1
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Shomar H, Bokinsky G. Harnessing iron‑sulfur enzymes for synthetic biology. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119718. [PMID: 38574823 DOI: 10.1016/j.bbamcr.2024.119718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/13/2024] [Accepted: 03/25/2024] [Indexed: 04/06/2024]
Abstract
Reactions catalysed by iron-sulfur (Fe-S) enzymes appear in a variety of biosynthetic pathways that produce valuable natural products. Harnessing these biosynthetic pathways by expression in microbial cell factories grown on an industrial scale would yield enormous economic and environmental benefits. However, Fe-S enzymes often become bottlenecks that limits the productivity of engineered pathways. As a consequence, achieving the production metrics required for industrial application remains a distant goal for Fe-S enzyme-dependent pathways. Here, we identify and review three core challenges in harnessing Fe-S enzyme activity, which all stem from the properties of Fe-S clusters: 1) limited Fe-S cluster supply within the host cell, 2) Fe-S cluster instability, and 3) lack of specialized reducing cofactor proteins often required for Fe-S enzyme activity, such as enzyme-specific flavodoxins and ferredoxins. We highlight successful methods developed for a variety of Fe-S enzymes and electron carriers for overcoming these difficulties. We use heterologous nitrogenase expression as a grand case study demonstrating how each of these challenges can be addressed. We predict that recent breakthroughs in protein structure prediction and design will prove well-suited to addressing each of these challenges. A reliable toolkit for harnessing Fe-S enzymes in engineered metabolic pathways will accelerate the development of industry-ready Fe-S enzyme-dependent biosynthesis pathways.
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Affiliation(s)
- Helena Shomar
- Institut Pasteur, université Paris Cité, Inserm U1284, Diversité moléculaire des microbes (Molecular Diversity of Microbes lab), 75015 Paris, France
| | - Gregory Bokinsky
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands.
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2
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Maio N, Heffner AL, Rouault TA. Iron‑sulfur clusters in viral proteins: Exploring their elusive nature, roles and new avenues for targeting infections. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119723. [PMID: 38599324 PMCID: PMC11139609 DOI: 10.1016/j.bbamcr.2024.119723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/13/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024]
Abstract
Viruses have evolved complex mechanisms to exploit host factors for replication and assembly. In response, host cells have developed strategies to block viruses, engaging in a continuous co-evolutionary battle. This dynamic interaction often revolves around the competition for essential resources necessary for both host cell and virus replication. Notably, iron, required for the biosynthesis of several cofactors, including iron‑sulfur (FeS) clusters, represents a critical element in the ongoing competition for resources between infectious agents and host. Although several recent studies have identified FeS cofactors at the core of virus replication machineries, our understanding of their specific roles and the cellular processes responsible for their incorporation into viral proteins remains limited. This review aims to consolidate our current knowledge of viral components that have been characterized as FeS proteins and elucidate how viruses harness these versatile cofactors to their benefit. Its objective is also to propose that viruses may depend on incorporation of FeS cofactors more extensively than is currently known. This has the potential to revolutionize our understanding of viral replication, thereby carrying significant implications for the development of strategies to target infections.
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Affiliation(s)
- Nunziata Maio
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
| | - Audrey L Heffner
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA; Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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3
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Quechol R, Solomon JB, Liu YA, Lee CC, Jasniewski AJ, Górecki K, Oyala P, Hedman B, Hodgson KO, Ribbe MW, Hu Y. Heterologous synthesis of the complex homometallic cores of nitrogenase P- and M-clusters in Escherichia coli. Proc Natl Acad Sci U S A 2023; 120:e2314788120. [PMID: 37871225 PMCID: PMC10622910 DOI: 10.1073/pnas.2314788120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 09/28/2023] [Indexed: 10/25/2023] Open
Abstract
Nitrogenase is an active target of heterologous expression because of its importance for areas related to agronomy, energy, and environment. One major hurdle for expressing an active Mo-nitrogenase in Escherichia coli is to generate the complex metalloclusters (P- and M-clusters) within this enzyme, which involves some highly unique bioinorganic chemistry/metalloenzyme biochemistry that is not generally dealt with in the heterologous expression of proteins via synthetic biology; in particular, the heterologous synthesis of the homometallic P-cluster ([Fe8S7]) and M-cluster core (or L-cluster; [Fe8S9C]) on their respective protein scaffolds, which represents two crucial checkpoints along the biosynthetic pathway of a complete nitrogenase, has yet to be demonstrated by biochemical and spectroscopic analyses of purified metalloproteins. Here, we report the heterologous formation of a P-cluster-containing NifDK protein upon coexpression of Azotobacter vinelandii nifD, nifK, nifH, nifM, and nifZ genes, and that of an L-cluster-containing NifB protein upon coexpression of Methanosarcina acetivorans nifB, nifS, and nifU genes alongside the A. vinelandii fdxN gene, in E. coli. Our metal content, activity, EPR, and XAS/EXAFS data provide conclusive evidence for the successful synthesis of P- and L-clusters in a nondiazotrophic host, thereby highlighting the effectiveness of our metallocentric, divide-and-conquer approach that individually tackles the key events of nitrogenase biosynthesis prior to piecing them together into a complete pathway for the heterologous expression of nitrogenase. As such, this work paves the way for the transgenic expression of an active nitrogenase while providing an effective tool for further tackling the biosynthetic mechanism of this important metalloenzyme.
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Affiliation(s)
- Robert Quechol
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
| | - Joseph B. Solomon
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
- Department of Chemistry, University of California, Irvine, CA92697-2025
| | - Yiling A. Liu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
| | - Chi Chung Lee
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
| | - Andrew J. Jasniewski
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
| | - Kamil Górecki
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
| | - Paul Oyala
- Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA91125
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, Stanford Linear Accelerator Center National Accelerator Laboratory, Stanford University, Menlo Park, CA94025
| | - Keith O. Hodgson
- Stanford Synchrotron Radiation Lightsource, Stanford Linear Accelerator Center National Accelerator Laboratory, Stanford University, Menlo Park, CA94025
- Department of Chemistry, Stanford University, Stanford, CA94305
| | - Markus W. Ribbe
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
- Department of Chemistry, University of California, Irvine, CA92697-2025
| | - Yilin Hu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA92697-3900
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4
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Dreishpoon MB, Bick NR, Petrova B, Warui DM, Cameron A, Booker SJ, Kanarek N, Golub TR, Tsvetkov P. FDX1 regulates cellular protein lipoylation through direct binding to LIAS. J Biol Chem 2023; 299:105046. [PMID: 37453661 PMCID: PMC10462841 DOI: 10.1016/j.jbc.2023.105046] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 07/18/2023] Open
Abstract
Ferredoxins are a family of iron-sulfur (Fe-S) cluster proteins that serve as essential electron donors in numerous cellular processes that are conserved through evolution. The promiscuous nature of ferredoxins as electron donors enables them to participate in many metabolic processes including steroid, heme, vitamin D, and Fe-S cluster biosynthesis in different organisms. However, the unique natural function(s) of each of the two human ferredoxins (FDX1 and FDX2) are still poorly characterized. We recently reported that FDX1 is both a crucial regulator of copper ionophore-induced cell death and serves as an upstream regulator of cellular protein lipoylation, a mitochondrial lipid-based post-translational modification naturally occurring on four mitochondrial enzymes that are crucial for TCA cycle function. Here we show that FDX1 directly regulates protein lipoylation by binding the lipoyl synthase (LIAS) enzyme promoting its functional binding to the lipoyl carrier protein GCSH and not through indirect regulation of cellular Fe-S cluster biosynthesis. Metabolite profiling revealed that the predominant cellular metabolic outcome of FDX1 loss of function is manifested through the regulation of the four lipoylation-dependent enzymes ultimately resulting in loss of cellular respiration and sensitivity to mild glucose starvation. Transcriptional profiling established that FDX1 loss-of-function results in the induction of both compensatory metabolism-related genes and the integrated stress response, consistent with our findings that FDX1 loss-of-function is conditionally lethal. Together, our findings establish that FDX1 directly engages with LIAS, promoting its role in cellular protein lipoylation, a process essential in maintaining cell viability under low glucose conditions.
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Affiliation(s)
| | - Nolan R Bick
- Broad Institute of Harvard and MIT, Cambridge, USA
| | - Boryana Petrova
- Harvard Medical School, Boston, Massachusetts, USA; Department of Pathology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Douglas M Warui
- Department of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes Medical Institute, The Pennsylvania State University, State College, Pennsylvania, USA
| | | | - Squire J Booker
- Department of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes Medical Institute, The Pennsylvania State University, State College, Pennsylvania, USA
| | - Naama Kanarek
- Broad Institute of Harvard and MIT, Cambridge, USA; Harvard Medical School, Boston, Massachusetts, USA; Department of Pathology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Todd R Golub
- Broad Institute of Harvard and MIT, Cambridge, USA; Harvard Medical School, Boston, Massachusetts, USA; Department of Pediatric Oncology, Dana Farber Cancer Institute, Boston, Massachusetts, USA; Division of Pediatric Hematology/Oncology, Boston Children's Hospital, Boston, Massachusetts, USA
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5
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Namkoong G, Suess DLM. Cluster-selective 57Fe labeling of a Twitch-domain-containing radical SAM enzyme. Chem Sci 2023; 14:7492-7499. [PMID: 37449070 PMCID: PMC10337720 DOI: 10.1039/d3sc02016a] [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: 04/19/2023] [Accepted: 06/02/2023] [Indexed: 07/18/2023] Open
Abstract
57Fe-specific techniques such as Mössbauer spectroscopy are invaluable tools in mechanistic studies of Fe-S proteins. However, they remain underutilized for proteins that bind multiple Fe-S clusters because such proteins are typically uniformly enriched with 57Fe. As a result, it can be unclear which spectroscopic responses derive from which cluster, and this in turn obscures the chemistry that takes place at each cluster. Herein, we report a facile method for cluster-selective 57Fe enrichment based on exchange between the protein's Fe-S clusters and exogenous Fe ions. Through a combination of inductively coupled plasma mass spectrometric and 57Fe Mössbauer spectroscopic analysis, we show that, of the two [Fe4S4] clusters in BtrN (a Twitch-domain-containing radical S-adenosyl-l-methionine (SAM) enzyme), the Fe ions in the SAM-binding cluster undergo faster exchange with exogenous Fe2+; the auxiliary cluster is essentially inert under the reaction conditions. Exploiting this rate difference allows for either of the two [Fe4S4] clusters to be selectively labeled: the SAM-binding cluster can be labeled by exchanging unlabeled BtrN with 57Fe2+, or the auxiliary cluster can be labeled by exchanging fully labeled BtrN with natural abundance Fe2+. The labeling selectivity likely originates primarily from differences in the clusters' accessibility to small molecules, with secondary contributions from the different redox properties of the clusters. This method for cluster-selective isotopic labeling could in principle be applied to any protein that binds multiple Fe-S clusters so long as the clusters undergo exchange with exogenous Fe ions at sufficiently different rates.
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Affiliation(s)
- Gil Namkoong
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA
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6
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McGregor AK, Chan ACK, Schroeder MD, Do LTM, Saini G, Murphy MEP, Wolthers KR. A new member of the flavodoxin superfamily from Fusobacterium nucleatum that functions in heme trafficking and reduction of anaerobilin. J Biol Chem 2023; 299:104902. [PMID: 37302554 PMCID: PMC10404700 DOI: 10.1016/j.jbc.2023.104902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/18/2023] [Accepted: 05/24/2023] [Indexed: 06/13/2023] Open
Abstract
Fusobacterium nucleatum is an opportunistic oral pathogen that is associated with various cancers. To fulfill its essential need for iron, this anaerobe will express heme uptake machinery encoded at a single genetic locus. The heme uptake operon includes HmuW, a class C radical SAM-dependent methyltransferase that degrades heme anaerobically to release Fe2+ and a linear tetrapyrrole called anaerobilin. The last gene in the operon, hmuF encodes a member of the flavodoxin superfamily of proteins. We discovered that HmuF and a paralog, FldH, bind tightly to both FMN and heme. The structure of Fe3+-heme-bound FldH (1.6 Å resolution) reveals a helical cap domain appended to the ⍺/β core of the flavodoxin fold. The cap creates a hydrophobic binding cleft that positions the heme planar to the si-face of the FMN isoalloxazine ring. The ferric heme iron is hexacoordinated to His134 and a solvent molecule. In contrast to flavodoxins, FldH and HmuF do not stabilize the FMN semiquinone but instead cycle between the FMN oxidized and hydroquinone states. We show that heme-loaded HmuF and heme-loaded FldH traffic heme to HmuW for degradation of the protoporphyrin ring. Both FldH and HmuF then catalyze multiple reductions of anaerobilin through hydride transfer from the FMN hydroquinone. The latter activity eliminates the aromaticity of anaerobilin and the electrophilic methylene group that was installed through HmuW turnover. Hence, HmuF provides a protected path for anaerobic heme catabolism, offering F. nucleatum a competitive advantage in the colonization of anoxic sites of the human body.
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Affiliation(s)
| | - Anson C K Chan
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Megan D Schroeder
- Department of Chemistry, University of British Columbia, Kelowna, Canada
| | - Long T M Do
- Department of Chemistry, University of British Columbia, Kelowna, Canada
| | - Gurpreet Saini
- Department of Chemistry, University of British Columbia, Kelowna, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Kirsten R Wolthers
- Department of Chemistry, University of British Columbia, Kelowna, Canada.
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7
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Dreishpoon MB, Bick NR, Petrova B, Warui DM, Cameron A, Booker SJ, Kanarek N, Golub TR, Tsvetkov P. FDX1 regulates cellular protein lipoylation through direct binding to LIAS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.03.526472. [PMID: 36778498 PMCID: PMC9915701 DOI: 10.1101/2023.02.03.526472] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Ferredoxins are a family of iron-sulfur (Fe-S) cluster proteins that serve as essential electron donors in numerous cellular processes that are conserved through evolution. The promiscuous nature of ferredoxins as electron donors enables them to participate in many metabolic processes including steroid, heme, vitamin D and Fe-S cluster biosynthesis in different organisms. However, the unique natural function(s) of each of the two human ferredoxins (FDX1 and FDX2) are still poorly characterized. We recently reported that FDX1 is both a crucial regulator of copper ionophore induced cell death and serves as an upstream regulator of cellular protein lipoylation, a mitochondrial lipid-based post translational modification naturally occurring on four mitochondrial enzymes that are crucial for TCA cycle function. Here we show that FDX1 regulates protein lipoylation by directly binding to the lipoyl synthase (LIAS) enzyme and not through indirect regulation of cellular Fe-S cluster biosynthesis. Metabolite profiling revealed that the predominant cellular metabolic outcome of FDX1 loss-of-function is manifested through the regulation of the four lipoylation-dependent enzymes ultimately resulting in loss of cellular respiration and sensitivity to mild glucose starvation. Transcriptional profiling of cells growing in either normal or low glucose conditions established that FDX1 loss-of-function results in the induction of both compensatory metabolism related genes and the integrated stress response, consistent with our findings that FDX1 loss-of-functions is conditionally lethal. Together, our findings establish that FDX1 directly engages with LIAS, promoting cellular protein lipoylation, a process essential in maintaining cell viability under low glucose conditions.
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Affiliation(s)
| | | | - Boryana Petrova
- Harvard Medical School, Boston, MA, USA
- Department of Pathology, Boston Children’s Hospital, Boston, MA USA
| | - Douglas M. Warui
- Department of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes Medical Institute, The Pennsylvania State University, PA, United States
| | | | - Squire J. Booker
- Department of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes Medical Institute, The Pennsylvania State University, PA, United States
| | - Naama Kanarek
- Broad Institute of Harvard and MIT, Cambridge, USA
- Harvard Medical School, Boston, MA, USA
- Department of Pathology, Boston Children’s Hospital, Boston, MA USA
| | - Todd R. Golub
- Broad Institute of Harvard and MIT, Cambridge, USA
- Harvard Medical School, Boston, MA, USA
- Department of Pediatric Oncology, Dana Farber Cancer Institute, Boston, MA, USA
- Division of Pediatric Hematology/Oncology, Boston Children’s Hospital, Boston, MA, USA
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8
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Rohaun SK, Imlay JA. The vulnerability of radical SAM enzymes to oxidants and soft metals. Redox Biol 2022; 57:102495. [PMID: 36240621 PMCID: PMC9576991 DOI: 10.1016/j.redox.2022.102495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 09/28/2022] [Accepted: 09/29/2022] [Indexed: 11/30/2022] Open
Abstract
Radical S-adenosylmethionine enzymes (RSEs) drive diverse biological processes by catalyzing chemically difficult reactions. Each of these enzymes uses a solvent-exposed [4Fe-4S] cluster to coordinate and cleave its SAM co-reactant. This cluster is destroyed during oxic handling, forcing investigators to work with these enzymes under anoxic conditions. Analogous substrate-binding [4Fe-4S] clusters in dehydratases are similarly sensitive to oxygen in vitro; they are also extremely vulnerable to reactive oxygen species (ROS) in vitro and in vivo. These observations suggested that ROS might similarly poison RSEs. This conjecture received apparent support by the observation that when E. coli experiences hydrogen peroxide stress, it induces a cluster-free isozyme of the RSE HemN. In the present study, surprisingly, the purified RSEs viperin and HemN proved quite resistant to peroxide and superoxide in vitro. Furthermore, pathways that require RSEs remained active inside E. coli cells that were acutely stressed by hydrogen peroxide and superoxide. Viperin, but not HemN, was gradually poisoned by molecular oxygen in vitro, forming an apparent [3Fe-4S]+ form that was readily reactivated. The modest rate of damage, and the known ability of cells to repair [3Fe-4S]+ clusters, suggest why these RSEs remain functional inside fully aerated organisms. In contrast, copper(I) damaged HemN and viperin in vitro as readily as it did fumarase, a known target of copper toxicity inside E. coli. Excess intracellular copper also impaired RSE-dependent biosynthetic processes. These data indicate that RSEs may be targets of copper stress but not of reactive oxygen species.
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Affiliation(s)
| | - James A Imlay
- Department of Microbiology, University of Illinois, Urbana, IL, 61801, USA.
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9
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Warui D, Sil D, Lee KH, Neti SS, Esakova OA, Knox HL, Krebs C, Booker SJ. In Vitro Demonstration of Human Lipoyl Synthase Catalytic Activity in the Presence of NFU1. ACS BIO & MED CHEM AU 2022; 2:456-468. [PMID: 36281303 PMCID: PMC9585516 DOI: 10.1021/acsbiomedchemau.2c00020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipoyl synthase (LS) catalyzes the last step in the biosynthesis of the lipoyl cofactor, which is the attachment of sulfur atoms at C6 and C8 of an n-octanoyllysyl side chain of a lipoyl carrier protein (LCP). The protein is a member of the radical S-adenosylmethionine (SAM) superfamily of enzymes, which use SAM as a precursor to a 5'-deoxyadenosyl 5'-radical (5'-dA·). The role of the 5'-dA· in the LS reaction is to abstract hydrogen atoms from C6 and C8 of the octanoyl moiety of the substrate to initiate subsequent sulfur attachment. All radical SAM enzymes have at least one [4Fe-4S] cluster that is used in the reductive cleavage of SAM to generate the 5'-dA·; however, LSs contain an additional auxiliary [4Fe-4S] cluster from which sulfur atoms are extracted during turnover, leading to degradation of the cluster. Therefore, these enzymes catalyze only 1 turnover in the absence of a system that restores the auxiliary cluster. In Escherichia coli, the auxiliary cluster of LS can be regenerated by the iron-sulfur (Fe-S) cluster carrier protein NfuA as fast as catalysis takes place, and less efficiently by IscU. NFU1 is the human ortholog of E. coli NfuA and has been shown to interact directly with human LS (i.e., LIAS) in yeast two-hybrid analyses. Herein, we show that NFU1 and LIAS form a tight complex in vitro and that NFU1 can efficiently restore the auxiliary cluster of LIAS during turnover. We also show that BOLA3, previously identified as being critical in the biosynthesis of the lipoyl cofactor in humans and Saccharomyces cerevisiae, has no direct effect on Fe-S cluster transfer from NFU1 or GLRX5 to LIAS. Further, we show that ISCA1 and ISCA2 can enhance LIAS turnover, but only slightly.
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Affiliation(s)
- Douglas
M. Warui
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Debangsu Sil
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Kyung-Hoon Lee
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Syam Sundar Neti
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Olga A. Esakova
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Hayley L. Knox
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Squire J. Booker
- Department
of Chemistry and Biochemistry and Molecular Biology and the Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
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10
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Neti SS, Sil D, Warui DM, Esakova OA, Solinski AE, Serrano DA, Krebs C, Booker SJ. Characterization of LipS1 and LipS2 from Thermococcus kodakarensis: Proteins Annotated as Biotin Synthases, which Together Catalyze Formation of the Lipoyl Cofactor. ACS BIO & MED CHEM AU 2022; 2:509-520. [PMID: 36281299 PMCID: PMC9585515 DOI: 10.1021/acsbiomedchemau.2c00018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 11/28/2022]
Abstract
Lipoic acid is an eight-carbon sulfur-containing biomolecule that functions primarily as a cofactor in several multienzyme complexes. It is biosynthesized as an attachment to a specific lysyl residue on one of the subunits of these multienzyme complexes. In Escherichia coli and many other organisms, this biosynthetic pathway involves two dedicated proteins: octanoyltransferase (LipB) and lipoyl synthase (LipA). LipB transfers an n-octanoyl chain from the octanoyl-acyl carrier protein to the target lysyl residue, and then, LipA attaches two sulfur atoms (one at C6 and one at C8) to give the final lipoyl cofactor. All classical lipoyl synthases (LSs) are radical S-adenosylmethionine (SAM) enzymes, which use an [Fe4S4] cluster to reductively cleave SAM to generate a 5'-deoxyadenosyl 5'-radical. Classical LSs also contain a second [Fe4S4] cluster that serves as the source of both appended sulfur atoms. Recently, a novel pathway for generating the lipoyl cofactor was reported. This pathway replaces the canonical LS with two proteins, LipS1 and LipS2, which act together to catalyze formation of the lipoyl cofactor. In this work, we further characterize LipS1 and LipS2 biochemically and spectroscopically. Although LipS1 and LipS2 were previously annotated as biotin synthases, we show that both proteins, unlike E. coli biotin synthase, contain two [Fe4S4] clusters. We identify the cluster ligands to both iron-sulfur clusters in both proteins and show that LipS2 acts only on an octanoyl-containing substrate, while LipS1 acts only on an 8-mercaptooctanoyl-containing substrate. Therefore, similarly to E. coli biotin synthase and in contrast to E. coli LipA, sulfur attachment takes place initially at the terminal carbon (C8) and then at the C6 methylene carbon.
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Affiliation(s)
- Syam Sundar Neti
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Debangsu Sil
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Douglas M. Warui
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Olga A. Esakova
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Amy E. Solinski
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Dante A. Serrano
- Department
of Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Squire J. Booker
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Howard
Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
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11
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Lloyd CT, Iwig DF, Wang B, Cossu M, Metcalf WW, Boal AK, Booker SJ. Discovery, structure, and mechanism of a tetraether lipid synthase. Nature 2022; 609:197-203. [PMID: 35882349 PMCID: PMC9433317 DOI: 10.1038/s41586-022-05120-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 07/18/2022] [Indexed: 11/20/2022]
Abstract
Archaea synthesize isoprenoid-based ether-linked membrane lipids, which enable them to withstand extreme environmental conditions, such as high temperatures, high salinity, and low or high pH values1–5. In some archaea, such as Methanocaldococcus jannaschii, these lipids are further modified by forming carbon–carbon bonds between the termini of two lipid tails within one glycerophospholipid to generate the macrocyclic archaeol or forming two carbon–carbon bonds between the termini of two lipid tails from two glycerophospholipids to generate the macrocycle glycerol dibiphytanyl glycerol tetraether (GDGT)1,2. GDGT contains two 40-carbon lipid chains (biphytanyl chains) that span both leaflets of the membrane, providing enhanced stability to extreme conditions. How these specialized lipids are formed has puzzled scientists for decades. The reaction necessitates the coupling of two completely inert sp3-hybridized carbon centres, which, to our knowledge, has not been observed in nature. Here we show that the gene product of mj0619 from M. jannaschii, which encodes a radical S-adenosylmethionine enzyme, is responsible for biphytanyl chain formation during synthesis of both the macrocyclic archaeol and GDGT membrane lipids6. Structures of the enzyme show the presence of four metallocofactors: three [Fe4S4] clusters and one mononuclear rubredoxin-like iron ion. In vitro mechanistic studies show that Csp3–Csp3 bond formation takes place on fully saturated archaeal lipid substrates and involves an intermediate bond between the substrate carbon and a sulfur of one of the [Fe4S4] clusters. Our results not only establish the biosynthetic route for tetraether formation but also improve the use of GDGT in GDGT-based paleoclimatology indices7–10. In Methanocaldococcus jannaschii, a radical S-adenosylmethionine enzyme catalyses the formation of the biphytanyl chain.
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Affiliation(s)
- Cody T Lloyd
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - David F Iwig
- The Howard Hughes Medical Institute, Pennsylvania State University, University. Park, PA, USA
| | - Bo Wang
- The Howard Hughes Medical Institute, Pennsylvania State University, University. Park, PA, USA
| | - Matteo Cossu
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - William W Metcalf
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, IL, USA.,Institute for Genomic Biology, University of Illinois Urbana- Champaign, Urbana, IL, USA
| | - Amie K Boal
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA. .,The Howard Hughes Medical Institute, Pennsylvania State University, University. Park, PA, USA.
| | - Squire J Booker
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA. .,The Howard Hughes Medical Institute, Pennsylvania State University, University. Park, PA, USA. .,Department of Chemistry, Pennsylvania State University, University Park, PA, USA.
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12
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Layer G, Jahn M, Moser J, Jahn D. Radical SAM Enzymes Involved in Tetrapyrrole Biosynthesis and Insertion. ACS BIO & MED CHEM AU 2022; 2:196-204. [PMID: 37101575 PMCID: PMC10114771 DOI: 10.1021/acsbiomedchemau.1c00061] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The anaerobic biosyntheses of heme, heme d 1, and bacteriochlorophyll all require the action of radical SAM enzymes. During heme biosynthesis in some bacteria, coproporphyrinogen III dehydrogenase (CgdH) catalyzes the decarboxylation of two propionate side chains of coproporphyrinogen III to the corresponding vinyl groups of protoporphyrinogen IX. Its solved crystal structure was the first published structure for a radical SAM enzyme. In bacteria, heme is inserted into enzymes by the cytoplasmic heme chaperone HemW, a radical SAM enzyme structurally highly related to CgdH. In an alternative heme biosynthesis route found in archaea and sulfate-reducing bacteria, the two radical SAM enzymes AhbC and AhbD catalyze the removal of two acetate groups (AhbC) or the decarboxylation of two propionate side chains (AhbD). NirJ, a close homologue of AhbC, is required for propionate side chain removal during the formation of heme d 1 in some denitrifying bacteria. Biosynthesis of the fifth ring (ring E) of all chlorophylls is based on an unusual six-electron oxidative cyclization step. The sophisticated conversion of Mg-protoporphyrin IX monomethylester to protochlorophyllide is facilitated by an oxygen-independent cyclase termed BchE, which is a cobalamin-dependent radical SAM enzyme. Most of the radical SAM enzymes involved in tetrapyrrole biosynthesis were recognized as such by Sofia et al. in 2001 (Nucleic Acids Res.2001, 29, 1097-1106) and were biochemically characterized thereafter. Although much has been achieved, the challenging tetrapyrrole substrates represent a limiting factor for enzyme/substrate cocrystallization and the ultimate elucidation of the corresponding enzyme mechanisms.
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Affiliation(s)
- Gunhild Layer
- Institut
für Pharmazeutische Wissenschaften, Pharmazeutische Biologie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Str. 19, 79104 Freiburg im Breisgau, Germany
- . Phone: ++49
0761 203 8373
| | - Martina Jahn
- Institut
für Mikrobiologie, Technische Universität
Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
| | - Jürgen Moser
- Institut
für Mikrobiologie, Technische Universität
Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany
| | - Dieter Jahn
- Braunschweig
Integrated Center of Systems Biology BRICS, Technische Universität Braunschweig, Rebenring 56, 38106 Braunschweig, Germany
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13
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Purification and characterization of sequential cobalamin-dependent radical SAM methylases ThnK and TokK in carbapenem β-lactam antibiotic biosynthesis. Methods Enzymol 2022; 669:29-44. [PMID: 35644176 DOI: 10.1016/bs.mie.2021.09.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
ThnK and TokK are cobalamin-dependent radical S-adenosylmethionine enzymes that catalyze sequential methylations of a common carbapenem biosynthetic intermediate. ThnK was an early characterized member of the subfamily of cobalamin-dependent radical S-adenosylmethionine enzymes. Since initial publication of the ThnK function, the field has progressed, and we have made methodological strides in the expression and purification of this enzyme and its ortholog TokK. An optimized protocol for obtaining the enzymes in pure and active form has enabled us to characterize their reactions and gain greater insight into the kinetic behavior of the sequential methylations they catalyze. We share here the methods and strategy that we have developed through our study of these enzymes.
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14
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Dill Z, Li B, Bridwell-Rabb J. Purification and structural elucidation of a cobalamin-dependent radical SAM enzyme. Methods Enzymol 2022; 669:91-116. [PMID: 35644182 DOI: 10.1016/bs.mie.2021.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The cobalamin (Cbl)-dependent radical S-adenosylmethionine (SAM) enzymes use a [4Fe-4S] cluster, SAM, and Cbl to carry out remarkable catalytic feats in a large number of biosynthetic pathways. However, despite the abundance of annotated Cbl-dependent radical SAM enzymes, relatively few molecular details exist regarding how these enzymes function. Traditionally, challenges associated with purifying and reconstituting Cbl-dependent radical SAM enzymes have hindered biochemical studies aimed at elucidating the structures and mechanisms of these enzymes. Herein, we describe a bottom-up approach that was used to crystallize OxsB, learn about the overall architecture of a Cbl-dependent radical SAM enzyme, and facilitate mechanistic studies. We report lessons learned from the crystallization of different states of OxsB, including the apo-, selenomethionine (SeMet)-labeled, and fully reconstituted form of OxsB that has a [4Fe-4S] cluster, SAM, and Cbl bound. Further, we suggest that, when appropriate, this bottom-up method can be used to facilitate studies on enzymes in this class for which there are challenges associated with purifying and reconstituting the active enzyme.
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Affiliation(s)
- Zerick Dill
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States; Program in Chemical Biology, University of Michigan, Ann Arbor, MI, United States
| | - Bin Li
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States
| | - Jennifer Bridwell-Rabb
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States; Program in Chemical Biology, University of Michigan, Ann Arbor, MI, United States.
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15
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Abstract
CyuA of Escherichia coli is an inducible desulfidase that degrades cysteine to pyruvate, ammonium, and hydrogen sulfide. Workers have conjectured that its role may be to defend bacteria against the toxic effects of cysteine. However, cyuA sits in an operon alongside cyuP, which encodes a cysteine importer that seems ill suited to protecting the cell from environmental cysteine. In this study, transport measurements established that CyuP is a cysteine-specific, high-flux importer. The concerted action of CyuP and CyuA allowed anaerobic E. coli to employ cysteine as either the sole nitrogen or the sole carbon/energy source. CyuA was essential for this function, and although other transporters can slowly bring cysteine into the cell, CyuP-proficient cells outcompeted cyuP mutants. Cells immediately consumed the ammonia and pyruvate that CyuA generated, with little or none escaping from the cell. The expression of the cyuPA operon depended upon both CyuR, a cysteine-activated transcriptional activator, and Crp. This control is consistent with its catabolic function. In fact, the cyuPA operon sits immediately downstream of the thrABCDEFG operon, which allows the analogous fermentation of serine and threonine; this arrangement suggests that this gene cluster may have moved jointly through the anaerobic biota, providing E. coli with the ability to ferment a limited set of amino acids. Interestingly, both the cyu- and thr-encoded pathways depend upon oxygen-sensitive enzymes and cannot contribute to amino acid catabolism in oxic environments.
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16
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D'Angelo F, Fernández-Fueyo E, Garcia PS, Shomar H, Pelosse M, Manuel RR, Büke F, Liu S, van den Broek N, Duraffourg N, de Ram C, Pabst M, Bouveret E, Gribaldo S, Py B, Ollagnier de Choudens S, Barras F, Bokinsky G. Cellular assays identify barriers impeding iron-sulfur enzyme activity in a non-native prokaryotic host. eLife 2022; 11:70936. [PMID: 35244541 PMCID: PMC8896826 DOI: 10.7554/elife.70936] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 02/03/2022] [Indexed: 11/24/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are ancient and ubiquitous protein cofactors and play irreplaceable roles in many metabolic and regulatory processes. Fe-S clusters are built and distributed to Fe-S enzymes by dedicated protein networks. The core components of these networks are widely conserved and highly versatile. However, Fe-S proteins and enzymes are often inactive outside their native host species. We sought to systematically investigate the compatibility of Fe-S networks with non-native Fe-S enzymes. By using collections of Fe-S enzyme orthologs representative of the entire range of prokaryotic diversity, we uncovered a striking correlation between phylogenetic distance and probability of functional expression. Moreover, coexpression of a heterologous Fe-S biogenesis pathway increases the phylogenetic range of orthologs that can be supported by the foreign host. We also find that Fe-S enzymes that require specific electron carrier proteins are rarely functionally expressed unless their taxon-specific reducing partners are identified and co-expressed. We demonstrate how these principles can be applied to improve the activity of a radical S-adenosyl methionine(rSAM) enzyme from a Streptomyces antibiotic biosynthesis pathway in Escherichia coli. Our results clarify how oxygen sensitivity and incompatibilities with foreign Fe-S and electron transfer networks each impede heterologous activity. In particular, identifying compatible electron transfer proteins and heterologous Fe-S biogenesis pathways may prove essential for engineering functional Fe-S enzyme-dependent pathways.
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Affiliation(s)
- Francesca D'Angelo
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France
| | - Elena Fernández-Fueyo
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Pierre Simon Garcia
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France.,Institut Pasteur, Université de Paris, CNRS UMR6047, Evolutionary Biology of the Microbial Cell, Department of Microbiology, Paris, France
| | - Helena Shomar
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Martin Pelosse
- Univ. Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, Grenoble, France
| | - Rita Rebelo Manuel
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Ferhat Büke
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Siyi Liu
- Aix-Marseille Université-CNRS, Laboratoire de Chimie Bactérienne UMR 7283, Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies Biotechnologie, Marseille, France
| | - Niels van den Broek
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Nicolas Duraffourg
- Univ. Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, Grenoble, France
| | - Carol de Ram
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Martin Pabst
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Emmanuelle Bouveret
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Université de Paris, CNRS UMR6047, Evolutionary Biology of the Microbial Cell, Department of Microbiology, Paris, France
| | - Béatrice Py
- Aix-Marseille Université-CNRS, Laboratoire de Chimie Bactérienne UMR 7283, Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies Biotechnologie, Marseille, France
| | | | - Frédéric Barras
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France
| | - Gregory Bokinsky
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
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17
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Sinner E, Marous DR, Townsend CA. Evolution of Methods for the Study of Cobalamin-Dependent Radical SAM Enzymes. ACS BIO & MED CHEM AU 2022; 2:4-10. [PMID: 35341020 PMCID: PMC8950095 DOI: 10.1021/acsbiomedchemau.1c00032] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While bioinformatic evidence of cobalamin-dependent radical S-adenosylmethionine (SAM) enzymes has existed since the naming of the radical SAM superfamily in 2001, none were biochemically characterized until 2011. In the past decade, the field has flourished as methodological advances have facilitated study of the subfamily. Because of the ingenuity and perseverance of researchers in this field, we now have functional, mechanistic, and structural insight into how this class of enzymes harnesses the power of both the cobalamin and radical SAM cofactors to achieve catalysis. All of the early characterized enzymes in this subfamily were methylases, but the activity of these enzymes has recently been expanded beyond methylation. We anticipate that the characterized functions of these enzymes will become both better understood and increasingly diverse with continued study.
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Affiliation(s)
- Erica
K. Sinner
- Department
of Chemistry, Johns Hopkins University, 3400 N Charles St., Baltimore, Maryland 21218, United States
| | - Daniel R. Marous
- Department
of Chemistry, Wittenberg University, 200 W Ward St., Springfield, Ohio 45504, United States
| | - Craig A. Townsend
- Department
of Chemistry, Johns Hopkins University, 3400 N Charles St., Baltimore, Maryland 21218, United States
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18
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Structure of a B 12-dependent radical SAM enzyme in carbapenem biosynthesis. Nature 2022; 602:343-348. [PMID: 35110734 DOI: 10.1038/s41586-021-04392-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 12/22/2021] [Indexed: 11/08/2022]
Abstract
Carbapenems are antibiotics of last resort in the clinic. Owing to their potency and broad-spectrum activity, they are an important part of the antibiotic arsenal. The vital role of carbapenems is exemplified by the approval acquired by Merck from the US Food and Drug Administration (FDA) for the use of an imipenem combination therapy to treat the increased levels of hospital-acquired and ventilator-associated bacterial pneumonia that have occurred during the COVID-19 pandemic1. The C6 hydroxyethyl side chain distinguishes the clinically used carbapenems from the other classes of β-lactam antibiotics and is responsible for their low susceptibility to inactivation by occluding water from the β-lactamase active site2. The construction of the C6 hydroxyethyl side chain is mediated by cobalamin- or B12-dependent radical S-adenosylmethionine (SAM) enzymes3. These radical SAM methylases (RSMTs) assemble the alkyl backbone by sequential methylation reactions, and thereby underlie the therapeutic usefulness of clinically used carbapenems. Here we present X-ray crystal structures of TokK, a B12-dependent RSMT that catalyses three-sequential methylations during the biosynthesis of asparenomycin A. These structures, which contain the two metallocofactors of the enzyme and were determined in the presence and absence of a carbapenam substrate, provide a visualization of a B12-dependent RSMT that uses the radical mechanism that is shared by most of these enzymes. The structures provide insight into the stereochemistry of initial C6 methylation and suggest that substrate positioning governs the rate of each methylation event.
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19
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Brimberry MA, Mathew L, Lanzilotta W. Making and breaking carbon-carbon bonds in class C radical SAM methyltransferases. J Inorg Biochem 2022; 226:111636. [PMID: 34717253 PMCID: PMC8667262 DOI: 10.1016/j.jinorgbio.2021.111636] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 01/03/2023]
Abstract
Radical S-adenosylmethionine (SAM) enzymes utilize a [4Fe-4S]1+ cluster and S-(5'-adenosyl)-L-methionine, (SAM), to generate a highly reactive radical and catalyze what is arguably the most diverse set of chemical reactions for any known enzyme family. At the heart of radical SAM catalysis is a highly reactive 5'-deoxyadenosyl radical intermediate (5'-dAdo●) generated through reductive cleavage of SAM or nucleophilic attack of the unique iron of the [4Fe-4S]+ cluster on the 5' C atom of SAM. Spectroscopic studies reveal the 5'-dAdo● is transiently captured in an FeC bond (Ω species). In the presence of substrate, homolytic scission of this metal‑carbon bond regenerates the 5'-dAdo● for catalytic hydrogen atom abstraction. While reminiscent of the adenosylcobalamin mechanism, radical SAM enzymes appear to encompass greater catalytic diversity. In this review we discuss recent developments for radical SAM enzymes involved in unique chemical rearrangements, specifically regarding class C radical SAM methyltransferases. Illuminating this class of radical SAM enzymes is especially significant as many enzymes have been shown to play critical roles in pathogenesis and the synthesis of novel antimicrobial compounds.
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Affiliation(s)
- Marley A. Brimberry
- Department of Biochemistry and Molecular Biology & Center for Metalloenzyme Studies,,Department of Chemistry University of Georgia, Athens GA 30602
| | - Liju Mathew
- Department of Biochemistry and Molecular Biology & Center for Metalloenzyme Studies,,Department of Chemistry University of Georgia, Athens GA 30602
| | - William Lanzilotta
- Department of Biochemistry and Molecular Biology & Center for Metalloenzyme Studies,,Department of Chemistry University of Georgia, Athens GA 30602.,To whom correspondence should be addressed. Phone, (706) 542-1324; fax, (706) 542-1738;
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20
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Experimental guidelines for trapping paramagnetic reaction intermediates in radical S-adenosylmethionine enzymes. Methods Enzymol 2022; 666:451-468. [DOI: 10.1016/bs.mie.2022.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Esakova OA, Grove TL, Yennawar NH, Arcinas AJ, Wang B, Krebs C, Almo SC, Booker SJ. Structural basis for tRNA methylthiolation by the radical SAM enzyme MiaB. Nature 2021; 597:566-570. [PMID: 34526715 PMCID: PMC9107155 DOI: 10.1038/s41586-021-03904-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 08/12/2021] [Indexed: 02/08/2023]
Abstract
Numerous post-transcriptional modifications of transfer RNAs have vital roles in translation. The 2-methylthio-N6-isopentenyladenosine (ms2i6A) modification occurs at position 37 (A37) in transfer RNAs that contain adenine in position 36 of the anticodon, and serves to promote efficient A:U codon-anticodon base-pairing and to prevent unintended base pairing by near cognates, thus enhancing translational fidelity1-4. The ms2i6A modification is installed onto isopentenyladenosine (i6A) by MiaB, a radical S-adenosylmethionine (SAM) methylthiotransferase. As a radical SAM protein, MiaB contains one [Fe4S4]RS cluster used in the reductive cleavage of SAM to form a 5'-deoxyadenosyl 5'-radical, which is responsible for removing the C2 hydrogen of the substrate5. MiaB also contains an auxiliary [Fe4S4]aux cluster, which has been implicated6-9 in sulfur transfer to C2 of i6A37. How this transfer takes place is largely unknown. Here we present several structures of MiaB from Bacteroides uniformis. These structures are consistent with a two-step mechanism, in which one molecule of SAM is first used to methylate a bridging µ-sulfido ion of the auxiliary cluster. In the second step, a second SAM molecule is cleaved to a 5'-deoxyadenosyl 5'-radical, which abstracts the C2 hydrogen of the substrate but only after C2 has undergone rehybridization from sp2 to sp3. This work advances our understanding of how enzymes functionalize inert C-H bonds with sulfur.
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Affiliation(s)
- Olga A. Esakova
- The Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Tyler L. Grove
- The Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Neela H. Yennawar
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Arthur J. Arcinas
- The Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA,Present address: AGC Biologics, Seattle, WA
| | - Bo Wang
- The Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Carsten Krebs
- The Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA,The Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Steven C. Almo
- The Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Squire J. Booker
- The Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA,The Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA,Howard Hughes Medical Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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22
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Radical SAM Enzyme QmpB Installs Two 9-Membered Ring Sactionine Macrocycles during Biogenesis of a Ribosomal Peptide Natural Product. J Org Chem 2021; 86:11284-11289. [PMID: 34351169 DOI: 10.1021/acs.joc.1c01507] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the reaction catalyzed by QmpB, a new radical S-adenosylmethionine enzyme encoded by a ribosomal peptide natural product gene cluster in Streptococcus suis. Using isotopic labeling, site-directed mutagenesis, high-resolution mass spectrometry, and multidimensional NMR spectroscopy, we show that QmpB installs two 9-membered ring sactionine bridges, connecting a Cys residue with an upstream Asn via an α-thioether bridge, with the two macrocycles separated by a single residue. QmpB is only the second type II sactionine synthase characterized to date.
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23
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Abstract
57Fe Mӧssbauer spectroscopy is unparalleled in the study of Fe-S cluster-containing proteins because of its unique ability to detect all forms of iron. Enrichment of biological samples with the 57Fe isotope and manipulation of experimental parameters such as temperature and magnetic field allow for elucidation of the number of Fe-S clusters present in a given protein, their nuclearity, oxidation state, geometry, and ligation environment, as well as any transient states relevant to enzyme chemistry. This chapter is arranged in five sections to help navigate an experimentalist to utilize 57Fe Mӧssbauer spectroscopy for delineating the role and structure of biological Fe-S clusters. The first section lays out the tools and technical considerations for the preparation of 57Fe-labeled samples. The choice of experimental parameters and their effects on the Mӧssbauer spectra are presented in the following two sections. The last two sections provide a theoretical and practical guide on spectral acquisition and analysis relevant to Fe-S centers.
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24
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Maio N, Lafont BAP, Sil D, Li Y, Bollinger JM, Krebs C, Pierson TC, Linehan WM, Rouault TA. Fe-S cofactors in the SARS-CoV-2 RNA-dependent RNA polymerase are potential antiviral targets. Science 2021; 373:236-241. [PMID: 34083449 PMCID: PMC8892629 DOI: 10.1126/science.abi5224] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 05/28/2021] [Indexed: 01/18/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of COVID-19, uses an RNA-dependent RNA polymerase (RdRp) for the replication of its genome and the transcription of its genes. We found that the catalytic subunit of the RdRp, nsp12, ligates two iron-sulfur metal cofactors in sites that were modeled as zinc centers in the available cryo-electron microscopy structures of the RdRp complex. These metal binding sites are essential for replication and for interaction with the viral helicase. Oxidation of the clusters by the stable nitroxide TEMPOL caused their disassembly, potently inhibited the RdRp, and blocked SARS-CoV-2 replication in cell culture. These iron-sulfur clusters thus serve as cofactors for the SARS-CoV-2 RdRp and are targets for therapy of COVID-19.
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Affiliation(s)
- Nunziata Maio
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bernard A P Lafont
- SARS-CoV-2 Virology Core, Laboratory of Viral Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Debangsu Sil
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - J Martin Bollinger
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Carsten Krebs
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Theodore C Pierson
- Laboratory of Viral Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Tracey A Rouault
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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25
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Wang J, Ma S, Ding W, Chen T, Zhang Q. Mechanistic Study of Oxidoreductase
AprQ
Involved in Biosynthesis of Aminoglycoside Antibiotic Apramycin. CHINESE J CHEM 2021. [DOI: 10.1002/cjoc.202100070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jinxiu Wang
- State Key Laboratory of Cryospheric Science, Key Laboratory of Extreme Environmental Microbial Resources and Engineering, Northwest Institute of Eco‐Environment and Resources, Chinese Academy of Sciences Lanzhou Gansu 730000 China
- Department of Chemistry, Fudan University Shanghai 200433 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Suze Ma
- Department of Chemistry, Fudan University Shanghai 200433 China
| | - Wei Ding
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University Shanghai 200240 China
| | - Tuo Chen
- State Key Laboratory of Cryospheric Science, Key Laboratory of Extreme Environmental Microbial Resources and Engineering, Northwest Institute of Eco‐Environment and Resources, Chinese Academy of Sciences Lanzhou Gansu 730000 China
| | - Qi Zhang
- Department of Chemistry, Fudan University Shanghai 200433 China
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26
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Trapping a cross-linked lysine-tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB. Proc Natl Acad Sci U S A 2021; 118:2101571118. [PMID: 34001621 DOI: 10.1073/pnas.2101571118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The radical S-adenosylmethionine (rSAM) enzyme SuiB catalyzes the formation of an unusual carbon-carbon bond between the sidechains of lysine (Lys) and tryptophan (Trp) in the biosynthesis of a ribosomal peptide natural product. Prior work on SuiB has suggested that the Lys-Trp cross-link is formed via radical electrophilic aromatic substitution (rEAS), in which an auxiliary [4Fe-4S] cluster (AuxI), bound in the SPASM domain of SuiB, carries out an essential oxidation reaction during turnover. Despite the prevalence of auxiliary clusters in over 165,000 rSAM enzymes, direct evidence for their catalytic role has not been reported. Here, we have used electron paramagnetic resonance (EPR) spectroscopy to dissect the SuiB mechanism. Our studies reveal substrate-dependent redox potential tuning of the AuxI cluster, constraining it to the oxidized [4Fe-4S]2+ state, which is active in catalysis. We further report the trapping and characterization of an unprecedented cross-linked Lys-Trp radical (Lys-Trp•) in addition to the organometallic Ω intermediate, providing compelling support for the proposed rEAS mechanism. Finally, we observe oxidation of the Lys-Trp• intermediate by the redox-tuned [4Fe-4S]2+ AuxI cluster by EPR spectroscopy. Our findings provide direct evidence for a role of a SPASM domain auxiliary cluster and consolidate rEAS as a mechanistic paradigm for rSAM enzyme-catalyzed carbon-carbon bond-forming reactions.
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27
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Brimberry M, Toma MA, Hines KM, Lanzilotta WN. HutW from Vibrio cholerae Is an Anaerobic Heme-Degrading Enzyme with Unique Functional Properties. Biochemistry 2021; 60:699-710. [PMID: 33600151 DOI: 10.1021/acs.biochem.0c00950] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Increasing antibiotic resistance, and a growing recognition of the importance of the human microbiome, demand that new therapeutic targets be identified. Characterization of metabolic pathways that are unique to enteric pathogens represents a promising approach. Iron is often the rate-limiting factor for growth, and Vibrio cholerae, the causative agent of cholera, has been shown to contain numerous genes that function in the acquisition of iron from the environment. Included in this arsenal of genes are operons dedicated to obtaining iron from heme and heme-containing proteins. Given the persistence of cholera, an important outstanding question is whether V. cholerae is capable of anaerobic heme degradation as was recently reported for enterohemorrhagic Escherichia coli O157:H7. In this work, we demonstrate that HutW from V. cholerae is a radical S-adenosylmethionine methyl transferase involved in the anaerobic opening of the porphyrin ring of heme. However, in contrast to the enzyme ChuW, found in enterohemorrhagic E. coli O157:H7, there are notable differences in the mechanism and products of the HutW reaction. Of particular interest are data that demonstrate HutW will catalyze ring opening as well as tetrapyrrole reduction and can utilize reduced nicotinamide adenine dinucleotide phosphate as an electron source. The biochemical and biophysical properties of HutW are presented, and the evolutionary implications are discussed.
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28
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Knox HL, Chen PYT, Blaszczyk AJ, Mukherjee A, Grove TL, Schwalm EL, Wang B, Drennan CL, Booker SJ. Structural basis for non-radical catalysis by TsrM, a radical SAM methylase. Nat Chem Biol 2021; 17:485-491. [PMID: 33462497 PMCID: PMC7990684 DOI: 10.1038/s41589-020-00717-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 11/09/2020] [Accepted: 11/24/2020] [Indexed: 12/19/2022]
Abstract
TsrM methylates C2 of the indole ring of L-tryptophan (Trp) during the biosynthesis of the quinaldic acid moiety of thiostrepton. It is annotated as a cobalamin-dependent radical S-adenosylmethionine (SAM) methylase; however, TsrM does not reductively cleave SAM to the universal 5ʹ-deoxyadenosyl 5ʹ-radical intermediate, a hallmark of radical-SAM (RS) enzymes. Herein, we report structures of TsrM from Kitasatospora setae, the first of a cobalamin-dependent radical SAM methylase. Unexpectedly, the structures show an essential arginine residue that resides in the proximal coordination sphere of the cobalamin cofactor and a [4Fe–4S] cluster that is ligated by a glutamyl residue and three cysteines in a canonical CxxxCxxC RS motif. Structures in the presence of substrates suggest a substrate-assisted mechanism of catalysis, wherein the carboxylate group of SAM serves as a general base to deprotonate N1 of the tryptophan substrate, facilitating formation of a C2 carbanion. The first crystal structures of a cobalamin-dependent radical SAM methylase reveal an unexpected mode of methylation.
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Affiliation(s)
- Hayley L Knox
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA
| | - Percival Yang-Ting Chen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.,Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - Anthony J Blaszczyk
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA.,Catalent Pharma Solutions, Gaithersburg, MD, USA
| | - Arnab Mukherjee
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA
| | - Tyler L Grove
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Erica L Schwalm
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA.,Merck & Co., Inc., Rahway, NJ, USA
| | - Bo Wang
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Squire J Booker
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA. .,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA. .,Howard Hughes Medical Institute, Pennsylvania State University, University Park, PA, USA.
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29
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Corless EI, Saad Imran SM, Watkins MB, Bacik JP, Mattice JR, Patterson A, Danyal K, Soffe M, Kitelinger R, Seefeldt LC, Origanti S, Bennett B, Bothner B, Ando N, Antony E. The flexible N-terminus of BchL autoinhibits activity through interaction with its [4Fe-4S] cluster and released upon ATP binding. J Biol Chem 2021; 296:100107. [PMID: 33219127 PMCID: PMC7948495 DOI: 10.1074/jbc.ra120.016278] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/10/2020] [Accepted: 11/20/2020] [Indexed: 11/10/2022] Open
Abstract
A key step in bacteriochlorophyll biosynthesis is the reduction of protochlorophyllide to chlorophyllide, catalyzed by dark-operative protochlorophyllide oxidoreductase. Dark-operative protochlorophyllide oxidoreductase contains two [4Fe-4S]-containing component proteins (BchL and BchNB) that assemble upon ATP binding to BchL to coordinate electron transfer and protochlorophyllide reduction. But the precise nature of the ATP-induced conformational changes is poorly understood. We present a crystal structure of BchL in the nucleotide-free form where a conserved, flexible region in the N-terminus masks the [4Fe-4S] cluster at the docking interface between BchL and BchNB. Amino acid substitutions in this region produce a hyperactive enzyme complex, suggesting a role for the N-terminus in autoinhibition. Hydrogen-deuterium exchange mass spectrometry shows that ATP binding to BchL produces specific conformational changes leading to release of the flexible N-terminus from the docking interface. The release also promotes changes within the local environment surrounding the [4Fe-4S] cluster and promotes BchL-complex formation with BchNB. A key patch of amino acids, Asp-Phe-Asp (the 'DFD patch'), situated at the mouth of the BchL ATP-binding pocket promotes intersubunit cross stabilization of the two subunits. A linked BchL dimer with one defective ATP-binding site does not support protochlorophyllide reduction, illustrating nucleotide binding to both subunits as a prerequisite for the intersubunit cross stabilization. The masking of the [4Fe-4S] cluster by the flexible N-terminal region and the associated inhibition of the activity is a novel mechanism of regulation in metalloproteins. Such mechanisms are possibly an adaptation to the anaerobic nature of eubacterial cells with poor tolerance for oxygen.
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Affiliation(s)
- Elliot I Corless
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA; Department of Biochemistry, Saint Louis University School of Medicine, St Louis, Missouri, USA
| | | | - Maxwell B Watkins
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - John-Paul Bacik
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - Jenna R Mattice
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Angela Patterson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Karamatullah Danyal
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| | - Mark Soffe
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| | - Robert Kitelinger
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| | - Sofia Origanti
- Department of Biology, Saint Louis University, St Louis, Missouri, USA
| | - Brian Bennett
- Department of Physics, Marquette University, Milwaukee, Wisconsin, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Nozomi Ando
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA.
| | - Edwin Antony
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA; Department of Biochemistry, Saint Louis University School of Medicine, St Louis, Missouri, USA.
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30
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Liu G, Sil D, Maio N, Tong WH, Bollinger JM, Krebs C, Rouault TA. Heme biosynthesis depends on previously unrecognized acquisition of iron-sulfur cofactors in human amino-levulinic acid dehydratase. Nat Commun 2020; 11:6310. [PMID: 33298951 PMCID: PMC7725820 DOI: 10.1038/s41467-020-20145-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/06/2020] [Indexed: 12/18/2022] Open
Abstract
Heme biosynthesis and iron-sulfur cluster (ISC) biogenesis are two major mammalian metabolic pathways that require iron. It has long been known that these two pathways interconnect, but the previously described interactions do not fully explain why heme biosynthesis depends on intact ISC biogenesis. Herein we identify a previously unrecognized connection between these two pathways through our discovery that human aminolevulinic acid dehydratase (ALAD), which catalyzes the second step of heme biosynthesis, is an Fe-S protein. We find that several highly conserved cysteines and an Ala306-Phe307-Arg308 motif of human ALAD are important for [Fe4S4] cluster acquisition and coordination. The enzymatic activity of human ALAD is greatly reduced upon loss of its Fe-S cluster, which results in reduced heme biosynthesis in human cells. As ALAD provides an early Fe-S-dependent checkpoint in the heme biosynthetic pathway, our findings help explain why heme biosynthesis depends on intact ISC biogenesis. Heme biosynthesis depends on iron-sulfur (Fe-S) cluster biogenesis but the molecular connection between these pathways is not fully understood. Here, the authors show that the heme biosynthesis enzyme ALAD contains an Fe-S cluster, disruption of which reduces ALAD activity and heme production in human cells.
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Affiliation(s)
- Gang Liu
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Debangsu Sil
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nunziata Maio
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Wing-Hang Tong
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - J Martin Bollinger
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Carsten Krebs
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Tracey Ann Rouault
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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31
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Chen Y, Yang Y, Ji X, Zhao R, Li G, Gu Y, Shi A, Jiang W, Zhang Q. The SCIFF-Derived Ranthipeptides Participate in Quorum Sensing in Solventogenic Clostridia. Biotechnol J 2020; 15:e2000136. [PMID: 32713052 DOI: 10.1002/biot.202000136] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/25/2020] [Indexed: 12/29/2022]
Abstract
Ranthipeptides, defined as radical non-α thioether-containing peptides, are a newly emerging class of natural products belonging to the ribosomally synthesized and post-translationally modified peptide (RiPP) superfamily. Ranthipeptides are shown to be widespread in the bacterial kingdom, whereas heretofore their biological functions remain completely elusive. In this work, putative ranthipeptides are investigated from two solventogenic clostridia, Clostridium beijerinckii and Clostridium ljungdahlii, which are derived from the so-called six Cys in forty-five residues (SCIFF) family of precursor peptides. A series of analysis show that these two ranthipeptides participate in quorum sensing and controlling cellular metabolism. These results highlight the diverse biological functions of the ever-increasing family of RiPP natural products and showcase the potential to engineer industrially interesting organisms by manipulating their RiPP biosynthetic pathways.
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Affiliation(s)
- Yunliang Chen
- School of Agricultural Equipment Engineering, Jiangsu University, Zhenjiang, 212013, China.,Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Yunpeng Yang
- Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai Institute of Plant Physiology and Ecology, Shanghai, 200032, China.,Institute of Neuroscience, Chinese Academy of Sciences (CAS) Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, CAS, Shanghai Institutes for Biological Sciences, Shanghai, 200031, China
| | - Xinjian Ji
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Ran Zhao
- Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai Institute of Plant Physiology and Ecology, Shanghai, 200032, China
| | - Guoquan Li
- School of Agricultural Equipment Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Yang Gu
- Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai Institute of Plant Physiology and Ecology, Shanghai, 200032, China
| | - Aiping Shi
- School of Agricultural Equipment Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Weihong Jiang
- Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai Institute of Plant Physiology and Ecology, Shanghai, 200032, China
| | - Qi Zhang
- Department of Chemistry, Fudan University, Shanghai, 200433, China
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32
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Carl AG, Harris LD, Feng M, Nordstrøm LU, Gerfen GJ, Evans GB, Silakov A, Almo SC, Grove TL. Narrow-Spectrum Antibiotic Targeting of the Radical SAM Enzyme MqnE in Menaquinone Biosynthesis. Biochemistry 2020; 59:2562-2575. [DOI: 10.1021/acs.biochem.0c00070] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Ayala G. Carl
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Lawrence D. Harris
- The Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand
- The Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 5040, New Zealand
| | - Mu Feng
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Lars U. Nordstrøm
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Gary J. Gerfen
- Department of Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Gary B. Evans
- The Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand
- The Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland 5040, New Zealand
| | - Alexey Silakov
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Steven C. Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Tyler L. Grove
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
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33
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Funabashi M, Grove TL, Wang M, Varma Y, McFadden ME, Brown LC, Guo C, Higginbottom S, Almo SC, Fischbach MA. A metabolic pathway for bile acid dehydroxylation by the gut microbiome. Nature 2020; 582:566-570. [PMID: 32555455 PMCID: PMC7319900 DOI: 10.1038/s41586-020-2396-4] [Citation(s) in RCA: 270] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 03/18/2020] [Indexed: 12/12/2022]
Abstract
The gut microbiota synthesize hundreds of molecules, many of which influence host physiology. Among the most abundant metabolites are the secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA), which accumulate at concentrations of around 500 μM and are known to block the growth of Clostridium difficile1, promote hepatocellular carcinoma2 and modulate host metabolism via the G-protein-coupled receptor TGR5 (ref. 3). More broadly, DCA, LCA and their derivatives are major components of the recirculating pool of bile acids4; the size and composition of this pool are a target of therapies for primary biliary cholangitis and nonalcoholic steatohepatitis. Nonetheless, despite the clear impact of DCA and LCA on host physiology, an incomplete knowledge of their biosynthetic genes and a lack of genetic tools to enable modification of their native microbial producers limit our ability to modulate secondary bile acid levels in the host. Here we complete the pathway to DCA and LCA by assigning and characterizing enzymes for each of the steps in its reductive arm, revealing a strategy in which the A-B rings of the steroid core are transiently converted into an electron acceptor for two reductive steps carried out by Fe-S flavoenzymes. Using anaerobic in vitro reconstitution, we establish that a set of six enzymes is necessary and sufficient for the eight-step conversion of cholic acid to DCA. We then engineer the pathway into Clostridium sporogenes, conferring production of DCA and LCA on a nonproducing commensal and demonstrating that a microbiome-derived pathway can be expressed and controlled heterologously. These data establish a complete pathway to two central components of the bile acid pool.
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Affiliation(s)
- Masanori Funabashi
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA, USA
- Translational Research Department, Daiichi Sankyo RD Novare Co. Ltd, Tokyo, Japan
| | - Tyler L Grove
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Min Wang
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA, USA
| | - Yug Varma
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA, USA
| | - Molly E McFadden
- Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - Laura C Brown
- Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - Chunjun Guo
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA, USA
| | - Steven Higginbottom
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Michael A Fischbach
- Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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34
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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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35
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Solomon JB, Lee CC, Jasniewski AJ, Rasekh MF, Ribbe MW, Hu Y. Heterologous Expression and Engineering of the Nitrogenase Cofactor Biosynthesis Scaffold NifEN. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201916598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Joseph B. Solomon
- Department of Molecular Biology & Biochemistry University of California, Irvine Irvine CA 92697-3900 USA
- Department Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Chi Chung Lee
- Department of Molecular Biology & Biochemistry University of California, Irvine Irvine CA 92697-3900 USA
| | - Andrew J. Jasniewski
- Department of Molecular Biology & Biochemistry University of California, Irvine Irvine CA 92697-3900 USA
| | - Mahtab F. Rasekh
- Department of Molecular Biology & Biochemistry University of California, Irvine Irvine CA 92697-3900 USA
- Department Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Markus W. Ribbe
- Department of Molecular Biology & Biochemistry University of California, Irvine Irvine CA 92697-3900 USA
- Department Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Yilin Hu
- Department of Molecular Biology & Biochemistry University of California, Irvine Irvine CA 92697-3900 USA
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36
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Solomon JB, Lee CC, Jasniewski AJ, Rasekh MF, Ribbe MW, Hu Y. Heterologous Expression and Engineering of the Nitrogenase Cofactor Biosynthesis Scaffold NifEN. Angew Chem Int Ed Engl 2020; 59:6887-6893. [PMID: 32022452 DOI: 10.1002/anie.201916598] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Indexed: 01/01/2023]
Abstract
NifEN plays a crucial role in the biosynthesis of nitrogenase, catalyzing the final step of cofactor maturation prior to delivering the cofactor to NifDK, the catalytic component of nitrogenase. The difficulty in expressing NifEN, a complex, heteromultimeric metalloprotein sharing structural/functional homology with NifDK, is a major challenge in the heterologous expression of nitrogenase. Herein, we report the expression and engineering of Azotobacter vinelandii NifEN in Escherichia coli. Biochemical and spectroscopic analyses demonstrate the integrity of the heterologously expressed NifEN in composition and functionality and, additionally, the ability of an engineered NifEN variant to mimic NifDK in retaining the matured cofactor at an analogous cofactor-binding site. This is an important step toward piecing together a viable pathway for the heterologous expression of nitrogenase and identifying variants for the mechanistic investigation of this enzyme.
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Affiliation(s)
- Joseph B Solomon
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA.,Department Chemistry, University of California, Irvine, Irvine, CA, 92697-2025, USA
| | - Chi Chung Lee
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
| | - Andrew J Jasniewski
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
| | - Mahtab F Rasekh
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA.,Department Chemistry, University of California, Irvine, Irvine, CA, 92697-2025, USA
| | - Markus W Ribbe
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA.,Department Chemistry, University of California, Irvine, Irvine, CA, 92697-2025, USA
| | - Yilin Hu
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
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37
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Zhang B, Arcinas AJ, Radle MI, Silakov A, Booker SJ, Krebs C. First Step in Catalysis of the Radical S-Adenosylmethionine Methylthiotransferase MiaB Yields an Intermediate with a [3Fe-4S] 0-Like Auxiliary Cluster. J Am Chem Soc 2020; 142:1911-1924. [PMID: 31899624 PMCID: PMC7008301 DOI: 10.1021/jacs.9b11093] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The enzyme MiaB catalyzes the attachment of a methylthio (-SCH3) group at the C2 position of N6-(isopentenyl)adenosine (i6A) in the final step of the biosynthesis of the hypermodified tRNA nucleotide 2-methythio-N6-(isopentenyl)adenosine (ms2i6A). MiaB belongs to the expanding subgroup of enzymes of the radical S-adenosylmethionine (SAM) superfamily that harbor one or more auxiliary [4Fe-4S] clusters in addition to the [4Fe-4S] cluster that all family members require for the reductive cleavage of SAM to afford the common 5'-deoxyadenosyl 5'-radical (5'-dA•) intermediate. While the role of the radical SAM cluster in generating the 5'-dA• is well understood, the detailed role of the auxiliary cluster, which is essential for MiaB catalysis, remains unclear. It has been proposed that the auxiliary cluster may serve as a coordination site for exogenously derived sulfur destined for attachment to the substrate or that the cluster itself provides the sulfur atom and is sacrificed during turnover. In this work, we report spectroscopic and biochemical evidence that the auxiliary [4Fe-4S]2+ cluster in Bacteroides thetaiotaomicron (Bt) MiaB is converted to a [3Fe-4S]0-like cluster during the methylation step of catalysis. Mössbauer characterization of the MiaB [3Fe-4S]0-like cluster revealed unusual spectroscopic properties compared to those of other well-characterized cuboidal [3Fe-4S]0 clusters. Specifically, the Fe sites of the mixed-valent moiety do not have identical Mössbauer parameters. Our results support a mechanism where the auxiliary [4Fe-4S] cluster is the direct sulfur source during catalysis.
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38
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Arcinas AJ, Maiocco SJ, Elliott SJ, Silakov A, Booker SJ. Ferredoxins as interchangeable redox components in support of MiaB, a radical S-adenosylmethionine methylthiotransferase. Protein Sci 2020; 28:267-282. [PMID: 30394621 DOI: 10.1002/pro.3548] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 11/10/2022]
Abstract
MiaB is a member of the methylthiotransferase subclass of the radical S-adenosylmethionine (SAM) superfamily of enzymes, catalyzing the methylthiolation of C2 of adenosines bearing an N6 -isopentenyl (i6 A) group found at position 37 in several tRNAs to afford 2-methylthio-N6 -(isopentenyl)adenosine (ms2 i6 A). MiaB uses a reduced [4Fe-4S]+ cluster to catalyze a reductive cleavage of SAM to generate a 5'-deoxyadenosyl 5'-radical (5'-dA•)-a required intermediate in its reaction-as well as an additional [4Fe-4S]2+ auxiliary cluster. In Escherichia coli and many other organisms, re-reduction of the [4Fe-4S]2+ cluster to the [4Fe-4S]+ state is accomplished by the flavodoxin reducing system. Most mechanistic studies of MiaBs have been carried out on the enzyme from Thermotoga maritima (Tm), which lacks the flavodoxin reducing system, and which is not activated by E. coli flavodoxin. However, the genome of this organism encodes five ferredoxins (TM0927, TM1175, TM1289, TM1533, and TM1815), each of which might donate the requisite electron to MiaB and perhaps to other radical SAM enzymes. The genes encoding each of these ferredoxins were cloned, and the associated proteins were isolated and shown to support turnover by Tm MiaB. In addition, TM1639, the ferredoxin-NADP+ oxidoreductase subunit α (NfnA) from Tm was overproduced and isolated and shown to provide electrons to the Tm ferredoxins during Tm MiaB turnover. The resulting reactions demonstrate improved coupling between formation of the 5'-dA• and ms2 i6 A production, indicating that only one hydrogen atom abstraction is required for the reaction.
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Affiliation(s)
- Arthur J Arcinas
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | | | - Sean J Elliott
- Department of Chemistry, Boston University, Boston, Massachusetts, 02215
| | - Alexey Silakov
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, 1680
| | - Squire J Booker
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802.,Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, 1680.,Howard Hughes Medical Institute, The Pennsylvania State University, University Park, Pennsylvania, 16802
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39
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cfr(B), cfr(C), and a New cfr-Like Gene, cfr(E), in Clostridium difficile Strains Recovered across Latin America. Antimicrob Agents Chemother 2019; 64:AAC.01074-19. [PMID: 31685464 DOI: 10.1128/aac.01074-19] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/08/2019] [Indexed: 12/18/2022] Open
Abstract
Cfr is a radical S-adenosyl-l-methionine (SAM) enzyme that confers cross-resistance to antibiotics targeting the 23S rRNA through hypermethylation of nucleotide A2503. Three cfr-like genes implicated in antibiotic resistance have been described, two of which, cfr(B) and cfr(C), have been sporadically detected in Clostridium difficile However, the methylase activity of Cfr(C) has not been confirmed. We found cfr(B), cfr(C), and a cfr-like gene that shows only 51 to 58% protein sequence identity to Cfr and Cfr-like enzymes in clinical C. difficile isolates recovered across nearly a decade in Mexico, Honduras, Costa Rica, and Chile. This new resistance gene was termed cfr(E). In agreement with the anticipated function of the cfr-like genes detected, all isolates exhibited high MIC values for several ribosome-targeting antibiotics. In addition, in vitro assays confirmed that Cfr(C) and Cfr(E) methylate Escherichia coli and, to a lesser extent, C. difficile 23S rRNA fragments at the expected positions. The analyzed isolates do not have mutations in 23S rRNA genes or genes encoding the ribosomal proteins L3 and L4 and lack poxtA, optrA, and pleuromutilin resistance genes. Moreover, these cfr-like genes were found in Tn6218-like transposons or integrative and conjugative elements (ICE) that could facilitate their transfer. These results indicate selection of potentially mobile cfr-like genes in C. difficile from Latin America and provide the first assessment of the methylation activity of Cfr(C) and Cfr(E), which belong to a cluster of Cfr-like proteins that does not include the functionally characterized enzymes Cfr, Cfr(B), and Cfr(D).
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40
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Mo T, Ji X, Yuan W, Mandalapu D, Wang F, Zhong Y, Li F, Chen Q, Ding W, Deng Z, Yu S, Zhang Q. Thuricin Z: A Narrow‐Spectrum Sactibiotic that Targets the Cell Membrane. Angew Chem Int Ed Engl 2019; 58:18793-18797. [DOI: 10.1002/anie.201908490] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/19/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Tianlu Mo
- Department of ChemistryFudan University Shanghai 200433 China
| | - Xinjian Ji
- Department of ChemistryFudan University Shanghai 200433 China
| | - Wei Yuan
- Department of ChemistryFudan University Shanghai 200433 China
| | - Dhanaraju Mandalapu
- Department of ChemistryFudan University Shanghai 200433 China
- Institute of Mass SpectrometrySchool of Material Science and Chemical EngineeringNingbo University Ningbo Zhejiang 315211 China
| | - Fangting Wang
- Department of ChemistryFudan University Shanghai 200433 China
| | - Yuting Zhong
- Department of ChemistryFudan University Shanghai 200433 China
| | - Fuyou Li
- Department of ChemistryFudan University Shanghai 200433 China
| | - Qin Chen
- Department of ChemistryFudan University Shanghai 200433 China
| | - Wei Ding
- State Key Laboratory of Microbial MetabolismSchool of Life Sciences & BiotechnologyShanghai Jiao Tong University Shanghai 200240 China
| | - Zixin Deng
- State Key Laboratory of Microbial MetabolismSchool of Life Sciences & BiotechnologyShanghai Jiao Tong University Shanghai 200240 China
| | - Shaoning Yu
- Institute of Mass SpectrometrySchool of Material Science and Chemical EngineeringNingbo University Ningbo Zhejiang 315211 China
| | - Qi Zhang
- Department of ChemistryFudan University Shanghai 200433 China
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41
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Mo T, Ji X, Yuan W, Mandalapu D, Wang F, Zhong Y, Li F, Chen Q, Ding W, Deng Z, Yu S, Zhang Q. Thuricin Z: A Narrow‐Spectrum Sactibiotic that Targets the Cell Membrane. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Tianlu Mo
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Xinjian Ji
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Wei Yuan
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Dhanaraju Mandalapu
- Department of Chemistry Fudan University Shanghai 200433 China
- Institute of Mass Spectrometry School of Material Science and Chemical Engineering Ningbo University Ningbo Zhejiang 315211 China
| | - Fangting Wang
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Yuting Zhong
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Fuyou Li
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Qin Chen
- Department of Chemistry Fudan University Shanghai 200433 China
| | - Wei Ding
- State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University Shanghai 200240 China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University Shanghai 200240 China
| | - Shaoning Yu
- Institute of Mass Spectrometry School of Material Science and Chemical Engineering Ningbo University Ningbo Zhejiang 315211 China
| | - Qi Zhang
- Department of Chemistry Fudan University Shanghai 200433 China
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42
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Wang SC. Cobalamin-dependent radical S-adenosyl-l-methionine enzymes in natural product biosynthesis. Nat Prod Rep 2019; 35:707-720. [PMID: 30079906 DOI: 10.1039/c7np00059f] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Covering: 2011 to 2018 This highlight summarizes the investigation of cobalamin (Cbl)- and radical S-adenosyl-l-methionine (SAM)-dependent enzymes found in natural product biosynthesis to date and suggests some possibilities for the future. Though some mechanistic aspects are apparently shared, the overall diversity of this family's functions and abilities is significant and may be tailored to the specific substrate and/or reaction being catalyzed. A little over a year ago, the first crystal structure of a Cbl- and radical SAM-dependent enzyme was solved, providing the first insight into what may be the shared scaffolding of these enzymes.
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Affiliation(s)
- Susan C Wang
- Case Western Reserve University School of Medicine, Department of Biochemistry, USA.
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43
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Gumkowski JD, Martinie RJ, Corrigan PS, Pan J, Bauerle MR, Almarei M, Booker SJ, Silakov A, Krebs C, Boal AK. Analysis of RNA Methylation by Phylogenetically Diverse Cfr Radical S-Adenosylmethionine Enzymes Reveals an Iron-Binding Accessory Domain in a Clostridial Enzyme. Biochemistry 2019; 58:3169-3184. [PMID: 31246421 DOI: 10.1021/acs.biochem.9b00197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cfr is a radical S-adenosylmethionine (SAM) RNA methylase linked to multidrug antibiotic resistance in bacterial pathogens. It catalyzes a chemically challenging C-C bond-forming reaction to methylate C8 of A2503 (Escherichia coli numbering) of 23S rRNA during ribosome assembly. The cfr gene has been identified as a mobile genetic element in diverse bacteria and in the genome of select Bacillales and Clostridiales species. Despite the importance of Cfr, few representatives have been purified and characterized in vitro. Here we show that Cfr homologues from Bacillus amyloliquefaciens, Enterococcus faecalis, Paenibacillus lautus, and Clostridioides difficile act as C8 adenine RNA methylases in biochemical assays. C. difficile Cfr contains an additional Cys-rich C-terminal domain that binds a mononuclear Fe2+ ion in a rubredoxin-type Cys4 motif. The C-terminal domain can be truncated with minimal impact on C. difficile Cfr activity, but the rate of turnover is decreased upon disruption of the Fe2+-binding site by Zn2+ substitution or ligand mutation. These findings indicate an important purpose for the observed C-terminal iron in the native fusion protein. Bioinformatic analysis of the C. difficile Cfr Cys-rich domain shows that it is widespread (∼1400 homologues) as a stand-alone gene in pathogenic or commensal Bacilli and Clostridia, with >10% encoded adjacent to a predicted radical SAM RNA methylase. Although the domain is not essential for in vitro C. difficile Cfr activity, the genomic co-occurrence and high abundance in the human microbiome suggest a possible functional role for a specialized rubredoxin in certain radical SAM RNA methylases that are relevant to human health.
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Affiliation(s)
- James D Gumkowski
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Ryan J Martinie
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Patrick S Corrigan
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Juan Pan
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Matthew R Bauerle
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Mohamed Almarei
- Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Squire J Booker
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Howard Hughes Medical Institute , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Alexey Silakov
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Carsten Krebs
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Amie K Boal
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States.,Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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44
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Clark KA, Bushin LB, Seyedsayamdost MR. Aliphatic Ether Bond Formation Expands the Scope of Radical SAM Enzymes in Natural Product Biosynthesis. J Am Chem Soc 2019; 141:10610-10615. [PMID: 31246011 DOI: 10.1021/jacs.9b05151] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The biosynthetic pathways of microbial natural products provide a rich source of novel enzyme-catalyzed transformations. Using a new bioinformatic search strategy, we recently identified an abundance of gene clusters for ribosomally synthesized and post-translationally modified peptides (RiPPs) that contain at least one radical S-adenosylmethionine (RaS) metalloenzyme and are regulated by quorum sensing. In the present study, we characterize a RaS enzyme from one such RiPP gene cluster and find that it installs an aliphatic ether cross-link at an unactivated carbon center, linking the oxygen of a Thr side chain to the α-carbon of a Gln residue. This reaction marks the first ether cross-link installed by a RaS enzyme. Additionally, it leads to a new heterocyclization motif and underlines the utility of our bioinformatics approach in finding new families of RiPP modifications.
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Affiliation(s)
- Kenzie A Clark
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Leah B Bushin
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Mohammad R Seyedsayamdost
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States.,Department of Molecular Biology , Princeton University , Princeton , New Jersey 08544 , United States
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45
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Radle MI, Miller DV, Laremore TN, Booker SJ. Methanogenesis marker protein 10 (Mmp10) from Methanosarcina acetivorans is a radical S-adenosylmethionine methylase that unexpectedly requires cobalamin. J Biol Chem 2019; 294:11712-11725. [PMID: 31113866 DOI: 10.1074/jbc.ra119.007609] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/10/2019] [Indexed: 11/06/2022] Open
Abstract
Methyl coenzyme M reductase (MCR) catalyzes the last step in the biological production of methane by methanogenic archaea, as well as the first step in the anaerobic oxidation of methane to methanol by methanotrophic archaea. MCR contains a number of unique post-translational modifications in its α subunit, including thioglycine, 1-N-methylhistidine, S-methylcysteine, 5-C-(S)-methylarginine, and 2-C-(S)-methylglutamine. Recently, genes responsible for the thioglycine and methylarginine modifications have been identified in bioinformatics studies and in vivo complementation of select mutants; however, none of these reactions has been verified in vitro Herein, we purified and biochemically characterized the radical S-adenosylmethionine (SAM) protein MaMmp10, the product of the methanogenesis marker protein 10 gene in the methane-producing archaea Methanosarcina acetivorans Using an array of approaches, including kinetic assays, LC-MS-based quantification, and MALDI TOF-TOF MS analyses, we found that MaMmp10 catalyzes the methylation of the equivalent of Arg285 in a peptide substrate surrogate, but only in the presence of cobalamin. We noted that the methyl group derives from SAM, with cobalamin acting as an intermediate carrier, and that MaMmp10 contains a C-terminal cobalamin-binding domain. Given that Mmp10 has not been annotated as a cobalamin-binding protein, these findings suggest that cobalamin-dependent radical SAM proteins are more prevalent than previously thought.
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Affiliation(s)
- Matthew I Radle
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Danielle V Miller
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Tatiana N Laremore
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Squire J Booker
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802 .,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802.,Howard Hughes Medical Institute, Pennsylvania State University, University Park, Pennsylvania 16802
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46
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McCarthy EL, Rankin AN, Dill ZR, Booker SJ. The A-type domain in Escherichia coli NfuA is required for regenerating the auxiliary [4Fe-4S] cluster in Escherichia coli lipoyl synthase. J Biol Chem 2018; 294:1609-1617. [PMID: 30538130 DOI: 10.1074/jbc.ra118.006171] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 12/10/2018] [Indexed: 11/06/2022] Open
Abstract
The lipoyl cofactor plays an integral role in several essential biological processes. The last step in its de novo biosynthetic pathway, the attachment of two sulfur atoms at C6 and C8 of an n-octanoyllysyl chain, is catalyzed by lipoyl synthase (LipA), a member of the radical SAM superfamily. In addition to the [4Fe-4S] cluster common to all radical SAM enzymes, LipA contains a second [4Fe-4S] auxiliary cluster, which is sacrificed during catalysis to supply the requisite sulfur atoms, rendering the protein inactive for further turnovers. Recently, it was shown that the Fe-S cluster carrier protein NfuA from Escherichia coli can regenerate the auxiliary cluster of E. coli LipA after each turnover, but the molecular mechanism is incompletely understood. Herein, using protein-protein interaction and kinetic assays as well as site-directed mutagenesis, we provide further insight into the mechanism of NfuA-mediated cluster regeneration. In particular, we show that the N-terminal A-type domain of E. coli NfuA is essential for its tight interaction with LipA. Further, we demonstrate that NfuA from Mycobacterium tuberculosis can also regenerate the auxiliary cluster of E. coli LipA. However, an Nfu protein from Staphylococcus aureus, which lacks the A-type domain, was severely diminished in facilitating cluster regeneration. Of note, addition of the N-terminal domain of E. coli NfuA to S. aureus Nfu, fully restored cluster-regenerating activity. These results expand our understanding of the newly discovered mechanism by which the auxiliary cluster of LipA is restored after each turnover.
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Affiliation(s)
- Erin L McCarthy
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ananda N Rankin
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Zerick R Dill
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Squire J Booker
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802; Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802; Howard Hughes Medical Institute, The Pennsylvania State University, University Park, Pennsylvania 16802.
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47
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Caruso A, Bushin LB, Clark KA, Martinie RJ, Seyedsayamdost MR. Radical Approach to Enzymatic β-Thioether Bond Formation. J Am Chem Soc 2018; 141:990-997. [DOI: 10.1021/jacs.8b11060] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Alessio Caruso
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Leah B. Bushin
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Kenzie A. Clark
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Ryan J. Martinie
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Mohammad R. Seyedsayamdost
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
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48
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Bushin LB, Clark KA, Pelczer I, Seyedsayamdost MR. Charting an Unexplored Streptococcal Biosynthetic Landscape Reveals a Unique Peptide Cyclization Motif. J Am Chem Soc 2018; 140:17674-17684. [PMID: 30398325 DOI: 10.1021/jacs.8b10266] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Peptide natural products are often used as signals or antibiotics and contain unusual structural modifications, thus providing opportunities for expanding our understanding of Nature's therapeutic and biosynthetic repertoires. Herein, we have investigated the under-explored biosynthetic potential of Streptococci, prevalent bacteria in mammalian microbiomes that include mutualistic, commensal, and pathogenic members. Using a new bioinformatic search strategy, in which we linked the versatile radical S-adenosylmethionine (RaS) enzyme superfamily to an emerging class of natural products in the context of quorum sensing control, we identified numerous, uncharted biosynthetic loci. Focusing on one such locus, we identified an unprecedented post-translational modification, consisting of a tetrahydro[5,6]benzindole cyclization motif in which four unactivated positions are linked by two C-C bonds in a regio- and stereospecific manner by a single RaS enzyme. Our results expand the scope of reactions that microbes have at their disposal in concocting complex ribosomal peptides.
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Affiliation(s)
- Leah B Bushin
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Kenzie A Clark
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - István Pelczer
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Mohammad R Seyedsayamdost
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States.,Department of Molecular Biology , Princeton University , Princeton , New Jersey 08544 , United States
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49
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Gagnon DM, Stich TA, Mehta AP, Abdelwahed SH, Begley TP, Britt RD. An Aminoimidazole Radical Intermediate in the Anaerobic Biosynthesis of the 5,6-Dimethylbenzimidazole Ligand to Vitamin B12. J Am Chem Soc 2018; 140:12798-12807. [PMID: 30208703 DOI: 10.1021/jacs.8b05686] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organisms that perform the de novo biosynthesis of cobalamin (vitamin B12) do so via unique pathways depending on the presence of oxygen in the environment. The anaerobic biosynthesis pathway of 5,6-dimethylbenzimidazole, the so-called "lower ligand" to the cobalt center, has been recently identified. This process begins with the conversion of 5-aminoimidazole ribotide (AIR) to 5-hydroxybenzimidazole (HBI) by the radical S-adenosyl-l-methionine (SAM) enzyme BzaF, also known as HBI synthase. In this work we report the characterization of a radical intermediate in the reaction of BzaF using electron paramagnetic resonance spectroscopy. Using various isotopologues of AIR, we extracted hyperfine parameters for a number of nuclei, allowing us to propose plausible chemical compositions and structures for this intermediate. Specifically, we find that an aminoimidazole radical is formed in close proximity to a fragment of the ribose ring. These findings induce the revision of past proposed mechanisms and illustrate the ability of radical SAM enzymes to tightly control the radical chemistry that they engender.
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Affiliation(s)
- Derek M Gagnon
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - Troy A Stich
- Department of Chemistry , University of California , Davis , California 95616 , United States
| | - Angad P Mehta
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - Sameh H Abdelwahed
- 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
| | - R David Britt
- Department of Chemistry , University of California , Davis , California 95616 , United States
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50
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Bauerle MR, Grove TL, Booker SJ. Investigation of Solvent Hydron Exchange in the Reaction Catalyzed by the Antibiotic Resistance Protein Cfr. Biochemistry 2018; 57:4431-4439. [PMID: 29787246 DOI: 10.1021/acs.biochem.8b00347] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cfr is a radical S-adenosylmethionine (RS) methylase that appends methyl groups to C8 and C2 of adenosine 2503 in 23S rRNA. Methylation of C8 confers resistance to several classes of antibiotics that bind in or near the peptidyltransferase center of the bacterial ribosome, including the synthetic antibiotic linezolid. The Cfr reaction requires the action of five conserved cysteines, three of which ligate a required [4Fe-4S] cluster cofactor. The two remaining cysteines play a more intricate role in the reaction; one (Cys338) becomes transiently methylated during catalysis. The function of the second (Cys105) has not been rigorously established; however, in the related RlmN reaction, it (Cys118) initiates resolution of a key protein-nucleic acid cross-linked intermediate by abstracting the proton from the carbon center (C2) undergoing methylation. We previously proposed that, unlike RlmN, Cfr would utilize a polyprotic base during resolution of the protein-nucleic acid cross-linked intermediate during C8 methylation and, like RlmN, use a monoprotic base during C2 methylation. We based this proposal on the fact that solvent hydrons could exchange into the product during C8 methylation, but not during C2 methylation. Herein, we show that Cys105 of Cfr has a function similar to that of Cys118 of RlmN while methylating C8 of A2503 and provide evidence for one molecule of water that is in close contact with it, which provides the exchangeable protons during catalysis.
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