1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Bai Y, Jiao W, Vörster J, Parker EJ. Conformational interdomain flexibility in a bacterial α-isopropylmalate synthase is necessary for leucine biosynthesis. J Biol Chem 2022; 299:102789. [PMID: 36509144 PMCID: PMC9860122 DOI: 10.1016/j.jbc.2022.102789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
α-Isopropylmalate synthase (IPMS) catalyzes the first step in leucine (Leu) biosynthesis and is allosterically regulated by the pathway end product, Leu. IPMS is a dimeric enzyme with each chain consisting of catalytic, accessory, and regulatory domains, with the accessory and regulatory domains of each chain sitting adjacent to the catalytic domain of the other chain. The IPMS crystal structure shows significant asymmetry because of different relative domain conformations in each chain. Owing to the challenges posed by the dynamic and asymmetric structures of IPMS enzymes, the molecular details of their catalytic and allosteric mechanisms are not fully understood. In this study, we have investigated the allosteric feedback mechanism of the IPMS enzyme from the bacterium that causes meningitis, Neisseria meningitidis (NmeIPMS). By combining molecular dynamics simulations with small-angle X-ray scattering, mutagenesis, and heterodimer generation, we demonstrate that Leu-bound NmeIPMS is in a rigid conformational state stabilized by asymmetric interdomain polar interactions. Furthermore, we found removing these polar interactions by mutagenesis impaired the allosteric response without compromising Leu binding. Our results suggest that the allosteric inhibition of NmeIPMS is achieved by restricting the flexibility of the accessory and regulatory domains, demonstrating that significant conformational flexibility is required for catalysis.
Collapse
Affiliation(s)
- Yu Bai
- Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand,Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Wanting Jiao
- Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand,Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Jan Vörster
- School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Emily J. Parker
- Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand,Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand,For correspondence: Emily J. Parker
| |
Collapse
|
3
|
H/D Exchange Characterization of Silent Coupling: Entropy-Enthalpy Compensation in Allostery. Biophys J 2020; 118:2966-2978. [PMID: 32479745 DOI: 10.1016/j.bpj.2020.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 11/24/2022] Open
Abstract
The allosteric coupling constant in K-type allosteric systems is defined as a ratio of the binding of substrate in the absence of effector to the binding of the substrate in the presence of a saturating concentration of effector. As a result, the coupling constant is itself an equilibrium value comprised of a ΔH and a TΔS component. In the scenario in which TΔS completely compensates ΔH, no allosteric influence of effector binding on substrate affinity is observed. However, in this "silent coupling" scenario, the presence of effector causes a change in the ΔH associated with substrate binding. A suggestion has now been made that "silent modulators" are ideal drug leads because they can be modified to act as either allosteric activators or inhibitors. Any attempt to rationally design the effector to be an allosteric activator or inhibitor is likely to be benefitted by knowledge of the mechanism that gives rise to coupling. Hydrogen/deuterium exchange with mass spectrometry detection has now been used to identify regions of proteins that experience conformational and/or dynamic changes in the allosteric regulation. Here, we demonstrate the expected temperature dependence of the allosteric regulation of rabbit muscle pyruvate kinase by Ala to demonstrate that this effector reduces substrate (phosphoenolpyruvate) affinity at 35°C and at 10°C but is silent at intermediate temperatures. We then explore the use of hydrogen/deuterium exchange with mass spectrometry to evaluate the areas of the protein that are modified in the mechanism that gives rise to the silent coupling between Ala and phosphoenolpyruvate. Many of the peptide regions of the protein identified as changing in this silent system (Ala as the effector) were included in changes previously identified for allosteric inhibition by Phe.
Collapse
|
4
|
Yoshida A, Yoshida M, Kuzuyama T, Nishiyama M, Kosono S. Protein acetylation on 2-isopropylmalate synthase from Thermus thermophilus HB27. Extremophiles 2019; 23:377-388. [PMID: 30919057 DOI: 10.1007/s00792-019-01090-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/14/2019] [Indexed: 12/23/2022]
Abstract
Protein lysine Nε-acetylation is one of the important factors regulating cellular metabolism. We performed a proteomic analysis to identify acetylated proteins in the extremely thermophilic bacterium, Thermus thermophilus HB27. A total of 335 unique acetylated lysine residues, including many metabolic enzymes and ribosomal proteins, were identified in 208 proteins. Enzymes involved in amino acid metabolism were the most abundant among acetylated metabolic proteins. 2-Isopropylmalate synthase (IPMS), which catalyzes the first step in leucine biosynthesis, was acetylated at four lysine residues. Acetylation-mimicking mutations at Lys332 markedly decreased IPMS activity in vitro, suggesting that Lys332, which is located in subdomain II, plays a regulatory role in IPMS activity. We also investigated the acetylation-deacetylation mechanism of IPMS and revealed that it was acetylated non-enzymatically by acetyl-CoA and deacetylated enzymatically by TT_C0104. The present results suggest that leucine biosynthesis is regulated by post-translational protein modifications, in addition to feedback inhibition/repression, and that metabolic enzymes are regulated by protein acetylation in T. thermophilus.
Collapse
Affiliation(s)
- Ayako Yoshida
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Minoru Yoshida
- RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan.,Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Tomohisa Kuzuyama
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Makoto Nishiyama
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Saori Kosono
- Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. .,RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan. .,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| |
Collapse
|
5
|
Distinct mechanisms of substrate selectivity in the DRE-TIM metallolyase superfamily: A role for the LeuA dimer regulatory domain. Arch Biochem Biophys 2019; 664:1-8. [DOI: 10.1016/j.abb.2019.01.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/14/2019] [Accepted: 01/16/2019] [Indexed: 11/20/2022]
|
6
|
Yoshida A, Kosono S, Nishiyama M. Characterization of two 2-isopropylmalate synthase homologs from Thermus thermophilus HB27. Biochem Biophys Res Commun 2018; 501:465-470. [DOI: 10.1016/j.bbrc.2018.05.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 05/02/2018] [Indexed: 10/16/2022]
|
7
|
Sternisha SM, Liu P, Marshall AG, Miller BG. Mechanistic Origins of Enzyme Activation in Human Glucokinase Variants Associated with Congenital Hyperinsulinism. Biochemistry 2018; 57:1632-1639. [PMID: 29425029 DOI: 10.1021/acs.biochem.8b00022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human glucokinase (GCK) acts as the body's primary glucose sensor and plays a critical role in glucose homeostatic maintenance. Gain-of-function mutations in gck produce hyperactive enzyme variants that cause congenital hyperinsulinism. Prior biochemical and biophysical studies suggest that activated disease variants can be segregated into two mechanistically distinct classes, termed α-type and β-type. Steady-state viscosity variation studies indicate that the kcat values of wild-type GCK and an α-type variant are partially diffusion-limited, whereas the kcat value of a β-type variant is viscosity-independent. Transient-state chemical quench-flow analyses demonstrate that wild-type GCK and the α-type variant display burst kinetics, whereas the β-type variant lacks a burst phase. Comparative hydrogen-deuterium exchange mass spectrometry of unliganded enzymes demonstrates that a disordered active site loop, which folds upon binding of glucose, is protected from exchange in the α-type variant. The α-type variant also displays an increased level of exchange within a β-strand located near the enzyme's hinge region, which becomes more solvent-exposed upon glucose binding. In contrast, β-type activation causes no substantial difference in global or local exchange relative to that of unliganded, wild-type GCK. Together, these results demonstrate that α-type activation results from a shift in the conformational ensemble of unliganded GCK toward a state resembling the glucose-bound conformation, whereas β-type activation is attributable to an accelerated rate of product release. This work elucidates the molecular basis of naturally occurring, activated GCK disease variants and provides insight into the structural and dynamic origins of GCK's unique kinetic cooperativity.
Collapse
Affiliation(s)
- Shawn M Sternisha
- Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States
| | - Peilu Liu
- Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States
| | - Alan G Marshall
- Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States.,Ion Cyclotron Resonance Program , The National High Magnetic Field Laboratory , Tallahassee , Florida 32310 , United States
| | - Brian G Miller
- Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States
| |
Collapse
|
8
|
Offenbacher AR, Hu S, Poss EM, Carr CAM, Scouras AD, Prigozhin DM, Iavarone AT, Palla A, Alber T, Fraser JS, Klinman JP. Hydrogen-Deuterium Exchange of Lipoxygenase Uncovers a Relationship between Distal, Solvent Exposed Protein Motions and the Thermal Activation Barrier for Catalytic Proton-Coupled Electron Tunneling. ACS CENTRAL SCIENCE 2017; 3:570-579. [PMID: 28691068 PMCID: PMC5492416 DOI: 10.1021/acscentsci.7b00142] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Indexed: 05/11/2023]
Abstract
Defining specific pathways for efficient heat transfer from protein-solvent interfaces to their active sites represents one of the compelling and timely challenges in our quest for a physical description of the origins of enzyme catalysis. Enzymatic hydrogen tunneling reactions constitute excellent systems in which to validate experimental approaches to this important question, given the inherent temperature independence of quantum mechanical wave function overlap. Herein, we present the application of hydrogen-deuterium exchange coupled to mass spectrometry toward the spatial resolution of protein motions that can be related to an enzyme's catalytic parameters. Employing the proton-coupled electron transfer reaction of soybean lipoxygenase as proof of principle, we first corroborate the impact of active site mutations on increased local flexibility and, second, uncover a solvent-exposed loop, 15-34 Å from the reactive ferric center whose temperature-dependent motions are demonstrated to mirror the enthalpic barrier for catalytic C-H bond cleavage. A network that connects this surface loop to the active site is structurally identified and supported by changes in kinetic parameters that result from site-specific mutations.
Collapse
Affiliation(s)
- Adam R. Offenbacher
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Shenshen Hu
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Erin M. Poss
- Department
of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, California 94158, United States
| | - Cody A. M. Carr
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Alexander D. Scouras
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
| | - Daniil M. Prigozhin
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
| | - Anthony T. Iavarone
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
| | - Ali Palla
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Tom Alber
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
| | - James S. Fraser
- Department
of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, California 94158, United States
| | - Judith P. Klinman
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, United States
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
- E-mail:
| |
Collapse
|
9
|
Tang Q, Fenton AW. Whole-protein alanine-scanning mutagenesis of allostery: A large percentage of a protein can contribute to mechanism. Hum Mutat 2017; 38:1132-1143. [PMID: 28407397 DOI: 10.1002/humu.23231] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/17/2017] [Accepted: 04/09/2017] [Indexed: 11/09/2022]
Abstract
Many studies of allosteric mechanisms use limited numbers of mutations to test whether residues play "key" roles. However, if a large percentage of the protein contributes to allosteric function, mutating any residue would have a high probability of modifying allostery. Thus, a predicted mechanism that is dependent on only a few residues could erroneously appear to be supported. We used whole-protein alanine-scanning mutagenesis to determine which amino acid sidechains of human liver pyruvate kinase (hL-PYK; approved symbol PKLR) contribute to regulation by fructose-1,6-bisphosphate (Fru-1,6-BP; activator) and alanine (inhibitor). Each nonalanine/nonglycine residue of hL-PYK was mutated to alanine to generate 431 mutant proteins. Allosteric functions in active proteins were quantified by following substrate affinity over a concentration range of effectors. Results show that different residues contribute to the two allosteric functions. Only a small fraction of mutated residues perturbed inhibition by alanine. In contrast, a large percentage of mutated residues influenced activation by Fru-1,6-BP; inhibition by alanine is not simply the reverse of activation by Fru-1,6-BP. Moreover, the results show that Fru-1,6-BP activation would be extremely difficult to elucidate using a limited number of mutations. Additionally, this large mutational data set will be useful to train and test computational algorithms aiming to predict allosteric mechanisms.
Collapse
Affiliation(s)
- Qingling Tang
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Aron W Fenton
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| |
Collapse
|
10
|
Carlson GM, Fenton AW. What Mutagenesis Can and Cannot Reveal About Allostery. Biophys J 2017; 110:1912-23. [PMID: 27166800 DOI: 10.1016/j.bpj.2016.03.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/24/2016] [Accepted: 03/14/2016] [Indexed: 10/21/2022] Open
Abstract
Allosteric regulation of protein function is recognized to be widespread throughout biology; however, knowledge of allosteric mechanisms, the molecular changes within a protein that couple one binding site to another, is limited. Although mutagenesis is often used to probe allosteric mechanisms, we consider herein what the outcome of a mutagenesis study truly reveals about an allosteric mechanism. Arguably, the best way to evaluate the effects of a mutation on allostery is to monitor the allosteric coupling constant (Qax), a ratio of the substrate binding constants in the absence versus presence of an allosteric effector. A range of substitutions at a given residue position in a protein can reveal when a particular substitution causes gain-of-function, which addresses a key challenge in interpreting mutation-dependent changes in the magnitude of Qax. Thus, whole-protein mutagenesis studies offer an acceptable means of identifying residues that contribute to an allosteric mechanism. With this focus on monitoring Qax, and keeping in mind the equilibrium nature of allostery, we consider alternative possibilities for what an allosteric mechanism might be. We conclude that different possible mechanisms (rotation-of-solid-domains, movement of secondary structure, side-chain repacking, changes in dynamics, etc.) will result in different findings in whole-protein mutagenesis studies.
Collapse
Affiliation(s)
- Gerald M Carlson
- Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Aron W Fenton
- Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas.
| |
Collapse
|
11
|
Chen J, Zhang Q, Ren W, Li W. Piecing Together the Allosteric Patterns of Chaperonin GroEL. J Phys Chem B 2017; 121:4987-4996. [PMID: 28430446 DOI: 10.1021/acs.jpcb.7b01992] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite considerable efforts, elucidating the allostery of large macromolecular assemblies at a molecular level in solution remains technically challenging due to its structural complexity. Here we have employed an approach combining amide backbone hydrogen/deuterium exchange coupled with mass spectrometry, fluorescence spectroscopy, and molecular simulations to characterize allosteric patterns of chaperonin GroEL, an ∼800 kDa tetradecamer from E. coli. Using available crystal structures of GroEL, we quantitatively map out GroEL allosteric changes in solution by resolving exchange behaviors of 133 overlapping proteolytic peptides with more than 95% sequence coverage. This comprehensive analysis gives a refined resolution down to five residues to pilot the GroEL allosteric determinants, of which the localized dynamics is monitored by tryptophan-mutated GroEL. Furthermore, the GroEL conformational transition is evaluated by molecular dynamics simulations with an atomic-interaction-based coarse-grained model. Collectively, we provide a practical methodology to analyze GroEL allostery in solution.
Collapse
Affiliation(s)
- Jin Chen
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences , Okazaki 444-8787, Japan
| | - Qian Zhang
- Department of Chemistry, Florida State University , Tallahassee, Florida 32306, United States
| | - Weitong Ren
- National Laboratory of Solid State Microstructure, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Wenfei Li
- National Laboratory of Solid State Microstructure, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| |
Collapse
|
12
|
Abstract
Allosteric transition, defined as conformational changes induced by ligand binding, is one of the fundamental properties of proteins. Allostery has been observed and characterized in many proteins, and has been recently utilized to control protein function via regulation of protein activity. Here, we review the physical and evolutionary origin of protein allostery, as well as its importance to protein regulation, drug discovery, and biological processes in living systems. We describe recently developed approaches to identify allosteric pathways, connected sets of pairwise interactions that are responsible for propagation of conformational change from the ligand-binding site to a distal functional site. We then present experimental and computational protein engineering approaches for control of protein function by modulation of allosteric sites. As an example of application of these approaches, we describe a synergistic computational and experimental approach to rescue the cystic-fibrosis-associated protein cystic fibrosis transmembrane conductance regulator, which upon deletion of a single residue misfolds and causes disease. This example demonstrates the power of allosteric manipulation in proteins to both elucidate mechanisms of molecular function and to develop therapeutic strategies that rescue those functions. Allosteric control of proteins provides a tool to shine a light on the complex cascades of cellular processes and facilitate unprecedented interrogation of biological systems.
Collapse
Affiliation(s)
- Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina , Chapel Hill, North Carolina 27599, United States
| |
Collapse
|
13
|
Zhang Z, Wu J, Lin W, Wang J, Yan H, Zhao W, Ma J, Ding J, Zhang P, Zhao GP. Subdomain II of α-isopropylmalate synthase is essential for activity: inferring a mechanism of feedback inhibition. J Biol Chem 2014; 289:27966-78. [PMID: 25128527 DOI: 10.1074/jbc.m114.559716] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The committed step of leucine biosynthesis, converting acetyl-CoA and α-ketoisovalerate into α-isopropylmalate, is catalyzed by α-isopropylmalate synthase (IPMS), an allosteric enzyme subjected to feedback inhibition by the end product L-leucine. We characterized the short form IPMS from Leptospira biflexa (LbIPMS2), which exhibits a catalytic activity comparable with that of the long form IPMS (LbIPMS1) and has a similar N-terminal domain followed by subdomain I and subdomain II but lacks the whole C-terminal regulatory domain. We found that partial deletion of the regulatory domain of LbIPMS1 resulted in a loss of about 50% of the catalytic activity; however, when the regulatory domain was deleted up to Arg-385, producing a protein that is almost equivalent to the intact LbIPMS2, about 90% of the activity was maintained. Moreover, in LbIPMS2 or LbIPMS1, further deletion of several residues from the C terminus of subdomain II significantly impaired or completely abolished the catalytic activity, respectively. These results define a complete and independently functional catalytic module of IPMS consisting of both the N-terminal domain and the two subdomains. Structural comparison of LbIPMS2 and the Mycobacterium tuberculosis IPMS revealed two different conformations of subdomain II that likely represent two substrate-binding states related to cooperative catalysis. The biochemical and structural analyses together with the previously published hydrogen-deuterium exchange data led us to propose a conformation transition mechanism for feedback inhibition mediated by subdomains I and II that might associated with alteration of the binding affinity toward acetyl-CoA.
Collapse
Affiliation(s)
- Zilong Zhang
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and Shanghai International Travel Healthcare Center, Shanghai Entry-Exit Inspection and Quarantine Bureau, Shanghai 200335, China
| | - Jian Wu
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Wei Lin
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Jin Wang
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Han Yan
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Wei Zhao
- Key Laboratory of Medical Molecular Virology affiliated to the Ministries of Education and Health, Shanghai Medical College, and Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jun Ma
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Jianping Ding
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China,
| | - Peng Zhang
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China,
| | - Guo-Ping Zhao
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and Key Laboratory of Medical Molecular Virology affiliated to the Ministries of Education and Health, Shanghai Medical College, and Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China, Shanghai-Ministry of Science and Technology Key Laboratory for Health and Disease Genomics, Chinese National Human Genome Center, Shanghai 201203, China, Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong Special Administrative Region 999077, China, and
| |
Collapse
|
14
|
Kumar G, Frantom PA. Evolutionarily Distinct Versions of the Multidomain Enzyme α-Isopropylmalate Synthase Share Discrete Mechanisms of V-Type Allosteric Regulation. Biochemistry 2014; 53:4847-56. [DOI: 10.1021/bi500702u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Garima Kumar
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Patrick A. Frantom
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| |
Collapse
|
15
|
Casey AK, Hicks MA, Johnson JL, Babbitt PC, Frantom PA. Mechanistic and bioinformatic investigation of a conserved active site helix in α-isopropylmalate synthase from Mycobacterium tuberculosis, a member of the DRE-TIM metallolyase superfamily. Biochemistry 2014; 53:2915-25. [PMID: 24720347 PMCID: PMC4025573 DOI: 10.1021/bi500246z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The characterization of functionally diverse enzyme superfamilies provides the opportunity to identify evolutionarily conserved catalytic strategies, as well as amino acid substitutions responsible for the evolution of new functions or specificities. Isopropylmalate synthase (IPMS) belongs to the DRE-TIM metallolyase superfamily. Members of this superfamily share common active site elements, including a conserved active site helix and an HXH divalent metal binding motif, associated with stabilization of a common enolate anion intermediate. These common elements are overlaid by variations in active site architecture resulting in the evolution of a diverse set of reactions that include condensation, lyase/aldolase, and carboxyl transfer activities. Here, using IPMS, an integrated biochemical and bioinformatics approach has been utilized to investigate the catalytic role of residues on an active site helix that is conserved across the superfamily. The construction of a sequence similarity network for the DRE-TIM metallolyase superfamily allows for the biochemical results obtained with IPMS variants to be compared across superfamily members and within other condensation-catalyzing enzymes related to IPMS. A comparison of our results with previous biochemical data indicates an active site arginine residue (R80 in IPMS) is strictly required for activity across the superfamily, suggesting that it plays a key role in catalysis, most likely through enolate stabilization. In contrast, differential results obtained from substitution of the C-terminal residue of the helix (Q84 in IPMS) suggest that this residue plays a role in reaction specificity within the superfamily.
Collapse
Affiliation(s)
- Ashley K Casey
- Department of Chemistry, The University of Alabama , 250 Hackberry Lane, Tuscaloosa, Alabama 35406, United States
| | | | | | | | | |
Collapse
|
16
|
Modifying the determinants of α-ketoacid substrate selectivity inmycobacterium tuberculosisα-isopropylmalate synthase. FEBS Lett 2014; 588:1603-7. [DOI: 10.1016/j.febslet.2014.02.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 02/22/2014] [Accepted: 02/24/2014] [Indexed: 11/21/2022]
|
17
|
O'Brien JP, Mayberry LK, Murphy PA, Browning KS, Brodbelt JS. Evaluating the conformation and binding interface of cap-binding proteins and complexes via ultraviolet photodissociation mass spectrometry. J Proteome Res 2013; 12:5867-77. [PMID: 24200290 DOI: 10.1021/pr400869u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We report the structural analysis of cap-binding proteins using a chemical probe/ultraviolet photodissociation (UVPD) mass spectrometry strategy for evaluating solvent accessibility of proteins. Our methodology utilized a chromogenic probe (NN) to probe the exposed amine residues of wheat eukaryotic translation initiation factor 4E (eIF4E), eIF4E in complex with a fragment of eIF4G ("mini-eIF4F"), eIF4E in complex with full length eIF4G, and the plant specific cap-binding protein, eIFiso4E. Structural changes of eIF4E in the absence and presence of excess dithiothreitol and in complex with a fragment of eIF4G or full-length eIF4G are mapped. The results indicate that there are particular lysine residues whose environment changes in the presence of dithiothreitol or eIF4G, suggesting that changes in the structure of eIF4E are occurring. On the basis of the crystal structure of wheat eIF4E and a constructed homology model of the structure for eIFiso4E, the reactivities of lysines in each protein are rationalized. Our results suggest that chemical probe/UVPD mass spectrometry can successfully predict dynamic structural changes in solution that are consistent with known crystal structures. Our findings reveal that the binding of m(7)GTP to eIF4E and eIFiso4E appears to be dependent on the redox state of a pair of cysteines near the m(7)GTP binding site. In addition, tertiary structural changes of eIF4E initiated by the formation of a complex containing a fragment of eIF4G and eIF4E were observed.
Collapse
Affiliation(s)
- John P O'Brien
- Department of Chemistry and Biochemistry and ‡Institute for Cell and Molecular Biology, The University of Texas at Austin , 1 University Station A5300, Austin, Texas 78712, United States
| | | | | | | | | |
Collapse
|
18
|
Emerging computational approaches for the study of protein allostery. Arch Biochem Biophys 2013; 538:6-15. [DOI: 10.1016/j.abb.2013.07.025] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/23/2013] [Accepted: 07/30/2013] [Indexed: 12/12/2022]
|
19
|
Casey AK, Schwalm EL, Hays BN, Frantom PA. V-type allosteric inhibition is described by a shift in the rate-determining step for α-isopropylmalate synthase from Mycobacterium tuberculosis. Biochemistry 2013; 52:6737-9. [PMID: 24033269 DOI: 10.1021/bi401186v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetic parameters affected by allosteric mechanisms contain collections of rate constants that vary based on differences in the relative rates of individual steps in the reaction. Thus, it may not be useful to compare enzymes with similar allosteric mechanisms unless the point of regulation has been identified. Rapid reaction kinetics and kinetic isotope effects provide a detailed description of V-type feedback allosteric inhibition in α-isopropylmalate synthase from Mycobacterium tuberculosis, an evolutionarily conserved model allosteric system. Results are consistent with a shift in the rate-determining step from product release to the hydrolytic step in catalysis in the presence of the effector.
Collapse
Affiliation(s)
- Ashley K Casey
- Department of Chemistry, The University of Alabama , Tuscaloosa, Alabama 35487, United States
| | | | | | | |
Collapse
|
20
|
O'Brien JP, Pruet JM, Brodbelt JS. Chromogenic chemical probe for protein structural characterization via ultraviolet photodissociation mass spectrometry. Anal Chem 2013; 85:7391-7. [PMID: 23855605 DOI: 10.1021/ac401305f] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A chemical probe/ultraviolet photodissociation (UVPD) mass spectrometry strategy for evaluating structures of proteins and protein complexes is reported, as demonstrated for lysozyme and beta-lactoglobulin with and without bound ligands. The chemical probe, NN, incorporates a UV chromophore that endows peptides with high cross sections at 351 nm, a wavelength not absorbed by unmodified peptides. Thus, NN-modified peptides can readily be differentiated from nonmodified peptides in complex tryptic digests created upon proteolysis of proteins after their exposure to the NN chemical probe. The NN chemical probe also affords two diagnostic reporter ions detected upon UVPD of the NN-modified peptide that provides a facile method for the identification of NN peptides within complex mixtures. Quantitation of the modified and unmodified peptides allows estimation of the surface accessibilities of lysine residues based on their relative reactivities with the NN chemical probe.
Collapse
Affiliation(s)
- John P O'Brien
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, United States
| | | | | |
Collapse
|
21
|
Amino-acid substitutions at the domain interface affect substrate and allosteric inhibitor binding in α-isopropylmalate synthase from Mycobacterium tuberculosis. Biochem Biophys Res Commun 2013; 433:249-54. [PMID: 23500460 DOI: 10.1016/j.bbrc.2013.02.092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 02/27/2013] [Indexed: 11/22/2022]
Abstract
α-Isopropylmalate synthase (α-IPMS) is a multi-domain protein catalysing the condensation of α-ketoisovalerate (α-KIV) and acetyl coenzyme A (AcCoA) to form α-isopropylmalate. This reaction is the first committed step in the leucine biosynthetic pathway in bacteria and plants, and α-IPMS is allosterically regulated by this amino acid. Existing crystal structures of α-IPMS from Mycobacterium tuberculosis (MtuIPMS) indicate that this enzyme has a strikingly different domain arrangement in each monomer of the homodimeric protein. This asymmetry results in two distinct interfaces between the N-terminal catalytic domains and the C-terminal regulatory domains in the dimer. In this study, residues Arg97 and Asp444 across one of these unequal domain interfaces were substituted to evaluate the importance of protein asymmetry and salt bridge formation between this pair of residues. Analysis of solution-phase structures of wild-type and variant MtuIPMS indicates that substitutions of these residues have little effect on overall protein conformation, a result also observed for addition of the feedback inhibitor leucine to the wild-type enzyme. All variants had increased catalytic efficiency relative to wild-type MtuIPMS, and those with an Asp444 substitution displayed increased affinity for the substrate AcCoA. All variants also showed reduced sensitivity to leucine and altered biphasic reaction kinetics when compared with those of the wild-type enzyme. It is proposed that substituting residues at the asymmetric domain interface increases flexibility in the protein, particularly affecting the AcCoA binding site and the response to leucine, without penalty on catalysis.
Collapse
|
22
|
Manley G, Rivalta I, Loria JP. Solution NMR and computational methods for understanding protein allostery. J Phys Chem B 2013; 117:3063-73. [PMID: 23445323 DOI: 10.1021/jp312576v] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Allosterism is an essential biological regulatory mechanism. In enzymes, allosteric regulation results in an activation or inhibition of catalytic turnover. The mechanisms by which this is accomplished are unclear and vary significantly depending on the enzyme. It is commonly the case that a metabolite binds to the enzyme at a site distant from the catalytic site, yet its binding is coupled to and sensed by the active site. This coupling can manifest in changes in structure, dynamics, or both at the active site. These interactions between the allosteric and active site, which are often quite distant from one another, involve numerous atoms as well as complex conformational rearrangements of the protein secondary and tertiary structure. Interrogation of this complex biological phenomenon necessitates multiple experimental approaches. In this article, we outline a combined solution NMR spectroscopic and computational approach using molecular dynamics and network models to uncover mechanistic aspects of allostery in the enzyme imidazole glycerol phosphate synthase.
Collapse
Affiliation(s)
- Gregory Manley
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | | | | |
Collapse
|
23
|
Prasannan CB, Villar MT, Artigues A, Fenton AW. Identification of regions of rabbit muscle pyruvate kinase important for allosteric regulation by phenylalanine, detected by H/D exchange mass spectrometry. Biochemistry 2013; 52:1998-2006. [PMID: 23418858 DOI: 10.1021/bi400117q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mass spectrometry has been used to determine the number of exchangeable backbone amide protons and the associated rate constants that are altered when rabbit muscle pyruvate kinase (rM1-PYK) binds either the allosteric inhibitor (phenylalanine) or a nonallosteric analogue of the inhibitor. Alanine is used as the nonallosteric analogue because it binds competitively with phenylalanine but elicits a negligible allosteric inhibition, i.e., a negligible reduction in the affinity of rM1-PYK for the substrate, phosphoenolpyruvate. This experimental design is expected to distinguish changes in the protein caused by effector binding (i.e., those changes common upon the addition of alanine vs phenylalanine) from changes associated with allosteric regulation (i.e., those elicited by the addition of phenylalanine binding, but not alanine binding). High-quality peptic fragments covering 98% of the protein were identified. Changes in both the number of exchangeable protons per peptide and in the rate constant associated with exchange highlight regions of the protein with allosteric roles. The set of allosterically relevant peptides identified by this technique includes residues previously identified by mutagenesis to have roles in allosteric regulation by phenylalanine.
Collapse
Affiliation(s)
- Charulata B Prasannan
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, MS 3030, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | | | | | | |
Collapse
|
24
|
Zhang Q, Chen J, Kuwajima K, Zhang HM, Xian F, Young NL, Marshall AG. Nucleotide-induced conformational changes of tetradecameric GroEL mapped by H/D exchange monitored by FT-ICR mass spectrometry. Sci Rep 2013; 3:1247. [PMID: 23409238 PMCID: PMC3570780 DOI: 10.1038/srep01247] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/06/2012] [Indexed: 11/29/2022] Open
Abstract
Here we employ hydrogen/deuterium exchange mass spectrometry (HDX-MS) to access E. coli chaperonin GroEL conformation. The ~800 kDa tetradecameric GroEL plays an essential role in the proper folding of many proteins. Previous studies of the structural dynamics of GroEL upon ATP binding have been inconsistent, showing either minimal or major allosteric changes. Our results, based on the native, non-mutated, protein under physiological conditions in solution demonstrate substantial changes in conformation and/or flexibility upon ATP binding. We capture the pivotal step in its functional cycle by use of a non-hydrolyzable ATP analog, ATPγS, to mimic the ATP-bound GroEL state. Comparison of HDX-MS results for apo GroEL and GroEL-ATPγS enables the characterization of the nucleotide-regulated conformational changes throughout the entire protein with high sequence resolution. The 14-mer GroEL complex is the largest protein assembly yet accessed by HDX-MS, with sequence resolution of segments of as few as five amino acids.
Collapse
Affiliation(s)
- Qian Zhang
- Florida State University, Department of Chemistry, Tallahassee, FL 32306, USA
- These authors contributed equally to this work
| | - Jin Chen
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
- These authors contributed equally to this work
| | - Kunihiro Kuwajima
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (Sokendai), 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Hui-Min Zhang
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Feng Xian
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Nicolas L. Young
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Alan G. Marshall
- Florida State University, Department of Chemistry, Tallahassee, FL 32306, USA
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| |
Collapse
|
25
|
Casey AK, Baugh J, Frantom PA. The slow-onset nature of allosteric inhibition in α-isopropylmalate synthase from Mycobacterium tuberculosis is mediated by a flexible loop. Biochemistry 2012; 51:4773-5. [PMID: 22662746 DOI: 10.1021/bi300671u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The identification of structure-function relationships in allosteric enzymes is essential to describing a molecular mechanism for allosteric processes. The enzyme α-isopropylmalate synthase from Mycobacterium tuberculosis (MtIPMS) is subject to slow-onset, allosteric inhibition by l-leucine. Here we report that alternate amino acids act as rapid equilibrium noncompetitive inhibitors of MtIPMS failing to display biphasic inhibition kinetics. Amino acid substitutions on a flexible loop covering the regulatory binding pocket generate enzyme variants that have significant affinity for l-leucine but lack biphasic inhibition kinetics. Taken together, these results are consistent with the flexible loop mediating the slow-onset step of allosteric inhibition.
Collapse
Affiliation(s)
- Ashley K Casey
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, USA
| | | | | |
Collapse
|
26
|
Huisman FHA, Koon N, Bulloch EMM, Baker HM, Baker EN, Squire CJ, Parker EJ. Removal of the C-terminal regulatory domain of α-isopropylmalate synthase disrupts functional substrate binding. Biochemistry 2012; 51:2289-97. [PMID: 22352945 DOI: 10.1021/bi201717j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
α-Isopropylmalate synthase (α-IPMS) catalyzes the metal-dependent aldol reaction between α-ketoisovalerate (α-KIV) and acetyl-coenzyme A (AcCoA) to give α-isopropylmalate (α-IPM). This reaction is the first committed step in the biosynthesis of leucine in bacteria. α-IPMS is homodimeric, with monomers consisting of (β/α)(8) barrel catalytic domains fused to a C-terminal regulatory domain, responsible for binding leucine and providing feedback regulation for leucine biosynthesis. In these studies, we demonstrate that removal of the regulatory domain from the α-IPMS enzymes of both Neisseria meningitidis (NmeIPMS) and Mycobacterium tuberculosis (MtuIPMS) results in enzymes that are unable to catalyze the formation of α-IPM, although truncated NmeIPMS was still able to slowly hydrolyze AcCoA. The lack of catalytic activity of these truncation variants was confirmed by complementation studies with Escherichia coli cells lacking the α-IPMS gene, where transformation with the plasmids encoding the truncated α-IPMS enzymes was not able to rescue α-IPMS activity. X-ray crystal structures of both truncation variants reveal that both proteins are dimeric and that the catalytic sites of the proteins are intact, although the divalent metal ion that is thought to be responsible for activating substrate α-KIV is displaced slightly relative to its position in the substrate-bound, wild-type structure. Isothermal titration calorimetry and WaterLOGSY nuclear magnetic resonance experiments demonstrate that although these truncation variants are not able to catalyze the reaction between α-KIV and AcCoA, they are still able to bind the substrate α-KIV. It is proposed that the regulatory domain is crucial for ensuring protein dynamics necessary for competent catalysis.
Collapse
Affiliation(s)
- Frances H A Huisman
- Biomolecular Interaction Centre and Department of Chemistry, University of Canterbury, Christchurch, New Zealand
| | | | | | | | | | | | | |
Collapse
|
27
|
Structural and functional characterization of α-isopropylmalate synthase and citramalate synthase, members of the LeuA dimer superfamily. Arch Biochem Biophys 2012; 519:202-9. [DOI: 10.1016/j.abb.2011.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 10/12/2011] [Accepted: 10/13/2011] [Indexed: 11/19/2022]
|
28
|
Zhang Q, Willison LN, Tripathi P, Sathe SK, Roux KH, Emmett MR, Blakney GT, Zhang HM, Marshall AG. Epitope mapping of a 95 kDa antigen in complex with antibody by solution-phase amide backbone hydrogen/deuterium exchange monitored by Fourier transform ion cyclotron resonance mass spectrometry. Anal Chem 2011; 83:7129-36. [PMID: 21861454 PMCID: PMC3173601 DOI: 10.1021/ac201501z] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The epitopes of a homohexameric food allergen protein, cashew Ana o 2, identified by two monoclonal antibodies, 2B5 and 1F5, were mapped by solution-phase amide backbone H/D exchange (HDX) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and the results were compared to previous mapping by immunological and mutational analyses. Antibody 2B5 defines a conformational epitope, and 1F5 defines a linear epitope. Intact murine IgG antibodies were incubated with recombinant Ana o 2 (rAna o 2) to form antigen-monoclonal antibody (Ag-mAb) complexes. mAb-complexed and uncomplexed (free) rAna o 2 were then subjected to HDX. HDX instrumentation and automation were optimized to achieve high sequence coverage by protease XIII digestion. The regions protected from H/D exchange upon antibody binding overlap and thus confirm the previously identified epitope-bearing segments: the first extension of HDX monitored by mass spectrometry to a full-length antigen-antibody complex in solution.
Collapse
Affiliation(s)
- Qian Zhang
- Department Chemistry & Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306
| | - LeAnna N. Willison
- Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306
| | - Pallavi Tripathi
- Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306
| | - Shridhar K. Sathe
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL 32306
| | - Kenneth H. Roux
- Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306
| | - Mark R. Emmett
- Department Chemistry & Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State Universitiy, 1800 E. Paul Dirac Drive, Tallahassee, FL 323010-4005
| | - Greg T. Blakney
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State Universitiy, 1800 E. Paul Dirac Drive, Tallahassee, FL 323010-4005
| | - Hui-Min Zhang
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State Universitiy, 1800 E. Paul Dirac Drive, Tallahassee, FL 323010-4005
| | - Alan G. Marshall
- Department Chemistry & Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State Universitiy, 1800 E. Paul Dirac Drive, Tallahassee, FL 323010-4005
| |
Collapse
|
29
|
Monitoring allostery in D2O: a necessary control in studies using hydrogen/deuterium exchange to characterize allosteric regulation. Anal Bioanal Chem 2011; 401:1083-6. [PMID: 21701851 DOI: 10.1007/s00216-011-5133-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 04/15/2011] [Accepted: 05/20/2011] [Indexed: 10/18/2022]
Abstract
There is currently a renewed focus aimed at understanding allosteric mechanisms at atomic resolution. This current interest seeks to understand how both changes in protein conformations and changes in protein dynamics contribute to relaying an allosteric signal between two ligand binding sites on a protein (e.g., active and allosteric sites). Both nuclear magnetic resonance (NMR), by monitoring protein dynamics directly, and hydrogen/deuterium exchange, by monitoring solvent accessibility of backbone amides, offer insights into protein dynamics. Unfortunately, many allosteric proteins exceed the size limitations of standard NMR techniques. Although hydrogen/deuterium exchange as detected by mass spectrometry (H/DX-MS) offers an alternative evaluation method, any application of hydrogen/deuterium exchange requires that the property being measured functions in both H(2)O and D(2)O. Due to the promising future H/DX-MS has in the evaluation of allosteric mechanisms in large proteins, we demonstrate an evaluation of allosteric regulation in D(2)O. Exemplified using phenylalanine inhibition of rabbit muscle pyruvate kinase, we find that binding of the inhibitor is greatly reduced in D(2)O, but the effector continues to elicit an allosteric response.
Collapse
|
30
|
Edwards AA, Tipton JD, Brenowitz MD, Emmett MR, Marshall AG, Evans GB, Tyler PC, Schramm VL. Conformational states of human purine nucleoside phosphorylase at rest, at work, and with transition state analogues. Biochemistry 2010; 49:2058-67. [PMID: 20108972 DOI: 10.1021/bi902041j] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human purine nucleoside phosphorylase (PNP) is a homotrimer binding tightly to the transition state analogues Immucillin-H (ImmH; K(d) = 56 pM) and DATMe-ImmH-Immucillin-H (DATMe-ImmH; K(d) = 8.6 pM). ImmH binds with a larger entropic penalty than DATMe-ImmH, a chemically more flexible inhibitor. The testable hypothesis is that PNP conformational states are more relaxed (dynamic) with DATMe-ImmH, despite tighter binding than with ImmH. PNP conformations are probed by peptide amide deuterium exchange (HDX) using liquid chromatography high-resolution Fourier transform ion cyclotron resonance mass spectrometry and by sedimentation rates. Catalytically equilibrating Michaelis complexes (PNP.PO(4).inosine <--> PNP.Hx.R-1-P) and inhibited complexes (PNP.PO(4).DATMe-ImmH and PNP.PO(4).ImmH) show protection from HDX at 9, 13, and 15 sites per subunit relative to resting PNP (PNP.PO(4)) in extended incubations. The PNP.PO(4).ImmH complex is more compact (by sedimentation rate) than the other complexes. HDX kinetic analysis of ligand-protected sites corresponds to peptides near the catalytic sites. HDX and sedimentation results establish that PNP protein conformation (dynamic motion) correlates more closely with entropy of binding than with affinity. Catalytically active turnover with saturated substrate sites causes less change in HDX and sedimentation rates than binding of transition state analogues. DATMe-ImmH more closely mimics the transition of human PNP than does ImmH and achieves strong binding interactions at the catalytic site while causing relatively modest alterations of the protein dynamic motion. Transition state analogues causing the most rigid, closed protein conformation are therefore not necessarily the most tightly bound. Close mimics of the transition state are hypothesized to retain enzymatic dynamic motions related to transition state formation.
Collapse
Affiliation(s)
- Achelle A Edwards
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Kazazic S, Zhang HM, Schaub TM, Emmett MR, Hendrickson CL, Blakney GT, Marshall AG. Automated data reduction for hydrogen/deuterium exchange experiments, enabled by high-resolution Fourier transform ion cyclotron resonance mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:550-8. [PMID: 20116280 PMCID: PMC2901854 DOI: 10.1016/j.jasms.2009.12.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 12/17/2009] [Accepted: 12/18/2009] [Indexed: 05/12/2023]
Abstract
Mass analysis of proteolytic fragment peptides following hydrogen/deuterium exchange offers a general measure of solvent accessibility/hydrogen bonding (and thus conformation) of solution-phase proteins and their complexes. The primary problem in such mass analyses is reliable and rapid assignment of mass spectral peaks to the correct charge state and degree of deuteration of each fragment peptide, in the presence of substantial overlap between isotopic distributions of target peptides, autolysis products, and other interferant species. Here, we show that at sufficiently high mass resolving power (m/Delta m(50%) > or = 100,000), it becomes possible to resolve enough of those overlaps so that automated data reduction becomes possible, based on the actual elemental composition of each peptide without the need to deconvolve isotopic distributions. We demonstrate automated, rapid, reliable assignment of peptide masses from H/D exchange experiments, based on electrospray ionization FT-ICR mass spectra from H/D exchange of solution-phase myoglobin. Combined with previously demonstrated automated data acquisition for such experiments, the present data reduction algorithm enhances automation (and thus expands generality and applicability) for high-resolution mass spectrometry-based analysis of H/D exchange of solution-phase proteins.
Collapse
Affiliation(s)
- Sasa Kazazic
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310-4005, USA
| | | | | | | | | | | | | |
Collapse
|
32
|
Zhang HM, McLoughlin SM, Frausto SD, Tang H, Emmett MR, Marshall AG. Simultaneous reduction and digestion of proteins with disulfide bonds for hydrogen/deuterium exchange monitored by mass spectrometry. Anal Chem 2010; 82:1450-4. [PMID: 20099838 PMCID: PMC2825376 DOI: 10.1021/ac902550n] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Proteolyzed peptides provide the basis for mass-analyzed hydrogen/deuterium exchange (HDX) for mapping solvent access to various segments of solution-phase proteins. Aspergillus saitoi protease type XIII and porcine pepsin can generate peptides of overlapping sequences and high sequence coverage. However, if disulfide bonds are present, proteolysis can be severely limited, particularly in the vicinity of the disulfide linkage(s). Disulfide bonds cannot be reduced before or during the H/D exchange reaction without affecting the protein higher-order structure. Here, we demonstrate simultaneous quench/digestion/reduction following H/D exchange, for subsequent mass analysis. Proteolysis is conducted in the presence of tris(2-carboxyethyl)phosphine hydrochloride (TCEP.HCl) and urea, and all other steps of the H/D exchange and analysis are maintained. This method yields dramatically increased sequence coverage and localization of solvent-exposed segments for mass-analyzed solution-phase H/D exchange of proteins containing disulfide bonds.
Collapse
Affiliation(s)
- Hui-Min Zhang
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310-4005
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306
| | - Shaun M. McLoughlin
- Abbott Laboratories, GPRD/R418, 200 Abbott Park Road, AP31/L144, Abbott Park, IL 60064
| | | | - Hengli Tang
- Department of Biology, Florida State University, Tallahassee, FL, 32306
| | - Mark R. Emmett
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310-4005
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306
| | - Alan G. Marshall
- Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310-4005
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306
| |
Collapse
|
33
|
Nagy K, Redeuil K, Rezzi S. Online Hydrogen/Deuterium Exchange Performed in the Ion Mobility Cell of a Hybrid Mass Spectrometer. Anal Chem 2009; 81:9365-71. [DOI: 10.1021/ac901736j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kornél Nagy
- Metabonomics and Biomarkers Group, BioAnalytical Science Department, Nestlé Research Centre, Nestec Limited, Vers-Chez-les-Blanc, 1000 Lausanne, Switzerland
| | - Karine Redeuil
- Metabonomics and Biomarkers Group, BioAnalytical Science Department, Nestlé Research Centre, Nestec Limited, Vers-Chez-les-Blanc, 1000 Lausanne, Switzerland
| | - Serge Rezzi
- Metabonomics and Biomarkers Group, BioAnalytical Science Department, Nestlé Research Centre, Nestec Limited, Vers-Chez-les-Blanc, 1000 Lausanne, Switzerland
| |
Collapse
|