1
|
Hu P, Qian Y, Liu J, Gao L, Li Y, Xu Y, Wu J, Hong Y, Ford T, Radian A, Yang Y, Gu JD. Delineation of the complex microbial nitrogen-transformation network in an anammox-driven full-scale wastewater treatment plant. WATER RESEARCH 2023; 235:119799. [PMID: 36965294 DOI: 10.1016/j.watres.2023.119799] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Microbial-driven nitrogen removal is a crucial step in modern full-scale wastewater treatment plants (WWTPs), and the complexity of nitrogen transformation is integral to the various wastewater treatment processes. A full understanding of the overall nitrogen cycling networks in WWTPs is therefore a prerequisite for the further enhancement and optimization of wastewater treatment processes. In this study, metagenomics and metatranscriptomics were used to elucidate the microbial nitrogen removal processes in an ammonium-enriched full-scale WWTP, which was configured as an anaerobic-anoxic-anaerobic-oxic system for efficient nitrogen removal (99.63%) on a duck breeding farm. A typical simultaneous nitrification-anammox-denitrification (SNAD) process was established in each tank of this WWTP. Ammonia was oxidized by ammonia-oxidizing bacteria (AOB), archaea (AOA), and nitrite-oxidizing bacteria (NOB), and the produced nitrite and nitrate were further reduced to dinitrogen gas (N2) by anammox and denitrifying bacteria. Visible red anammox biofilms were formed successfully on the sponge carriers submerged in the anoxic tank, and the nitrogen removal rate by anammox reaction was 4.85 times higher than that by denitrification based on 15N isotope labeling and analysis. This supports the significant accumulation of anammox bacteria on the carriers responsible for efficient nitrogen removal. Two distinct anammox bacteria, named "Ca. Brocadia sp. PF01" and "Ca. Jettenia sp. PF02", were identified from the biofilm in this investigation. By recovering their genomic features and their metabolic capabilities, our results indicate that the highly active core anammox process found in PF01, suggests extending its niche within the plant. With the possible contribution of the dissimilatory nitrate reduction to ammonium (DNRA) reaction, enriching PF02 within the biofilm may also be warranted. Collectively, this study highlights the effective design strategies of a full-scale WWTP with enrichment of anammox bacteria on the carrier materials for nitrogen removal and therefore the biochemical reaction mechanisms of the contributing members.
Collapse
Affiliation(s)
- Pengfei Hu
- Civil and Environmental Engineering, Technion - Israel Institute of Technology, Haifa 320003, Israel; Environmental Science and Engineering Research Group, Guangdong Technion -Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, the People's Republic of China
| | - Youfen Qian
- Civil and Environmental Engineering, Technion - Israel Institute of Technology, Haifa 320003, Israel; Environmental Science and Engineering Research Group, Guangdong Technion -Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, the People's Republic of China
| | - Jinye Liu
- State Key Laboratory of Biocontrol, School of Ecology, Sun Yat-sen University, Guangzhou, Guangdong 510275, the People's Republic of China
| | - Lin Gao
- Civil and Environmental Engineering, Technion - Israel Institute of Technology, Haifa 320003, Israel; Environmental Science and Engineering Research Group, Guangdong Technion -Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, the People's Republic of China
| | - Yuxin Li
- School of Environmental Sciences and Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006, the People's Republic of China
| | - Yanbin Xu
- School of Environmental Sciences and Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006, the People's Republic of China
| | - Jiapeng Wu
- Institute of Environmental Research at Greater Bay, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, Guangdong 510006, the People's Republic of China
| | - Yiguo Hong
- Institute of Environmental Research at Greater Bay, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, Guangdong 510006, the People's Republic of China
| | - Tim Ford
- Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Adi Radian
- Civil and Environmental Engineering, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Yuchun Yang
- State Key Laboratory of Biocontrol, School of Ecology, Sun Yat-sen University, Guangzhou, Guangdong 510275, the People's Republic of China.
| | - Ji-Dong Gu
- Civil and Environmental Engineering, Technion - Israel Institute of Technology, Haifa 320003, Israel; Environmental Science and Engineering Research Group, Guangdong Technion -Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, the People's Republic of China; Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion - Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, the People's Republic of China.
| |
Collapse
|
2
|
Kint N, Morvan C, Martin-Verstraete I. Oxygen response and tolerance mechanisms in Clostridioides difficile. Curr Opin Microbiol 2021; 65:175-182. [PMID: 34896836 DOI: 10.1016/j.mib.2021.11.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/08/2021] [Accepted: 11/17/2021] [Indexed: 01/11/2023]
Abstract
While the gut is typically thought of as anoxic, there are two intersecting and decreasing oxygen gradients that are observed in the gut: oxygen decreases from the small to the large intestine and from the intestinal epithelium toward the colon lumen. Gut oxygen levels also increase following antibiotic induced-dysbiosis. While dysbiosis favors growth of Clostridioides difficile, the oxygen increase also causes stress to this anaerobic enteropathogen. To circumvent oxygen threat, C. difficile has developed efficient strategies: sporulation, biofilm formation, the rerouting of central metabolism and the production of oxygen detoxification enzymes. Especially, reverse rubrerythrins and flavodiiron proteins involved in oxygen reduction are crucial in C. difficile ability to tolerate and survive the oxygen concentrations encountered in the gastrointestinal tract. Two regulators, σB and PerR, play pivotal role in the mastering of these adaptive responses by controlling the various systems that protect cells from oxidative damages.
Collapse
Affiliation(s)
- Nicolas Kint
- Institut Pasteur, Université de Paris, UMR CNRS 2001, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Claire Morvan
- Institut Pasteur, Université de Paris, UMR CNRS 2001, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Isabelle Martin-Verstraete
- Institut Pasteur, Université de Paris, UMR CNRS 2001, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France; Institut Universitaire de France, France.
| |
Collapse
|
3
|
Morvan C, Folgosa F, Kint N, Teixeira M, Martin-Verstraete I. Responses of Clostridia to oxygen: from detoxification to adaptive strategies. Environ Microbiol 2021; 23:4112-4125. [PMID: 34245087 DOI: 10.1111/1462-2920.15665] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/02/2021] [Accepted: 07/07/2021] [Indexed: 11/30/2022]
Abstract
Clostridia comprise bacteria of environmental, biotechnological and medical interest and many commensals of the gut microbiota. Because of their strictly anaerobic lifestyle, oxygen is a major stress for Clostridia. However, recent data showed that these bacteria can cope with O2 better than expected for obligate anaerobes through their ability to scavenge, detoxify and consume O2 . Upon O2 exposure, Clostridia redirect their central metabolism onto pathways less O2 -sensitive and induce the expression of genes encoding enzymes involved in O2 -reduction and in the repair of oxidized damaged molecules. While Faecalibacterium prausnitzii efficiently consumes O2 through a specific extracellular electron shuttling system requiring riboflavin, enzymes such as rubrerythrins and flavodiiron proteins with NAD(P)H-dependent O2 - and/or H2 O2 -reductase activities are usually encoded in other Clostridia. These two classes of enzymes play indeed a pivotal role in O2 tolerance in Clostridioides difficile and Clostridium acetobutylicum. Two main signalling pathways triggering O2 -induced responses have been described so far in Clostridia. PerR acts as a key regulator of the O2 - and/or reactive oxygen species-defence machinery while in C. difficile, σB , the sigma factor of the general stress response also plays a crucial role in O2 tolerance by controlling the expression of genes involved in O2 scavenging and repair systems.
Collapse
Affiliation(s)
- Claire Morvan
- Laboratoire Pathogenèses des Bactéries Anaérobies, Institut Pasteur, Université de Paris, Paris, F-75015, France
| | - Filipe Folgosa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
| | - Nicolas Kint
- Laboratoire Pathogenèses des Bactéries Anaérobies, Institut Pasteur, Université de Paris, Paris, F-75015, France
| | - Miguel Teixeira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
| | - Isabelle Martin-Verstraete
- Laboratoire Pathogenèses des Bactéries Anaérobies, Institut Pasteur, Université de Paris, Paris, F-75015, France
- Institut Universitaire de France, Paris, France
| |
Collapse
|
4
|
Sarasa-Buisan C, Guio J, Broset E, Peleato ML, Fillat MF, Sevilla E. FurC (PerR) from Anabaena sp. PCC7120: a versatile transcriptional regulator engaged in the regulatory network of heterocyst development and nitrogen fixation. Environ Microbiol 2021; 24:566-582. [PMID: 33938105 DOI: 10.1111/1462-2920.15552] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/19/2021] [Accepted: 04/30/2021] [Indexed: 11/29/2022]
Abstract
FurC (PerR) from Anabaena sp. PCC7120 was previously described as a key transcriptional regulator involved in setting off the oxidative stress response. In the last years, the cross-talk between oxidative stress, iron homeostasis and nitrogen metabolism is becoming more and more evident. In this work, the transcriptome of a furC-overexpressing strain was compared with that of a wild-type strain under both standard and nitrogen-deficiency conditions. The results showed that the overexpression of furC deregulates genes involved in several categories standing out photosynthesis, iron transport and nitrogen metabolism. The novel FurC-direct targets included some regulatory elements that control heterocyst development (hetZ and asr1734), genes directly involved in the heterocyst envelope formation (devBCA and hepC) and genes which participate in the nitrogen fixation process (nifHDK and nifH2, rbrA rubrerythrin and xisHI excisionase). Likewise, furC overexpression notably impacts the mRNA levels of patA encoding a key protein in the heterocyst pattern formation. The relevance of FurC in these processes is bringing out by the fact that the overexpression of furC impairs heterocyst development and cell growth under nitrogen step-down conditions. In summary, this work reveals a new player in the complex regulatory network of heterocyst formation and nitrogen fixation.
Collapse
Affiliation(s)
- Cristina Sarasa-Buisan
- Departamento de Bioquímica y Biología Molecular y Celular and Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain
| | - Jorge Guio
- Departamento de Bioquímica y Biología Molecular y Celular and Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain
| | - Esther Broset
- Departamento de Bioquímica y Biología Molecular y Celular and Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain
| | - M Luisa Peleato
- Departamento de Bioquímica y Biología Molecular y Celular and Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain
| | - María F Fillat
- Departamento de Bioquímica y Biología Molecular y Celular and Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain
| | - Emma Sevilla
- Departamento de Bioquímica y Biología Molecular y Celular and Institute for Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain
| |
Collapse
|
5
|
Sevilla E, Bes MT, Peleato ML, Fillat MF. Fur-like proteins: Beyond the ferric uptake regulator (Fur) paralog. Arch Biochem Biophys 2021; 701:108770. [PMID: 33524404 DOI: 10.1016/j.abb.2021.108770] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/12/2021] [Accepted: 01/17/2021] [Indexed: 10/22/2022]
Abstract
Proteins belonging to the FUR (ferric uptake regulator) family are the cornerstone of metalloregulation in most prokaryotes. Although numerous reviews have been devoted to these proteins, these reports are mainly focused on the Fur paralog that gives name to the family. In the last years, the increasing knowledge on the other, less ubiquitous members of this family has evidenced their importance in bacterial metabolism. As the Fur paralog, the major regulator of iron homeostasis, Zur, Irr, BosR and PerR are tightly related to stress defenses and host-pathogen interaction being in many cases essential for virulence. Furthermore, the Nur and Mur paralogs largely contribute to control nickel and manganese homeostasis, which are cofactors of pivotal proteins for host colonization and bacterial redox homeostasis. The present review highlights the main features of FUR proteins that differ to the canonical Fur paralog either in the coregulatory metal, such as Zur, Nur and Mur, or in the action mechanism to control target genes, such as PerR, Irr and BosR.
Collapse
Affiliation(s)
- Emma Sevilla
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC and BIFI-IQFR Joint Units), Universidad de Zaragoza, Zaragoza, Spain
| | - M Teresa Bes
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC and BIFI-IQFR Joint Units), Universidad de Zaragoza, Zaragoza, Spain
| | - M Luisa Peleato
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC and BIFI-IQFR Joint Units), Universidad de Zaragoza, Zaragoza, Spain
| | - María F Fillat
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC and BIFI-IQFR Joint Units), Universidad de Zaragoza, Zaragoza, Spain.
| |
Collapse
|
6
|
Nóbrega CS, Pauleta SR. Reduction of hydrogen peroxide in gram-negative bacteria - bacterial peroxidases. Adv Microb Physiol 2019; 74:415-464. [PMID: 31126534 DOI: 10.1016/bs.ampbs.2019.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Bacteria display an array of enzymes to detoxify reactive oxygen species that cause damage to DNA and to other biomolecules leading to cell death. Hydrogen peroxide is one of these species, with endogenous and exogenous sources, such as lactic acid bacteria, oxidative burst of the immune system or chemical reactions at oxic-anoxic interfaces. The enzymes that detoxify hydrogen peroxide will be the focus of this review, with special emphasis on bacterial peroxidases that reduce hydrogen peroxide to water. Bacterial peroxidases are periplasmic cytochromes with either two or three c-type haems, which have been classified as classical and non-classical bacterial peroxidases, respectively. Most of the studies have been focus on the classical bacterial peroxidases, showing the presence of a reductive activation in the presence of calcium ions. Mutagenesis studies have clarified the catalytic mechanism of this enzyme and were used to propose an intramolecular electron transfer pathway, with far less being known about the intermolecular electron transfer that occurs between reduced electron donors and the enzyme. The physiological function of these enzymes was not very clear until it was shown, for the non-classical bacterial peroxidase, that this enzyme is required for the bacteria to use hydrogen peroxide as terminal electron acceptor under anoxic conditions. These non-classical bacterial peroxidases are quinol peroxidases that do not require reductive activation but need calcium ions to attain maximum activity and share similar catalytic intermediates with the classical bacterial peroxidases.
Collapse
Affiliation(s)
- Cláudia S Nóbrega
- Microbial Stress Lab, UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Sofia R Pauleta
- Microbial Stress Lab, UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| |
Collapse
|
7
|
Abstract
SIGNIFICANCE Iron is required for growth and is often redox active under cytosolic conditions. As a result of its facile redox chemistry, iron homeostasis is intricately involved with oxidative stress. Bacterial adaptation to iron limitation and oxidative stress often involves ferric uptake regulator (Fur) proteins: a diverse set of divalent cation-dependent, DNA-binding proteins that vary widely in both metal selectivity and sensitivity to metal-catalyzed oxidation. Recent Advances: Bacteria contain two Fur family metalloregulators that use ferrous iron (Fe2+) as their cofactor, Fur and PerR. Fur functions to regulate iron homeostasis in response to changes in intracellular levels of Fe2+. PerR also binds Fe2+, which enables metal-catalyzed protein oxidation as a mechanism for sensing hydrogen peroxide (H2O2). CRITICAL ISSUES To effectively regulate iron homeostasis, Fur has an Fe2+ affinity tuned to monitor the labile iron pool of the cell and may be under selective pressure to minimize iron oxidation, which would otherwise lead to an inappropriate increase in iron uptake under oxidative stress conditions. Conversely, Fe2+ is bound more tightly to PerR but exhibits high H2O2 reactivity, which enables a rapid induction of peroxide stress genes. FUTURE DIRECTIONS The features that determine the disparate reactivity of these proteins with oxidants are still poorly understood. A controlled, comparative analysis of the affinities of Fur/PerR proteins for their metal cofactors and their rate of reactivity with H2O2, combined with structure/function analyses, will be needed to define the molecular mechanisms that have facilitated this divergence of function between these two paralogous regulators.
Collapse
Affiliation(s)
| | - John D Helmann
- Department of Microbiology, Cornell University , Ithaca, New York
| |
Collapse
|
8
|
Urresti S, Cartmell A, Liu F, Walton PH, Davies GJ. Structural studies of the unusual metal-ion site of the GH124 endoglucanase from Ruminiclostridium thermocellum. Acta Crystallogr F Struct Biol Commun 2018; 74:496-505. [PMID: 30084399 PMCID: PMC6096483 DOI: 10.1107/s2053230x18006842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/03/2018] [Indexed: 12/20/2022] Open
Abstract
The recent discovery of `lytic' polysaccharide monooxygenases, copper-dependent enzymes for biomass degradation, has provided new impetus for the analysis of unusual metal-ion sites in carbohydrate-active enzymes. In this context, the CAZY family GH124 endoglucanase from Ruminiclostridium thermocellum contains an unusual metal-ion site, which was originally modelled as a Ca2+ site but features aspartic acid, asparagine and two histidine imidazoles as coordinating residues, which are more consistent with a transition-metal binding environment. It was sought to analyse whether the GH124 metal-ion site might accommodate other metals. It is demonstrated through thermal unfolding experiments that this metal-ion site can accommodate a range of transition metals (Fe2+, Cu2+, Mn2+ and Ni2+), whilst the three-dimensional structure and mass spectrometry show that one of the histidines is partially covalently modified and is present as a 2-oxohistidine residue; a feature that is rarely observed but that is believed to be involved in an `off-switch' to transition-metal binding. Atomic resolution (<1.1 Å) complexes define the metal-ion site and also reveal the binding of an unusual fructosylated oligosaccharide, which was presumably present as a contaminant in the cellohexaose used for crystallization. Although it has not been possible to detect a biological role for the unusual metal-ion site, this work highlights the need to study some of the many metal-ion sites in carbohydrate-active enzymes that have long been overlooked or previously mis-assigned.
Collapse
Affiliation(s)
- Saioa Urresti
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
| | - Alan Cartmell
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, England
| | - Feng Liu
- Department of Chemistry, University of British Columbia, Vancouver V6T 1Z1, Canada
| | - Paul H. Walton
- Department of Chemistry, University of York, York YO10 5DD, England
| | - Gideon J. Davies
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
| |
Collapse
|
9
|
Kebouchi M, Saul F, Taher R, Landier A, Beaudeau B, Dubrac S, Weber P, Haouz A, Picardeau M, Benaroudj N. Structure and function of the Leptospira interrogans peroxide stress regulator (PerR), an atypical PerR devoid of a structural metal-binding site. J Biol Chem 2017; 293:497-509. [PMID: 29146596 DOI: 10.1074/jbc.m117.804443] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/10/2017] [Indexed: 01/24/2023] Open
Abstract
Peroxide sensing is essential for bacterial survival during aerobic metabolism and host infection. Peroxide stress regulators (PerRs) are homodimeric transcriptional repressors with each monomer typically containing both structural and regulatory metal-binding sites. PerR binding to gene promoters is controlled by the presence of iron in the regulatory site, and iron-catalyzed oxidation of PerR by H2O2 leads to the dissociation of PerR from DNA. In addition to a regulatory metal, most PerRs require a structural metal for proper dimeric assembly. We present here a structural and functional characterization of the PerR from the pathogenic spirochete Leptospira interrogans, a rare example of PerR lacking a structural metal-binding site. In vivo studies showed that the leptospiral PerR belongs to the peroxide stimulon in pathogenic species and is involved in controlling resistance to peroxide. Moreover, a perR mutant had decreased fitness in other host-related stress conditions, including at 37 °C or in the presence of superoxide anion. In vitro, leptospiral PerR could bind to the perR promoter region in a metal-dependent manner. The crystal structure of the leptospiral PerR revealed an asymmetric homodimer, with one monomer displaying complete regulatory metal coordination in the characteristic caliper-like DNA-binding conformation and the second monomer exhibiting disrupted regulatory metal coordination in an open non-DNA-binding conformation. This structure showed that leptospiral PerR assembles into a dimer in which a metal-induced conformational switch can occur independently in the two monomers. Our study demonstrates that structural metal binding is not compulsory for PerR dimeric assembly and for regulating peroxide stress.
Collapse
Affiliation(s)
| | | | | | | | | | - Sarah Dubrac
- Unité de Biologie des Bactéries Pathogènes à Gram Positif, Institut Pasteur, F-75015 Paris, France
| | | | - Ahmed Haouz
- Plate-forme de Cristallographie, CNRS UMR 3528, and
| | | | | |
Collapse
|