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Elmendorf LD, Brunold TC. Electronic structure studies of free and enzyme-bound B 12 species by magnetic circular dichroism and complementary spectroscopic techniques. Methods Enzymol 2022; 669:333-365. [PMID: 35644179 DOI: 10.1016/bs.mie.2022.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Electronic absorption (Abs) and circular dichroism (CD) spectroscopic techniques have been used successfully for over half a century in studies of free and enzyme-bound B12 species. More recently, magnetic circular dichroism (MCD) spectroscopy and other complementary techniques have provided an increasingly detailed understanding of the electronic structure of cobalamins. While CD spectroscopy measures the difference in the absorption of left- and right-circularly polarized light, MCD spectroscopy adds the application of a magnetic field parallel to the direction of light propagation. Transitions that are formally forbidden according to the Abs and CD selection rules, such as ligand field (or d→d) transitions, can gain MCD intensity through spin-orbit coupling. As such, MCD spectroscopy provides a uniquely sensitive probe of the different binding modes, Co oxidation states, and axial ligand environments of B12 species in enzyme active sites, and thus the distinct reactivities displayed by these species. This chapter summarizes representative MCD studies of free and enzyme-bound B12 species, including those present in adenosyltransferases, isomerases, and reductive dehalogenases. Complementary spectroscopic and computational data are also presented and discussed where appropriate.
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Affiliation(s)
- Laura D Elmendorf
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States
| | - Thomas C Brunold
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States.
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Toraya T, Tobimatsu T, Mori K, Yamanishi M, Shibata N. Coenzyme B 12-dependent eliminases: Diol and glycerol dehydratases and ethanolamine ammonia-lyase. Methods Enzymol 2022; 668:181-242. [PMID: 35589194 DOI: 10.1016/bs.mie.2021.11.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Adenosylcobalamin (AdoCbl) or coenzyme B12-dependent enzymes catalyze intramolecular group-transfer reactions and ribonucleotide reduction in a wide variety of organisms from bacteria to animals. They use a super-reactive primary-carbon radical formed by the homolysis of the coenzyme's Co-C bond for catalysis and thus belong to the larger class of "radical enzymes." For understanding the general mechanisms of radical enzymes, it is of great importance to establish the general mechanism of AdoCbl-dependent catalysis using enzymes that catalyze the simplest reactions-such as diol dehydratase, glycerol dehydratase and ethanolamine ammonia-lyase. These enzymes are often called "eliminases." We have studied AdoCbl and eliminases for more than a half century. Progress has always been driven by the development of new experimental methodologies. In this chapter, we describe our investigations on these enzymes, including their metabolic roles, gene cloning, preparation, characterization, activity assays, and mechanistic studies, that have been conducted using a wide range of biochemical and structural methodologies we have developed.
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Affiliation(s)
- Tetsuo Toraya
- Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan.
| | - Takamasa Tobimatsu
- Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Koichi Mori
- Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Mamoru Yamanishi
- Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan
| | - Naoki Shibata
- Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo, Japan
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Dawson CD, Irwin SM, Backman LRF, Le C, Wang JX, Vennelakanti V, Yang Z, Kulik HJ, Drennan CL, Balskus EP. Molecular basis of C-S bond cleavage in the glycyl radical enzyme isethionate sulfite-lyase. Cell Chem Biol 2021; 28:1333-1346.e7. [PMID: 33773110 PMCID: PMC8473560 DOI: 10.1016/j.chembiol.2021.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 02/04/2021] [Accepted: 03/03/2021] [Indexed: 01/07/2023]
Abstract
Desulfonation of isethionate by the bacterial glycyl radical enzyme (GRE) isethionate sulfite-lyase (IslA) generates sulfite, a substrate for respiration that in turn produces the disease-associated metabolite hydrogen sulfide. Here, we present a 2.7 Å resolution X-ray structure of wild-type IslA from Bilophila wadsworthia with isethionate bound. In comparison with other GREs, alternate positioning of the active site β strands allows for distinct residue positions to contribute to substrate binding. These structural differences, combined with sequence variations, create a highly tailored active site for the binding of the negatively charged isethionate substrate. Through the kinetic analysis of 14 IslA variants and computational analyses, we probe the mechanism by which radical chemistry is used for C-S bond cleavage. This work further elucidates the structural basis of chemistry within the GRE superfamily and will inform structure-based inhibitor design of IsIA and thus of microbial hydrogen sulfide production.
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Affiliation(s)
- Christopher D Dawson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Stephania M Irwin
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
| | - Lindsey R F Backman
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chip Le
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
| | - Jennifer X Wang
- Harvard Center for Mass Spectrometry, Faculty of Arts and Sciences Division of Science, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA
| | - Vyshnavi Vennelakanti
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zhongyue Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Catherine L Drennan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA; Broad Institute, Cambridge, MA 02139, USA.
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Backman LRF, Huang YY, Andorfer MC, Gold B, Raines RT, Balskus EP, Drennan CL. Molecular basis for catabolism of the abundant metabolite trans-4-hydroxy-L-proline by a microbial glycyl radical enzyme. eLife 2020; 9:e51420. [PMID: 32180548 PMCID: PMC7077986 DOI: 10.7554/elife.51420] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/19/2020] [Indexed: 02/04/2023] Open
Abstract
The glycyl radical enzyme (GRE) superfamily utilizes a glycyl radical cofactor to catalyze difficult chemical reactions in a variety of anaerobic microbial metabolic pathways. Recently, a GRE, trans-4-hydroxy-L-proline (Hyp) dehydratase (HypD), was discovered that catalyzes the dehydration of Hyp to (S)-Δ1-pyrroline-5-carboxylic acid (P5C). This enzyme is abundant in the human gut microbiome and also present in prominent bacterial pathogens. However, we lack an understanding of how HypD performs its unusual chemistry. Here, we have solved the crystal structure of HypD from the pathogen Clostridioides difficile with Hyp bound in the active site. Biochemical studies have led to the identification of key catalytic residues and have provided insight into the radical mechanism of Hyp dehydration.
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Affiliation(s)
- Lindsey RF Backman
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Yolanda Y Huang
- Department of Chemistry and Chemical Biology, Harvard UniversityCambridgeUnited States
| | - Mary C Andorfer
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Brian Gold
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Ronald T Raines
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard UniversityCambridgeUnited States
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
- Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States
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Abstract
This Perspective provides the first detailed overview of the photoresponse of vitamin B12 and its derivatives, from the early, photophysical events to the burgeoning area of B12-dependent photobiology.
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Affiliation(s)
- Alex R. Jones
- School of Chemistry
- Photon Science Institute and Manchester Institute of Biotechnology
- The University of Manchester
- Manchester
- UK
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Bodea S, Funk MA, Balskus EP, Drennan CL. Molecular Basis of C-N Bond Cleavage by the Glycyl Radical Enzyme Choline Trimethylamine-Lyase. Cell Chem Biol 2016; 23:1206-1216. [PMID: 27642068 DOI: 10.1016/j.chembiol.2016.07.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/07/2016] [Accepted: 07/25/2016] [Indexed: 01/16/2023]
Abstract
Deamination of choline catalyzed by the glycyl radical enzyme choline trimethylamine-lyase (CutC) has emerged as an important route for the production of trimethylamine, a microbial metabolite associated with both human disease and biological methane production. Here, we have determined five high-resolution X-ray structures of wild-type CutC and mechanistically informative mutants in the presence of choline. Within an unexpectedly polar active site, CutC orients choline through hydrogen bonding with a putative general base, and through close interactions between phenolic and carboxylate oxygen atoms of the protein scaffold and the polarized methyl groups of the trimethylammonium moiety. These structural data, along with biochemical analysis of active site mutants, support a mechanism that involves direct elimination of trimethylamine. This work broadens our understanding of radical-based enzyme catalysis and will aid in the rational design of inhibitors of bacterial trimethylamine production.
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Affiliation(s)
- Smaranda Bodea
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
| | - Michael A Funk
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts, Avenue 68-680, Cambridge, MA 02139, USA
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts, Avenue 68-680, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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