1
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Swindell J, Dos Santos PC. Interactions with sulfur acceptors modulate the reactivity of cysteine desulfurases and define their physiological functions. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119794. [PMID: 39033933 DOI: 10.1016/j.bbamcr.2024.119794] [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: 03/23/2024] [Revised: 06/21/2024] [Accepted: 07/11/2024] [Indexed: 07/23/2024]
Abstract
Sulfur-containing biomolecules such as [FeS] clusters, thiamin, biotin, molybdenum cofactor, and sulfur-containing tRNA nucleosides are essential for various biochemical reactions. The amino acid l-cysteine serves as the major sulfur source for the biosynthetic pathways of these sulfur-containing cofactors in prokaryotic and eukaryotic systems. The first reaction in the sulfur mobilization involves a class of pyridoxal-5'-phosphate (PLP) dependent enzymes catalyzing a Cys:sulfur acceptor sulfurtransferase reaction. The first half of the catalytic reaction involves a PLP-dependent CS bond cleavage, resulting in a persulfide enzyme intermediate. The second half of the reaction involves the subsequent transfer of the thiol group to a specific acceptor molecule, which is responsible for the physiological role of the enzyme. Structural and biochemical analysis of these Cys sulfurtransferase enzymes shows that specific protein-protein interactions with sulfur acceptors modulate their catalytic reactivity and restrict their biochemical functions.
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Affiliation(s)
- Jimmy Swindell
- Department of Chemistry, Wake Forest University, Winston-Salem, NC, 27109, United States of America
| | - Patricia C Dos Santos
- Department of Chemistry, Wake Forest University, Winston-Salem, NC, 27109, United States of America.
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2
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Dussouchaud M, Barras F, Ollagnier de Choudens S. Fe-S biogenesis by SMS and SUF pathways: A focus on the assembly step. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119772. [PMID: 38838856 DOI: 10.1016/j.bbamcr.2024.119772] [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: 05/27/2024] [Accepted: 05/28/2024] [Indexed: 06/07/2024]
Abstract
FeS clusters are prosthetic groups present in all organisms. Proteins with FeS centers are involved in most cellular processes. ISC and SUF are machineries necessary for the formation and insertion of FeS in proteins. Recently, a phylogenetic analysis on more than 10,000 genomes of prokaryotes have uncovered two new systems, MIS and SMS, which were proposed to be ancestral to ISC and SUF. SMS is composed of SmsBC, two homologs of SufBC(D), the scaffolding complex of SUF. In this review, we will specifically focus on the current knowledge of the SUF system and on the new perspectives given by the recent discovery of its ancestor, the SMS system.
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Affiliation(s)
- Macha Dussouchaud
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Department of Microbiology, Unit Stress Adaptation and Metabolism in enterobacteria, Paris, France
| | - Frédéric Barras
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Department of Microbiology, Unit Stress Adaptation and Metabolism in enterobacteria, Paris, France
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3
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Garcia PS, Gribaldo S, Barras F. When iron and sulfur met on an anoxic planet and eventually made clusters essential for life. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119730. [PMID: 38631441 DOI: 10.1016/j.bbamcr.2024.119730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/11/2024] [Accepted: 04/04/2024] [Indexed: 04/19/2024]
Abstract
[FeS] clusters are co-factors that are essential for life and are synthesized by dedicated multiprotein cellular machineries. In this review, we present the current scenario for the emergence and the diversification of the [FeS] cluster biosynthesis machineries. In addition to well-known NIF, ISC and SUF machineries, two alternative minimal systems, SMS, and MIS, were recently identified. Taxonomic distribution and phylogeny analyses indicate that SMS and MIS were present in the Last Universal Common Ancestor (LUCA), well before the increase of oxygen on Earth. ISC, SUF and NIF systems emerged later in the history of life. The possible reasons for the emergence and diversification of these machineries are discussed.
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Affiliation(s)
- Pierre Simon Garcia
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Department of Microbiology, Unit Stress Adaptation and Metabolism in Enterobacteria, Paris, France; Institut Pasteur, Université Paris Cité, Department of Microbiology, Unit Evolutionary Biology of the Microbial Cell, Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Université Paris Cité, Department of Microbiology, Unit Evolutionary Biology of the Microbial Cell, Paris, France
| | - Frédéric Barras
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Department of Microbiology, Unit Stress Adaptation and Metabolism in Enterobacteria, Paris, France.
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4
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Marszalek J, Craig EA, Pitek M, Dutkiewicz R. Chaperone function in Fe-S protein biogenesis: Three possible scenarios. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119717. [PMID: 38574821 DOI: 10.1016/j.bbamcr.2024.119717] [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: 01/19/2024] [Revised: 02/22/2024] [Accepted: 03/25/2024] [Indexed: 04/06/2024]
Abstract
Among the six known iron‑sulfur (FeS) cluster biogenesis machineries that function across all domains of life only one involves a molecular chaperone system. This machinery, called ISC for 'iron sulfur cluster', functions in bacteria and in mitochondria of eukaryotes including humans. The chaperone system - a dedicated J-domain protein co-chaperone termed Hsc20 and its Hsp70 partner - is essential for proper ISC machinery function, interacting with the scaffold protein IscU which serves as a platform for cluster assembly and subsequent transfer onto recipient apo-proteins. Despite many years of research, surprisingly little is known about the specific role(s) that the chaperones play in the ISC machinery. Here we review three non-exclusive scenarios that range from involvement of the chaperones in the cluster transfer to regulation of the cellular levels of IscU itself.
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Affiliation(s)
- Jaroslaw Marszalek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
| | - Elizabeth A Craig
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States of America.
| | - Marcin Pitek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Rafal Dutkiewicz
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
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5
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Sourice M, Oriol C, Aubert C, Mandin P, Py B. Genetic dissection of the bacterial Fe-S protein biogenesis machineries. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119746. [PMID: 38719030 DOI: 10.1016/j.bbamcr.2024.119746] [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: 01/25/2024] [Revised: 04/12/2024] [Accepted: 05/03/2024] [Indexed: 05/13/2024]
Abstract
Iron‑sulfur (Fe-S) clusters are one of the most ancient and versatile inorganic cofactors present in the three domains of life. Fe-S clusters are essential cofactors for the activity of a large variety of metalloproteins that play crucial physiological roles. Fe-S protein biogenesis is a complex process that starts with the acquisition of the elements (iron and sulfur atoms) and their assembly into an Fe-S cluster that is subsequently inserted into the target proteins. The Fe-S protein biogenesis is ensured by multiproteic systems conserved across all domains of life. Here, we provide an overview on how bacterial genetics approaches have permitted to reveal and dissect the Fe-S protein biogenesis process in vivo.
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Affiliation(s)
- Mathieu Sourice
- Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies et Biotechnologie, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Charlotte Oriol
- Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies et Biotechnologie, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Corinne Aubert
- Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies et Biotechnologie, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Pierre Mandin
- Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies et Biotechnologie, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Béatrice Py
- Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies et Biotechnologie, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France.
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6
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Xu L, Wu Y, Yang X, Pang X, Wu Y, Li X, Liu X, Zhao Y, Yu L, Wang P, Ye B, Jiang S, Ma J, Zhang X. The Fe-S cluster biosynthesis in Enterococcus faecium is essential for anaerobic growth and gastrointestinal colonization. Gut Microbes 2024; 16:2359665. [PMID: 38831611 PMCID: PMC11152105 DOI: 10.1080/19490976.2024.2359665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 05/21/2024] [Indexed: 06/05/2024] Open
Abstract
The facultative anaerobic Gram-positive bacterium Enterococcus faecium is a ubiquitous member of the human gut microbiota. However, it has gradually evolved into a pathogenic and multidrug resistant lineage that causes nosocomial infections. The establishment of high-level intestinal colonization by enterococci represents a critical step of infection. The majority of current research on Enterococcus has been conducted under aerobic conditions, while limited attention has been given to its physiological characteristics in anaerobic environments, which reflects its natural colonization niche in the gut. In this study, a high-density transposon mutant library containing 26,620 distinct insertion sites was constructed. Tn-seq analysis identified six genes that significantly contribute to growth under anaerobic conditions. Under anaerobic conditions, deletion of sufB (encoding Fe-S cluster assembly protein B) results in more extensive and significant impairments on carbohydrate metabolism compared to aerobic conditions. Consistently, the pathways involved in this utilization-restricted carbohydrates were mostly expressed at significantly lower levels in mutant compared to wild-type under anaerobic conditions. Moreover, deletion of sufB or pflA (encoding pyruvate formate lyase-activating protein A) led to failure of gastrointestinal colonization in mice. These findings contribute to our understanding of the mechanisms by which E. faecium maintains proliferation under anaerobic conditions and establishes colonization in the gut.
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Affiliation(s)
- Linan Xu
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai’an, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xiangpeng Yang
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinxin Pang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yansha Wu
- Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Xingshuai Li
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yuzhong Zhao
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai’an, China
| | - Lumin Yu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Peikun Wang
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Bin Ye
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Shijin Jiang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai’an, China
| | - Junfei Ma
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinglin Zhang
- College of Agriculture and Forestry, Linyi University, Linyi, China
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7
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Bremer E, Calteau A, Danchin A, Harwood C, Helmann JD, Médigue C, Palsson BO, Sekowska A, Vallenet D, Zuniga A, Zuniga C. A model industrial workhorse:
Bacillus subtilis
strain 168 and its genome after a quarter of a century. Microb Biotechnol 2023; 16:1203-1231. [PMID: 37002859 DOI: 10.1111/1751-7915.14257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 03/20/2023] [Indexed: 04/04/2023] Open
Abstract
The vast majority of genomic sequences are automatically annotated using various software programs. The accuracy of these annotations depends heavily on the very few manual annotation efforts that combine verified experimental data with genomic sequences from model organisms. Here, we summarize the updated functional annotation of Bacillus subtilis strain 168, a quarter century after its genome sequence was first made public. Since the last such effort 5 years ago, 1168 genetic functions have been updated, allowing the construction of a new metabolic model of this organism of environmental and industrial interest. The emphasis in this review is on new metabolic insights, the role of metals in metabolism and macromolecule biosynthesis, functions involved in biofilm formation, features controlling cell growth, and finally, protein agents that allow class discrimination, thus allowing maintenance management, and accuracy of all cell processes. New 'genomic objects' and an extensive updated literature review have been included for the sequence, now available at the International Nucleotide Sequence Database Collaboration (INSDC: AccNum AL009126.4).
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Affiliation(s)
- Erhard Bremer
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
| | - Alexandra Calteau
- LABGeM, Génomique Métabolique, CEA, Genoscope, Institut de Biologie François Jacob Université d'Évry, Université Paris‐Saclay, CNRS Évry France
| | - Antoine Danchin
- School of Biomedical Sciences, Li KaShing Faculty of Medicine Hong Kong University Pokfulam SAR Hong Kong China
| | - Colin Harwood
- Centre for Bacterial Cell Biology, Biosciences Institute Newcastle University Baddiley Clark Building Newcastle upon Tyne UK
| | - John D. Helmann
- Department of Microbiology Cornell University Ithaca New York USA
| | - Claudine Médigue
- LABGeM, Génomique Métabolique, CEA, Genoscope, Institut de Biologie François Jacob Université d'Évry, Université Paris‐Saclay, CNRS Évry France
| | - Bernhard O. Palsson
- Department of Bioengineering University of California San Diego La Jolla USA
| | | | - David Vallenet
- LABGeM, Génomique Métabolique, CEA, Genoscope, Institut de Biologie François Jacob Université d'Évry, Université Paris‐Saclay, CNRS Évry France
| | - Abril Zuniga
- Department of Biology San Diego State University San Diego California USA
| | - Cristal Zuniga
- Bioinformatics and Medical Informatics Graduate Program San Diego State University San Diego California USA
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8
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Abstract
Living systems are built from a small subset of the atomic elements, including the bulk macronutrients (C,H,N,O,P,S) and ions (Mg,K,Na,Ca) together with a small but variable set of trace elements (micronutrients). Here, we provide a global survey of how chemical elements contribute to life. We define five classes of elements: those that are (i) essential for all life, (ii) essential for many organisms in all three domains of life, (iii) essential or beneficial for many organisms in at least one domain, (iv) beneficial to at least some species, and (v) of no known beneficial use. The ability of cells to sustain life when individual elements are absent or limiting relies on complex physiological and evolutionary mechanisms (elemental economy). This survey of elemental use across the tree of life is encapsulated in a web-based, interactive periodic table that summarizes the roles chemical elements in biology and highlights corresponding mechanisms of elemental economy.
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Affiliation(s)
- Kaleigh A Remick
- Department of Microbiology, Cornell University, New York, NY, United States
| | - John D Helmann
- Department of Microbiology, Cornell University, New York, NY, United States.
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9
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Fujishiro T, Nakamura R, Kunichika K, Takahashi Y. Structural diversity of cysteine desulfurases involved in iron-sulfur cluster biosynthesis. Biophys Physicobiol 2022; 19:1-18. [PMID: 35377584 PMCID: PMC8918507 DOI: 10.2142/biophysico.bppb-v19.0001] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/02/2022] [Indexed: 12/04/2022] Open
Abstract
Cysteine desulfurases are pyridoxal-5'-phosphate (PLP)-dependent enzymes that mobilize sulfur derived from the l-cysteine substrate to the partner sulfur acceptor proteins. Three cysteine desulfurases, IscS, NifS, and SufS, have been identified in ISC, NIF, and SUF/SUF-like systems for iron-sulfur (Fe-S) cluster biosynthesis, respectively. These cysteine desulfurases have been investigated over decades, providing insights into shared/distinct catalytic processes based on two types of enzymes (type I: IscS and NifS, type II: SufS). This review summarizes the insights into the structural/functional varieties of bacterial and eukaryotic cysteine desulfurases involved in Fe-S cluster biosynthetic systems. In addition, an inactive cysteine desulfurase IscS paralog, which contains pyridoxamine-5'-phosphate (PMP), instead of PLP, is also described to account for its hypothetical function in Fe-S cluster biosynthesis involving this paralog. The structural basis for cysteine desulfurase functions will be a stepping stone towards understanding the diversity and evolution of Fe-S cluster biosynthesis.
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Affiliation(s)
- Takashi Fujishiro
- Department of Biochemistry and Moecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Ryosuke Nakamura
- Department of Biochemistry and Moecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Kouhei Kunichika
- Department of Biochemistry and Moecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Yasuhiro Takahashi
- Department of Biochemistry and Moecular Biology, Graduate School of Science and Engineering, Saitama University
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10
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Shomar H, Bokinsky G. Towards a Synthetic Biology Toolset for Metallocluster Enzymes in Biosynthetic Pathways: What We Know and What We Need. Molecules 2021; 26:molecules26226930. [PMID: 34834021 PMCID: PMC8617995 DOI: 10.3390/molecules26226930] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022] Open
Abstract
Microbes are routinely engineered to synthesize high-value chemicals from renewable materials through synthetic biology and metabolic engineering. Microbial biosynthesis often relies on expression of heterologous biosynthetic pathways, i.e., enzymes transplanted from foreign organisms. Metallocluster enzymes are one of the most ubiquitous family of enzymes involved in natural product biosynthesis and are of great biotechnological importance. However, the functional expression of recombinant metallocluster enzymes in live cells is often challenging and represents a major bottleneck. The activity of metallocluster enzymes requires essential supporting pathways, involved in protein maturation, electron supply, and/or enzyme stability. Proper function of these supporting pathways involves specific protein-protein interactions that remain poorly characterized and are often overlooked by traditional synthetic biology approaches. Consequently, engineering approaches that focus on enzymatic expression and carbon flux alone often overlook the particular needs of metallocluster enzymes. This review highlights the biotechnological relevance of metallocluster enzymes and discusses novel synthetic biology strategies to advance their industrial application, with a particular focus on iron-sulfur cluster enzymes. Strategies to enable functional heterologous expression and enhance recombinant metallocluster enzyme activity in industrial hosts include: (1) optimizing specific maturation pathways; (2) improving catalytic stability; and (3) enhancing electron transfer. In addition, we suggest future directions for developing microbial cell factories that rely on metallocluster enzyme catalysis.
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Affiliation(s)
- Helena Shomar
- INSERM U722, Faculté de Médecine, Université de Paris, Site Xavier Bichat, 75018 Paris, France
- Correspondence: (H.S.); (G.B.)
| | - Gregory Bokinsky
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
- Correspondence: (H.S.); (G.B.)
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11
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Abstract
Building iron-sulfur (Fe-S) clusters and assembling Fe-S proteins are essential actions for life on Earth. The three processes that sustain life, photosynthesis, nitrogen fixation, and respiration, require Fe-S proteins. Genes coding for Fe-S proteins can be found in nearly every sequenced genome. Fe-S proteins have a wide variety of functions, and therefore, defective assembly of Fe-S proteins results in cell death or global metabolic defects. Compared to alternative essential cellular processes, there is less known about Fe-S cluster synthesis and Fe-S protein maturation. Moreover, new factors involved in Fe-S protein assembly continue to be discovered. These facts highlight the growing need to develop a deeper biological understanding of Fe-S cluster synthesis, holo-protein maturation, and Fe-S cluster repair. Here, we outline bacterial strategies used to assemble Fe-S proteins and the genetic regulation of these processes. We focus on recent and relevant findings and discuss future directions, including the proposal of using Fe-S protein assembly as an antipathogen target.
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12
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Ellepola K, Huang X, Riley RP, Bitoun JP, Wen ZT. Streptococcus mutans Lacking sufCDSUB Is Viable, but Displays Major Defects in Growth, Stress Tolerance Responses and Biofilm Formation. Front Microbiol 2021; 12:671533. [PMID: 34248879 PMCID: PMC8264796 DOI: 10.3389/fmicb.2021.671533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/11/2021] [Indexed: 11/13/2022] Open
Abstract
Streptococcus mutans appears to possess a sole iron-sulfur (Fe-S) cluster biosynthesis system encoded by the sufCDSUB cluster. This study was designed to examine the role of sufCDSUB in S. mutans physiology. Allelic exchange mutants deficient of the whole sufCDSUB cluster and in individual genes were constructed. Compared to the wild-type, UA159, the sufCDSUB-deficient mutant, Δsuf::kanr, had a significantly reduced growth rate, especially in medium with the absence of isoleucine, leucine or glutamate/glutamine, amino acids that require Fe-S clusters for biosynthesis and when grown with medium adjusted to pH 6.0 and under oxidative and nitrosative stress conditions. Relative to UA159, Δsuf::kanr had major defects in stress tolerance responses with reduced survival rate of > 2-logs following incubation at low pH environment or after hydrogen peroxide challenge. When compared to UA159, Δsuf::kanr tended to form aggregates in broth medium and accumulated significantly less biofilm. As shown by luciferase reporter fusion assays, the expression of sufCDSUB was elevated by > 5.4-fold when the reporter strain was transferred from iron sufficient medium to iron-limiting medium. Oxidative stress induced by methyl viologen increased sufCDSUB expression by > 2-fold, and incubation in a low pH environment led to reduction of sufCDSUB expression by > 7-fold. These results suggest that lacking of SufCDSUB in S. mutans causes major defects in various cellular processes of the deficient mutant, including growth, stress tolerance responses and biofilm formation. In addition, the viability of the deficient mutant also suggests that SUF, the sole Fe-S cluster machinery identified is non-essential in S. mutans, which is not known in any other bacterium lacking the NIF and/or ISC system. However, how the bacterium compensates the Fe-S deficiency and if any novel Fe-S assembly systems exist in this bacterium await further investigation.
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Affiliation(s)
- Kassapa Ellepola
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Xiaochang Huang
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Ryan P Riley
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Jacob P Bitoun
- Department of Microbiology, Tulane University, New Orleans, LA, United States
| | - Zezhang Tom Wen
- Department of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
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13
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Identification of Genes Involved in Fe-S Cluster Biosynthesis of Nitrogenase in Paenibacillus polymyxa WLY78. Int J Mol Sci 2021; 22:ijms22073771. [PMID: 33916504 PMCID: PMC8038749 DOI: 10.3390/ijms22073771] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/26/2021] [Accepted: 04/01/2021] [Indexed: 11/17/2022] Open
Abstract
NifS and NifU (encoded by nifS and nifU) are generally dedicated to biogenesis of the nitrogenase Fe–S cluster in diazotrophs. However, nifS and nifU are not found in N2-fixing Paenibacillus strains, and the mechanisms involved in Fe–S cluster biosynthesis of nitrogenase is not clear. Here, we found that the genome of Paenibacillus polymyxa WLY78 contains the complete sufCDSUB operon, a partial sufC2D2B2 operon, a nifS-like gene, two nifU-like genes (nfuA-like and yutI), and two iscS genes. Deletion and complementation studies showed that the sufC, sufD, and sufB genes of the sufCDSUB operon, and nifS-like and yutI genes were involved in the Fe–S cluster biosynthesis of nitrogenase. Heterologous complementation studies demonstrated that the nifS-like gene of P. polymyxa WLY78 is interchangeable with Klebsiella oxytoca nifS, but P. polymyxa WLY78 SufCDB cannot be functionally replaced by K. oxytoca NifU. In addition, K. oxytoca nifU and Escherichia coli nfuA are able to complement the P. polymyxa WLY78 yutI mutant. Our findings thus indicate that the NifS-like and SufCDB proteins are the specific sulfur donor and the molecular scaffold, respectively, for the Fe–S cluster formation of nitrogenase in P. polymyxa WLY78. YutI can be an Fe–S cluster carrier involved in nitrogenase maturation in P. polymyxa WLY78.
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14
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Sato S, Matsushima Y, Kanazawa M, Tanaka N, Fujishiro T, Kunichika K, Nakamura R, Tomioka H, Wada K, Takahashi Y. Evidence for dynamic in vivo interconversion of the conformational states of IscU during iron-sulfur cluster biosynthesis. Mol Microbiol 2020; 115:807-818. [PMID: 33202070 DOI: 10.1111/mmi.14646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/02/2020] [Accepted: 11/12/2020] [Indexed: 11/28/2022]
Abstract
IscU is a central component of the ISC machinery and serves as a scaffold for de novo assembly of Fe-S clusters. The dedicated chaperone system composed of the Hsp70-chaperone HscA and the J-protein cochaperone HscB synergistically interacts with IscU and facilitates cluster transfer from IscU to recipient apo-proteins. Here, we report that the otherwise essential roles of HscA and HscB can be bypassed in vivo by a number of single amino acid substitutions in IscU. CD spectroscopic studies of the variant IscU proteins capable of this bypass activity revealed dynamic interconversion between two conformations: the denatured (D) and the structured (S) state in the absence and presence of Zn2+ , respectively, which was far more prominent than interconversion observed in wild-type IscU. Furthermore, we found that neither the S-shifted (more structured) variants of IscU nor the perpetually denatured variants could perform their in vivo role regardless of whether the chaperone system was present or not. The present study thus provides for the first time evidence that an in vivo D-state of IscU exists and implies that conformational interconversion between the S- and D-states of the scaffolding protein is a fundamental requirement for the assembly and transfer of the Fe-S cluster.
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Affiliation(s)
- Sakiko Sato
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Yumeka Matsushima
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Miaki Kanazawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Naoyuki Tanaka
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Takashi Fujishiro
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Kouhei Kunichika
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Ryosuke Nakamura
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Hiroaki Tomioka
- Department of Science Education, Graduate School of Education, Saitama University, Saitama, Japan
| | - Kei Wada
- Department of Medical Sciences, University of Miyazaki, Miyazaki, Japan
| | - Yasuhiro Takahashi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
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15
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Abstract
Iron–sulfur (Fe–S) clusters are protein cofactors of a multitude of enzymes performing essential biological functions. Specialized multi-protein machineries present in all types of organisms support their biosynthesis. These machineries encompass a scaffold protein on which Fe–S clusters are assembled and a cysteine desulfurase that provides sulfur in the form of a persulfide. The sulfide ions are produced by reductive cleavage of the persulfide, which involves specific reductase systems. Several other components are required for Fe–S biosynthesis, including frataxin, a key protein of controversial function and accessory components for insertion of Fe–S clusters in client proteins. Fe–S cluster biosynthesis is thought to rely on concerted and carefully orchestrated processes. However, the elucidation of the mechanisms of their assembly has remained a challenging task due to the biochemical versatility of iron and sulfur and the relative instability of Fe–S clusters. Nonetheless, significant progresses have been achieved in the past years, using biochemical, spectroscopic and structural approaches with reconstituted system in vitro. In this paper, we review the most recent advances on the mechanism of assembly for the founding member of the Fe–S cluster family, the [2Fe2S] cluster that is the building block of all other Fe–S clusters. The aim is to provide a survey of the mechanisms of iron and sulfur insertion in the scaffold proteins by examining how these processes are coordinated, how sulfide is produced and how the dinuclear [2Fe2S] cluster is formed, keeping in mind the question of the physiological relevance of the reconstituted systems. We also cover the latest outcomes on the functional role of the controversial frataxin protein in Fe–S cluster biosynthesis.
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16
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Braymer JJ, Freibert SA, Rakwalska-Bange M, Lill R. Mechanistic concepts of iron-sulfur protein biogenesis in Biology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118863. [PMID: 33007329 DOI: 10.1016/j.bbamcr.2020.118863] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 09/14/2020] [Accepted: 09/17/2020] [Indexed: 02/08/2023]
Abstract
Iron-sulfur (Fe/S) proteins are present in virtually all living organisms and are involved in numerous cellular processes such as respiration, photosynthesis, metabolic reactions, nitrogen fixation, radical biochemistry, protein synthesis, antiviral defense, and genome maintenance. Their versatile functions may go back to the proposed role of their Fe/S cofactors in the origin of life as efficient catalysts and electron carriers. More than two decades ago, it was discovered that the in vivo synthesis of cellular Fe/S clusters and their integration into polypeptide chains requires assistance by complex proteinaceous machineries, despite the fact that Fe/S proteins can be assembled chemically in vitro. In prokaryotes, three Fe/S protein biogenesis systems are known; ISC, SUF, and the more specialized NIF. The former two systems have been transferred by endosymbiosis from bacteria to mitochondria and plastids, respectively, of eukaryotes. In their cytosol, eukaryotes use the CIA machinery for the biogenesis of cytosolic and nuclear Fe/S proteins. Despite the structural diversity of the protein constituents of these four machineries, general mechanistic concepts underlie the complex process of Fe/S protein biogenesis. This review provides a comprehensive and comparative overview of the various known biogenesis systems in Biology, and summarizes their common or diverging molecular mechanisms, thereby illustrating both the conservation and diverse adaptions of these four machineries during evolution and under different lifestyles. Knowledge of these fundamental biochemical pathways is not only of basic scientific interest, but is important for the understanding of human 'Fe/S diseases' and can be used in biotechnology.
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Affiliation(s)
- Joseph J Braymer
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, 35032 Marburg, Germany
| | - Sven A Freibert
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, 35032 Marburg, Germany
| | | | - Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, 35032 Marburg, Germany; SYNMIKRO Center for Synthetic Microbiology, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35043 Marburg, Germany.
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17
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Blahut M, Sanchez E, Fisher CE, Outten FW. Fe-S cluster biogenesis by the bacterial Suf pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118829. [PMID: 32822728 DOI: 10.1016/j.bbamcr.2020.118829] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 01/01/2023]
Abstract
Biogenesis of iron-sulfur (FeS) clusters in an essential process in living organisms due to the critical role of FeS cluster proteins in myriad cell functions. During biogenesis of FeS clusters, multi-protein complexes are used to drive the mobilization and protection of reactive sulfur and iron intermediates, regulate assembly of various FeS clusters on an ATPase-dependent, multi-protein scaffold, and target nascent clusters to their downstream protein targets. The evolutionarily ancient sulfur formation (Suf) pathway for FeS cluster assembly is found in bacteria and archaea. In Escherichia coli, the Suf pathway functions as an emergency pathway under conditions of iron limitation or oxidative stress. In other pathogenic bacteria, such as Mycobacterium tuberculosis and Enterococcus faecalis, the Suf pathway is the sole source for FeS clusters and therefore is a potential target for the development of novel antibacterial compounds. Here we summarize the considerable progress that has been made in characterizing the first step of mobilization and protection of reactive sulfur carried out by the SufS-SufE or SufS-SufU complex, FeS cluster assembly on SufBC2D scaffold complexes, and the downstream trafficking of nascent FeS clusters to A-type carrier (ATC) proteins. Cell Biology of Metals III edited by Roland Lill and Mick Petris.
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Affiliation(s)
- Matthew Blahut
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, SC 29208, USA
| | - Enis Sanchez
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, SC 29208, USA
| | - Claire E Fisher
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, SC 29208, USA
| | - F Wayne Outten
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, SC 29208, USA.
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18
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The Nonmevalonate Pathway of Isoprenoid Biosynthesis Supports Anaerobic Growth of Listeria monocytogenes. Infect Immun 2020; 88:IAI.00788-19. [PMID: 31792073 DOI: 10.1128/iai.00788-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 11/21/2019] [Indexed: 11/20/2022] Open
Abstract
Isoprenoids are an essential and diverse class of molecules, present in all forms of life, that are synthesized from an essential common precursor derived from either the mevalonate pathway or the nonmevalonate pathway. Most bacteria have one pathway or the other, but the Gram-positive, facultative intracellular pathogen Listeria monocytogenes is unusual because it carries all the genes for both pathways. While the mevalonate pathway has previously been reported to be essential, here we demonstrate that the nonmevalonate pathway can support growth of strains 10403S and EGD-e, but only anaerobically. L. monocytogenes lacking the gene hmgR, encoding the rate-limiting enzyme of the mevalonate pathway, had a doubling time of 4 h under anaerobic conditions, in contrast to the 45 min doubling time of the wild type. In contrast, deleting hmgR in two clinical isolates resulted in mutants that grew significantly faster, doubling in approximately 2 h anaerobically, although they still failed to grow under aerobic conditions without mevalonate. The difference in anaerobic growth rate was traced to three amino acid changes in the nonmevalonate pathway enzyme GcpE, and these changes were sufficient to increase the growth rate of 10403S to the rate observed in the clinical isolates. Despite an increased growth rate, virulence was still dependent on the mevalonate pathway in 10403S strains expressing the more active GcpE allele.
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19
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Nakamura R, Hikita M, Ogawa S, Takahashi Y, Fujishiro T. Snapshots of PLP‐substrate and PLP‐product external aldimines as intermediates in two types of cysteine desulfurase enzymes. FEBS J 2019; 287:1138-1154. [DOI: 10.1111/febs.15081] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 08/11/2019] [Accepted: 10/01/2019] [Indexed: 11/27/2022]
Affiliation(s)
- Ryosuke Nakamura
- Department of Biochemistry and Molecular Biology Graduate School of Science and Engineering Saitama University Saitama Japan
| | - Masahide Hikita
- Structural Biology Research Center, Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukuba Japan
| | - Shoko Ogawa
- Department of Biochemistry and Molecular Biology Graduate School of Science and Engineering Saitama University Saitama Japan
| | - Yasuhiro Takahashi
- Department of Biochemistry and Molecular Biology Graduate School of Science and Engineering Saitama University Saitama Japan
| | - Takashi Fujishiro
- Department of Biochemistry and Molecular Biology Graduate School of Science and Engineering Saitama University Saitama Japan
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20
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Tanaka N, Yuda E, Fujishiro T, Hirabayashi K, Wada K, Takahashi Y. Identification of IscU residues critical for de novo iron-sulfur cluster assembly. Mol Microbiol 2019; 112:1769-1783. [PMID: 31532036 DOI: 10.1111/mmi.14392] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2019] [Indexed: 01/16/2023]
Abstract
IscU is a central component of the ISC machinery and serves as a scaffold for the de novo assembly of iron-sulfur (Fe-S) clusters prior to their delivery to target apo-Fe-S proteins. However, the molecular mechanism is not yet fully understood. In this study, we have conducted mutational analysis of E. coli IscU using the recently developed genetic complementation system of a mutant that can survive without Fe-S clusters. The Fe-S cluster ligands (C37, C63, H105, C106) and the proximal D39 and K103 residues are essential for in vivo function of IscU and could not be substituted with any other amino acids. Furthermore, we found that substitution of Y3, a strictly conserved residue among IscU homologs, abolished in vivo functions. Surprisingly, a second-site suppressor mutation in IscS (A349V) reverted the defect caused by IscU Y3 substitutions. Biochemical analysis revealed that IscU Y3 was crucial for functional interaction with IscS and sulfur transfer between the two proteins. Our findings suggest that the critical role of IscU Y3 is linked to the conformational dynamics of the flexible loop of IscS, which is required for the ingenious sulfur transfer to IscU.
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Affiliation(s)
- Naoyuki Tanaka
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Eiki Yuda
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Takashi Fujishiro
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Kei Hirabayashi
- Department of Medical Sciences, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Kei Wada
- Department of Medical Sciences, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Yasuhiro Takahashi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
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21
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Zheng C, Guo S, Tennant WG, Pradhan PK, Black KA, Dos Santos PC. The Thioredoxin System Reduces Protein Persulfide Intermediates Formed during the Synthesis of Thio-Cofactors in Bacillus subtilis. Biochemistry 2019; 58:1892-1904. [PMID: 30855939 DOI: 10.1021/acs.biochem.9b00045] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biosynthesis of Fe-S clusters and other thio-cofactors requires the participation of redox agents. A shared feature in these pathways is the formation of transient protein persulfides, which are susceptible to reduction by artificial reducing agents commonly used in reactions in vitro. These agents modulate the reactivity and catalytic efficiency of biosynthetic reactions and, in some cases, skew the enzymes' kinetic behavior, bypassing sulfur acceptors known to be critical for the functionality of these pathways in vivo. Here, we provide kinetic evidence for the selective reactivity of the Bacillus subtilis Trx (thioredoxin) system toward protein-bound persulfide intermediates. Our results demonstrate that the redox flux of the Trx system modulates the rate of sulfide production in cysteine desulfurase assays. Likewise, the activity of the Trx system is dependent on the rate of persulfide formation, suggesting the occurrence of coupled reaction schemes between both enzymatic systems in vitro. Inactivation of TrxA (thioredoxin) or TrxR (thioredoxin reductase) impairs the activity of Fe-S enzymes in B. subtilis, indicating the involvement of the Trx system in Fe-S cluster metabolism. Surprisingly, biochemical characterization of TrxA reveals that this enzyme is able to coordinate Fe-S species, resulting in the loss of its reductase activity. The inactivation of TrxA through the coordination of a labile cluster, combined with its proposed role as a physiological reducing agent in sulfur transfer pathways, suggests a model for redox regulation. These findings provide a potential link between redox regulation and Fe-S metabolism.
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Affiliation(s)
- Chenkang Zheng
- Department of Chemistry , Wake Forest University , Winston-Salem , North Carolina 27106 , United States
| | - Selina Guo
- Department of Chemistry , Wake Forest University , Winston-Salem , North Carolina 27106 , United States
| | - William G Tennant
- Department of Chemistry , Wake Forest University , Winston-Salem , North Carolina 27106 , United States
| | - Pradyumna K Pradhan
- Department of Chemistry , Wake Forest University , Winston-Salem , North Carolina 27106 , United States.,Department of Chemistry and Biochemistry , The University of North Carolina at Greensboro , Greensboro , North Carolina 27412 , United States
| | - Katherine A Black
- Department of Chemistry , Wake Forest University , Winston-Salem , North Carolina 27106 , United States.,Department of Medicine , Weill Cornell Medicine , New York , New York 10065 , United States
| | - Patricia C Dos Santos
- Department of Chemistry , Wake Forest University , Winston-Salem , North Carolina 27106 , United States
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22
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Metallocluster transactions: dynamic protein interactions guide the biosynthesis of Fe-S clusters in bacteria. Biochem Soc Trans 2018; 46:1593-1603. [PMID: 30381339 DOI: 10.1042/bst20180365] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/12/2018] [Accepted: 09/14/2018] [Indexed: 12/22/2022]
Abstract
Iron-sulfur (Fe-S) clusters are ubiquitous cofactors present in all domains of life. The chemistries catalyzed by these inorganic cofactors are diverse and their associated enzymes are involved in many cellular processes. Despite the wide range of structures reported for Fe-S clusters inserted into proteins, the biological synthesis of all Fe-S clusters starts with the assembly of simple units of 2Fe-2S and 4Fe-4S clusters. Several systems have been associated with the formation of Fe-S clusters in bacteria with varying phylogenetic origins and number of biosynthetic and regulatory components. All systems, however, construct Fe-S clusters through a similar biosynthetic scheme involving three main steps: (1) sulfur activation by a cysteine desulfurase, (2) cluster assembly by a scaffold protein, and (3) guided delivery of Fe-S units to either final acceptors or biosynthetic enzymes involved in the formation of complex metalloclusters. Another unifying feature on the biological formation of Fe-S clusters in bacteria is that these systems are tightly regulated by a network of protein interactions. Thus, the formation of transient protein complexes among biosynthetic components allows for the direct transfer of reactive sulfur and Fe-S intermediates preventing oxygen damage and reactions with non-physiological targets. Recent studies revealed the importance of reciprocal signature sequence motifs that enable specific protein-protein interactions and consequently guide the transactions between physiological donors and acceptors. Such findings provide insights into strategies used by bacteria to regulate the flow of reactive intermediates and provide protein barcodes to uncover yet-unidentified cellular components involved in Fe-S metabolism.
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