1
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Krishnan A, Waheed SO, Melayikandy S, LaRouche C, Paik M, Schofield CJ, Karabencheva-Christova TG. Effects of Clinical Mutations in the Second Coordination Sphere and Remote Regions on the Catalytic Mechanism of Non-Heme Fe(II)/2-Oxoglutarate-Dependent Aspartyl Hydroxylase AspH. Chemphyschem 2024; 25:e202400303. [PMID: 38839574 DOI: 10.1002/cphc.202400303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 06/07/2024]
Abstract
Aspartyl/asparaginyl hydroxylase (AspH) catalyzes the post-translational hydroxylations of vital human proteins, playing an essential role in maintaining their biological functions. Single-point mutations in the Second Coordination Sphere (SCS) and long-range (LR) residues of AspH have been linked to pathological conditions such as the ophthalmologic condition Traboulsi syndrome and chronic kidney disease (CKD). Although the clinical impacts of these mutations are established, there is a critical knowledge gap regarding their specific atomistic effects on the catalytic mechanism of AspH. In this study, we report integrated computational investigations on the potential mechanistic implications of four mutant forms of human AspH with clinical importance: R735W, R735Q, R688Q, and G434V. All the mutant forms exhibited altered binding interactions with the co-substrate 2-oxoglutarate (2OG) and the main substrate in the ferric-superoxo and ferryl complexes, which are critical for catalysis, compared to the wild-type (WT). Importantly, the mutations strongly influence the energetics of the frontier molecular orbitals (FMOs) and, thereby, the activation energies for the hydrogen atom transfer (HAT) step compared to the WT AspH. Insights from our study can contribute to enzyme engineering and the development of selective modulators for WT and mutants of AspH, ultimately aiding in treating cancers, Traboulsi syndrome and, CKD.
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Affiliation(s)
- Anandhu Krishnan
- Department of Chemistry, Michigan Technological University, Houghton, MI-49931, USA
| | - Sodiq O Waheed
- Department of Chemistry, Michigan Technological University, Houghton, MI-49931, USA
| | - Sreerag Melayikandy
- Department of Chemistry, Michigan Technological University, Houghton, MI-49931, USA
| | - Ciara LaRouche
- Department of Chemical Engineering, Michigan Techno, Department of Chemistry, Michigan Technological University, Houghton, MI-49931, USA
| | - Meredith Paik
- Department of Chemistry, Michigan Technological University, Houghton, MI-49931, USA
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, Oxford, OX1 3TA, United Kingdom
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2
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Fiorini G, Schofield CJ. Biochemistry of the hypoxia-inducible factor hydroxylases. Curr Opin Chem Biol 2024; 79:102428. [PMID: 38330792 DOI: 10.1016/j.cbpa.2024.102428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/11/2024] [Accepted: 01/11/2024] [Indexed: 02/10/2024]
Abstract
The hypoxia-inducible factors are α,β-heterodimeric transcription factors that mediate the chronic response to hypoxia in humans and other animals. Protein hydroxylases belonging to two different structural subfamilies of the Fe(II) and 2-oxoglutarate (2OG)-dependent oxygenase superfamily modify HIFα. HIFα prolyl-hydroxylation, as catalysed by the PHDs, regulates HIFα levels and, consequently, α,β-HIF levels. HIFα asparaginyl-hydroxylation, as catalysed by factor inhibiting HIF (FIH), regulates the transcriptional activity of α,β-HIF. The activities of the PHDs and FIH are regulated by O2 availability, enabling them to act as hypoxia sensors. We provide an overview of the biochemistry of the HIF hydroxylases, discussing evidence that their kinetic and structural properties may be tuned to their roles in the HIF system. Avenues for future research and therapeutic modulation are discussed.
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Affiliation(s)
- Giorgia Fiorini
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, 12 Mansfield Road, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United Kingdom
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, 12 Mansfield Road, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United Kingdom.
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3
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Krishnan A, Waheed SO, Varghese A, Cherilakkudy FH, Schofield CJ, Karabencheva-Christova TG. Unusual catalytic strategy by non-heme Fe(ii)/2-oxoglutarate-dependent aspartyl hydroxylase AspH. Chem Sci 2024; 15:3466-3484. [PMID: 38455014 PMCID: PMC10915816 DOI: 10.1039/d3sc05974j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 02/02/2024] [Indexed: 03/09/2024] Open
Abstract
Biocatalytic C-H oxidation reactions are of important synthetic utility, provide a sustainable route for selective synthesis of important organic molecules, and are an integral part of fundamental cell processes. The multidomain non-heme Fe(ii)/2-oxoglutarate (2OG) dependent oxygenase AspH catalyzes stereoselective (3R)-hydroxylation of aspartyl- and asparaginyl-residues. Unusually, compared to other 2OG hydroxylases, crystallography has shown that AspH lacks the carboxylate residue of the characteristic two-His-one-Asp/Glu Fe-binding triad. Instead, AspH has a water molecule that coordinates Fe(ii) in the coordination position usually occupied by the Asp/Glu carboxylate. Molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) studies reveal that the iron coordinating water is stabilized by hydrogen bonding with a second coordination sphere (SCS) carboxylate residue Asp721, an arrangement that helps maintain the six coordinated Fe(ii) distorted octahedral coordination geometry and enable catalysis. AspH catalysis follows a dioxygen activation-hydrogen atom transfer (HAT)-rebound hydroxylation mechanism, unusually exhibiting higher activation energy for rebound hydroxylation than for HAT, indicating that the rebound step may be rate-limiting. The HAT step, along with substrate positioning modulated by the non-covalent interactions with SCS residues (Arg688, Arg686, Lys666, Asp721, and Gln664), are essential in determining stereoselectivity, which likely proceeds with retention of configuration. The tetratricopeptide repeat (TPR) domain of AspH influences substrate binding and manifests dynamic motions during catalysis, an observation of interest with respect to other 2OG oxygenases with TPR domains. The results provide unique insights into how non-heme Fe(ii) oxygenases can effectively catalyze stereoselective hydroxylation using only two enzyme-derived Fe-ligating residues, potentially guiding enzyme engineering for stereoselective biocatalysis, thus advancing the development of non-heme Fe(ii) based biomimetic C-H oxidation catalysts, and supporting the proposal that the 2OG oxygenase superfamily may be larger than once perceived.
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Affiliation(s)
- Anandhu Krishnan
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | - Sodiq O Waheed
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | - Ann Varghese
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | | | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford OX1 3TA Oxford UK
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4
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Martin CB, Taabazuing CY, Knapp MJ. Dynamic Domain Links Substrate Binding and Catalysis in the Factor-Inhibiting-HIF-1. Biochemistry 2023; 62:2442-2449. [PMID: 37526986 DOI: 10.1021/acs.biochem.3c00231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
The interplay between active-site chemistry and functionally relevant enzyme motions can provide useful insights into selective enzyme modulation. Modulation of the hypoxia-sensing function of factor-inhibiting-HIF-1 (FIH) enzyme is a potential therapeutic strategy in disease states such as ischemia and cancer. The hypoxia-sensing function of FIH relies in major part on the tight coupling of the first half of the catalytic mechanism which involves O2 activation and eventual succinate production to the second half which involves HIF-1α/CTAD substrate hydroxylation. In this study, we demonstrate the role of a loop hinge domain in FIH (FIH102-118) called the 100s loop in maintaining this particular tight coupling. Molecular dynamics patterns from Gaussian Network Model (iGNM) database analysis of FIH identified the 100s loop as one dynamic domain containing a hinge residue (Tyr102) with a potential substrate positioning role. Enzymological and biophysical studies of the 100s loop point mutants revealed altered enzyme kinetics with the exception of the conservative FIH mutant Y102F, which suggests a sterics-related role for this residue. Removal of the bulk of Tyr102 (Y102A) resulted in succinate production, autohydroxylation, and an O2 binding environment comparable to wild-type FIH. However, the HIF-1α/CTAD substrate hydroxylation of this mutant was significantly reduced which implies that (1) the FIH loop hinge residue Tyr102 does not affect O2 activation, (2) the stacking steric interaction of Tyr102 is important in substrate positioning for productive hydroxylation, and (3) Tyr102 is important for the synchronization of O2 activation and substrate hydroxylation.
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Affiliation(s)
- Cristina B Martin
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Cornelius Y Taabazuing
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Song B, Modjewski LD, Kapust N, Mizrahi I, Martin WF. The origin and distribution of the main oxygen sensing mechanism across metazoans. Front Physiol 2022; 13:977391. [PMID: 36324306 PMCID: PMC9618697 DOI: 10.3389/fphys.2022.977391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/07/2022] [Indexed: 11/13/2022] Open
Abstract
Oxygen sensing mechanisms are essential for metazoans, their origin and evolution in the context of oxygen in Earth history are of interest. To trace the evolution of a main oxygen sensing mechanism among metazoans, the hypoxia induced factor, HIF, we investigated the phylogenetic distribution and phylogeny of 11 of its components across 566 eukaryote genomes. The HIF based oxygen sensing machinery in eukaryotes can be traced as far back as 800 million years (Ma) ago, likely to the last metazoan common ancestor (LMCA), and arose at a time when the atmospheric oxygen content corresponded roughly to the Pasteur point, or roughly 1% of present atmospheric level (PAL). By the time of the Cambrian explosion (541–485 Ma) as oxygen levels started to approach those of the modern atmosphere, the HIF system with its key components HIF1α, HIF1β, PHD1, PHD4, FIH and VHL was well established across metazoan lineages. HIF1α is more widely distributed and therefore may have evolved earlier than HIF2α and HIF3α, and HIF1β and is more widely distributed than HIF2β in invertebrates. PHD1, PHD4, FIH, and VHL appear in all 13 metazoan phyla. The O2 consuming enzymes of the pathway, PHDs and FIH, have a lower substrate affinity, Km, for O2 than terminal oxidases in the mitochondrial respiratory chain, in line with their function as an environmental signal to switch to anaerobic energy metabolic pathways. The ancient HIF system has been conserved and widespread during the period when metazoans evolved and diversified together with O2 during Earth history.
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Affiliation(s)
- Bing Song
- Department of Biology, Institute for Molecular Evolution, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Luca David Modjewski
- Department of Biology, Institute for Molecular Evolution, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Nils Kapust
- Department of Biology, Institute for Molecular Evolution, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Itzhak Mizrahi
- Department of Life Sciences, Ben-Gurion University of the Negev and the National Institute for Biotechnology in the Negev, Marcus Family Campus, Be’er-Sheva, Israel
| | - William F. Martin
- Department of Biology, Institute for Molecular Evolution, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
- *Correspondence: William F. Martin,
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6
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Mingroni MA, Chaplin Momaney V, Barlow AN, Jaen Maisonet I, Knapp MJ. Measurement of kinetic isotope effects on peptide hydroxylation using MALDI-MS. Methods Enzymol 2022; 679:363-380. [PMID: 36682871 DOI: 10.1016/bs.mie.2022.08.019] [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] [Indexed: 01/25/2023]
Abstract
Primary kinetic isotope effects (KIEs) provide unique insight into enzymatic reactions, as they can reveal rate-limiting steps and detailed chemical mechanisms. HIF hydroxylases, part of a family of 2-oxoglutarate (2OG) oxygenases are central to the regulation of many crucial biological processes through O2-sensing, but present a challenge to monitor due to the large size of the protein substrate and the similarity between native and hydroxylated substrate. MALDI-TOF MS is a convenient tool to measure peptide masses, which can also be used to measure the discontinuous kinetics of peptide hydroxylation for Factor Inhibiting HIF (FIH). Using this technique, rate data can be observed from the mole-fraction of CTAD and CTAD-OH in small volumes, allowing noncompetitive H/D KIEs to be measured. Slow dCTAD substrate leads to extensive uncoupling of O2 consumption from peptide hydroxylation, leading to enzyme autohydroxylation, which is observed using UV-vis spectroscopy. Simultaneously measuring both the normal product, CTAD-OH, and the uncoupled product, autohydroxylated enzyme, the KIE on the microscopic step of hydrogen atom transfer (HAT) can be estimated. MALDI-MS analysis is a strong method for monitoring reactions that hydroxylate peptides, and can be generalized to other similar reactions, and simultaneous kinetic detection of branched products can provide valuable insight on microscopic KIEs at intermediate mechanistic steps.
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Affiliation(s)
- Michael A Mingroni
- Department of Chemistry, University of Massachusetts, Amherst, MA, United States
| | | | - Alexandra N Barlow
- Department of Chemistry, University of Massachusetts, Amherst, MA, United States
| | | | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, MA, United States.
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7
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Schmidl D, Jonasson NSW, Menke A, Schneider S, Daumann L. Spectroscopic and in vitro investigations of Fe2+/α-Ketoglutarate-dependent enzymes involved in nucleic acid repair and modification. Chembiochem 2022; 23:e202100605. [PMID: 35040547 PMCID: PMC9401043 DOI: 10.1002/cbic.202100605] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/14/2022] [Indexed: 11/08/2022]
Abstract
The activation of molecular oxygen for the highly selective functionalization and repair of DNA and RNA nucleobases is achieved by α-ketoglutarate (α-KG)/iron-dependent dioxygenases. Enzymes of special interest are the human homologs AlkBH of Escherichia coli EcAlkB and ten-eleven translocation (TET) enzymes. These enzymes are involved in demethylation or dealkylation of DNA and RNA, although additional physiological functions are continuously being revealed. Given their importance, studying enzyme-substrate interactions, turnover and kinetic parameters is pivotal for the understanding of the mode of action of these enzymes. Diverse analytical methods, including X-ray crystallography, UV/Vis absorption, electron paramagnetic resonance (EPR), circular dichroism (CD) and NMR spectroscopy have been employed to study the changes in the active site and the overall enzyme structure upon substrate, cofactor and inhibitor addition. Several methods are now available to assess activity of these enzymes. By discussing limitations and possibilities of these techniques for EcAlkB, AlkBH and TET we aim to give a comprehensive synopsis from a bioinorganic point of view, addressing researchers from different disciplines working in the highly interdisciplinary and rapidly evolving field of epigenetic processes and DNA/RNA repair and modification.
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Affiliation(s)
- David Schmidl
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen, Chemistry, GERMANY
| | - Niko S W Jonasson
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen, Chemistry, GERMANY
| | - Annika Menke
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen, Chemistry, GERMANY
| | - Sabine Schneider
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen, Chemistry, GERMANY
| | - Lena Daumann
- Ludwig-Maximilians-Universität München, Department of Chemistry, Butenandtstr. 5-13, 81377, München, GERMANY
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8
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Mingroni MA, Knapp MJ. Kinetic Studies of the Hydrogen Atom Transfer in a Hypoxia-Sensing Enzyme, FIH-1: KIE and O 2 Reactivity. Biochemistry 2021; 60:3315-3322. [PMID: 34714626 DOI: 10.1021/acs.biochem.1c00476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cellular hypoxia plays a crucial role in tissue development and adaptation to pO2. Central to cellular oxygen sensing is factor-inhibiting HIF-1α (FIH), an α-ketoglutarate (αKG)/non-heme iron(II)-dependent dioxygenase that hydroxylates a specific asparagine residue of hypoxia inducible factor-1α (HIF-1α). The high KM(O2) and rate-limiting decarboxylation step upon O2 activation are key features of the enzyme that classify it as an oxygen sensor and set it apart from other αKG/Fe(II)-dependent dioxygenases. Although the chemical intermediates following decarboxylation are presumed to follow the consensus mechanism of other αKG/Fe(II)-dependent dioxygenases, experiments have not previously demonstrated these canonical steps in FIH. In this work, a deuterated peptide substrate was used as a mechanistic probe for the canonical hydrogen atom transfer (HAT). Our data show a large kinetic isotope effect (KIE) in steady-state kinetics (Dkcat = 10 ± 1), revealing that the HAT occurs and is partially rate limiting on kcat. Kinetic studies showed that the deuterated peptide led FIH to uncouple O2 activation and provided the opportunity to spectroscopically observe the ferryl intermediate. This enzyme uncoupling was used as an internal competition with respect to the fate of the ferryl intermediate, demonstrating a large observed KIE on the uncoupling (Dk5 = 1.147 ± 0.005) and an intrinsic KIE on the HAT step (Dk > 15). The close energy barrier between αKG decarboxylation and HAT distinguishes FIH as an O2-sensing enzyme and is crucial for ensuring substrate specificity in the regulation of cellular O2 homeostasis.
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Affiliation(s)
- Michael A Mingroni
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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9
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Greve JM, Pinkham AM, Thompson Z, Cowan JA. Active site characterization and activity of the human aspartyl (asparaginyl) β-hydroxylase. Metallomics 2021; 13:6372921. [PMID: 34543426 DOI: 10.1093/mtomcs/mfab056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 09/06/2021] [Indexed: 01/18/2023]
Abstract
Human aspartyl/asparaginyl beta-hydroxylase (HAAH) is a member of the superfamily of nonheme Fe2+/α-ketoglutarate (αKG) dependent oxygenase enzymes with a noncanonical active site. HAAH hydroxylates epidermal growth factor (EGF) like domains to form the β-hydroxylated product from substrate asparagine or aspartic acid and has been suggested to have a negative impact in a variety of cancers. In addition to iron, HAAH also binds divalent calcium, although the role of the latter is not understood. Herein, the metal binding chemistry and influence on enzyme stability and activity have been evaluated by a combined biochemical and biophysical approach. Metal binding parameters for the HAAH active site were determined by use of isothermal titration calorimetry, demonstrating a high-affinity regulatory binding site for Ca2+ in the catalytic domain in addition to the catalytic Fe2+ cofactor. We have analyzed various active site derivatives, utilizing LC-MS and a new HPLC technique to determine the role of metal binding and the second coordination sphere in enzyme activity, discovering a previously unreported residue as vital for HAAH turnover. This analysis of the in vitro biochemical function of HAAH furthers the understanding of its importance to cellular biochemistry and metabolic pathways.
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Affiliation(s)
- Jenna M Greve
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - Andrew M Pinkham
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - Zechariah Thompson
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - J A Cowan
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
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10
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Greve JM, Pinkham AM, Cowan JA. Human Aspartyl (Asparaginyl) Hydroxylase. A Multifaceted Enzyme with Broad Intra- and Extracellular Activity. Metallomics 2021; 13:6324587. [PMID: 34283245 DOI: 10.1093/mtomcs/mfab044] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 06/29/2021] [Indexed: 01/12/2023]
Abstract
Human aspartyl (asparaginyl) β-hydroxylase (HAAH), a unique iron and 2-oxoglutarate dependent oxygenase, has shown increased importance as a suspected oncogenic protein. HAAH and its associated mRNA are upregulated in a wide variety of cancer types, however, the current role of HAAH in the malignant transformation of cells is unknown. HAAH is suspected to play an important role in NOTCH signaling via selective hydroxylation of aspartic acid and asparagine residues of epidermal growth factor (EGF)-like domains. HAAH hydroxylation also potentially mediates calcium signaling and oxygen sensing. In this review we summarize the current state of understanding of the biochemistry and chemical biology of this enzyme, identify key differences from other family members, outline its broader intra- and extracellular roles, and identify the most promising areas for future research efforts.
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Affiliation(s)
- Jenna M Greve
- Contribution from the Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
| | - Andrew M Pinkham
- Contribution from the Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
| | - J A Cowan
- Contribution from the Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
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11
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Li H, Zhu W, Liu Y. Mechanism of Uncoupled Carbocyclization and Epimerization Catalyzed by Two Non-Heme Iron/α-Ketoglutarate Dependent Enzymes. J Chem Inf Model 2019; 59:5086-5098. [PMID: 31790238 DOI: 10.1021/acs.jcim.9b00837] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The non-heme iron/α-ketoglutarate dependent enzymes SnoK and SnoN from Streptomyces nogalater are involved in the biosynthesis of anthracycline nogalamycin. Although they have similar active sites, SnoK is responsible for carbocyclization whereas SnoN solely catalyzes the hydroxyl epimerization. Herein, we performed docking, molecular simulations, and a series of combined quantum mechanics and molecular mechanics (QM/MM) calculations to illuminate the mechanisms of two enzymes. The catalytic reactions of two enzymes occur on the quintet state surface. For SnoK, the whole reaction includes two separated hydrogen-abstraction steps and one radical addition, and the latter step is calculated to be rate limiting with an energy barrier of 21.7 kcal/mol. Residue D106 is confirmed to participate in the construction of the hydrogen bond network, which plays a crucial role in positioning the bulky substrate in a specific orientation. Moreover, it is found that SnoN is only responsible for the hydrogen abstraction of the intermediate, and no residue was suggested to be suitable for donating a hydrogen atom to the substrate radical, which further confirms the suggestion based on experiments that either a cellular reductant or another enzyme protein could donate a hydrogen atom to the substrate. Our docking results coincide with the previous structural study that the different roles of two enzymes are achieved by minor changes in the alignment of the substrates in front of the reactive ferryl-oxo species. This work highlights the reaction mechanisms catalyzed by SnoK and SnoN, which is helpful for engineering the enzymes for the biosynthesis of anthracycline nogalamycin.
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Affiliation(s)
- Hong Li
- Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shandong University , Jinan , Shandong 250100 , China
| | - Wenyou Zhu
- College of Chemistry and Chemical Engineering , Xuzhou Institute of Technology , Xuzhou , Jiangsu 221111 , China
| | - Yongjun Liu
- Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shandong University , Jinan , Shandong 250100 , China
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12
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Chaplin VD, Valliere MA, Hangasky JA, Knapp MJ. Investigations on the role of a solvent tunnel in the α-ketoglutarate dependent oxygenase factor inhibiting HIF (FIH). J Inorg Biochem 2017; 178:63-69. [PMID: 29078149 DOI: 10.1016/j.jinorgbio.2017.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 09/27/2017] [Accepted: 10/06/2017] [Indexed: 01/25/2023]
Abstract
Non-heme Fe(II)/α-ketoglutarate (αKG)-dependent oxygenases catalyze a wide array of reactions through coupling oxidative decarboxylation of αKG to substrate oxygenation. This class of enzymes follows a sequential mechanism in which O2 reacts only after binding primary substrate, raising questions over how protein structure tailors molecular access to the Fe(II) cofactor. The enzyme "factor inhibiting hypoxia inducible factor" (FIH) senses pO2 in human cells by hydroxylating the C-terminal transactivation domain (CTAD), suggesting that structural elements limiting molecular access to the active site may limit the pO2 response. In this study, we tested the impact of a solvent-accessible tunnel in FIH on molecular access to the active site in FIH. The size of the tunnel was increased through alanine point mutagenesis (Y93A, E105A, and Q147A), followed by a suite of mechanistic and spectroscopic probes. Steady-state kinetics varying O2 or CTAD indicated that O2 passage through the tunnel was not affected by Ala substitutions, allowing us to conclude that this narrow tunnel did not impact pO2 sensing by FIH. Steady-state kinetics with varied αKG concentrations revealed increased substrate inhibition for the Ala variants, suggesting that a second αKG molecule may bind near the active site of FIH. If this solvent-accessible tunnel is the O2 entry tunnel, it may be narrow in order to permit O2 access while preventing metabolic intermediates, such as αKG, from inhibiting FIH under physiological conditions.
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Affiliation(s)
- Vanessa D Chaplin
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - Meaghan A Valliere
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - John A Hangasky
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, United States.
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13
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Su H, Sheng X, Zhu W, Ma G, Liu Y. Mechanistic Insights into the Decoupled Desaturation and Epoxidation Catalyzed by Dioxygenase AsqJ Involved in the Biosynthesis of Quinolone Alkaloids. ACS Catal 2017. [DOI: 10.1021/acscatal.7b01606] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Hao Su
- School of Chemistry and Chemical
Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Xiang Sheng
- School of Chemistry and Chemical
Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Wenyou Zhu
- School of Chemistry and Chemical
Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Guangcai Ma
- School of Chemistry and Chemical
Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yongjun Liu
- School of Chemistry and Chemical
Engineering, Shandong University, Jinan, Shandong 250100, China
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Hangasky JA, Taabazuing CY, Martin CB, Eron SJ, Knapp MJ. The facial triad in the α-ketoglutarate dependent oxygenase FIH: A role for sterics in linking substrate binding to O 2 activation. J Inorg Biochem 2017; 166:26-33. [PMID: 27815979 PMCID: PMC5161613 DOI: 10.1016/j.jinorgbio.2016.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/07/2016] [Accepted: 10/13/2016] [Indexed: 02/06/2023]
Abstract
The factor inhibiting hypoxia inducible factor-1α (FIH) is a nonheme Fe(II)/αKG oxygenase using a 2-His-1-Asp facial triad. FIH activates O2 via oxidative decarboxylation of α-ketoglutarate (αKG) to generate an enzyme-based oxidant which hydroxylates the Asn803 residue within the C-terminal transactivation domain (CTAD) of HIF-1α. Tight coupling of these two sequential reactions requires a structural linkage between the Fe(II) and the substrate binding site to ensure that O2 activation occurs after substrate binds. We tested the hypothesis that the facial triad carboxylate (Asp201) of FIH linked substrate binding and O2 binding sites. Asp201 variants of FIH were constructed and thoroughly characterized in vitro using steady-state kinetics, crystallography, autohydroxylation, and coupling measurements. Our studies revealed each variant activated O2 with a catalytic efficiency similar to that of wild-type (WT) FIH (kcataKM(O2)=0.17μM-1min-1), but led to defects in the coupling of O2 activation to substrate hydroxylation. Steady-state kinetics showed similar catalytic efficiencies for hydroxylation by WT-FIH (kcat/KM(CTAD)=0.42μM-1min-1) and D201G (kcat/KM(CTAD)=0.34μM-1min-1); hydroxylation by D201E was greatly impaired, while hydroxylation by D201A was undetectable. Analysis of the crystal structure of the D201E variant revealed steric crowding near the diffusible ligand site supporting a role for sterics from the facial triad carboxylate in the O2 binding order. Our data support a model in which the facial triad carboxylate Asp201 provides both steric and polar contacts to favor O2 access to the Fe(II) only after substrate binds, leading to coupled turnover in FIH and other αKG oxygenases.
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Affiliation(s)
- John A Hangasky
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | | | - Cristina B Martin
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - Scott J Eron
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, United States.
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Ma G, Zhu W, Su H, Cheng N, Liu Y. Uncoupled Epimerization and Desaturation by Carbapenem Synthase: Mechanistic Insights from QM/MM Studies. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01275] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Guangcai Ma
- Key Laboratory
of Colloid
and Interface Chemistry, Ministry of Education, School of Chemistry
and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Wenyou Zhu
- Key Laboratory
of Colloid
and Interface Chemistry, Ministry of Education, School of Chemistry
and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Hao Su
- Key Laboratory
of Colloid
and Interface Chemistry, Ministry of Education, School of Chemistry
and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Na Cheng
- Key Laboratory
of Colloid
and Interface Chemistry, Ministry of Education, School of Chemistry
and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yongjun Liu
- Key Laboratory
of Colloid
and Interface Chemistry, Ministry of Education, School of Chemistry
and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
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