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Zheng Y, Chen N, Ji Z, Ye Q, Huang P, Chen X, Cui G, Duan L, Zhang F. Adjusting Catalytic Activity of β-Amyrin Synthase GgBAS by Utilizing the Plasticity Residues of an Active Site. J Chem Inf Model 2024; 64:3933-3941. [PMID: 38666964 DOI: 10.1021/acs.jcim.4c00297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
β-Amyrin synthase (bAS) is a representative plant oxidosqualene cyclase (OSC), and previous studies have identified many functional residues and mutants that can alter its catalytic activity. However, the regulatory mechanism of the active site architecture for adjusting the catalytic activity remains unclear. In this study, we investigate the function of key residues and their regulatory effects on the catalytic activity of Glycyrrhiza glabra β-amyrin synthase (GgbAS) through molecular dynamics simulations and site-directed mutagenesis experiments. We identified the plasticity residues located in two active site regions and explored the interactions between these residues and tetracyclic/pentacyclic intermediates. Based on computational and experimental results, we further categorize these plasticity residues into three types: effector, adjuster, and supporter residues, according to their functions in the catalytic process. This study provides valuable insights into the catalytic mechanism and active site plasticity of GgbAS, offering important references for the rational enzyme engineering of other OSC enzyme.
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Affiliation(s)
- Ying Zheng
- Guangzhou University of Chinese Medicine, Guangzhou 510006, P.R. China
- State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, Beijing 100700, P. R. China
| | - Nianhang Chen
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, P. R. China
| | - Zhongju Ji
- Guangzhou University of Chinese Medicine, Guangzhou 510006, P.R. China
- Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
| | - Qiongyu Ye
- Guangzhou University of Chinese Medicine, Guangzhou 510006, P.R. China
- Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
| | - Pingping Huang
- Guangzhou University of Chinese Medicine, Guangzhou 510006, P.R. China
- Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
| | - Xiaodie Chen
- Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
| | - Guanghong Cui
- State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, Beijing 100700, P. R. China
| | - Lixin Duan
- Guangzhou University of Chinese Medicine, Guangzhou 510006, P.R. China
- Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
| | - Fan Zhang
- Guangzhou University of Chinese Medicine, Guangzhou 510006, P.R. China
- Guangdong Provincial Key Laboratory of Translational Cancer Research of Chinese Medicines, Joint International Research Laboratory of Translational Cancer Research of Chinese Medicines, International Institute for Translational Chinese Medicine, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
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Yabukarski F, Doukov T, Pinney MM, Biel JT, Fraser JS, Herschlag D. Ensemble-function relationships to dissect mechanisms of enzyme catalysis. SCIENCE ADVANCES 2022; 8:eabn7738. [PMID: 36240280 PMCID: PMC9565801 DOI: 10.1126/sciadv.abn7738] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 08/30/2022] [Indexed: 05/27/2023]
Abstract
Decades of structure-function studies have established our current extensive understanding of enzymes. However, traditional structural models are snapshots of broader conformational ensembles of interchanging states. We demonstrate the need for conformational ensembles to understand function, using the enzyme ketosteroid isomerase (KSI) as an example. Comparison of prior KSI cryogenic x-ray structures suggested deleterious mutational effects from a misaligned oxyanion hole catalytic residue. However, ensemble information from room-temperature x-ray crystallography, combined with functional studies, excluded this model. Ensemble-function analyses can deconvolute effects from altering the probability of occupying a state (P-effects) and changing the reactivity of each state (k-effects); our ensemble-function analyses revealed functional effects arising from weakened oxyanion hole hydrogen bonding and substrate repositioning within the active site. Ensemble-function studies will have an integral role in understanding enzymes and in meeting the future goals of a predictive understanding of enzyme catalysis and engineering new enzymes.
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Affiliation(s)
- Filip Yabukarski
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Tzanko Doukov
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Margaux M. Pinney
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Justin T. Biel
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - James S. Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
- Stanford ChEM-H, Stanford University, Stanford, CA 94305, USA
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3
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Krivacic C, Kundert K, Pan X, Pache RA, Liu L, Conchúir SO, Jeliazkov JR, Gray JJ, Thompson MC, Fraser JS, Kortemme T. Accurate positioning of functional residues with robotics-inspired computational protein design. Proc Natl Acad Sci U S A 2022; 119:e2115480119. [PMID: 35254891 PMCID: PMC8931229 DOI: 10.1073/pnas.2115480119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/27/2022] [Indexed: 11/18/2022] Open
Abstract
SignificanceComputational protein design promises to advance applications in medicine and biotechnology by creating proteins with many new and useful functions. However, new functions require the design of specific and often irregular atom-level geometries, which remains a major challenge. Here, we develop computational methods that design and predict local protein geometries with greater accuracy than existing methods. Then, as a proof of concept, we leverage these methods to design new protein conformations in the enzyme ketosteroid isomerase that change the protein's preference for a key functional residue. Our computational methods are openly accessible and can be applied to the design of other intricate geometries customized for new user-defined protein functions.
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Affiliation(s)
- Cody Krivacic
- UC Berkeley–UCSF Graduate Program in Bioengineering, University of California, San Francisco, CA 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - Kale Kundert
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
- Biophysics Graduate Program, University of California, San Francisco, CA 94158
| | - Xingjie Pan
- UC Berkeley–UCSF Graduate Program in Bioengineering, University of California, San Francisco, CA 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - Roland A. Pache
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - Lin Liu
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - Shane O Conchúir
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | | | - Jeffrey J. Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Michael C. Thompson
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
| | - James S. Fraser
- UC Berkeley–UCSF Graduate Program in Bioengineering, University of California, San Francisco, CA 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
- Biophysics Graduate Program, University of California, San Francisco, CA 94158
- Quantitative Biosciences Institute, University of California, San Francisco, CA 94158
| | - Tanja Kortemme
- UC Berkeley–UCSF Graduate Program in Bioengineering, University of California, San Francisco, CA 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94158
- Biophysics Graduate Program, University of California, San Francisco, CA 94158
- Quantitative Biosciences Institute, University of California, San Francisco, CA 94158
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4
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Assessment of enzyme active site positioning and tests of catalytic mechanisms through X-ray-derived conformational ensembles. Proc Natl Acad Sci U S A 2020; 117:33204-33215. [PMID: 33376217 DOI: 10.1073/pnas.2011350117] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
How enzymes achieve their enormous rate enhancements remains a central question in biology, and our understanding to date has impacted drug development, influenced enzyme design, and deepened our appreciation of evolutionary processes. While enzymes position catalytic and reactant groups in active sites, physics requires that atoms undergo constant motion. Numerous proposals have invoked positioning or motions as central for enzyme function, but a scarcity of experimental data has limited our understanding of positioning and motion, their relative importance, and their changes through the enzyme's reaction cycle. To examine positioning and motions and test catalytic proposals, we collected "room temperature" X-ray crystallography data for Pseudomonas putida ketosteroid isomerase (KSI), and we obtained conformational ensembles for this and a homologous KSI from multiple PDB crystal structures. Ensemble analyses indicated limited change through KSI's reaction cycle. Active site positioning was on the 1- to 1.5-Å scale, and was not exceptional compared to noncatalytic groups. The KSI ensembles provided evidence against catalytic proposals invoking oxyanion hole geometric discrimination between the ground state and transition state or highly precise general base positioning. Instead, increasing or decreasing positioning of KSI's general base reduced catalysis, suggesting optimized Ångstrom-scale conformational heterogeneity that allows KSI to efficiently catalyze multiple reaction steps. Ensemble analyses of surrounding groups for WT and mutant KSIs provided insights into the forces and interactions that allow and limit active-site motions. Most generally, this ensemble perspective extends traditional structure-function relationships, providing the basis for a new era of "ensemble-function" interrogation of enzymes.
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Beker W, Sokalski WA. Bottom-Up Nonempirical Approach To Reducing Search Space in Enzyme Design Guided by Catalytic Fields. J Chem Theory Comput 2020; 16:3420-3429. [PMID: 32282205 PMCID: PMC7467639 DOI: 10.1021/acs.jctc.0c00139] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Currently developed protocols of theozyme design still lead to biocatalysts with much lower catalytic activity than enzymes existing in nature, and, so far, the only avenue of improvement was the in vitro laboratory-directed evolution (LDE) experiments. In this paper, we propose a different strategy based on "reversed" methodology of mutation prediction. Instead of common "top-down" approach, requiring numerous assumptions and vast computational effort, we argue for a "bottom-up" approach that is based on the catalytic fields derived directly from transition state and reactant complex wave functions. This enables direct one-step determination of the general quantitative angular characteristics of optimal catalytic site and simultaneously encompasses both the transition-state stabilization (TSS) and ground-state destabilization (GSD) effects. We further extend the static catalytic field approach by introducing a library of atomic multipoles for amino acid side-chain rotamers, which, together with the catalytic field, allow one to determine the optimal side-chain orientations of charged amino acids constituting the elusive structure of a preorganized catalytic environment. Obtained qualitative agreement with experimental LDE data for Kemp eliminase KE07 mutants validates the proposed procedure, yielding, in addition, a detailed insight into possible dynamic and epistatic effects.
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Affiliation(s)
- Wiktor Beker
- Wroclaw University of Science and Technology, Wroclaw, Poland
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6
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Pagano P, Guo Q, Ranasinghe C, Schroeder E, Robben K, Häse F, Ye H, Wickersham K, Aspuru-Guzik A, Major DT, Gakhar L, Kohen A, Cheatum CM. Oscillatory Active-site Motions Correlate with Kinetic Isotope Effects in Formate Dehydrogenase. ACS Catal 2019; 9:11199-11206. [PMID: 33996196 PMCID: PMC8118594 DOI: 10.1021/acscatal.9b03345] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Thermal motions of enzymes have been invoked to explain the temperature dependence of kinetic isotope effects (KIE) in enzyme-catalyzed hydride transfers. Formate dehydrogenase (FDH) from Candida boidinii exhibits a temperature independent KIE that becomes temperature dependent upon mutation of hydrophobic residues in the active site. Ternary complexes of FDH that mimic the transition state structure allow investigation of how these mutations influence active-site dynamics. A combination of X-ray crystallography, two-dimensional infrared (2D IR) spectroscopy, and molecular dynamic simulations characterize the structure and dynamics of the active site. FDH exhibits oscillatory frequency fluctuations on the picosecond timescale, and the amplitude of these fluctuations correlates with the temperature dependence of the KIE. Both the kinetic and dynamic phenomena can be reproduced computationally. These results provide experimental evidence for a connection between the temperature dependence of KIEs and motions of the active site in an enzyme-catalyzed reaction consistent with activated tunneling models of the hydride transfer reaction.
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Affiliation(s)
- Philip Pagano
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Qi Guo
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Chethya Ranasinghe
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Evan Schroeder
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Kevin Robben
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Florian Häse
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Hepeng Ye
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Kyle Wickersham
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Alán Aspuru-Guzik
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
- Senior Fellow, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1Z8, Canada
| | - Dan T. Major
- Chemistry Department, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Lokesh Gakhar
- Protein Crystallography Facility and Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States
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7
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Peng F, Cheng X, Wang H, Song S, Chen T, Li X, He Y, Huang Y, Liu S, Yang F, Su Z. Structure-based reconstruction of a Mycobacterium hypothetical protein into an active Δ 5-3-ketosteroid isomerase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:821-830. [PMID: 31226491 DOI: 10.1016/j.bbapap.2019.06.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 06/12/2019] [Accepted: 06/14/2019] [Indexed: 11/25/2022]
Abstract
Protein engineering based on structure homology holds the potential to engineer steroid-transforming enzymes on demand. Based on the genome sequencing analysis of industrial Mycobacterium strain HGMS2 to produce 4-androstene-3,17-dione (4-AD), three hypothetical proteins were predicted as putative Δ5-3-ketosteroid isomerases (KSIs) to catalyze an intramolecular proton transfer involving the transformation of 5-androstene-3,17-dione (5-AD) into 4-AD, which were defined as mKSI228, mKSI291 and mKSI753. Activity assays indicated that mKSI228 and mKSI291 exhibited weak activity, as low as 0.7% and 1.5%, respectively, of a well-studied and highly active KSI from Pseudomonas putida KSI (pKSI), while mKSI753 had no activity similar to Mycobacterium tuberculosis KSI (mtKSI). Although the 3D structures of the putative mKSIs were homologous to pKSI, their amino acid sequences were significantly different from those of pKSI and tKSI. Thus, by use of these two KSIs as homology models, we were able to convert the low-active mKSI291 into a high-active active KSI by site-directed mutagenesis. On the other hand, an X-ray crystallographic structure of mKSI291 identified a water molecule in its active site. This unique water molecule might function as a bridge to connect Ser-OH, Tyr57-OH and C3O of the intermediate form a hydrogen-bonding network that was responsible for its weak activity, compared with that of mtKSI. Our results not only demonstrated the use of a protein engineering approach to understanding KSI catalytic mechanism, but also provided an example for engineering the catalytic active sites and gaining a functional enzyme based on homologous structures.
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Affiliation(s)
- Fei Peng
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Xiyao Cheng
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China; Wuhan Amersino Biodevelop Inc, B1-Building, Biolake Park, Wuhan 430075, China
| | - Hongwei Wang
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Shikui Song
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Tian Chen
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Xin Li
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Yijun He
- Hubei Goto Biotech Inc, No. 1 Baiguoshu Road, Shuidu Industrial Park, Danjiangkou, Hubei 442700, China
| | - Yongqi Huang
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Sen Liu
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Fei Yang
- College of Life Sciences, Wuhan University, Wuhan 430072, China.
| | - Zhengding Su
- Key Laboratory of Industrial Fermentation (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics and Department of Biological and Food Engineering, Hubei University of Technology, Wuhan 430068, China; Wuhan Amersino Biodevelop Inc, B1-Building, Biolake Park, Wuhan 430075, China.
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8
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Kundert K, Kortemme T. Computational design of structured loops for new protein functions. Biol Chem 2019; 400:275-288. [PMID: 30676995 PMCID: PMC6530579 DOI: 10.1515/hsz-2018-0348] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/18/2018] [Indexed: 12/20/2022]
Abstract
The ability to engineer the precise geometries, fine-tuned energetics and subtle dynamics that are characteristic of functional proteins is a major unsolved challenge in the field of computational protein design. In natural proteins, functional sites exhibiting these properties often feature structured loops. However, unlike the elements of secondary structures that comprise idealized protein folds, structured loops have been difficult to design computationally. Addressing this shortcoming in a general way is a necessary first step towards the routine design of protein function. In this perspective, we will describe the progress that has been made on this problem and discuss how recent advances in the field of loop structure prediction can be harnessed and applied to the inverse problem of computational loop design.
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Affiliation(s)
- Kale Kundert
- Graduate Group in Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
| | - Tanja Kortemme
- Graduate Group in Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
- Chan Zuckerberg Biohub, 499 Illinois St, San Francisco, CA 94158, USA
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9
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Lamba V, Yabukarski F, Herschlag D. An Activator-Blocker Pair Provides a Controllable On-Off Switch for a Ketosteroid Isomerase Active Site Mutant. J Am Chem Soc 2017; 139:11089-11095. [PMID: 28719738 DOI: 10.1021/jacs.7b03547] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Control of enzyme activity is fundamental to biology and represents a long-term goal in bioengineering and precision therapeutics. While several powerful molecular strategies have been developed, limitations remain in their generalizability and dynamic range. We demonstrate a control mechanism via separate small molecules that turn on the enzyme (activator) and turn off the activation (blocker). We show that a pocket created near the active site base of the enzyme ketosteriod isomerase (KSI) allows efficient and saturable base rescue when the enzyme's natural general base is removed. Binding a small molecule with similar properties but lacking general-base capability in this pocket shuts off rescue. The ability of small molecules to directly participate in and directly block catalysis may afford a broad controllable dynamic range. This approach may be amenable to numerous enzymes and to engineering and screening approaches to identify activators and blockers with strong, specific binding for engineering and therapeutic applications.
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Affiliation(s)
- Vandana Lamba
- Department of Biochemistry, ‡Department of Chemistry, §Department of Chemical Engineering, and ∥Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
| | - Filip Yabukarski
- Department of Biochemistry, ‡Department of Chemistry, §Department of Chemical Engineering, and ∥Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
| | - Daniel Herschlag
- Department of Biochemistry, ‡Department of Chemistry, §Department of Chemical Engineering, and ∥Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
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10
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Abstract
What happens inside an enzyme's active site to allow slow and difficult chemical reactions to occur so rapidly? This question has occupied biochemists' attention for a long time. Computer models of increasing sophistication have predicted an important role for electrostatic interactions in enzymatic reactions, yet this hypothesis has proved vexingly difficult to test experimentally. Recent experiments utilizing the vibrational Stark effect make it possible to measure the electric field a substrate molecule experiences when bound inside its enzyme's active site. These experiments have provided compelling evidence supporting a major electrostatic contribution to enzymatic catalysis. Here, we review these results and develop a simple model for electrostatic catalysis that enables us to incorporate disparate concepts introduced by many investigators to describe how enzymes work into a more unified framework stressing the importance of electric fields at the active site.
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Affiliation(s)
- Stephen D Fried
- Proteins and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom;
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305;
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11
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Wu Y, Boxer SG. A Critical Test of the Electrostatic Contribution to Catalysis with Noncanonical Amino Acids in Ketosteroid Isomerase. J Am Chem Soc 2016; 138:11890-5. [PMID: 27545569 PMCID: PMC5063566 DOI: 10.1021/jacs.6b06843] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The vibrational Stark effect (VSE) has been used to measure the electric field in the active site of ketosteroid isomerase (KSI). These measured fields correlate with ΔG(⧧) in a series of conventional mutants, yielding an estimate for the electrostatic contribution to catalysis (Fried et al. Science 2014, 346, 1510-1513). In this work we test this result with much more conservative variants in which individual Tyr residues in the active site are replaced by 3-chlorotyrosine via amber suppression. The electric fields sensed at the position of the carbonyl bond involved in charge displacement during catalysis were characterized using the VSE, where the field sensitivity has been calibrated by vibrational Stark spectroscopy, solvatochromism, and MD simulations. A linear relationship is observed between the electric field and ΔG(⧧) that interpolates between wild-type and more drastic conventional mutations, reinforcing the evaluation of the electrostatic contribution to catalysis in KSI. A simplified model and calculation are developed to estimate changes in the electric field accompanying changes in the extended hydrogen-bond network in the active site. The results are consistent with a model in which the O-H group of a key active site tyrosine functions by imposing a static electrostatic potential onto the carbonyl bond. The model suggests that the contribution to catalysis from the active site hydrogen bonds is of similar weight to the distal interactions from the rest of the protein. A similar linear correlation was also observed between the proton affinity of KSI's active site and the catalytic rate, suggesting a direct connection between the strength of the H-bond and the electric field it exerts.
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Affiliation(s)
- Yufan Wu
- Department of Chemistry, Stanford University , Stanford, California 94305-5012, United States
| | - Steven G Boxer
- Department of Chemistry, Stanford University , Stanford, California 94305-5012, United States
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12
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Lamba V, Yabukarski F, Pinney M, Herschlag D. Evaluation of the Catalytic Contribution from a Positioned General Base in Ketosteroid Isomerase. J Am Chem Soc 2016; 138:9902-9. [PMID: 27410422 DOI: 10.1021/jacs.6b04796] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Proton transfer reactions are ubiquitous in enzymes and utilize active site residues as general acids and bases. Crystal structures and site-directed mutagenesis are routinely used to identify these residues, but assessment of their catalytic contribution remains a major challenge. In principle, effective molarity measurements, in which exogenous acids/bases rescue the reaction in mutants lacking these residues, can estimate these catalytic contributions. However, these exogenous moieties can be restricted in reactivity by steric hindrance or enhanced by binding interactions with nearby residues, thereby resulting in over- or underestimation of the catalytic contribution, respectively. With these challenges in mind, we investigated the catalytic contribution of an aspartate general base in ketosteroid isomerase (KSI) by exogenous rescue. In addition to removing the general base, we systematically mutated nearby residues and probed each mutant with a series of carboxylate bases of similar pKa but varying size. Our results underscore the need for extensive and multifaceted variation to assess and minimize steric and positioning effects and determine effective molarities that estimate catalytic contributions. We obtained consensus effective molarities of ∼5 × 10(4) M for KSI from Comamonas testosteroni (tKSI) and ∼10(3) M for KSI from Pseudomonas putida (pKSI). An X-ray crystal structure of a tKSI general base mutant showed no additional structural rearrangements, and double mutant cycles revealed similar contributions from an oxyanion hole mutation in the wild-type and base-rescued reactions, providing no indication of mutational effects extending beyond the general base site. Thus, the high effective molarities suggest a large catalytic contribution associated with the general base. A significant portion of this effect presumably arises from positioning of the base, but its large magnitude suggests the involvement of additional catalytic mechanisms as well.
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Affiliation(s)
- Vandana Lamba
- Department of Biochemistry, ‡Department of Chemistry, #Department of Chemical Engineering, §Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
| | - Filip Yabukarski
- Department of Biochemistry, ‡Department of Chemistry, #Department of Chemical Engineering, §Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
| | - Margaux Pinney
- Department of Biochemistry, ‡Department of Chemistry, #Department of Chemical Engineering, §Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
| | - Daniel Herschlag
- Department of Biochemistry, ‡Department of Chemistry, #Department of Chemical Engineering, §Stanford ChEM-H, Stanford University , Stanford, California 94305, United States
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Cha HJ, Jang DS, Jeong JH, Hong BH, Yun YS, Shin EJ, Choi KY. Role of conserved Met112 residue in the catalytic activity and stability of ketosteroid isomerase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1322-7. [PMID: 27375051 DOI: 10.1016/j.bbapap.2016.06.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 06/11/2016] [Accepted: 06/29/2016] [Indexed: 10/21/2022]
Abstract
Ketosteroid isomerase (3-oxosteroid Δ(5)-Δ(4)-isomerase, KSI) from Pseudomonas putida catalyzes allylic rearrangement of the 5,6-double bond of Δ(5)-3-ketosteroid to 4,5-position by stereospecific intramolecular transfer of a proton. The active site of KSI is formed by several hydrophobic residues and three catalytic residues (Tyr14, Asp38, and Asp99). In this study, we investigated the role of a hydrophobic Met112 residue near the active site in the catalysis, steroid binding, and stability of KSI. Replacing Met112 with alanine (yields M112A) or leucine (M112L) decreased the kcat by 20- and 4-fold, respectively. Compared with the wild type (WT), M112A and M112L KSIs showed increased KD values for equilenin, an intermediate analogue; these changes suggest that loss of packing at position 112 might lead to unfavorable steroid binding, thereby resulting in decreased catalytic activity. Furthermore, M112A and M112L mutations reduced melting temperature (Tm) by 6.4°C and 2.5°C, respectively. These changes suggest that favorable packing in the core is important for the maintenance of stability in KSI. The M112K mutation decreased kcat by 2000-fold, compared with the WT. In M112K KSI structure, a new salt bridge was formed between Asp38 and Lys112. This bridge could change the electrostatic potential of Asp38, and thereby contribute to the decreased catalytic activity. The M112K mutation also decreased the stability by reducing Tm by 4.1°C. Our data suggest that the Met112 residue may contribute to the catalytic activity and stability of KSI by providing favorable hydrophobic environments and compact packing in the catalytic core.
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Affiliation(s)
- Hyung Jin Cha
- Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Do Soo Jang
- Department of Life Sciences, POSTECH, Pohang, Republic of Korea
| | - Jae-Hee Jeong
- Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Bee Hak Hong
- Department of Life Sciences, POSTECH, Pohang, Republic of Korea
| | - Young Sung Yun
- Department of Life Sciences, POSTECH, Pohang, Republic of Korea
| | - Eun Ju Shin
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Kwan Yong Choi
- Department of Life Sciences, POSTECH, Pohang, Republic of Korea.
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Schwans JP, Sunden F, Gonzalez A, Tsai Y, Herschlag D. Correction to "Evaluating the Catalytic Contribution from the Oxyanion Hole in Ketosteroid Isomerase". J Am Chem Soc 2016; 138:7801-2. [PMID: 27299372 DOI: 10.1021/jacs.6b04665] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Aronica P, Verma C, Popovic B, Leatherbarrow R, Gould IR. The Parasol Protocol for computational mutagenesis. Protein Eng Des Sel 2016; 29:253-61. [DOI: 10.1093/protein/gzw009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 03/15/2016] [Indexed: 11/12/2022] Open
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16
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Avila-Montiel C, Tapia-Benavides AR, Falcón-León M, Ariza-Castolo A, Tlahuext H, Tlahuextl M. Synthesis and structural studies of amino amide salts derived from 2-(aminomethyl)benzimidazole and α-amino acids. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.07.072] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Fried SD, Boxer SG. BIOPHYSICS. Response to Comments on "Extreme electric fields power catalysis in the active site of ketosteroid isomerase". Science 2015; 349:936. [PMID: 26315428 DOI: 10.1126/science.aab1627] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/24/2015] [Indexed: 01/28/2023]
Abstract
Natarajan et al. and Chen and Savidge comment that comparing the electric field in ketosteroid isomerase's (KSI's) active site to zero overestimates the catalytic effect of KSI's electric field because the reference reaction occurs in water, which itself exerts a sizable electrostatic field. To compensate, Natarajan et al. argue that additional catalytic weight arises from positioning of the general base, whereas Chen and Savidge propose a separate contribution from desolvation of the general base. We note that the former claim is not well supported by published results, and the latter claim is intriguing but lacks experimental basis. We also take the opportunity to clarify some of the more conceptually subtle aspects of electrostatic catalysis.
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Affiliation(s)
- Stephen D Fried
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
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