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Whittington C, Sharma A, Hill SG, Iavarone AT, Hoffman BM, Offenbacher AR. Impact of N-Glycosylation on Protein Structure and Dynamics Linked to Enzymatic C-H Activation in the M. oryzae Lipoxygenase. Biochemistry 2024; 63:1335-1346. [PMID: 38690768 DOI: 10.1021/acs.biochem.4c00109] [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: 05/03/2024]
Abstract
Lipoxygenases (LOXs) from pathogenic fungi are potential therapeutic targets for defense against plant and select human diseases. In contrast to the canonical LOXs in plants and animals, fungal LOXs are unique in having appended N-linked glycans. Such important post-translational modifications (PTMs) endow proteins with altered structure, stability, and/or function. In this study, we present the structural and functional outcomes of removing or altering these surface carbohydrates on the LOX from the devastating rice blast fungus, M. oryzae, MoLOX. Alteration of the PTMs did notinfluence the active site enzyme-substrate ground state structures as visualized by electron-nuclear double resonance (ENDOR) spectroscopy. However, removal of the eight N-linked glycans by asparagine-to-glutamine mutagenesis nonetheless led to a change in substrate selectivity and an elevated activation energy for the reaction with substrate linoleic acid, as determined by kinetic measurements. Comparative hydrogen-deuterium exchange mass spectrometry (HDX-MS) analysis of wild-type and Asn-to-Gln MoLOX variants revealed a regionally defined impact on the dynamics of the arched helix that covers the active site. Guided by these HDX results, a single glycan sequon knockout was generated at position 72, and its comparative substrate selectivity from kinetics nearly matched that of the Asn-to-Gln variant. The cumulative data from model glyco-enzyme MoLOX showcase how the presence, alteration, or removal of even a single N-linked glycan can influence the structural integrity and dynamics of the protein that are linked to an enzyme's catalytic proficiency, while indicating that extensive glycosylation protects the enzyme during pathogenesis by protecting it from protease degradation.
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Affiliation(s)
- Chris Whittington
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Ajay Sharma
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - S Gage Hill
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Anthony T Iavarone
- California Institute for Quantitative Biosciences, Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Adam R Offenbacher
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
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Brenna JT, Sergeeva MG, Pestov NB, Korneenko TV, Shchepinov MS. Arachidonic acid: reconciling the dichotomy of its oxidative cascade through specific deuteration. Free Radic Res 2023:1-11. [PMID: 37897398 DOI: 10.1080/10715762.2023.2277145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023]
Abstract
A new approach to attenuating pathological inflammatory reactions by buffering the eicosanoid pathways with oxidation-resistant hexadeuterated arachidonic acid (D-ARA) is discussed. Enzymatic processing of ARA, released by phospholipase A2, by lipoxygenases, cyclooxygenases, and cytochromes yields a wide range of bioactive eicosanoids, including pro-inflammation, pro-angiogenesis and pro-thrombosis species that, when produced in excess, are an underlying cause of pathology. Conversely, some products of ARA oxidation possess pro-resolving properties. Non-enzymatic free radical oxidation of ARA generates another large group of products such as isoprostanes and their metabolites, associated with inflammation, ischemia-reperfusion stress, and atherosclerosis. A separate group comprises reactive carbonyl derivatives that irreversibly damage diverse biomolecules. Being resistant to both enzymatic and non-enzymatic oxidation pathways due to large kinetic isotope effects, D-ARA may play a role in mitigating inflammation-related disorders and conditions, including inflammaging.
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Affiliation(s)
- J Thomas Brenna
- University of TX at Austin, Departments of Pediatrics, of Chemistry, and of Nutrition, Dell Pediatric Research Institute, Austin, TX, USA
| | - Marina G Sergeeva
- Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Nikolay B Pestov
- Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products, Laboratory of Tick-Borne Encephalitis and other Encephalitides, Moscow, Russia
- Institute of Biomedical Chemistry, Moscow, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Group of Cross-Linking Enzymes, Moscow, Russia
| | - Tatyana V Korneenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Group of Cross-Linking Enzymes, Moscow, Russia
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Guevara L, Gouge M, Ohler A, Hill SG, Patel S, Offenbacher AR. Effect of solvent viscosity on the activation barrier of hydrogen tunneling in the lipoxygenase reaction. Arch Biochem Biophys 2023; 747:109740. [PMID: 37678425 DOI: 10.1016/j.abb.2023.109740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 08/22/2023] [Accepted: 09/05/2023] [Indexed: 09/09/2023]
Abstract
Hydrogen tunneling in enzyme reactions has played an important role in linking protein thermal motions to the chemical steps of catalysis. Lipoxygenases (LOXs) have served as model systems for such reactions, showcasing deep hydrogen tunneling mechanisms associated with enzymatic C-H bond cleavage from polyunsaturated fatty acids. Here, we examined the effect of solvent viscosity on the protein thermal motions associated with LOX catalysis using trehalose and glucose as viscogens. Kinetic analysis of the reaction of the paradigm plant orthologue, soybean lipoxygenase (SLO), with linoleic acid revealed no effect on the first-order rate constants, kcat, or activation energy, Ea. Further studies of SLO active site mutants displaying varying Eas, which have been used to probe catalytically relevant motions, likewise provided no evidence for viscogen-dependent motions. Kinetic analyses were extended to a representative fungal LOX from M. oryzae, MoLOX, and a human LOX, 15-LOX-2. While MoLOX behaved similarly to SLO, we show that viscogens inhibit 15-LOX-2 activity. The latter implicates viscogen sensitive, conformational motions in animal LOX reactions. The data provide insight into the role of water hydration layers in facilitating hydrogen (quantum) tunneling in LOX.
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Affiliation(s)
- Luis Guevara
- Department of Chemistry, East Carolina University, Greenville, NC, 27858, USA
| | - Melissa Gouge
- Department of Chemistry and Biochemistry, Ohio Northern University, Ada, OH, 45810, USA
| | - Amanda Ohler
- Department of Chemistry, East Carolina University, Greenville, NC, 27858, USA
| | - S Gage Hill
- Department of Chemistry, East Carolina University, Greenville, NC, 27858, USA
| | - Soham Patel
- Department of Chemistry, East Carolina University, Greenville, NC, 27858, USA
| | - Adam R Offenbacher
- Department of Chemistry, East Carolina University, Greenville, NC, 27858, USA.
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Zaragoza JPT, Offenbacher AR, Hu S, Gee CL, Firestein ZM, Minnetian N, Deng Z, Fan F, Iavarone AT, Klinman JP. Temporal and spatial resolution of distal protein motions that activate hydrogen tunneling in soybean lipoxygenase. Proc Natl Acad Sci U S A 2023; 120:e2211630120. [PMID: 36867685 PMCID: PMC10013837 DOI: 10.1073/pnas.2211630120] [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: 07/06/2022] [Accepted: 01/27/2023] [Indexed: 03/05/2023] Open
Abstract
The enzyme soybean lipoxygenase (SLO) provides a prototype for deep tunneling mechanisms in hydrogen transfer catalysis. This work combines room temperature X-ray studies with extended hydrogen-deuterium exchange experiments to define a catalytically-linked, radiating cone of aliphatic side chains that connects an active site iron center of SLO to the protein-solvent interface. Employing eight variants of SLO that have been appended with a fluorescent probe at the identified surface loop, nanosecond fluorescence Stokes shifts have been measured. We report a remarkable identity of the energies of activation (Ea) for the Stokes shifts decay rates and the millisecond C-H bond cleavage step that is restricted to side chain mutants within an identified thermal network. These findings implicate a direct coupling of distal protein motions surrounding the exposed fluorescent probe to active site motions controlling catalysis. While the role of dynamics in enzyme function has been predominantly attributed to a distributed protein conformational landscape, the presented data implicate a thermally initiated, cooperative protein reorganization that occurs on a timescale faster than nanosecond and represents the enthalpic barrier to the reaction of SLO.
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Affiliation(s)
- Jan Paulo T. Zaragoza
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Adam R. Offenbacher
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, East Carolina University, Greenville, NC27858
| | - Shenshen Hu
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Christine L. Gee
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA94720
| | | | - Natalie Minnetian
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Zhenyu Deng
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Flora Fan
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Anthony T. Iavarone
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Judith P. Klinman
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA94720
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Ouaray Z, Benner SA, Georgiadis MM, Richards NGJ. Building better polymerases: Engineering the replication of expanded genetic alphabets. J Biol Chem 2020; 295:17046-17059. [PMID: 33004440 PMCID: PMC7863901 DOI: 10.1074/jbc.rev120.013745] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/30/2020] [Indexed: 11/30/2022] Open
Abstract
DNA polymerases are today used throughout scientific research, biotechnology, and medicine, in part for their ability to interact with unnatural forms of DNA created by synthetic biologists. Here especially, natural DNA polymerases often do not have the "performance specifications" needed for transformative technologies. This creates a need for science-guided rational (or semi-rational) engineering to identify variants that replicate unnatural base pairs (UBPs), unnatural backbones, tags, or other evolutionarily novel features of unnatural DNA. In this review, we provide a brief overview of the chemistry and properties of replicative DNA polymerases and their evolved variants, focusing on the Klenow fragment of Taq DNA polymerase (Klentaq). We describe comparative structural, enzymatic, and molecular dynamics studies of WT and Klentaq variants, complexed with natural or noncanonical substrates. Combining these methods provides insight into how specific amino acid substitutions distant from the active site in a Klentaq DNA polymerase variant (ZP Klentaq) contribute to its ability to replicate UBPs with improved efficiency compared with Klentaq. This approach can therefore serve to guide any future rational engineering of replicative DNA polymerases.
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Affiliation(s)
- Zahra Ouaray
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, Alachua, Florida, USA
| | - Millie M Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Nigel G J Richards
- School of Chemistry, Cardiff University, Park Place, Cardiff, United Kingdom; Foundation for Applied Molecular Evolution, Alachua, Florida, USA.
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Offenbacher AR, Holman TR. Fatty Acid Allosteric Regulation of C-H Activation in Plant and Animal Lipoxygenases. Molecules 2020; 25:molecules25153374. [PMID: 32722330 PMCID: PMC7436259 DOI: 10.3390/molecules25153374] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 12/18/2022] Open
Abstract
Lipoxygenases (LOXs) catalyze the (per) oxidation of fatty acids that serve as important mediators for cell signaling and inflammation. These reactions are initiated by a C-H activation step that is allosterically regulated in plant and animal enzymes. LOXs from higher eukaryotes are equipped with an N-terminal PLAT (Polycystin-1, Lipoxygenase, Alpha-Toxin) domain that has been implicated to bind to small molecule allosteric effectors, which in turn modulate substrate specificity and the rate-limiting steps of catalysis. Herein, the kinetic and structural evidence that describes the allosteric regulation of plant and animal lipoxygenase chemistry by fatty acids and their derivatives are summarized.
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Affiliation(s)
- Adam R. Offenbacher
- Department of Chemistry, East Carolina University, Greenville, NC 27858, USA
- Correspondence:
| | - Theodore R. Holman
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA 95064, USA;
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