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McCullagh M, Zeczycki TN, Kariyawasam CS, Durie CL, Halkidis K, Fitzkee NC, Holt JM, Fenton AW. What is allosteric regulation? Exploring the exceptions that prove the rule! J Biol Chem 2024; 300:105672. [PMID: 38272229 PMCID: PMC10897898 DOI: 10.1016/j.jbc.2024.105672] [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: 06/21/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 01/27/2024] Open
Abstract
"Allosteric" was first introduced to mean the other site (i.e., a site distinct from the active or orthosteric site), an adjective for "regulation" to imply a regulatory outcome resulting from ligand binding at another site. That original idea outlines a system with two ligand-binding events at two distinct locations on a macromolecule (originally a protein system), which defines a four-state energy cycle. An allosteric energy cycle provides a quantifiable allosteric coupling constant and focuses our attention on the unique properties of the four equilibrated protein complexes that constitute the energy cycle. Because many observed phenomena have been referenced as "allosteric regulation" in the literature, the goal of this work is to use literature examples to explore which systems are and are not consistent with the two-ligand thermodynamic energy cycle-based definition of allosteric regulation. We emphasize the need for consistent language so comparisons can be made among the ever-increasing number of allosteric systems. Building on the mutually exclusive natures of an energy cycle definition of allosteric regulation versus classic two-state models, we conclude our discussion by outlining how the often-proposed Rube-Goldberg-like mechanisms are likely inconsistent with an energy cycle definition of allosteric regulation.
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Affiliation(s)
- Martin McCullagh
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Tonya N Zeczycki
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - Chathuri S Kariyawasam
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, USA
| | - Clarissa L Durie
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Konstantine Halkidis
- Department of Hematologic Malignancies and Cellular Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas, USA; Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Nicholas C Fitzkee
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, USA
| | - Jo M Holt
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Aron W Fenton
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas, USA.
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Wang J, Samanta R, Custer G, Look C, Matysiak S, Beckett D. Tuning Allostery through Integration of Disorder to Order with a Residue Network. Biochemistry 2020; 59:790-801. [PMID: 31899864 DOI: 10.1021/acs.biochem.9b01006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In allostery, a signal from one site in a protein is transmitted to a second site to alter its function. Due to its ubiquity in biology and the potential for its exploitation in drug and protein design, the molecular basis of allosteric communication continues to be the subject of intense research. Although allosterically coupled sites are frequently characterized by disorder, how communication between disordered segments occurs remains obscure. Allosteric activation of Escherichia coli BirA dimerization occurs via coupled distant disorder-to-order transitions. In this work, combined structural and computational studies reveal an extensive residue network in BirA. Substitution of several network residues yields large perturbations to allostery. Force distribution analysis reveals that disruptions to the disorder-to-order transitions through amino acid substitution are manifested in shifts in the energy experienced by network residues as well as alterations in packing of an α-helix that plays a critical role in allostery. The combined results reveal a highly distributed allosteric mechanism that is robust to sequence change.
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Affiliation(s)
- Jingheng Wang
- Department of Chemistry & Biochemistry , University of Maryland , College Park , Maryland 20742 , United States
| | - Riya Samanta
- Biophysics Graduate Program , University of Maryland , College Park , Maryland 20742 , United States
| | - Gregory Custer
- Fischell Department of Bioengineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Christopher Look
- Fischell Department of Bioengineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Silvina Matysiak
- Fischell Department of Bioengineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Dorothy Beckett
- Department of Chemistry & Biochemistry , University of Maryland , College Park , Maryland 20742 , United States
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Capdevila DA, Edmonds KA, Campanello GC, Wu H, Gonzalez-Gutierrez G, Giedroc DP. Functional Role of Solvent Entropy and Conformational Entropy of Metal Binding in a Dynamically Driven Allosteric System. J Am Chem Soc 2018; 140:9108-9119. [PMID: 29953213 PMCID: PMC6425489 DOI: 10.1021/jacs.8b02129] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Allostery is a regulatory phenomenon whereby ligand binding to one site influences the binding of the same or a different ligand to another site on a macromolecule. The physical origins of allosteric regulation remain under intense investigation. In general terms, ligand-induced structural changes, perturbations of residue-specific dynamics, and surrounding solvent molecules all potentially contribute to the global energetics of allostery. While the role of solvent is generally well understood in regulatory events associated with major protein structural rearrangements, the degree to which protein dynamics impact solvent degrees of freedom is unclear, particularly in cases of dynamically driven allostery. With the aid of new crystal structures, extensive calorimetric and residue-specific dynamics studies over a range of time scales and temperatures, we dissect for the first time the relative degree to which changes in solvent entropy and residue-specific dynamics impact dynamically driven, allosteric inhibition of DNA binding by Zn in the zinc efflux repressor, CzrA (chromosomal zinc-regulated repressor). We show that non-native residue-specific dynamics in allosterically impaired CzrA mutants are accompanied by significant perturbations in solvent entropy that cannot be predicted from crystal structures. We conclude that functional dynamics are not necessarily restricted to protein residues but involve surface water molecules that may be responding to ligand (Zn)-mediated perturbations in protein internal motions that define the conformational ensemble, rather than major structural rearrangements.
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Affiliation(s)
- Daiana A. Capdevila
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102 United States
| | - Katherine A. Edmonds
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102 United States
| | - Gregory C. Campanello
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102 United States
| | - Hongwei Wu
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102 United States
| | - Giovanni Gonzalez-Gutierrez
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405 United States
| | - David P. Giedroc
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102 United States
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405 United States
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Wang J, Custer G, Beckett D, Matysiak S. Long Distance Modulation of Disorder-to-Order Transitions in Protein Allostery. Biochemistry 2017; 56:4478-4488. [PMID: 28718281 DOI: 10.1021/acs.biochem.7b00496] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Elucidation of the molecular details of allosteric communication between distant sites in a protein is key to understanding and manipulating many biological regulatory processes. Although protein disorder is acknowledged to play an important thermodynamic role in allostery, the molecular mechanisms by which this disorder is harnessed for long distance communication are known for a limited number of systems. Transcription repression by the Escherichia coli biotin repressor, BirA, is allosterically activated by binding of the small molecule effector biotinoyl-5'-AMP. The effector acts by promoting BirA dimerization, which is a prerequisite for sequence-specific binding to the biotin biosynthetic operon operator sequence. A 30 Å distance separates the effector binding and dimerization surfaces in BirA, and previous studies indicate that allostery is mediated, in part, by disorder-to-order transitions on the two coupled sites. In this work, combined experimental and computational methods have been applied to investigate the molecular basis of allosteric communication in BirA. Double-mutant cycle analysis coupled with thermodynamic measurements indicates functional coupling between residues in disordered loops on the two distant surfaces. All atom molecular dynamics simulations reveal that this coupling occurs through long distance reciprocal modulation of the structure and dynamics of disorder-to-order transitions on the two surfaces.
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Affiliation(s)
- Jingheng Wang
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Gregory Custer
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Dorothy Beckett
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Silvina Matysiak
- Fischell Department of Bioengineering and ‡Department of Chemistry & Biochemistry, University of Maryland , College Park, Maryland 20742, United States
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