1
|
Qu D, Ge P, Botella L, Park SW, Lee HN, Thornton N, Bean JM, Krieger IV, Sacchettini JC, Ehrt S, Aldrich CC, Schnappinger D. Mycobacterial biotin synthases require an auxiliary protein to convert dethiobiotin into biotin. Nat Commun 2024; 15:4161. [PMID: 38755122 PMCID: PMC11099021 DOI: 10.1038/s41467-024-48448-1] [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: 11/27/2023] [Accepted: 04/24/2024] [Indexed: 05/18/2024] Open
Abstract
Lipid biosynthesis in the pathogen Mycobacterium tuberculosis depends on biotin for posttranslational modification of key enzymes. However, the mycobacterial biotin synthetic pathway is not fully understood. Here, we show that rv1590, a gene of previously unknown function, is required by M. tuberculosis to synthesize biotin. Chemical-generic interaction experiments mapped the function of rv1590 to the conversion of dethiobiotin to biotin, which is catalyzed by biotin synthases (BioB). Biochemical studies confirmed that in contrast to BioB of Escherichia coli, BioB of M. tuberculosis requires Rv1590 (which we named "biotin synthase auxiliary protein" or BsaP), for activity. We found homologs of bsaP associated with bioB in many actinobacterial genomes, and confirmed that BioB of Mycobacterium smegmatis also requires BsaP. Structural comparisons of BsaP-associated biotin synthases with BsaP-independent biotin synthases suggest that the need for BsaP is determined by the [2Fe-2S] cluster that inserts sulfur into dethiobiotin. Our findings open new opportunities to seek BioB inhibitors to treat infections with M. tuberculosis and other pathogens.
Collapse
Affiliation(s)
- Di Qu
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Peng Ge
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Laure Botella
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Sae Woong Park
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Ha-Na Lee
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Natalie Thornton
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - James M Bean
- Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Inna V Krieger
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - James C Sacchettini
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA.
| | - Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA.
| |
Collapse
|
2
|
Unusual structures and unknown roles of FeS clusters in metalloenzymes seen from a resonance Raman spectroscopic perspective. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214287] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
3
|
Sirithanakorn C, Cronan JE. Biotin, a universal and essential cofactor: Synthesis, ligation and regulation. FEMS Microbiol Rev 2021; 45:6081095. [PMID: 33428728 DOI: 10.1093/femsre/fuab003] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/08/2021] [Indexed: 12/22/2022] Open
Abstract
Biotin is a covalently attached enzyme cofactor required for intermediary metabolism in all three domains of life. Several important human pathogens (e.g. Mycobacterium tuberculosis) require biotin synthesis for pathogenesis. Humans lack a biotin synthetic pathway hence bacterial biotin synthesis is a prime target for new therapeutic agents. The biotin synthetic pathway is readily divided into early and late segments. Although pimelate, a seven carbon α,ω-dicarboxylic acid that contributes seven of the ten biotin carbons atoms, was long known to be a biotin precursor, its biosynthetic pathway was a mystery until the E. coli pathway was discovered in 2010. Since then, diverse bacteria encode evolutionarily distinct enzymes that replace enzymes in the E. coli pathway. Two new bacterial pimelate synthesis pathways have been elucidated. In contrast to the early pathway the late pathway, assembly of the fused rings of the cofactor, was long thought settled. However, a new enzyme that bypasses a canonical enzyme was recently discovered as well as homologs of another canonical enzyme that functions in synthesis of another protein-bound coenzyme, lipoic acid. Most bacteria tightly regulate transcription of the biotin synthetic genes in a biotin-responsive manner. The bifunctional biotin ligases which catalyze attachment of biotin to its cognate enzymes and repress biotin gene transcription are best understood regulatory system.
Collapse
Affiliation(s)
- Chaiyos Sirithanakorn
- Faculty of Medicine, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand.,Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
| | - John E Cronan
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.,Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
| |
Collapse
|
4
|
Kertess L, Wittkamp F, Sommer C, Esselborn J, Rüdiger O, Reijerse EJ, Hofmann E, Lubitz W, Winkler M, Happe T, Apfel UP. Chalcogenide substitution in the [2Fe] cluster of [FeFe]-hydrogenases conserves high enzymatic activity. Dalton Trans 2018; 46:16947-16958. [PMID: 29177350 DOI: 10.1039/c7dt03785f] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[FeFe]-Hydrogenases efficiently catalyze the uptake and evolution of H2 due to the presence of an inorganic [6Fe-6S]-cofactor (H-cluster). This cofactor is comprised of a [4Fe-4S] cluster coupled to a unique [2Fe] cluster where the catalytic turnover of H2/H+ takes place. We herein report on the synthesis of a selenium substituted [2Fe] cluster [Fe2{μ(SeCH2)2NH}(CO)4(CN)2]2- (ADSe) and its successful in vitro integration into the native protein scaffold of [FeFe]-hydrogenases HydA1 from Chlamydomonas reinhardtii and CpI from Clostridium pasteurianum yielding fully active enzymes (HydA1-ADSe and CpI-ADSe). FT-IR spectroscopy and X-ray structure analysis confirmed the presence of structurally intact ADSe at the active site. Electrochemical assays reveal that the selenium containing enzymes are more biased towards hydrogen production than their native counterparts. In contrast to previous chalcogenide exchange studies, the S to Se exchange herein is not based on a simple reconstitution approach using ionic cluster constituents but on the in vitro maturation with a pre-synthesized selenium-containing [2Fe] mimic. The combination of biological and chemical methods allowed for the creation of a novel [FeFe]-hydrogenase with a [2Fe2Se]-active site which confers individual catalytic features.
Collapse
Affiliation(s)
- L Kertess
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - F Wittkamp
- Ruhr-Universität Bochum, Anorganische Chemie I/Bioanorganische Chemie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - C Sommer
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - J Esselborn
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - O Rüdiger
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - E J Reijerse
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - E Hofmann
- Ruhr-Universität Bochum, Lehrstuhl für Biophysik, AG Röntgenstrukturanalyse an Proteinen, Universitätsstraße 150, 44801 Bochum, Germany
| | - W Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - M Winkler
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - T Happe
- Ruhr-Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstraße 150, 44801 Bochum, Germany.
| | - U-P Apfel
- Ruhr-Universität Bochum, Anorganische Chemie I/Bioanorganische Chemie, Universitätsstraße 150, 44801 Bochum, Germany.
| |
Collapse
|
5
|
Reed KB, Alper HS. Expanding beyond canonical metabolism: Interfacing alternative elements, synthetic biology, and metabolic engineering. Synth Syst Biotechnol 2018; 3:20-33. [PMID: 29911196 PMCID: PMC5884228 DOI: 10.1016/j.synbio.2017.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/08/2017] [Accepted: 12/09/2017] [Indexed: 12/15/2022] Open
Abstract
Metabolic engineering offers an exquisite capacity to produce new molecules in a renewable manner. However, most industrial applications have focused on only a small subset of elements from the periodic table, centered around carbon biochemistry. This review aims to illustrate the expanse of chemical elements that can currently (and potentially) be integrated into useful products using cellular systems. Specifically, we describe recent advances in expanding the cellular scope to include the halogens, selenium and the metalloids, and a variety of metal incorporations. These examples range from small molecules, heteroatom-linked uncommon elements, and natural products to biomining and nanotechnology applications. Collectively, this review covers the promise of an expanded range of elemental incorporations and the future impacts it may have on biotechnology.
Collapse
Affiliation(s)
- Kevin B. Reed
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200E Dean Keeton St. Stop C0400, Austin, TX 78712, USA
| | - Hal S. Alper
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200E Dean Keeton St. Stop C0400, Austin, TX 78712, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, 2500 Speedway Avenue, Austin, TX 78712, USA
| |
Collapse
|
6
|
Characterization of Radical S-adenosylmethionine Enzymes and Intermediates in their Reactions by Continuous Wave and Pulse Electron Paramagnetic Resonance Spectroscopies. FUTURE DIRECTIONS IN METALLOPROTEIN AND METALLOENZYME RESEARCH 2017. [DOI: 10.1007/978-3-319-59100-1_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
|
7
|
Noth J, Esselborn J, Güldenhaupt J, Brünje A, Sawyer A, Apfel UP, Gerwert K, Hofmann E, Winkler M, Happe T. [FeFe]-Hydrogenase with Chalcogenide Substitutions at the H-Cluster Maintains Full H2
Evolution Activity. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201511896] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jens Noth
- Ruhr Universität Bochum; Lehrstuhl für Biochemie der Pflanzen; AG Photobiotechnologie; Universitätsstrasse 150 44801 Bochum Germany
| | - Julian Esselborn
- Ruhr Universität Bochum; Lehrstuhl für Biochemie der Pflanzen; AG Photobiotechnologie; Universitätsstrasse 150 44801 Bochum Germany
| | - Jörn Güldenhaupt
- Ruhr Universität Bochum; Lehrstuhl für Biophysik, AG Spektroskopie; Universitätsstrasse 150 44801 Bochum Germany
| | - Annika Brünje
- Ruhr Universität Bochum; Lehrstuhl für Biochemie der Pflanzen; AG Photobiotechnologie; Universitätsstrasse 150 44801 Bochum Germany
| | - Anne Sawyer
- Ruhr Universität Bochum; Lehrstuhl für Biochemie der Pflanzen; AG Photobiotechnologie; Universitätsstrasse 150 44801 Bochum Germany
| | - Ulf-Peter Apfel
- Ruhr Universität Bochum; Fakultät für Chemie und Biochemie; Lehrstuhl für Anorganische Chemie I/ Bioanorganische Chemie; Universitätsstrasse 150 44801 Bochum Germany
| | - Klaus Gerwert
- Ruhr Universität Bochum; Lehrstuhl für Biophysik, AG Spektroskopie; Universitätsstrasse 150 44801 Bochum Germany
| | - Eckhard Hofmann
- Ruhr Universität Bochum; Lehrstuhl für Biophysik; AG Röntgenstrukturanalyse an Proteinen; Universitätsstrasse 150 44801 Bochum Germany
| | - Martin Winkler
- Ruhr Universität Bochum; Lehrstuhl für Biochemie der Pflanzen; AG Photobiotechnologie; Universitätsstrasse 150 44801 Bochum Germany
| | - Thomas Happe
- Ruhr Universität Bochum; Lehrstuhl für Biochemie der Pflanzen; AG Photobiotechnologie; Universitätsstrasse 150 44801 Bochum Germany
| |
Collapse
|
8
|
Noth J, Esselborn J, Güldenhaupt J, Brünje A, Sawyer A, Apfel UP, Gerwert K, Hofmann E, Winkler M, Happe T. [FeFe]-Hydrogenase with Chalcogenide Substitutions at the H-Cluster Maintains Full H2 Evolution Activity. Angew Chem Int Ed Engl 2016; 55:8396-400. [PMID: 27214763 DOI: 10.1002/anie.201511896] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/27/2016] [Indexed: 01/08/2023]
Abstract
The [FeFe]-hydrogenase HYDA1 from Chlamydomonas reinhardtii is particularly amenable to biochemical and biophysical characterization because the H-cluster in the active site is the only inorganic cofactor present. Herein, we present the complete chemical incorporation of the H-cluster into the HYDA1-apoprotein scaffold and, furthermore, the successful replacement of sulfur in the native [4FeH ] cluster with selenium. The crystal structure of the reconstituted pre-mature HYDA1[4Fe4Se]H protein was determined, and a catalytically intact artificial H-cluster variant was generated upon in vitro maturation. Full hydrogen evolution activity as well as native-like composition and behavior of the redesigned enzyme were verified through kinetic assays, FTIR spectroscopy, and X-ray structure analysis. These findings reveal that even a bioinorganic active site with exceptional complexity can exhibit a surprising level of compositional plasticity.
Collapse
Affiliation(s)
- Jens Noth
- Ruhr Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Julian Esselborn
- Ruhr Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Jörn Güldenhaupt
- Ruhr Universität Bochum, Lehrstuhl für Biophysik, AG Spektroskopie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Annika Brünje
- Ruhr Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Anne Sawyer
- Ruhr Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Ulf-Peter Apfel
- Ruhr Universität Bochum, Fakultät für Chemie und Biochemie, Lehrstuhl für Anorganische Chemie I/ Bioanorganische Chemie, Universitätsstrasse 150, 44801, Bochum, Germany.
| | - Klaus Gerwert
- Ruhr Universität Bochum, Lehrstuhl für Biophysik, AG Spektroskopie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Eckhard Hofmann
- Ruhr Universität Bochum, Lehrstuhl für Biophysik, AG Röntgenstrukturanalyse an Proteinen, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Martin Winkler
- Ruhr Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Thomas Happe
- Ruhr Universität Bochum, Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Universitätsstrasse 150, 44801, Bochum, Germany.
| |
Collapse
|
9
|
Landgraf BJ, Booker SJ. Stereochemical Course of the Reaction Catalyzed by RimO, a Radical SAM Methylthiotransferase. J Am Chem Soc 2016; 138:2889-92. [PMID: 26871608 DOI: 10.1021/jacs.5b11035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RimO is a member of the growing radical S-adenosylmethionine (SAM) superfamily of enzymes, which use a reduced [4Fe-4S] cluster to effect reductive cleavage of the 5' C-S bond of SAM to form a 5'-deoxyadenosyl 5'-radical (5'-dA(•)) intermediate. RimO uses this potent oxidant to catalyze the attachment of a methylthio group (-SCH3) to C3 of aspartate 89 of protein S12, one of 21 proteins that compose the 30S subunit of the bacterial ribosome. However, the exact mechanism by which this transformation takes place has remained elusive. Herein, we describe the stereochemical course of the RimO reaction. Using peptide mimics of the S12 protein bearing deuterium at the 3 pro-R or 3 pro-S positions of the target aspartyl residue, we show that RimO from Bacteroides thetaiotaomicron (Bt) catalyzes abstraction of the pro-S hydrogen atom, as evidenced by the transfer of deuterium into 5'-deoxyadenosine (5'-dAH). The observed kinetic isotope effect on H atom versus D atom abstraction is ∼1.9, suggesting that this step is at least partially rate determining. We also demonstrate that Bt RimO can utilize the flavodoxin/flavodoxin oxidoreductase/NADPH reducing system from Escherichia coli as a source of requisite electrons. Use of this in vivo reducing system decreases, but does not eliminate, formation of 5'-dAH in excess of methylthiolated product.
Collapse
Affiliation(s)
- Bradley J Landgraf
- Department of Chemistry, ‡Department of 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, ‡Department of Biochemistry and Molecular Biology, and §The Howard Hughes Medical Institute, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| |
Collapse
|
10
|
Abstract
Two vitamins, biotin and lipoic acid, are essential in all three domains of life. Both coenzymes function only when covalently attached to key metabolic enzymes. There they act as "swinging arms" that shuttle intermediates between two active sites (= covalent substrate channeling) of key metabolic enzymes. Although biotin was discovered over 100 years ago and lipoic acid 60 years ago, it was not known how either coenzyme is made until recently. In Escherichia coli the synthetic pathways for both coenzymes have now been worked out for the first time. The late steps of biotin synthesis, those involved in assembling the fused rings, were well described biochemically years ago, although recent progress has been made on the BioB reaction, the last step of the pathway in which the biotin sulfur moiety is inserted. In contrast, the early steps of biotin synthesis, assembly of the fatty acid-like "arm" of biotin were unknown. It has now been demonstrated that the arm is made by using disguised substrates to gain entry into the fatty acid synthesis pathway followed by removal of the disguise when the proper chain length is attained. The BioC methyltransferase is responsible for introducing the disguise, and the BioH esterase is responsible for its removal. In contrast to biotin, which is attached to its cognate proteins as a finished molecule, lipoic acid is assembled on its cognate proteins. An octanoyl moiety is transferred from the octanoyl acyl carrier protein of fatty acid synthesis to a specific lysine residue of a cognate protein by the LipB octanoyltransferase followed by sulfur insertion at carbons C-6 and C-8 by the LipA lipoyl synthetase. Assembly on the cognate proteins regulates the amount of lipoic acid synthesized, and, thus, there is no transcriptional control of the synthetic genes. In contrast, transcriptional control of the biotin synthetic genes is wielded by a remarkably sophisticated, yet simple, system, exerted through BirA, a dual-function protein that both represses biotin operon transcription and ligates biotin to its cognate proteins.
Collapse
|
11
|
Abstract
Two vitamins, biotin and lipoic acid, are essential in all three domains of life. Both coenzymes function only when covalently attached to key metabolic enzymes. There they act as "swinging arms" that shuttle intermediates between two active sites (= covalent substrate channeling) of key metabolic enzymes. Although biotin was discovered over 100 years ago and lipoic acid was discovered 60 years ago, it was not known how either coenzyme is made until recently. In Escherichia coli the synthetic pathways for both coenzymes have now been worked out for the first time. The late steps of biotin synthesis, those involved in assembling the fused rings, were well described biochemically years ago, although recent progress has been made on the BioB reaction, the last step of the pathway, in which the biotin sulfur moiety is inserted. In contrast, the early steps of biotin synthesis, assembly of the fatty acid-like "arm" of biotin, were unknown. It has now been demonstrated that the arm is made by using disguised substrates to gain entry into the fatty acid synthesis pathway followed by removal of the disguise when the proper chain length is attained. The BioC methyltransferase is responsible for introducing the disguise and the BioH esterase for its removal. In contrast to biotin, which is attached to its cognate proteins as a finished molecule, lipoic acid is assembled on its cognate proteins. An octanoyl moiety is transferred from the octanoyl-ACP of fatty acid synthesis to a specific lysine residue of a cognate protein by the LipB octanoyl transferase, followed by sulfur insertion at carbons C6 and C8 by the LipA lipoyl synthetase. Assembly on the cognate proteins regulates the amount of lipoic acid synthesized, and thus there is no transcriptional control of the synthetic genes. In contrast, transcriptional control of the biotin synthetic genes is wielded by a remarkably sophisticated, yet simple, system exerted through BirA, a dual-function protein that both represses biotin operon transcription and ligates biotin to its cognate protein.
Collapse
|
12
|
Density functional theory calculations on the active site of biotin synthase: mechanism of S transfer from the Fe2S2 cluster and the role of 1st and 2nd sphere residues. J Biol Inorg Chem 2015; 20:1147-62. [DOI: 10.1007/s00775-015-1296-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 09/02/2015] [Indexed: 10/23/2022]
|
13
|
Cutsail GE, Telser J, Hoffman BM. Advanced paramagnetic resonance spectroscopies of iron-sulfur proteins: Electron nuclear double resonance (ENDOR) and electron spin echo envelope modulation (ESEEM). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1370-94. [PMID: 25686535 DOI: 10.1016/j.bbamcr.2015.01.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 01/29/2015] [Accepted: 01/29/2015] [Indexed: 12/20/2022]
Abstract
The advanced electron paramagnetic resonance (EPR) techniques, electron nuclear double resonance (ENDOR) and electron spin echo envelope modulation (ESEEM) spectroscopies, provide unique insights into the structure, coordination chemistry, and biochemical mechanism of nature's widely distributed iron-sulfur cluster (FeS) proteins. This review describes the ENDOR and ESEEM techniques and then provides a series of case studies on their application to a wide variety of FeS proteins including ferredoxins, nitrogenase, and radical SAM enzymes. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
Collapse
Affiliation(s)
- George E Cutsail
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Joshua Telser
- Department of Biological, Chemical and Physical Sciences, Roosevelt University, Chicago, IL 60605, USA
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
| |
Collapse
|
14
|
Structures of lipoyl synthase reveal a compact active site for controlling sequential sulfur insertion reactions. Biochem J 2015; 464:123-33. [PMID: 25100160 DOI: 10.1042/bj20140895] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Lipoyl cofactors are essential for living organisms and are produced by the insertion of two sulfur atoms into the relatively unreactive C-H bonds of an octanoyl substrate. This reaction requires lipoyl synthase, a member of the radical S-adenosylmethionine (SAM) enzyme superfamily. In the present study, we solved crystal structures of lipoyl synthase with two [4Fe-4S] clusters bound at opposite ends of the TIM barrel, the usual fold of the radical SAM superfamily. The cluster required for reductive SAM cleavage conserves the features of the radical SAM superfamily, but the auxiliary cluster is bound by a CX4CX5C motif unique to lipoyl synthase. The fourth ligand to the auxiliary cluster is an extremely unusual serine residue. Site-directed mutants show this conserved serine ligand is essential for the sulfur insertion steps. One crystallized lipoyl synthase (LipA) complex contains 5'-methylthioadenosine (MTA), a breakdown product of SAM, bound in the likely SAM-binding site. Modelling has identified an 18 Å (1 Å=0.1 nm) deep channel, well-proportioned to accommodate an octanoyl substrate. These results suggest that the auxiliary cluster is the likely sulfur donor, but access to a sulfide ion for the second sulfur insertion reaction requires the loss of an iron atom from the auxiliary cluster, which the serine ligand may enable.
Collapse
|
15
|
Lanz ND, Pandelia ME, Kakar ES, Lee KH, Krebs C, Booker SJ. Evidence for a catalytically and kinetically competent enzyme-substrate cross-linked intermediate in catalysis by lipoyl synthase. Biochemistry 2014; 53:4557-72. [PMID: 24901788 PMCID: PMC4216189 DOI: 10.1021/bi500432r] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lipoyl synthase (LS) catalyzes the final step in lipoyl cofactor biosynthesis: the insertion of two sulfur atoms at C6 and C8 of an (N(6)-octanoyl)-lysyl residue on a lipoyl carrier protein (LCP). LS is a member of the radical SAM superfamily, enzymes that use a [4Fe-4S] cluster to effect the reductive cleavage of S-adenosyl-l-methionine (SAM) to l-methionine and a 5'-deoxyadenosyl 5'-radical (5'-dA(•)). In the LS reaction, two equivalents of 5'-dA(•) are generated sequentially to abstract hydrogen atoms from C6 and C8 of the appended octanoyl group, initiating sulfur insertion at these positions. The second [4Fe-4S] cluster on LS, termed the auxiliary cluster, is proposed to be the source of the inserted sulfur atoms. Herein, we provide evidence for the formation of a covalent cross-link between LS and an LCP or synthetic peptide substrate in reactions in which insertion of the second sulfur atom is slowed significantly by deuterium substitution at C8 or by inclusion of limiting concentrations of SAM. The observation that the proteins elute simultaneously by anion-exchange chromatography but are separated by aerobic SDS-PAGE is consistent with their linkage through the auxiliary cluster that is sacrificed during turnover. Generation of the cross-linked species with a small, unlabeled (N(6)-octanoyl)-lysyl-containing peptide substrate allowed demonstration of both its chemical and kinetic competence, providing strong evidence that it is an intermediate in the LS reaction. Mössbauer spectroscopy of the cross-linked intermediate reveals that one of the [4Fe-4S] clusters, presumably the auxiliary cluster, is partially disassembled to a 3Fe-cluster with spectroscopic properties similar to those of reduced [3Fe-4S](0) clusters.
Collapse
Affiliation(s)
- Nicholas D Lanz
- Department of Biochemistry and Molecular Biology and ‡Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | | | | | | | | | | |
Collapse
|
16
|
Broderick JB, Duffus B, Duschene KS, Shepard EM. Radical S-adenosylmethionine enzymes. Chem Rev 2014; 114:4229-317. [PMID: 24476342 PMCID: PMC4002137 DOI: 10.1021/cr4004709] [Citation(s) in RCA: 576] [Impact Index Per Article: 57.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Joan B. Broderick
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Benjamin
R. Duffus
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Kaitlin S. Duschene
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Eric M. Shepard
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| |
Collapse
|
17
|
Forouhar F, Arragain S, Atta M, Gambarelli S, Mouesca JM, Hussain M, Xiao R, Kieffer-Jaquinod S, Seetharaman J, Acton TB, Montelione GT, Mulliez E, Hunt JF, Fontecave M. Two Fe-S clusters catalyze sulfur insertion by radical-SAM methylthiotransferases. Nat Chem Biol 2013; 9:333-8. [PMID: 23542644 DOI: 10.1038/nchembio.1229] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 03/05/2013] [Indexed: 11/09/2022]
Abstract
How living organisms create carbon-sulfur bonds during the biosynthesis of critical sulfur-containing compounds is still poorly understood. The methylthiotransferases MiaB and RimO catalyze sulfur insertion into tRNAs and ribosomal protein S12, respectively. Both belong to a subgroup of radical-S-adenosylmethionine (radical-SAM) enzymes that bear two [4Fe-4S] clusters. One cluster binds S-adenosylmethionine and generates an Ado• radical via a well-established mechanism. However, the precise role of the second cluster is unclear. For some sulfur-inserting radical-SAM enzymes, this cluster has been proposed to act as a sacrificial source of sulfur for the reaction. In this paper, we report parallel enzymological, spectroscopic and crystallographic investigations of RimO and MiaB, which provide what is to our knowledge the first evidence that these enzymes are true catalysts and support a new sulfation mechanism involving activation of an exogenous sulfur cosubstrate at an exchangeable coordination site on the second cluster, which remains intact during the reaction.
Collapse
Affiliation(s)
- Farhad Forouhar
- Northeast Structural Genomics Consortium, New York, New York, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Lanz ND, Booker SJ. Identification and function of auxiliary iron-sulfur clusters in radical SAM enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1196-212. [PMID: 22846545 DOI: 10.1016/j.bbapap.2012.07.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 11/27/2022]
Abstract
Radical SAM (RS) enzymes use a 5'-deoxyadenosyl 5'-radical generated from a reductive cleavage of S-adenosyl-l-methionine to catalyze over 40 distinct reaction types. A distinguishing feature of these enzymes is a [4Fe-4S] cluster to which each of three iron ions is ligated by three cysteinyl residues most often located in a Cx(3)Cx(2)C motif. The α-amino and α-carboxylate groups of SAM anchor the molecule to the remaining iron ion, which presumably facilitates its reductive cleavage. A subset of RS enzymes contains additional iron-sulfur clusters, - which we term auxiliary clusters - most of which have unidentified functions. Enzymes in this subset are involved in cofactor biosynthesis and maturation, post-transcriptional and post-translational modification, enzyme activation, and antibiotic biosynthesis. The additional clusters in these enzymes have been proposed to function in sulfur donation, electron transfer, and substrate anchoring. This review will highlight evidence supporting the presence of multiple iron-sulfur clusters in these enzymes as well as their predicted roles in catalysis. This article is part of a special issue entitled: Radical SAM enzymes and radical enzymology.
Collapse
Affiliation(s)
- Nicholas D Lanz
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | | |
Collapse
|
19
|
Fugate CJ, Jarrett JT. Biotin synthase: insights into radical-mediated carbon-sulfur bond formation. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1213-22. [PMID: 22326745 DOI: 10.1016/j.bbapap.2012.01.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
The enzyme cofactor and essential vitamin biotin is biosynthesized in bacteria, fungi, and plants through a pathway that culminates with the addition of a sulfur atom to generate the five-membered thiophane ring. The immediate precursor, dethiobiotin, has methylene and methyl groups at the C6 and C9 positions, respectively, and formation of a thioether bridging these carbon atoms requires cleavage of unactivated CH bonds. Biotin synthase is an S-adenosyl-l-methionine (SAM or AdoMet) radical enzyme that catalyzes reduction of the AdoMet sulfonium to produce 5'-deoxyadenosyl radicals, high-energy carbon radicals that can directly abstract hydrogen atoms from dethiobiotin. The available experimental and structural data suggest that a [2Fe-2S](2+) cluster bound deep within biotin synthase provides a sulfur atom that is added to dethiobiotin in a stepwise reaction, first at the C9 position to generate 9-mercaptodethiobiotin, and then at the C6 position to close the thiophane ring. The formation of sulfur-containing biomolecules through a radical reaction involving an iron-sulfur cluster is an unprecedented reaction in biochemistry; however, recent enzyme discoveries suggest that radical sulfur insertion reactions may be a distinct subgroup within the burgeoning Radical SAM superfamily. This article is part of a Special Issue entitled: Radical SAM enzymes and Radical Enzymology.
Collapse
Affiliation(s)
- Corey J Fugate
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | | |
Collapse
|
20
|
Matsumoto J, Kajita Y, Masuda H. Synthesis, Characterization, and Reactivity of a Novel μ-η2:η2-Diselenidodicopper(II) Complex. Inorg Chem 2012; 51:1236-8. [DOI: 10.1021/ic202690e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jun Matsumoto
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yuji Kajita
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Masuda
- Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| |
Collapse
|
21
|
Taylor AM, Stoll S, Britt RD, Jarrett JT. Reduction of the [2Fe-2S] cluster accompanies formation of the intermediate 9-mercaptodethiobiotin in Escherichia coli biotin synthase. Biochemistry 2011; 50:7953-63. [PMID: 21859080 DOI: 10.1021/bi201042r] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Biotin synthase catalyzes the conversion of dethiobiotin (DTB) to biotin through the oxidative addition of sulfur between two saturated carbon atoms, generating a thiophane ring fused to the existing ureido ring. Biotin synthase is a member of the radical SAM superfamily, composed of enzymes that reductively cleave S-adenosyl-l-methionine (SAM or AdoMet) to generate a 5'-deoxyadenosyl radical that can abstract unactivated hydrogen atoms from a variety of organic substrates. In biotin synthase, abstraction of a hydrogen atom from the C9 methyl group of DTB would result in formation of a dethiobiotinyl methylene carbon radical, which is then quenched by a sulfur atom to form a new carbon-sulfur bond in the intermediate 9-mercaptodethiobiotin (MDTB). We have proposed that this sulfur atom is the μ-sulfide of a [2Fe-2S](2+) cluster found near DTB in the enzyme active site. In the present work, we show that formation of MDTB is accompanied by stoichiometric generation of a paramagnetic FeS cluster. The electron paramagnetic resonance (EPR) spectrum is modeled as a 2:1 mixture of components attributable to different forms of a [2Fe-2S](+) cluster, possibly distinguished by slightly different coordination environments. Mutation of Arg260, one of the ligands to the [2Fe-2S] cluster, causes a distinctive change in the EPR spectrum. Furthermore, magnetic coupling of the unpaired electron with (14)N from Arg260, detectable by electron spin envelope modulation (ESEEM) spectroscopy, is observed in WT enzyme but not in the Arg260Met mutant enzyme. Both results indicate that the paramagnetic FeS cluster formed during catalytic turnover is a [2Fe-2S](+) cluster, consistent with a mechanism in which the [2Fe-2S](2+) cluster simultaneously provides and oxidizes sulfide during carbon-sulfur bond formation.
Collapse
Affiliation(s)
- Andrew M Taylor
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
| | | | | | | |
Collapse
|
22
|
Lin S, Cronan JE. Closing in on complete pathways of biotin biosynthesis. MOLECULAR BIOSYSTEMS 2011; 7:1811-21. [PMID: 21437340 DOI: 10.1039/c1mb05022b] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Biotin is an enzyme cofactor indispensable to metabolic fixation of carbon dioxide in all three domains of life. Although the catalytic and physiological roles of biotin have been well characterized, the biosynthesis of biotin remains to be fully elucidated. Studies in microbes suggest a two-stage biosynthetic pathway in which a pimelate moiety is synthesized and used to begin assembly of the biotin bicyclic ring structure. The enzymes involved in the bicyclic ring assembly have been studied extensively. In contrast the synthesis of pimelate, a seven carbon α,ω-dicarboxylate, has long been an enigma. Support for two different routes of pimelate synthesis has recently been obtained in Escherichia coli and Bacillus subtilis. The E. coli BioC-BioH pathway employs a methylation and demethylation strategy to allow elongation of a temporarily disguised malonate moiety to a pimelate moiety by the fatty acid synthetic enzymes whereas the B. subtilis BioI-BioW pathway utilizes oxidative cleavage of fatty acyl chains. Both pathways produce the pimelate thioester precursor essential for the first step in assembly of the fused rings of biotin. The enzymatic mechanisms and biochemical strategies of these pimelate synthesis models will be discussed in this review.
Collapse
Affiliation(s)
- Steven Lin
- Department of Microbiology, University of Illinois, B103 Chemical and Life Sciences Laboratory, 601 S. Goodwin Ave, Urbana, Illinois 61801, USA
| | | |
Collapse
|
23
|
Kuchenreuther JM, Stapleton JA, Swartz JR. Tyrosine, cysteine, and S-adenosyl methionine stimulate in vitro [FeFe] hydrogenase activation. PLoS One 2009; 4:e7565. [PMID: 19855833 PMCID: PMC2762031 DOI: 10.1371/journal.pone.0007565] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 10/04/2009] [Indexed: 11/29/2022] Open
Abstract
Background [FeFe] hydrogenases are metalloenzymes involved in the anaerobic metabolism of H2. These proteins are distinguished by an active site cofactor known as the H-cluster. This unique [6Fe–6S] complex contains multiple non-protein moieties and requires several maturation enzymes for its assembly. The pathways and biochemical precursors for H-cluster biosynthesis have yet to be elucidated. Principal Findings We report an in vitro maturation system in which, for the first time, chemical additives enhance [FeFe] hydrogenase activation, thus signifying in situ H-cluster biosynthesis. The maturation system is comprised of purified hydrogenase apoprotein; a dialyzed Escherichia coli cell lysate containing heterologous HydE, HydF, and HydG maturases; and exogenous small molecules. Following anaerobic incubation of the Chlamydomonas reinhardtii HydA1 apohydrogenase with S-adenosyl methionine (SAM), cysteine, tyrosine, iron, sulfide, and the non-purified maturases, hydrogenase activity increased 5-fold relative to incubations without the exogenous substrates. No conditions were identified in which addition of guanosine triphosphate (GTP) improved hydrogenase maturation. Significance The in vitro system allows for direct investigation of [FeFe] hydrogenase activation. This work also provides a foundation for studying the biosynthetic mechanisms of H-cluster biosynthesis using solely purified enzymes and chemical additives.
Collapse
Affiliation(s)
- Jon M. Kuchenreuther
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
| | - James A. Stapleton
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
| | - James R. Swartz
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
- * E-mail:
| |
Collapse
|
24
|
Product inhibition in the radical S-adenosylmethionine family. FEBS Lett 2009; 583:1358-62. [PMID: 19328201 DOI: 10.1016/j.febslet.2009.03.044] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 03/20/2009] [Accepted: 03/22/2009] [Indexed: 11/22/2022]
Abstract
Members of the radical S-adenosylmethionine (AdoMet) superfamily reductively cleave AdoMet to generate the highly reactive 5'-deoxyadenosyl radical (DOA()) which initiates biological transformations by abstraction of a hydrogen atom. We demonstrate that three members of the family: biotin synthase (BioB), lipoyl synthase (LipA) and tyrosine lyase (ThiH) are inhibited in vitro by a combination of the products 5'-deoxyadenosine (DOA) and methionine. These results suggest the observed inhibition is a common feature of the radical AdoMet proteins that form DOA and methionine as products. Addition of 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) to BioB, LipA or ThiH activity assays removed the product inhibition by catalysing the hydrolysis of DOA and gave an increase in activity.
Collapse
|
25
|
Booker SJ. Anaerobic functionalization of unactivated C-H bonds. Curr Opin Chem Biol 2009; 13:58-73. [PMID: 19297239 DOI: 10.1016/j.cbpa.2009.02.036] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 02/24/2009] [Accepted: 02/24/2009] [Indexed: 12/30/2022]
Abstract
The functionalization of alkanes was once thought to lie strictly within the domain of enzymes that activate dioxygen in order to generate an oxidant with suitable potency to cleave inert C-H bonds. The emergence of the radical SAM superfamily of enzymes-those which use S-adenosyl-l-methionine as a precursor to a 5'-deoxyadenosyl 5'-radical-has kindled a renaissance in the study of radical-dependent enzymatic reactions, and is ushering in a wealth of new and intriguing chemistry that remains to be elucidated. This review will focus on a special subclass of radical SAM enzymes that functionalize inert C-H bonds, highlighting the functional groups and the chemistry that leads to their insertion. Within this class are first, enzymes that catalyze sulfur insertion, the prototype of which is biotin synthase; second, enzymes that catalyze P-methylation or C-methylation, such as P-methylase or Fom3; third, enzymes that catalyze oxygen insertion, such as the anaerobic magnesium protoporphyrin-IX oxidative cyclase (BchE); and fourth, enzymes that functionalize n-hexane or other alkanes as the first step in the metabolism of these inert compounds by certain bacteria. In addition to surveying reactions that have been studied at various levels of detail, this review will speculate on the mechanisms of other types of reactions that this chemistry lends itself to.
Collapse
Affiliation(s)
- Squire J Booker
- Department of Chemistry, The Pennsylvania State University, University Park, 16802, United States.
| |
Collapse
|
26
|
Taylor AM, Farrar CE, Jarrett JT. 9-Mercaptodethiobiotin is formed as a competent catalytic intermediate by Escherichia coli biotin synthase. Biochemistry 2008; 47:9309-17. [PMID: 18690713 DOI: 10.1021/bi801035b] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biotin synthase (BS) catalyzes the oxidative addition of a sulfur atom to dethiobiotin (DTB) to generate the biotin thiophane ring. This enzyme is an S-adenosylmethionine (AdoMet) radical enzyme that catalyzes the reductive cleavage of AdoMet, generating methionine and a transient 5'-deoxyadenosyl radical. In our working mechanism, the 5'-deoxyadenosyl radical oxidizes DTB by abstracting a hydrogen from C6 or C9, generating a dethiobiotinyl carbon radical that is quenched by a sulfide from a [2Fe-2S] (2+) cluster. A similar reaction sequence directed at the other position generates the second C-S bond in the thiophane ring. Since the BS active site holds only one AdoMet and one DTB, it follows that dissociation of methionine and 5'-deoxyadenosine and binding of a second equivalent of AdoMet must be intermediate steps in the formation of biotin. During these dissociation-association steps, a discrete DTB-derived intermediate must remain bound to the enzyme. In this work, we confirm that the conversion of DTB to biotin is accompanied by the reductive cleavage of 2 equiv of AdoMet. A discrepancy between DTB consumption and biotin formation suggests the presence of an intermediate, and we use liquid chromatography and mass spectrometry to demonstrate that this intermediate is indeed 9-mercaptodethiobiotin, generated at approximately 10% of the total enzyme concentration. The amount of intermediate observed is increased when the reaction is run with substoichiometric levels of AdoMet or with the defective enzyme containing the Asn153Ser mutation. The retention of 9-mercaptodethiobiotin as a tightly bound intermediate is consistent with a mechanism involving the stepwise radical-mediated oxidative abstraction of sulfide from an iron-sulfur cluster.
Collapse
Affiliation(s)
- Andrew M Taylor
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
| | | | | |
Collapse
|
27
|
Abdel-Hamid AM, Cronan JE. In vivo resolution of conflicting in vitro results: synthesis of biotin from dethiobiotin does not require pyridoxal phosphate. ACTA ACUST UNITED AC 2008; 14:1215-20. [PMID: 18022560 DOI: 10.1016/j.chembiol.2007.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 10/01/2007] [Accepted: 10/16/2007] [Indexed: 11/30/2022]
Abstract
The source of the biotin sulfur atom remains a contested point in studies of biotin synthase (BioB) in vitro. Recent reports that BioB has an intrinsic pyridoxal phosphate (PLP)-dependent cysteine desulfurase activity were tested by depleting Escherichia coli cells of PLP. The BioB-dependent conversion of dethiobiotin to biotin proceeded in these cells irrespective of the presence or absence of PLP.
Collapse
|
28
|
Booker SJ, Cicchillo RM, Grove TL. Self-sacrifice in radical S-adenosylmethionine proteins. Curr Opin Chem Biol 2007; 11:543-52. [PMID: 17936058 DOI: 10.1016/j.cbpa.2007.08.028] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 08/22/2007] [Accepted: 08/22/2007] [Indexed: 01/10/2023]
Abstract
The radical SAM superfamily of metalloproteins catalyze the reductive cleavage of S-adenosyl-l-methionine to generate a 5'-deoxyadenosyl radical (5'-dA*) intermediate that is obligate for turnover. The 5'-dA* acts as a potent oxidant, initiating turnover by abstracting a hydrogen atom from an appropriate substrate. A special class of these enzymes use this strategy to functionalize unactivated C-H bonds by insertion of sulfur atoms. This review will describe the characterization of three members of this class - biotin synthase, lipoyl synthase, and MiaB protein - each of which has been shown to cannibalize itself during turnover.
Collapse
Affiliation(s)
- Squire J Booker
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16803, United States.
| | | | | |
Collapse
|
29
|
Reyda MR, Dippold R, Dotson ME, Jarrett JT. Loss of iron-sulfur clusters from biotin synthase as a result of catalysis promotes unfolding and degradation. Arch Biochem Biophys 2007; 471:32-41. [PMID: 18155152 DOI: 10.1016/j.abb.2007.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 12/04/2007] [Accepted: 12/05/2007] [Indexed: 11/30/2022]
Abstract
Biotin synthase (BioB) is an S-adenosylmethionine radical enzyme that catalyzes addition of sulfur to dethiobiotin to form the biotin thiophane ring. In vitro, Escherichia coli BioB is active for only one turnover, during which the [2Fe-2S]2+ cluster is destroyed, one sulfide from the cluster is incorporated as the biotin thiophane sulfur, while Fe2+ ions and the remaining S2- ion are released from the protein. The present work examines the fate of the protein following the loss of the FeS clusters. We examine the quaternary structure and thermal stability of active and inactive states of BioB, and find that loss of either the [4Fe-4S]2+ or [2Fe-2S]2+ clusters results in destabilization but not global unfolding of BioB. Using susceptibility to limited proteolysis as a guide, we find that specific regions of the protein appear to be transiently unfolded following loss of these clusters. We also examine the in vivo degradation of biotin synthase during growth in low-iron minimal media and find that BioB is degraded by an apparent ATP-dependent proteolysis mechanism that sequentially cleaves small fragments starting at the C-terminus. BioB appears to be resistant to degradation and capable of multiple turnovers only under high-iron conditions that favor repair of the FeS clusters, a process most likely mediated by the Isc or Suf iron-sulfur cluster assembly systems.
Collapse
Affiliation(s)
- Michael R Reyda
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822-2275, United States
| | | | | | | |
Collapse
|
30
|
Mühlenhoff U, Gerl MJ, Flauger B, Pirner HM, Balser S, Richhardt N, Lill R, Stolz J. The ISC [corrected] proteins Isa1 and Isa2 are required for the function but not for the de novo synthesis of the Fe/S clusters of biotin synthase in Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 6:495-504. [PMID: 17259550 PMCID: PMC1828929 DOI: 10.1128/ec.00191-06] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The yeast Saccharomyces cerevisiae is able to use some biotin precursors for biotin biosynthesis. Insertion of a sulfur atom into desthiobiotin, the final step in the biosynthetic pathway, is catalyzed by biotin synthase (Bio2). This mitochondrial protein contains two iron-sulfur (Fe/S) clusters that catalyze the reaction and are thought to act as a sulfur donor. To identify new components of biotin metabolism, we performed a genetic screen and found that Isa2, a mitochondrial protein involved in the formation of Fe/S proteins, is necessary for the conversion of desthiobiotin to biotin. Depletion of Isa2 or the related Isa1, however, did not prevent the de novo synthesis of any of the two Fe/S centers of Bio2. In contrast, Fe/S cluster assembly on Bio2 strongly depended on the Isu1 and Isu2 proteins. Both isa mutants contained low levels of Bio2. This phenotype was also found in other mutants impaired in mitochondrial Fe/S protein assembly and in wild-type cells grown under iron limitation. Low Bio2 levels, however, did not cause the inability of isa mutants to utilize desthiobiotin, since this defect was not cured by overexpression of BIO2. Thus, the Isa proteins are crucial for the in vivo function of biotin synthase but not for the de novo synthesis of its Fe/S clusters. Our data demonstrate that the Isa proteins are essential for the catalytic activity of Bio2 in vivo.
Collapse
Affiliation(s)
- Ulrich Mühlenhoff
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, 35033 Marburg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Marquet A, Bui BTS, Smith AG, Warren MJ. Iron–sulfur proteins as initiators of radical chemistry. Nat Prod Rep 2007; 24:1027-40. [PMID: 17898896 DOI: 10.1039/b703109m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iron-sulfur proteins are very versatile biological entities for which many new functions are continuously being unravelled. This review focus on their role in the initiation of radical chemistry, with special emphasis on radical-SAM enzymes, since several members of the family catalyse key steps in the biosynthetic pathways of cofactors such as biotin, lipoate, thiamine, heme and the molybdenum cofactor. It will also include other examples to show the chemical logic which is emerging from the presently available data on this family of enzymes. The common step in all the (quite different) reactions described here is the monoelectronic reductive cleavage of SAM by a reduced [4Fe-4S](1+) cluster, producing methionine and a highly oxidising deoxyadenosyl radical, which can initiate chemically difficult reactions. This set of enzymes, which represent a means to perform oxidation under reductive conditions, are often present in anaerobic organisms. Some other, non-SAM-dependent, radical reactions obeying the same chemical logic are also covered.
Collapse
Affiliation(s)
- Andrée Marquet
- Université Pierre et Marie Curie-Paris 6, CNRS UMR 7613, (Synthèse, Structure et Fonction de Molécules Bioactives), Paris, France.
| | | | | | | |
Collapse
|
32
|
Broach RB, Jarrett JT. Role of the [2Fe-2S]2+ cluster in biotin synthase: mutagenesis of the atypical metal ligand arginine 260. Biochemistry 2006; 45:14166-74. [PMID: 17115711 PMCID: PMC2442824 DOI: 10.1021/bi061576p] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biotin synthase (BS) is an S-adenosylmethionine (AdoMet)-dependent radical enzyme that catalyzes the addition of sulfur to dethiobiotin. Like other AdoMet radical enzymes, BS contains a [4Fe-4S] cluster that is coordinated by a highly conserved CxxxCxxC sequence motif and by the methionyl amine and carboxylate of AdoMet. The close association of the [4Fe-4S]+ cluster with AdoMet facilitates reductive cleavage of the sulfonium and the generation of transient 5'-deoxyadenosyl radicals, which are then proposed to sequentially abstract hydrogen atoms from the substrate to produce carbon radicals at C9 and C6 of dethiobiotin. BS also contains a [2Fe-2S]2+ cluster located approximately 4-5 A from dethiobiotin, and we have proposed that a bridging sulfide of this cluster quenches the substrate radicals, leading to formation of the thiophane ring of biotin. In BS from Escherichia coli, the [2Fe-2S]2+ cluster is coordinated by cysteines 97, 128, and 188, and the atypical metal ligand, arginine 260. The evolutionary conservation of an arginine guanidinium as a metal ligand suggests a novel role for this residue in tuning the reactivity or stability of the [2Fe-2S]2+ cluster. In this work, we explore the effects of mutagenesis of Arg260 to Ala, Cys, His, and Met. Although perturbations in a number of characteristics of the [2Fe-2S]2+ cluster and the proteins are noted, the reconstituted enzymes have in vitro single-turnover activities that are 30-120% of that of the wild type. Further, in vivo expression of each mutant enzyme was sufficient to sustain growth of a bioB- mutant strain on dethiobiotin-supplemented medium, suggesting the enzymes were active and efficiently reconstituted by the in vivo iron-sulfur cluster (ISC) assembly system. Although we cannot exclude an as-yet-unidentified in vivo role in cluster repair or retention, we can conclude that Arg260 is not essential for the catalytic reaction of BS.
Collapse
Affiliation(s)
- Robyn B Broach
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | |
Collapse
|