1
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Fernandez-Cantos MV, Garcia-Morena D, Yi Y, Liang L, Gómez-Vázquez E, Kuipers OP. Bioinformatic mining for RiPP biosynthetic gene clusters in Bacteroidales reveals possible new subfamily architectures and novel natural products. Front Microbiol 2023; 14:1219272. [PMID: 37469430 PMCID: PMC10352776 DOI: 10.3389/fmicb.2023.1219272] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 06/16/2023] [Indexed: 07/21/2023] Open
Abstract
The Bacteroidales order, widely distributed among diverse human populations, constitutes a key component of the human microbiota. Members of this Gram-negative order have been shown to modulate the host immune system, play a fundamental role in the gut's microbial food webs, or be involved in pathogenesis. Bacteria inhabiting such a complex environment as the human microbiome are expected to display social behaviors and, hence, possess factors that mediate cooperative and competitive interactions. Different types of molecules can mediate interference competition, including non-ribosomal peptides (NRPs), polyketides, and bacteriocins. The present study investigates the potential of Bacteroidales bacteria to biosynthesize class I bacteriocins, which are ribosomally synthesized and post-translationally modified peptides (RiPPs). For this purpose, 1,136 genome-sequenced strains from this order were mined using BAGEL4. A total of 1,340 areas of interest (AOIs) were detected. The most commonly identified enzymes involved in RiPP biosynthesis were radical S-adenosylmethionine (rSAM), either alone or in combination with other biosynthetic enzymes such as YcaO. A more comprehensive analysis of a subset of 9 biosynthetic gene clusters (BGCs) revealed a consistent association in Bacteroidales BGCs between peptidase-containing ATP-binding transporters (PCATs) and precursor peptides with GG-motifs. This finding suggests a possibly shared mechanism for leader peptide cleavage and transport of mature products. Notably, human metagenomic studies showed a high prevalence and abundance of the RiPP BGCs from Phocaeicola vulgatus and Porphyromonas gulae. The mature product of P. gulae BGC is hypothesized to display γ-thioether linkages and a C-terminal backbone amidine, a potential new combination of post-translational modifications (PTM). All these findings highlight the RiPP biosynthetic potential of Bacteroidales bacteria, as a rich source of novel peptide structures of possible relevance in the human microbiome context.
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Affiliation(s)
- Maria Victoria Fernandez-Cantos
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Diego Garcia-Morena
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Yunhai Yi
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | | | - Emilio Gómez-Vázquez
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Oscar P. Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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2
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Hazra S, Begley TP. Alkylcysteine Sulfoxide C-S Monooxygenase Uses a Flavin-Dependent Pummerer Rearrangement. J Am Chem Soc 2023; 145:11933-11938. [PMID: 37229602 PMCID: PMC10863075 DOI: 10.1021/jacs.3c03545] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Indexed: 05/27/2023]
Abstract
Flavoenzymes are highly versatile and participate in the catalysis of a wide range of reactions, including key reactions in the metabolism of sulfur-containing compounds. S-Alkyl cysteine is formed primarily by the degradation of S-alkyl glutathione generated during electrophile detoxification. A recently discovered S-alkyl cysteine salvage pathway uses two flavoenzymes (CmoO and CmoJ) to dealkylate this metabolite in soil bacteria. CmoO catalyzes a stereospecific sulfoxidation, and CmoJ catalyzes the cleavage of one of the sulfoxide C-S bonds in a new reaction of unknown mechanism. In this paper, we investigate the mechanism of CmoJ. We provide experimental evidence that eliminates carbanion and radical intermediates and conclude that the reaction proceeds via an unprecedented enzyme-mediated modified Pummerer rearrangement. The elucidation of the mechanism of CmoJ adds a new motif to the flavoenzymology of sulfur-containing natural products and demonstrates a new strategy for the enzyme-catalyzed cleavage of C-S bonds.
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Affiliation(s)
- Sohan Hazra
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
| | - Tadhg P. Begley
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
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3
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Abstract
Covering: up to 2022The report provides a broad approach to deciphering the evolution of coenzyme biosynthetic pathways. Here, these various pathways are analyzed with respect to the coenzymes required for this purpose. Coenzymes whose biosynthesis relies on a large number of coenzyme-mediated reactions probably appeared on the scene at a later stage of biological evolution, whereas the biosyntheses of pyridoxal phosphate (PLP) and nicotinamide (NAD+) require little additional coenzymatic support and are therefore most likely very ancient biosynthetic pathways.
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Affiliation(s)
- Andreas Kirschning
- Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 1B, D-30167 Hannover, Germany.
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4
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Hazra S, Bhandari DM, Krishnamoorthy K, Sekowska A, Danchin A, Begley TP. Cysteine Dealkylation in Bacillus subtilis by a Novel Flavin-Dependent Monooxygenase. Biochemistry 2022; 61:952-955. [PMID: 35584544 DOI: 10.1021/acs.biochem.2c00020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we describe the biochemical reconstitution of a cysteine salvage pathway and the biochemical characterization of each of the five enzymes involved. The salvage begins with amine acetylation of S-alkylcysteine, followed by thioether oxidation. The C-S bond of the resulting sulfoxide is cleaved using a new flavoenzyme catalytic motif to give N-acetylcysteine sulfenic acid. This is then reduced to the thiol and deacetylated to complete the salvage pathway. We propose that this pathway is important in the catabolism of alkylated cysteine generated by proteolysis of alkylated glutathione formed in the detoxification of a wide range of electrophiles.
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Affiliation(s)
- Sohan Hazra
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Dhananjay M Bhandari
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | | | | | | | - Tadhg P Begley
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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5
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Wang J, Gisriel CJ, Reiss K, Huang HL, Armstrong WH, Brudvig GW, Batista VS. Heterogeneous Composition of Oxygen-Evolving Complexes in Crystal Structures of Dark-Adapted Photosystem II. Biochemistry 2021; 60:3374-3384. [PMID: 34714055 DOI: 10.1021/acs.biochem.1c00611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photosystem II (PSII) is a homodimeric protein complex that catalyzes water oxidation at the oxygen-evolving complex (OEC), a heterocubanoid calcium-tetramanganese cluster. Here, we analyze the omit electron density peaks of the OEC's metal ions in five X-ray free-electron laser PSII structures at resolutions between 2.15 and 1.95 Å. The omit peaks can be described by the total number of electrons and approximated by the variance of electron density distribution when the distributions are spherically symmetric. We show that the number of electrons of metal centers is different in the two OECs of PSII dimers, implying that the oxidation states and/or occupancies of individual metal ions are different in the two monomers. In either case, we find that the two OECs of dark-adapted PSII dimers in crystals are not fully synchronized in the S1 state. Differences in redox states of the OEC in PSII only partially account for the observation that the electron densities integrate to a smaller number of electrons than expected. Differences between the determined and expected relative electron numbers are much larger than the estimated errors, indicating heterogeneity in the OEC composition.
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Affiliation(s)
- Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, United States
| | - Christopher J Gisriel
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Krystle Reiss
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Hao-Li Huang
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - William H Armstrong
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Gary W Brudvig
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, United States.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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6
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Lewis JK, Jochimsen AS, Lefave SJ, Young AP, Kincannon WM, Roberts AG, Kieber-Emmons MT, Bandarian V. New Role for Radical SAM Enzymes in the Biosynthesis of Thio(seleno)oxazole RiPP Natural Products. Biochemistry 2021; 60:3347-3361. [PMID: 34730336 DOI: 10.1021/acs.biochem.1c00469] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ribosomally synthesized post-translationally modified peptides (RiPPs) are ubiquitous and represent a structurally diverse class of natural products. The ribosomally encoded precursor polypeptides are often extensively modified post-translationally by enzymes that are encoded by coclustered genes. Radical S-adenosyl-l-methionine (SAM) enzymes catalyze numerous chemically challenging transformations. In RiPP biosynthetic pathways, these transformations include the formation of C-H, C-C, C-S, and C-O linkages. In this paper, we show that the Geobacter lovleyi sbtM gene encodes a radical SAM protein, SbtM, which catalyzes the cyclization of a Cys/SeCys residue in a minimal peptide substrate. Biochemical studies of this transformation support a mechanism involving H-atom abstraction at the C-3 of the substrate Cys to initiate the chemistry. Several possible cyclization products were considered. The collective biochemical, spectroscopic, mass spectral, and computational observations point to a thiooxazole as the product of the SbtM-catalyzed modification. To our knowledge, this is the first example of a radical SAM enzyme that catalyzes a transformation involving a SeCys-containing peptide and represents a new paradigm for formation of oxazole-containing RiPP natural products.
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Affiliation(s)
- Julia K Lewis
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Andrew S Jochimsen
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Sarah J Lefave
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Anthony P Young
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - William M Kincannon
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Andrew G Roberts
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Matthew T Kieber-Emmons
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Vahe Bandarian
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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7
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Pang H, Lilla EA, Zhang P, Zhang D, Shields TP, Scott LG, Yang W, Yokoyama K. Mechanism of Rate Acceleration of Radical C-C Bond Formation Reaction by a Radical SAM GTP 3',8-Cyclase. J Am Chem Soc 2020; 142:9314-9326. [PMID: 32348669 DOI: 10.1021/jacs.0c01200] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
While the number of characterized radical S-adenosyl-l-methionine (SAM) enzymes is increasing, the roles of these enzymes in radical catalysis remain largely ambiguous. In radical SAM enzymes, the slow radical initiation step kinetically masks the subsequent steps, making it impossible to study the kinetics of radical chemistry. Due to this kinetic masking, it is unknown whether the subsequent radical reactions require rate acceleration by the enzyme active site. Here, we report the first evidence that a radical SAM enzyme MoaA accelerates the radical-mediated C-C bond formation. MoaA catalyzes an unprecedented 3',8-cyclization of GTP into 3',8-cyclo-7,8-dihydro-GTP (3',8-cH2GTP) during the molybdenum cofactor (Moco) biosynthesis. Through a series of EPR and biochemical characterizations, we found that MoaA catalyzes a shunt pathway in which an on-pathway intermediate, GTP C-3' radical, abstracts H-4' atom from (4'R)-5'-deoxyadenosine (5'-dA) to transiently generate 5'-deoxyadenos-4'-yl radical (5'-dA-C4'•) that is subsequently reduced stereospecifically to yield (4'S)-5'-dA. Detailed kinetic characterization of the shunt and the main pathways provided the comprehensive view of MoaA kinetics and determined the rate of the on-pathway 3',8-cyclization step as 2.7 ± 0.7 s-1. Together with DFT calculations, this observation suggested that the 3',8-cyclization by MoaA is accelerated by 6-9 orders of magnitude. Further experimental and theoretical characterizations suggested that the rate acceleration is achieved mainly by constraining the triphosphate and guanine base positions while leaving the ribose flexible, and a transition state stabilization through H-bond and electrostatic interactions with the positively charged R17 residue. This is the first evidence for rate acceleration of radical reactions by a radical SAM enzyme and provides insights into the mechanism by which radical SAM enzymes accelerate radical chemistry.
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Affiliation(s)
- Haoran Pang
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | - Edward A Lilla
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | - Pan Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27710, United States
| | - Du Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27710, United States
| | - Thomas P Shields
- Cassia, LLC, 3030 Bunker Hill Street, Suite 214, San Diego, California 92109, United States
| | - Lincoln G Scott
- Cassia, LLC, 3030 Bunker Hill Street, Suite 214, San Diego, California 92109, United States
| | - Weitao Yang
- Department of Chemistry, Duke University, Durham, North Carolina 27710, United States
| | - Kenichi Yokoyama
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, United States.,Department of Chemistry, Duke University, Durham, North Carolina 27710, United States
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8
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Maiocco SJ, Walker LM, Elliott SJ. Determining Redox Potentials of the Iron-Sulfur Clusters of the AdoMet Radical Enzyme Superfamily. Methods Enzymol 2018; 606:319-339. [PMID: 30097097 DOI: 10.1016/bs.mie.2018.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
While protein film electrochemistry (PFE) has proven to be an effective tool in the interrogation of redox cofactors and assessing the electrocatalytic activity of many different enzymes, recently it has been proven to be useful for the study of the redox potentials of the cofactors of AdoMet radical enzymes (AREs). In this chapter, we review the challenges and opportunities of examining the redox cofactors of AREs in a high level of detail, particularly for the deconvolution of redox potentials of multiple cofactors. We comment on how to best assess the electroactive nature of any given ARE, and we see that when applied well, PFE allows for not only determining redox potentials, but also determining proton-coupling and ligand-binding phenomena in the ARE superfamily.
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Affiliation(s)
| | - Lindsey M Walker
- Department of Chemistry, Boston University, Boston, MA, United States
| | - Sean J Elliott
- Department of Chemistry, Boston University, Boston, MA, United States.
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9
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Zanello P. Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part II. [4Fe-4S] and [3Fe-4S] iron-sulfur proteins. J Struct Biol 2018; 202:250-263. [DOI: 10.1016/j.jsb.2018.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/11/2018] [Accepted: 01/29/2018] [Indexed: 01/27/2023]
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10
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Wilcoxen J, Bruender NA, Bandarian V, Britt RD. A Radical Intermediate in Bacillus subtilis QueE during Turnover with the Substrate Analogue 6-Carboxypterin. J Am Chem Soc 2018; 140:1753-1759. [PMID: 29303575 DOI: 10.1021/jacs.7b10860] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
7-Carboxy-7-deazaguanine (CDG) synthase (QueE), a member of the radical S-deoxyadenosyl-l-methionine (SAM) superfamily of enzymes, catalyzes a radical-mediated ring rearrangement required to convert 6-carboxy-5,6,7,8-tetrahydropterin (CPH4) into CDG, forming the 7-dezapurine precursor to all pyrrolopyrimidine metabolites. Members of the radical SAM superfamily bind SAM to a [4Fe-4S] cluster, leveraging the reductive cleavage of SAM by the cluster to produce a highly reactive 5'-deoxyadenosyl radical which initiates chemistry by H atom abstraction from the substrate. QueE has recently been shown to use 6-carboxypterin (6-CP) as an alternative substrate, forming 6-deoxyadenosylpterin as the product. This reaction has been proposed to occur by radical addition between 5'-dAdo· and 6-CP, which upon oxidative decarboxylation yields the modified pterin. Here, we present spectroscopic evidence for a 6-CP-dAdo radical. The structure of this intermediate is determined by characterizing its electronic structure by continuous wave and pulse electron paramagnetic resonance spectroscopy.
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Affiliation(s)
- Jarett Wilcoxen
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
| | - Nathan A Bruender
- Department of Chemistry and Biochemistry, St. Cloud State University , St. Cloud, Minnesota 56301, United States
| | - Vahe Bandarian
- Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States
| | - R David Britt
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
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11
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Ulrich EC, Kamat SS, Hove-Jensen B, Zechel DL. Methylphosphonic Acid Biosynthesis and Catabolism in Pelagic Archaea and Bacteria. Methods Enzymol 2018; 605:351-426. [DOI: 10.1016/bs.mie.2018.01.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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12
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Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part I. [4Fe-4S] + [2Fe-2S] iron-sulfur proteins. J Struct Biol 2017; 200:1-19. [DOI: 10.1016/j.jsb.2017.05.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/25/2017] [Indexed: 01/08/2023]
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13
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Structures of the peptide-modifying radical SAM enzyme SuiB elucidate the basis of substrate recognition. Proc Natl Acad Sci U S A 2017; 114:10420-10425. [PMID: 28893989 DOI: 10.1073/pnas.1703663114] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Posttranslational modification of ribosomally synthesized peptides provides an elegant means for the production of biologically active molecules known as RiPPs (ribosomally synthesized and posttranslationally modified peptides). Although the leader sequence of the precursor peptide is often required for turnover, the exact mode of recognition by the modifying enzymes remains unclear for many members of this class of natural products. Here, we have used X-ray crystallography and computational modeling to examine the role of the leader peptide in the biosynthesis of a homolog of streptide, a recently identified peptide natural product with an intramolecular lysine-tryptophan cross-link, which is installed by the radical S-adenosylmethionine (SAM) enzyme, StrB. We present crystal structures of SuiB, a close ortholog of StrB, in various forms, including apo SuiB, SAM-bound SuiB, and a complex of SuiB with SAM and its peptide substrate, SuiA. Although the N-terminal domain of SuiB adopts a typical RRE (RiPP recognition element) motif, which has been implicated in precursor peptide recognition, we observe binding of the leader peptide in the catalytic barrel rather than the N-terminal domain. Computational simulations support a mechanism in which the leader peptide guides posttranslational modification by positioning the cross-linking residues of the precursor peptide within the active site. Together the results shed light onto binding of the precursor peptide and the associated conformational changes needed for the formation of the unique carbon-carbon cross-link in the streptide family of natural products.
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14
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Latham JA, Barr I, Klinman JP. At the confluence of ribosomally synthesized peptide modification and radical S-adenosylmethionine (SAM) enzymology. J Biol Chem 2017; 292:16397-16405. [PMID: 28830931 DOI: 10.1074/jbc.r117.797399] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Radical S-adenosylmethionine (RS) enzymology has emerged as a major biochemical strategy for the homolytic cleavage of unactivated C-H bonds. At the same time, the post-translational modification of ribosomally synthesized peptides is a rapidly expanding area of investigation. We discuss the functional cross-section of these two disciplines, highlighting the recently uncovered importance of protein-protein interactions, especially between the peptide substrate and its chaperone, which functions either as a stand-alone protein or as an N-terminal fusion to the respective RS enzyme. The need for further work on this class of enzymes is emphasized, given the poorly understood roles performed by multiple, auxiliary iron-sulfur clusters and the paucity of protein X-ray structural data.
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Affiliation(s)
- John A Latham
- From the Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208 and
| | - Ian Barr
- the California Institute of Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720
| | - Judith P Klinman
- the California Institute of Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720 .,the Departments of Chemistry and.,Molecular and Cell Biology and
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15
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Evans RL, Latham JA, Xia Y, Klinman JP, Wilmot CM. Nuclear Magnetic Resonance Structure and Binding Studies of PqqD, a Chaperone Required in the Biosynthesis of the Bacterial Dehydrogenase Cofactor Pyrroloquinoline Quinone. Biochemistry 2017; 56:2735-2746. [PMID: 28481092 DOI: 10.1021/acs.biochem.7b00247] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Biosynthesis of the ribosomally synthesized and post-translationally modified peptide (RiPP), pyrroloquinoline quinone (PQQ), is initiated when the precursor peptide, PqqA, is recognized and bound by the RiPP precursor peptide recognition element (RRE), PqqD, for presentation to the first enzyme in the pathway, PqqE. Unlike other RiPP-producing, postribosomal peptide synthesis (PRPS) pathways in which the RRE is a component domain of the first enzyme, PqqD is predominantly a separate scaffolding protein that forms a ternary complex with the precursor peptide and first tailoring enzyme. As PqqD is a stable, independent RRE, this makes the PQQ pathway an ideal PRPS model system for probing RRE interactions using nuclear magnetic resonance (NMR). Herein, we present both the solution NMR structure of Methylobacterium extorquens PqqD and results of 1H-15N HSQC binding experiments that identify the PqqD residues involved in binding the precursor peptide, PqqA, and the enzyme, PqqE. The reported structural model for an independent RRE, along with the mapped binding surfaces, will inform future efforts both to understand and to manipulate PRPS pathways.
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Affiliation(s)
- Robert L Evans
- Department of Biochemistry, Molecular Biology, and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities , St. Paul, Minnesota 55108, United States
| | - John A Latham
- Department of Chemistry and Department of Molecular and Cell Biology, University of California, Berkeley , Berkeley, California 94720, United States
| | - Youlin Xia
- Minnesota NMR Center, University of Minnesota, Twin Cities , Minneapolis, Minnesota 55455, United States
| | - Judith P Klinman
- Department of Chemistry and Department of Molecular and Cell Biology, University of California, Berkeley , Berkeley, California 94720, United States
| | - Carrie M Wilmot
- Department of Biochemistry, Molecular Biology, and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities , St. Paul, Minnesota 55108, United States
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16
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Truman AW. Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides. Beilstein J Org Chem 2016; 12:1250-68. [PMID: 27559376 PMCID: PMC4979651 DOI: 10.3762/bjoc.12.120] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/02/2016] [Indexed: 12/15/2022] Open
Abstract
Ribosomally synthesised and post-translationally modified peptides (RiPPs) are a large class of natural products that are remarkably chemically diverse given an intrinsic requirement to be assembled from proteinogenic amino acids. The vast chemical space occupied by RiPPs means that they possess a wide variety of biological activities, and the class includes antibiotics, co-factors, signalling molecules, anticancer and anti-HIV compounds, and toxins. A considerable amount of RiPP chemical diversity is generated from cyclisation reactions, and the current mechanistic understanding of these reactions will be discussed here. These cyclisations involve a diverse array of chemical reactions, including 1,4-nucleophilic additions, [4 + 2] cycloadditions, ATP-dependent heterocyclisation to form thiazolines or oxazolines, and radical-mediated reactions between unactivated carbons. Future prospects for RiPP pathway discovery and characterisation will also be highlighted.
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Affiliation(s)
- Andrew W Truman
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK
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17
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Barr I, Latham JA, Iavarone AT, Chantarojsiri T, Hwang JD, Klinman JP. Demonstration That the Radical S-Adenosylmethionine (SAM) Enzyme PqqE Catalyzes de Novo Carbon-Carbon Cross-linking within a Peptide Substrate PqqA in the Presence of the Peptide Chaperone PqqD. J Biol Chem 2016; 291:8877-84. [PMID: 26961875 DOI: 10.1074/jbc.c115.699918] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Indexed: 02/05/2023] Open
Abstract
The radical S-adenosylmethionine (SAM) protein PqqE is predicted to function in the pyrroloquinoline quinone (PQQ) biosynthetic pathway via catalysis of carbon-carbon bond formation between a glutamate and tyrosine side chain within the small peptide substrate PqqA. We report here that PqqE activity is dependent on the accessory protein PqqD, which was recently shown to bind PqqA tightly. In addition, PqqE activity in vitro requires the presence of a flavodoxin- and flavodoxin reductase-based reduction system, with other reductants leading to an uncoupled cleavage of the co-substrate SAM. These results indicate that PqqE, in conjunction with PqqD, carries out the first step in PQQ biosynthesis: a radical-mediated formation of a new carbon-carbon bond between two amino acid side chains on PqqA.
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Affiliation(s)
- Ian Barr
- From the Department of Chemistry, Department of Molecular and Cell Biology, and California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720
| | - John A Latham
- From the Department of Chemistry, California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720
| | - Anthony T Iavarone
- From the Department of Chemistry, California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720
| | | | | | - Judith P Klinman
- From the Department of Chemistry, Department of Molecular and Cell Biology, and California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720
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18
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Density functional theory calculations on the active site of biotin synthase: mechanism of S transfer from the Fe2S2 cluster and the role of 1st and 2nd sphere residues. J Biol Inorg Chem 2015; 20:1147-62. [DOI: 10.1007/s00775-015-1296-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 09/02/2015] [Indexed: 10/23/2022]
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19
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Non-canonical active site architecture of the radical SAM thiamin pyrimidine synthase. Nat Commun 2015; 6:6480. [PMID: 25813242 PMCID: PMC4389238 DOI: 10.1038/ncomms7480] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/30/2015] [Indexed: 01/04/2023] Open
Abstract
Radical S-adenosylmethionine (SAM) enzymes use a [4Fe-4S] cluster to generate a 5'-deoxyadenosyl radical. Canonical radical SAM enzymes are characterized by a β-barrel-like fold and SAM anchors to the differentiated iron of the cluster, which is located near the amino terminus and within the β-barrel, through its amino and carboxylate groups. Here we show that ThiC, the thiamin pyrimidine synthase in plants and bacteria, contains a tethered cluster-binding domain at its carboxy terminus that moves in and out of the active site during catalysis. In contrast to canonical radical SAM enzymes, we predict that SAM anchors to an additional active site metal through its amino and carboxylate groups. Superimposition of the catalytic domains of ThiC and glutamate mutase shows that these two enzymes share similar active site architectures, thus providing strong evidence for an evolutionary link between the radical SAM and adenosylcobalamin-dependent enzyme superfamilies.
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20
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Hover BM, Yokoyama K. C-Terminal glycine-gated radical initiation by GTP 3',8-cyclase in the molybdenum cofactor biosynthesis. J Am Chem Soc 2015; 137:3352-9. [PMID: 25697423 DOI: 10.1021/ja512997j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molybdenum cofactor (Moco) is an essential redox cofactor found in all kingdoms of life. Genetic mutations in the human Moco biosynthetic enzymes lead to a fatal metabolic disorder, Moco deficiency (MoCD). Greater than 50% of all human MoCD patients have mutations in MOCS1A, a radical S-adenosyl-l-methionine (SAM) enzyme involved in the conversion of guanosine 5'-triphosphate (GTP) into cyclic pyranopterin monophosphate. In MOCS1A, one of the frequently affected locations is the GG motif constituted of two consecutive Gly at the C-terminus. The GG motif is conserved among all MOCS1A homologues, but its role in catalysis or the mechanism by which its mutation causes MoCD was unknown. Here, we report the functional characterization of the GG motif using MoaA, a bacterial homologue of MOCS1A, as a model. Our study elucidated that the GG motif is essential for the activity of MoaA to produce 3',8-cH2GTP from GTP (GTP 3',8-cyclase), and that synthetic peptides corresponding to the C-terminal region of wt-MoaA rescue the GTP 3',8-cyclase activity of the GG-motif mutants. Further biochemical characterization suggested that the C-terminal tail containing the GG motif interacts with the SAM-binding pocket of MoaA, and is essential for the binding of SAM and subsequent radical initiation. In sum, these observations suggest that the C-terminal tail of MoaA provides an essential mechanism to trigger the free radical reaction, impairment of which results in the complete loss of catalytic function of the enzyme, and causes MoCD.
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Affiliation(s)
- Bradley M Hover
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
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21
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Grell TAJ, Goldman PJ, Drennan CL. SPASM and twitch domains in S-adenosylmethionine (SAM) radical enzymes. J Biol Chem 2015; 290:3964-71. [PMID: 25477505 PMCID: PMC4326806 DOI: 10.1074/jbc.r114.581249] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
S-Adenosylmethionine (SAM, also known as AdoMet) radical enzymes use SAM and a [4Fe-4S] cluster to catalyze a diverse array of reactions. They adopt a partial triose-phosphate isomerase (TIM) barrel fold with N- and C-terminal extensions that tailor the structure of the enzyme to its specific function. One extension, termed a SPASM domain, binds two auxiliary [4Fe-4S] clusters and is present within peptide-modifying enzymes. The first structure of a SPASM-containing enzyme, anaerobic sulfatase-maturating enzyme (anSME), revealed unexpected similarities to two non-SPASM proteins, butirosin biosynthetic enzyme 2-deoxy-scyllo-inosamine dehydrogenase (BtrN) and molybdenum cofactor biosynthetic enzyme (MoaA). The latter two enzymes bind one auxiliary cluster and exhibit a partial SPASM motif, coined a Twitch domain. Here we review the structure and function of auxiliary cluster domains within the SAM radical enzyme superfamily.
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Affiliation(s)
| | | | - Catherine L Drennan
- From the Departments of Chemistry and Biology and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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22
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de Lorenzo V, Sekowska A, Danchin A. Chemical reactivity drives spatiotemporal organisation of bacterial metabolism. FEMS Microbiol Rev 2014; 39:96-119. [PMID: 25227915 DOI: 10.1111/1574-6976.12089] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In this review, we examine how bacterial metabolism is shaped by chemical constraints acting on the material and dynamic layout of enzymatic networks and beyond. These are moulded not only for optimisation of given metabolic objectives (e.g. synthesis of a particular amino acid or nucleotide) but also for curbing the detrimental reactivity of chemical intermediates. Besides substrate channelling, toxicity is avoided by barriers to free diffusion (i.e. compartments) that separate otherwise incompatible reactions, along with ways for distinguishing damaging vs. harmless molecules. On the other hand, enzymes age and their operating lifetime must be tuned to upstream and downstream reactions. This time dependence of metabolic pathways creates time-linked information, learning and memory. These features suggest that the physical structure of existing biosystems, from operon assemblies to multicellular development may ultimately stem from the need to restrain chemical damage and limit the waste inherent to basic metabolic functions. This provides a new twist of our comprehension of fundamental biological processes in live systems as well as practical take-home lessons for the forward DNA-based engineering of novel biological objects.
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Affiliation(s)
- Víctor de Lorenzo
- Systems Biology Program, Centro Nacional de Biotecnología CSIC, Cantoblanco-Madrid, Spain
| | - Agnieszka Sekowska
- AMAbiotics SAS, Institut du Cerveau et de la Moëlle Épinière, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Antoine Danchin
- AMAbiotics SAS, Institut du Cerveau et de la Moëlle Épinière, Hôpital de la Pitié-Salpêtrière, Paris, France
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23
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Galperin MY, Makarova KS, Wolf YI, Koonin EV. Expanded microbial genome coverage and improved protein family annotation in the COG database. Nucleic Acids Res 2014; 43:D261-9. [PMID: 25428365 DOI: 10.1093/nar/gku1223] [Citation(s) in RCA: 987] [Impact Index Per Article: 98.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Microbial genome sequencing projects produce numerous sequences of deduced proteins, only a small fraction of which have been or will ever be studied experimentally. This leaves sequence analysis as the only feasible way to annotate these proteins and assign to them tentative functions. The Clusters of Orthologous Groups of proteins (COGs) database (http://www.ncbi.nlm.nih.gov/COG/), first created in 1997, has been a popular tool for functional annotation. Its success was largely based on (i) its reliance on complete microbial genomes, which allowed reliable assignment of orthologs and paralogs for most genes; (ii) orthology-based approach, which used the function(s) of the characterized member(s) of the protein family (COG) to assign function(s) to the entire set of carefully identified orthologs and describe the range of potential functions when there were more than one; and (iii) careful manual curation of the annotation of the COGs, aimed at detailed prediction of the biological function(s) for each COG while avoiding annotation errors and overprediction. Here we present an update of the COGs, the first since 2003, and a comprehensive revision of the COG annotations and expansion of the genome coverage to include representative complete genomes from all bacterial and archaeal lineages down to the genus level. This re-analysis of the COGs shows that the original COG assignments had an error rate below 0.5% and allows an assessment of the progress in functional genomics in the past 12 years. During this time, functions of many previously uncharacterized COGs have been elucidated and tentative functional assignments of many COGs have been validated, either by targeted experiments or through the use of high-throughput methods. A particularly important development is the assignment of functions to several widespread, conserved proteins many of which turned out to participate in translation, in particular rRNA maturation and tRNA modification. The new version of the COGs is expected to become an important tool for microbial genomics.
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 2094, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 2094, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 2094, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 2094, USA
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24
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Allpress CJ, Berreau LM. A Nickel‐Containing Model System of Acireductone Dioxygenases that Utilizes a C(1)‐H Acireductone Substrate. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402254] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Caleb J. Allpress
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT 84322‐0300, USA, http://lisaberreau.org/
| | - Lisa M. Berreau
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT 84322‐0300, USA, http://lisaberreau.org/
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25
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Cammack R, Balk J. Iron-sulfur Clusters. BINDING, TRANSPORT AND STORAGE OF METAL IONS IN BIOLOGICAL CELLS 2014. [DOI: 10.1039/9781849739979-00333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Iron-sulfur clusters are universally distributed groups occurring in iron-sulfur proteins. They have a wide range of cellular functions which reflect the chemistry of the clusters. Some clusters are involved in electron transport and energy transduction in photosynthesis and respiration. Others can bind substrates and participate in enzyme catalysis. Regulatory functions have also been documented for clusters that respond to oxygen partial pressure and iron availability. Finally, there are some for which no function has been defined; they may act as stabilizing structures, for example, in enzymes involved in nucleic acid metabolism. The clusters are constructed intracellularly and inserted into proteins, which can then be transported to intracellular targets, in some cases, across membranes. Three different types of iron-sulfur cluster assembly machinery have evolved in prokaryotes: NIF, ISC and SUF. Each system involves a scaffold protein on which the cluster is constructed (encoded by genes nifU, iscU, sufU or sufB) and a cysteine desulfurase (encoded by nifS, iscS or sufS) which provides the sulfide sulfur. In eukaryotic cells, clusters are formed in the mitochondria for the many iron-sulfur proteins in this organelle. The mitochondrial biosynthesis pathway is linked to the cytoplasmic iron-sulfur assembly system (CIA) for the maturation of cytoplasmic and nuclear iron-sulfur proteins. In plant cells, a SUF-type system is used for cluster assembly in the plastids. Many accessory proteins are involved in cluster transfer before insertion into the appropriate sites in Fe-S proteins.
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Affiliation(s)
- Richard Cammack
- King's College London, Department of Biochemistry, 150 Stamford Street London SE1 9NH UK
| | - Janneke Balk
- John Innes Centre and University of East Anglia Norwich Research Park, Colney Lane Norwich NR4 7UH UK
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26
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Dark-operative protochlorophyllide oxidoreductase generates substrate radicals by an iron-sulphur cluster in bacteriochlorophyll biosynthesis. Sci Rep 2014; 4:5455. [PMID: 24965831 PMCID: PMC4071322 DOI: 10.1038/srep05455] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 06/09/2014] [Indexed: 11/21/2022] Open
Abstract
Photosynthesis converts solar energy to chemical energy using chlorophylls (Chls). In a late stage of biosynthesis of Chls, dark-operative protochlorophyllide (Pchlide) oxidoreductase (DPOR), a nitrogenase-like enzyme, reduces the C17 = C18 double bond of Pchlide and drastically changes the spectral properties suitable for photosynthesis forming the parental chlorin ring for Chl a. We previously proposed that the spatial arrangement of the proton donors determines the stereospecificity of the Pchlide reduction based on the recently resolved structure of the DPOR catalytic component, NB-protein. However, it was not clear how the two-electron and two-proton transfer events are coordinated in the reaction. In this study, we demonstrate that DPOR initiates a single electron transfer reaction from a [4Fe-4S]-cluster (NB-cluster) to Pchlide, generating Pchlide anion radicals followed by a single proton transfer, and then, further electron/proton transfer steps transform the anion radicals into chlorophyllide (Chlide). Thus, DPOR is a unique iron-sulphur enzyme to form substrate radicals followed by sequential proton- and electron-transfer steps with the protein folding very similar to that of nitrogenase. This novel radical-mediated reaction supports the biosynthesis of Chl in a wide variety of photosynthetic organisms.
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27
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Schmerk CL, Welander PV, Hamad MA, Bain KL, Bernards MA, Summons RE, Valvano MA. Elucidation of theBurkholderia cenocepaciahopanoid biosynthesis pathway uncovers functions for conserved proteins in hopanoid-producing bacteria. Environ Microbiol 2014; 17:735-50. [DOI: 10.1111/1462-2920.12509] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 05/09/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Crystal L. Schmerk
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Paula V. Welander
- Department of Environmental Earth System Science; Stanford University; Stanford CA USA
| | - Mohamad A. Hamad
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Katie L. Bain
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Mark A. Bernards
- Department of Biology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Roger E. Summons
- Department of Earth, Atmospheric, and Planetary Sciences; Massachusetts Institute of Technology; Cambridge MA USA
| | - Miguel A. Valvano
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
- Centre for Infection and Immunity; Queen's University Belfast; Belfast BT9 5AE UK
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28
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Shisler KA, Broderick JB. Glycyl radical activating enzymes: structure, mechanism, and substrate interactions. Arch Biochem Biophys 2014; 546:64-71. [PMID: 24486374 PMCID: PMC4083501 DOI: 10.1016/j.abb.2014.01.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 11/20/2022]
Abstract
The glycyl radical enzyme activating enzymes (GRE-AEs) are a group of enzymes that belong to the radical S-adenosylmethionine (SAM) superfamily and utilize a [4Fe-4S] cluster and SAM to catalyze H-atom abstraction from their substrate proteins. GRE-AEs activate homodimeric proteins known as glycyl radical enzymes (GREs) through the production of a glycyl radical. After activation, these GREs catalyze diverse reactions through the production of their own substrate radicals. The GRE-AE pyruvate formate lyase activating enzyme (PFL-AE) is extensively characterized and has provided insights into the active site structure of radical SAM enzymes including GRE-AEs, illustrating the nature of the interactions with their corresponding substrate GREs and external electron donors. This review will highlight research on PFL-AE and will also discuss a few GREs and their respective activating enzymes.
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Affiliation(s)
- Krista A Shisler
- Department of Chemistry & Biochemistry and the Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, MT 59717, United States
| | - Joan B Broderick
- Department of Chemistry & Biochemistry and the Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, MT 59717, United States.
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29
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Tikh IB, Quin MB, Schmidt-Dannert C. A tale of two reductases: extending the bacteriochlorophyll biosynthetic pathway in E. coli. PLoS One 2014; 9:e89734. [PMID: 24586995 PMCID: PMC3931815 DOI: 10.1371/journal.pone.0089734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/23/2014] [Indexed: 12/23/2022] Open
Abstract
The creation of a synthetic microbe that can harvest energy from sunlight to drive its metabolic processes is an attractive approach to the economically viable biosynthetic production of target compounds. Our aim is to design and engineer a genetically tractable non-photosynthetic microbe to produce light-harvesting molecules. Previously we created a modular, multienzyme system for the heterologous production of intermediates of the bacteriochlorophyll (BChl) pathway in E. coli. In this report we extend this pathway to include a substrate promiscuous 8-vinyl reductase that can accept multiple intermediates of BChl biosynthesis. We present an informative comparative analysis of homologues of 8-vinyl reductase from the model photosynthetic organisms Rhodobacter sphaeroides and Chlorobaculum tepidum. The first purification of the enzymes leads to their detailed biochemical and biophysical characterization. The data obtained reveal that the two 8-vinyl reductases are substrate promiscuous, capable of reducing the C8-vinyl group of Mg protoporphyrin IX, Mg protoporphyrin IX methylester, and divinyl protochlorophyllide. However, activity is dependent upon the presence of chelated Mg2+ in the porphyrin ring, with no activity against non-Mg2+ chelated intermediates observed. Additionally, CD analyses reveal that the two 8-vinyl reductases appear to bind the same substrate in a different fashion. Furthermore, we discover that the different rates of reaction of the two 8-vinyl reductases both in vitro, and in vivo as part of our engineered system, results in the suitability of only one of the homologues for our BChl pathway in E. coli. Our results offer the first insights into the different functionalities of homologous 8-vinyl reductases. This study also takes us one step closer to the creation of a nonphotosynthetic microbe that is capable of harvesting energy from sunlight for the biosynthesis of molecules of choice.
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Affiliation(s)
- Ilya B. Tikh
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Maureen B. Quin
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Claudia Schmidt-Dannert
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, United States of America
- * E-mail:
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30
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Frey PA. Travels with carbon-centered radicals. 5'-deoxyadenosine and 5'-deoxyadenosine-5'-yl in radical enzymology. Acc Chem Res 2014; 47:540-9. [PMID: 24308628 DOI: 10.1021/ar400194k] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As a graduate student under Professor R. H. Abeles, I began my journey with 5'-deoxyadenosine, studying the coenzyme B12 (adenosylcobalamin)-dependent dioldehydrase (DDH). I proved that suicide inactivation of dioldehydrase by glycolaldehyde proceeded with irreversible cleavage of adenosylcobalamin to 5'-deoxyadenosine. I further showed that suicide inactivation by [2-(3)H]glycolaldehyde produced 5'-deoxy[(3)H]adenosine, the first demonstration of hydrogen transfer to adenosyl-C5' of adenosylcobalamin. The tritium kinetic isotope effect (T)k was 15, which correlated well with the measurement (D)k = 12 for transformation of [1-(2)H]propane-1,2-diol to [2-(2)H]propionaldehyde by DDH. After establishing my own research program, I returned to the glycolaldehyde inactivation of DDH, showing by EPR that suicide inactivation produced glycolaldehyde-2-yl. In retrospect, suicide inactivation involved scission of adenosylcobalamin to 5'-deoxyadenosine-5'-yl, which abstracted a hydrogen from glycolaldehyde. Captodative-stabilized glycolaldehyde-2-yl could not react further, leading to suicide inactivation. In 1986, my colleagues and I took up the problem of the mechanism by which lysine 2,3-aminomutase (LAM) catalyzes S-adenosylmethionine (SAM) and pyridoxal-5'-phosphate (PLP)-dependent interconversion of l-lysine and l-β-lysine. Because the reaction followed the pattern of adenosylcobalamin-dependent rearrangements, I postulated that SAM might be an evolutionary predecessor to adenosylcobalamin. Testing this hypothesis, we traced hydrogen transfer from lysine through the adenosyl-C5' of SAM to β-lysine. Thus, the 5'-deoxyadenosyl of SAM mediated hydrogen transfer by LAM exactly as in adenosylcobalamin mediated hydrogen transfer in B12-dependent isomerizations. The mechanism postulated that SAM cleaves to form 5'-deoxyadenosine-5'-yl followed by abstraction of C3(H) from PLP-α-lysine aldimine to form PLP-α-lysine-3-yl. PLP-α-lysine-3-yl isomerizes to pyridoxal-β-lysine-2-yl, and a hydrogen abstraction from 5'-deoxyadenosine regenerates 5'-deoxyadenosine-5'-yl and releases β-lysine. Of four radicals in the postulated mechanism, three have been characterized by EPR spectroscopy as kinetically competent intermediates. The analysis of the role of iron allowed researchers to elucidate the mechanism by which SAM is cleaved to 5'-deoxyadenosine-5'-yl. LAM contains one [4Fe-4S] cluster ligated by three cysteine residues. As shown by ENDOR spectroscopy and X-ray crystallography, the fourth ligand to the cluster is SAM, through the methionyl carboxylate and amino groups. Inner sphere electron transfer within the [4Fe-4S](1+)-SAM complex leads to [4Fe-4S](2+)-Met and 5'-deoxyadenosine-5'-yl. The iron-binding motif in LAM, CxxxCxxC, found by other groups in four other SAM-dependent enzymes, is the founding motif for the radical SAM superfamily. These enzymes number in the tens of thousands and are responsible for highly diverse and chemically difficult transformations in the biosphere. Available information supports the hypothesis that this superfamily provides the chemical context from which the much more structurally complex adenosylcobalamin evolved.
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Affiliation(s)
- Perry A. Frey
- University of Wisconsin—Madison, 1710 University Avenue, Madison, Wisconsin 53726, United States
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31
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Radical SAM enzyme QueE defines a new minimal core fold and metal-dependent mechanism. Nat Chem Biol 2014; 10:106-12. [PMID: 24362703 PMCID: PMC3939041 DOI: 10.1038/nchembio.1426] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 11/21/2013] [Indexed: 01/07/2023]
Abstract
7-carboxy-7-deazaguanine synthase (QueE) catalyzes a key S-adenosyl-L-methionine (AdoMet)- and Mg(2+)-dependent radical-mediated ring contraction step, which is common to the biosynthetic pathways of all deazapurine-containing compounds. QueE is a member of the AdoMet radical superfamily, which employs the 5'-deoxyadenosyl radical from reductive cleavage of AdoMet to initiate chemistry. To provide a mechanistic rationale for this elaborate transformation, we present the crystal structure of a QueE along with structures of pre- and post-turnover states. We find that substrate binds perpendicular to the [4Fe-4S]-bound AdoMet, exposing its C6 hydrogen atom for abstraction and generating the binding site for Mg(2+), which coordinates directly to the substrate. The Burkholderia multivorans structure reported here varies from all other previously characterized members of the AdoMet radical superfamily in that it contains a hypermodified (β6/α3) protein core and an expanded cluster-binding motif, CX14CX2C.
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32
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Kneuttinger AC, Kashiwazaki G, Prill S, Heil K, Müller M, Carell T. Formation and Direct Repair of UV-induced Dimeric DNA Pyrimidine Lesions. Photochem Photobiol 2013; 90:1-14. [PMID: 24354557 DOI: 10.1111/php.12197] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 10/17/2013] [Indexed: 12/11/2022]
Abstract
Direct repair of UV-induced DNA lesions represents an elegant method for many organisms to deal with these highly mutagenic and cytotoxic compounds. Although the participating proteins are structurally well investigated, the exact repair mechanism of the photolyase enzymes remains a vivid subject of current research. In this review, we summarize and highlight the recent contributions to this exciting field.
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Affiliation(s)
- Andrea Christa Kneuttinger
- Center for Integrated Protein Sciences at the Department of Chemistry, Ludwig-Maximilians Universität München, Munich, Germany
| | - Gengo Kashiwazaki
- Center for Integrated Protein Sciences at the Department of Chemistry, Ludwig-Maximilians Universität München, Munich, Germany
| | - Stefan Prill
- Center for Integrated Protein Sciences at the Department of Chemistry, Ludwig-Maximilians Universität München, Munich, Germany
| | - Korbinian Heil
- Center for Integrated Protein Sciences at the Department of Chemistry, Ludwig-Maximilians Universität München, Munich, Germany
| | - Markus Müller
- Center for Integrated Protein Sciences at the Department of Chemistry, Ludwig-Maximilians Universität München, Munich, Germany
| | - Thomas Carell
- Center for Integrated Protein Sciences at the Department of Chemistry, Ludwig-Maximilians Universität München, Munich, Germany
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33
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Palmer LD, Downs DM. The thiamine biosynthetic enzyme ThiC catalyzes multiple turnovers and is inhibited by S-adenosylmethionine (AdoMet) metabolites. J Biol Chem 2013; 288:30693-30699. [PMID: 24014032 DOI: 10.1074/jbc.m113.500280] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ThiC (4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase; EC 4.1.99.17) is a radical S-adenosylmethionine (AdoMet) enzyme that uses a [4Fe-4S](+) cluster to reductively cleave AdoMet to methionine and a 5'-deoxyadenosyl radical that initiates catalysis. In plants and bacteria, ThiC converts the purine intermediate 5-aminoimidazole ribotide to 4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate, an intermediate of thiamine pyrophosphate (coenzyme B1) biosynthesis. In this study, assay conditions were implemented that consistently generated 5-fold molar excess of HMP, demonstrating that ThiC undergoes multiple turnovers. ThiC activity was improved by in situ removal of product 5'-deoxyadenosine. The activity was inhibited by AdoMet metabolites S-adenosylhomocysteine, adenosine, 5'-deoxyadenosine, S-methyl-5'-thioadenosine, methionine, and homocysteine. Neither adenosine nor S-methyl-5'-thioadenosine had been shown to inhibit radical AdoMet enzymes, suggesting that ThiC is distinct from other family members. The parameters for improved ThiC activity and turnover described here will facilitate kinetic and mechanistic analyses of ThiC.
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Affiliation(s)
- Lauren D Palmer
- From the Department of Microbiology, University of Georgia, Athens, Georgia 30602
| | - Diana M Downs
- From the Department of Microbiology, University of Georgia, Athens, Georgia 30602.
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Reactivity landscape of pyruvate under simulated hydrothermal vent conditions. Proc Natl Acad Sci U S A 2013; 110:13283-8. [PMID: 23872841 DOI: 10.1073/pnas.1304923110] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pyruvate is an important "hub" metabolite that is a precursor for amino acids, sugars, cofactors, and lipids in extant metabolic networks. Pyruvate has been produced under simulated hydrothermal vent conditions from alkyl thiols and carbon monoxide in the presence of transition metal sulfides at 250 °C [Cody GD et al. (2000) Science 289(5483):1337-1340], so it is plausible that pyruvate was formed in hydrothermal systems on the early earth. We report here that pyruvate reacts readily in the presence of transition metal sulfide minerals under simulated hydrothermal vent fluids at more moderate temperatures (25-110 °C) that are more conducive to survival of biogenic molecules. We found that pyruvate partitions among five reaction pathways at rates that depend upon the nature of the mineral present; the concentrations of H2S, H2, and NH4Cl; and the temperature. In most cases, high yields of one or two primary products are found due to preferential acceleration of certain pathways. Reactions observed include reduction of ketones to alcohols and aldol condensation, both reactions that are common in extant metabolic networks. We also observed reductive amination to form alanine and reduction to form propionic acid. Amino acids and fatty acids formed by analogous processes may have been important components of a protometabolic network that allowed the emergence of life.
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Krzycki JA. The path of lysine to pyrrolysine. Curr Opin Chem Biol 2013; 17:619-25. [PMID: 23856058 DOI: 10.1016/j.cbpa.2013.06.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 06/12/2013] [Accepted: 06/17/2013] [Indexed: 01/05/2023]
Abstract
Pyrrolysine is the 22nd genetically encoded amino acid. For many years, its biosynthesis has been primarily a matter for conjecture. Recently, a pathway for the synthesis of pyrrolysine from two molecules of lysine was outlined in which a radical SAM enzyme acts as a lysine mutase to generate a methylated ornithine from lysine, which is then ligated to form an amide with the ɛ-amine of a second lysine. Oxidation of the isopeptide gives rise to pyrrolysine. Mechanisms have been proposed for both the mutase and the ligase, and structures now exist for each, setting the stage for a more detailed understanding of how pyrrolysine is synthesized and functions in bacteria and archaea.
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Affiliation(s)
- Joseph A Krzycki
- Department of Microbiology, 484 West 12th Avenue, Columbus, OH 43210, United States.
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