the SH2 binding properties of the probe using depletion and competition experiments indicated its ability to enrich complexes consisting of SH2 domain bearing regulatory PI3K subunits and catalytic phosphoinositide 3-kinase (PI3K) subunits that have no SH2 domain. CONCLUSION The results make this probe a promising starting point for the development of a mixed affinity resin with complete SH2 protein coverage. Moreover, the additional findings render it a valuable tool for the evaluation of PI3K complex interrupting inhibitors.
Collapse
Affiliation(s)
- Michael Höfener
- Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Stephanie Heinzlmeir
- Chair for Proteomics and Bioanalytics, Center of Life and Food Sciences Weihenstephan, Technische Universität München, Freising, Germany
- German Cancer Consortium (DKTK), Munich, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Bernhard Kuster
- Chair for Proteomics and Bioanalytics, Center of Life and Food Sciences Weihenstephan, Technische Universität München, Freising, Germany
- Center for Integrated Protein Science Munich, Freising, Germany
| | - Norbert Sewald
- Organic and Bioorganic Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| |
Collapse
|
4
|
Backer JM. The regulation of class IA PI 3-kinases by inter-subunit interactions. Curr Top Microbiol Immunol 2011; 346:87-114. [PMID: 20544340 DOI: 10.1007/82_2010_52] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Phosphoinositide 3-kinases (PI 3-kinases) are activated by growth factor and hormone receptors, and regulate cell growth, survival, motility, and responses to changes in nutritional conditions (Engelman et al. 2006). PI 3-kinases have been classified according to their subunit composition and their substrate specificity for phosphoinositides (Vanhaesebroeck et al. 2001). The class IA PI 3-kinase is a heterodimer consisting of one regulatory subunit (p85α, p85β, p55α, p50α, or p55γ) and one 110-kDa catalytic subunit (p110α, β or δ). The Class IB PI 3-kinase is also a dimer, composed of one regulatory subunit (p101 or p87) and one catalytic subunit (p110γ) (Wymann et al. 2003). Class I enzymes will utilize PI, PI[4]P, or PI[4,5]P2 as substrates in vitro, but are thought to primarily produce PI[3,4,5]P3 in cells.The crystal structure of the Class IB PI 3-kinase catalytic subunit p110γ was solved in 1999 (Walker et al. 1999), and crystal or NMR structures of the Class IA p110α catalytic subunit and all of the individual domains of the Class IA p85α regulatory subunit have been solved (Booker et al. 1992; Günther et al. 1996; Hoedemaeker et al. 1999; Huang et al. 2007; Koyama et al. 1993; Miled et al. 2007; Musacchio et al. 1996; Nolte et al. 1996; Siegal et al. 1998). However, a structure of an intact PI 3-kinase enzyme has remained elusive. In spite of this, studies over the past 10 years have lead to important insights into how the enzyme is regulated under physiological conditions. This chapter will specifically discuss the regulation of Class IA PI 3-kinase enzymatic activity, focusing on regulatory interactions between the p85 and p110 subunits and the modulation of these interactions by physiological activators and oncogenic mutations. The complex web of signaling downstream from Class IA PI 3-kinases will be discussed in other chapters in this volume.
Collapse
Affiliation(s)
- Jonathan M Backer
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| |
Collapse
|
5
|
Ward JM, Gorenstein NM, Tian J, Martin SF, Post CB. Constraining binding hot spots: NMR and molecular dynamics simulations provide a structural explanation for enthalpy-entropy compensation in SH2-ligand binding. J Am Chem Soc 2010; 132:11058-70. [PMID: 20698672 DOI: 10.1021/ja910535j] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
NMR spectroscopy and molecular dynamics (MD) simulations were used to probe the structure and dynamics of complexes of three phosphotyrosine-derived peptides with the Src SH2 domain in an effort to uncover a structural explanation for enthalpy-entropy compensation observed in the binding thermodynamics. The series of phosphotyrosine peptide derivatives comprises the natural pYEEI Src SH2 ligand, a constrained mimic, in which the phosphotyrosine (pY) residue is preorganized in the bound conformation for the purpose of gaining an entropic advantage to binding, and a flexible analogue of the constrained mimic. The expected gain in binding entropy of the constrained mimic was realized; however, a balancing loss in binding enthalpy was also observed that could not be rationalized from the crystallographic structures. We examined protein dynamics to evaluate whether the observed enthalpic penalty might be the result of effects arising from altered motions in the complex. (15)N-relaxation studies and positional fluctuations from molecular dynamics indicate that the main-chain dynamics of the protein show little variation among the three complexes. Root mean squared (rms) coordinate deviations vary by less than 1.5 A for all non-hydrogen atoms for the crystal structures and in the ensemble average structures calculated from the simulations. In contrast to this striking similarity in the structures and dynamics, there are a number of large chemical shift differences from residues across the binding interface, but particularly from key Src SH2 residues that interact with pY, the "hot spot" residue, which contributes about one-half of the binding free energy. Rank-order correlations between chemical shifts and ligand binding enthalpy for several pY-binding residues, coupled with available mutagenesis and calorimetric data, suggest that subtle structural perturbations (<1 A) from the conformational constraint of the pY residue sufficiently alter the geometry of enthalpically critical interactions in the binding pocket to cause the loss of binding enthalpy, leading to the observed enthalpy-entropy compensation. We find no evidence to support the premise that enthalpy-entropy compensation is an inherent property and conclude that preorganization of Src SH2 ligand residues involved in binding hot spots may eventuate in suboptimal interactions with the domain. We propose that introducing constraints elsewhere in the ligand could minimize enthalpy-entropy compensation effects. The results illustrate the utility of the NMR chemical shift to highlight small, but energetically significant, perturbations in structure that might otherwise go unnoticed in an apparently rigid protein.
Collapse
Affiliation(s)
- Joshua M Ward
- Department of Medicinal Chemistry, Markey Center for Structural Biology, and Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, USA
| | | | | | | | | |
Collapse
|
6
|
Shekar SC, Wu H, Fu Z, Yip SC, Cahill SM, Girvin ME, Backer JM. Mechanism of Constitutive Phosphoinositide 3-Kinase Activation by Oncogenic Mutants of the p85 Regulatory Subunit. J Biol Chem 2005; 280:27850-5. [PMID: 15932879 DOI: 10.1074/jbc.m506005200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p85/p110 phosphoinositide 3-kinases regulate multiple cell functions and are frequently mutated in human cancer. The p85 regulatory subunit stabilizes and inhibits the p110 catalytic subunit. The minimal fragment of p85 capable of regulating p110 is the N-terminal SH2 domain linked to the coiled-coil iSH2 domain (referred to as p85ni). We have previously proposed that the conformationally rigid iSH2 domain tethers p110 to p85, facilitating regulatory interactions between p110 and the p85 nSH2 domain. In an oncogenic mutant of murine p85, truncation at residue 571 leads to constitutively increased phosphoinositide 3-kinase activity, which has been proposed to result from either loss of an inhibitory Ser-608 autophosphorylation site or altered interactions with cellular regulatory factors. We have examined this mutant (referred to as p65) in vitro and find that p65 binds but does not inhibit p110, leading to constitutive p110 activity. This activated phenotype is observed with recombinant proteins in the absence of cellular factors. Importantly, this effect is also produced by truncating p85ni at residue 571. Thus, the phenotype is not because of loss of the Ser-608 inhibitory autophosphorylation site, which is not present in p85ni. To determine the structural basis for the phenotype of p65, we used a broadly applicable spin label/NMR approach to define the positioning of the nSH2 domain relative to the iSH2 domain. We found that one face of the nSH2 domain packs against the 581-593 region of the iSH2 domain. The loss of this interaction in the truncated p65 would remove the orienting constraints on the nSH2 domain, leading to a loss of p110 regulation by the nSH2. Based on these findings, we propose a general model for oncogenic mutants of p85 and p110 in which disruption of nSH2-p110 regulatory contacts leads to constitutive p110 activity.
Collapse
Affiliation(s)
- S Chandra Shekar
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | | | | | | | | | |
Collapse
|
7
|
Mittag T, Schaffhausen B, Günther UL. Tracing kinetic intermediates during ligand binding. J Am Chem Soc 2004; 126:9017-23. [PMID: 15264834 DOI: 10.1021/ja0392519] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Specific protein-ligand interactions are central to biological control. Although structure determination provides important insight into these interactions, it does not address dynamic events that occur during binding. While many biophysical techniques can provide a global view of these dynamics, NMR can be used to derive site-specific dynamics at atomic resolution. Here we show how NMR line shapes can be analyzed to identify long-lived kinetic intermediates for individual amino acids on the reaction pathway for a protein-ligand interaction. Different ligands cause different intermediate states. The lifetimes of these states determine the specificity of binding. This novel approach provides a direct, site-specific visualization of the kinetic mechanism of protein-ligand interactions.
Collapse
Affiliation(s)
- Tanja Mittag
- J. W. Goethe University, Frankfurt, Center for Biomolecular Magnetic Resonance, Institute of Biophysical Chemistry, Biocenter N230, Marie-Curie-Str. 9, 60439 Frankfurt, Germany
| | | | | |
Collapse
|
8
|
Abstract
In this chapter, we have described the biophysical investigations which have dissected the mechanisms of SH2 domain function. Due to nearly a decade and a half of investigation on SH2 domains, much about their binding mechanism has been characterized. SH2 domains have been found to have a positively charged binding cavity, largely conserved between different SH2 domains, which coordinates binding of the pTyr in the target. The ionic interactions between this pocket and the pTyr, in particular, between Arg beta B5 and the phosphate, provide the majority of the binding energy stabilizing SH2 domain-target interactions. The specificity in SH2 domain-target interactions emanates most often from the interactions between the residues C-terminal to the pTyr in the target and the specificity determining residues in the C-terminal half of the SH2 domain. However, the interactions in the specificity determining region of SH2 domains are weak, and hence single SH2 domains show only a modest level of specificity for tyrosine phosphorylated targets. Greater specificity in SH2 domain-containing protein-tyrosine phosphorylated target interactions can be achieved by placing SH2 domains in tandem (as is often found) or possibly through specific localization of SH2 domain-containing proteins within the cell. Although a relatively good understanding of how SH2 domains function in isolation has been obtained, the ways in which SH2 domain binding is coupled to allosteric transmission of signals in larger SH2 domain-containing proteins are still not clear. Hence, the future should bring further investigations of the mechanisms by which SH2 domain ligation alters the enzymatic activity and cellular localization of SH2 domain-containing proteins.
Collapse
Affiliation(s)
- J Michael Bradshaw
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|
9
|
Fu Z, Aronoff-Spencer E, Backer JM, Gerfen GJ. The structure of the inter-SH2 domain of class IA phosphoinositide 3-kinase determined by site-directed spin labeling EPR and homology modeling. Proc Natl Acad Sci U S A 2003; 100:3275-80. [PMID: 12629217 PMCID: PMC152282 DOI: 10.1073/pnas.0535975100] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phosphoinositide (PI) 3-kinases catalyze the phosphorylation of the D3 position of the inositol ring of PI, and its phosphorylated derivatives and play important roles in many intracellular signal transducing pathways. Class IA PI3-kinases contain distinct regulatory (p85) and catalytic (p110) subunits. p110 is stabilized and inhibited by constitutive association with p85, and is disinhibited when the SH2 domains of p85 bind to tyrosyl-phosphorylated proteins. Because the two subunits do not dissociate, disinhibition of p110 presumably occurs by an allosteric mechanism. To explore the means by which p85 regulates the activity of p110, structures of the inter-SH2 domain of p85 were determined with and without phosphopeptide by using a combination of site directed spin labeling EPR and homology modeling and molecular dynamics. The inter-SH2 domain is assigned as a rigid anti-parallel coiled-coil whose primary function is to bind p110, facilitating inhibition of p110 by the N-terminal SH2 domain of p85.
Collapse
Affiliation(s)
- Zheng Fu
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | | | | |
Collapse
|
10
|
Surdo PL, Bottomley MJ, Arcaro A, Siegal G, Panayotou G, Sankar A, Gaffney PR, Riley AM, Potter BV, Waterfield MD, Driscoll PC. Structural and biochemical evaluation of the interaction of the phosphatidylinositol 3-kinase p85alpha Src homology 2 domains with phosphoinositides and inositol polyphosphates. J Biol Chem 1999; 274:15678-85. [PMID: 10336465 DOI: 10.1074/jbc.274.22.15678] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Src homology 2 (SH2) domains exist in many intracellular proteins and have well characterized roles in signal transduction. SH2 domains bind to phosphotyrosine (Tyr(P))-containing proteins. Although tyrosine phosphorylation is essential for protein-SH2 domain interactions, the binding specificity also derives from sequences C-terminal to the Tyr(P) residue. The high affinity and specificity of this interaction is critical for precluding aberrant cross-talk between signaling pathways. The p85alpha subunit of phosphoinositide 3-kinase (PI 3-kinase) contains two SH2 domains, and it has been proposed that in competition with Tyr(P) binding they may also mediate membrane attachment via interactions with phosphoinositide products of PI 3-kinase. We used nuclear magnetic resonance spectroscopy and biosensor experiments to investigate interactions between the p85alpha SH2 domains and phosphoinositides or inositol polyphosphates. We reported previously a similar approach when demonstrating that some pleckstrin homology domains show binding specificity for distinct phosphoinositides (Salim, K., Bottomley, M. J., Querfurth, E., Zvelebil, M. J., Gout, I., Scaife, R., Margolis, R. L., Gigg, R., Smith, C. I., Driscoll, P. C., Waterfield, M. D., and Panayotou, G. (1996) EMBO J. 15, 6241-6250). However, neither SH2 domain exhibited binding specificity for phosphoinositides in phospholipid bilayers. We show that the p85alpha SH2 domain Tyr(P) binding pockets indiscriminately accommodate phosphoinositides and inositol polyphosphates. Binding of the SH2 domains to Tyr(P) peptides was only poorly competed for by phosphoinositides or inositol polyphosphates. We conclude that these ligands do not bind p85alpha SH2 domains with high affinity or specificity. Moreover, we observed that although wortmannin blocks PI 3-kinase activity in vivo, it does not affect the ability of tyrosine-phosphorylated proteins to bind to p85alpha. Consequently phosphoinositide products of PI 3-kinase are unlikely to regulate signaling through p85alpha SH2 domains.
Collapse
Affiliation(s)
- P L Surdo
- Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Lyubarskaya YV, Carr SA, Dunnington D, Prichett WP, Fisher SM, Appelbaum ER, Jones CS, Karger BL. Screening for high-affinity ligands to the Src SH2 domain using capillary isoelectric focusing-electrospray ionization ion trap mass spectrometry. Anal Chem 1998; 70:4761-70. [PMID: 9844572 DOI: 10.1021/ac980330q] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A solution-based microscale approach for determination of high-affinity noncovalent complexes from mixtures of compounds is presented, based on capillary isoelectric focusing coupled on-line with electrospray ionization ion trap mass spectrometry. The studies are performed using the src homology 2 domain and tyrosine-phosphorylated peptide ligands as a model system. Tight complexes are formed in solution, preconcentrated up to 2 orders of magnitude and separated on the basis of their isoelectric points. The complexes are then dissociated in the mass spectrometer and the freed ligands identified. Picomole or less amounts of protein reagent are consumed per experiment. Structural information for the ligands involved in tight complex formation may be obtained using the MSn capabilities of the ion trap. The methodology can potentially be used to screen rapidly combinatorial mixtures of compounds for high-affinity ligands.
Collapse
Affiliation(s)
- Y V Lyubarskaya
- Barnett Institute, Northeastern University, Boston, Massachusetts 02115, USA
| | | | | | | | | | | | | | | |
Collapse
|