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Huo X, Zhou Z, Liu H, Wang G, Shi K. A PadR family transcriptional repressor regulates the transcription of chromate efflux transporter in Enterobacter sp. Z1. J Microbiol 2024; 62:355-365. [PMID: 38587592 DOI: 10.1007/s12275-024-00117-0] [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: 09/25/2023] [Revised: 01/10/2024] [Accepted: 01/23/2024] [Indexed: 04/09/2024]
Abstract
Chromium is a prevalent toxic heavy metal, and chromate [Cr(VI)] exhibits high mutagenicity and carcinogenicity. The presence of the Cr(VI) efflux protein ChrA has been identified in strains exhibiting resistance to Cr(VI). Nevertheless, certain strains of bacteria that are resistant to Cr(VI) lack the presence of ChrB, a known regulatory factor. Here, a PadR family transcriptional repressor, ChrN, has been identified as a regulator in the response of Enterobacter sp. Z1(CCTCC NO: M 2019147) to Cr(VI). The chrN gene is cotranscribed with the chrA gene, and the transcriptional expression of this operon is induced by Cr(VI). The binding capacity of the ChrN protein to Cr(VI) was demonstrated by both the tryptophan fluorescence assay and Ni-NTA purification assay. The interaction between ChrN and the chrAN operon promoter was validated by reporter gene assay and electrophoretic mobility shift assay. Mutation of the conserved histidine residues His14 and His50 resulted in loss of ChrN binding with the promoter of the chrAN operon. This observation implies that these residues are crucial for establishing a DNA-binding site. These findings demonstrate that ChrN functions as a transcriptional repressor, modulating the cellular response of strain Z1 to Cr(VI) exposure.
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Affiliation(s)
- Xueqi Huo
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Zijie Zhou
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Hongliang Liu
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, 255000, Shandong Province, People's Republic of China
| | - Gejiao Wang
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Kaixiang Shi
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
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2
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Gupta PK, Nair VK, Dalvi V, Dhali S, Malik A, Pant KK. Field-scale assessment of soil, water, plant, and soil microbiome in and around Rania-Khan Chandpur Chromium contaminated site, India. JOURNAL OF HAZARDOUS MATERIALS 2024; 467:133747. [PMID: 38350323 DOI: 10.1016/j.jhazmat.2024.133747] [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: 09/03/2023] [Revised: 12/30/2023] [Accepted: 02/05/2024] [Indexed: 02/15/2024]
Abstract
Rania-Khan Chandpur site, (Kanpur Dehat, Uttar Pradesh, India), one of the highly Chromium (Cr) contaminated sites in India due to Chromite Ore Processing Residue (COPR), has been investigated at the field-scale. We found that the area around the COPR dumps was hazardously contaminated with the Cr where its concentrations in the surface water and groundwater were > 40 mgL-1, its maximum contents in the COPRs and in the soils of the adjoining lands were 9.6 wt% and 3.83 wt%, respectively. By exploring the vegetation and microbial distribution across the site, we advocate the appropriateness of Cynodon dactylon, Chrysopogon zizanioides, Cyperus sp., and Typha angustifolia as the most suitable phytoremediation agent because their association with Cr remediating bacterial species (Pseudomonas sp., Clostridium sp. and Bacillus sp.) was strong. Using this remarkable information for the bioremediation projects, this site can be re-vegetated and bioaugmented to remediate Cr in soils, waterlogged ditches, surface water, and in groundwater systems.
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Affiliation(s)
- Pankaj Kumar Gupta
- Applied Microbiology Laboratory, Centre for Rural Development and Technology (CRDT), Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India; Wetland Hydrology Research Laboratory, Faculty of Environment, University of Waterloo, 200 University Ave W, Waterloo, ON N2L3G1, Canada
| | - Vivek Kumar Nair
- Applied Microbiology Laboratory, Centre for Rural Development and Technology (CRDT), Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India; School of Interdisciplinary Research, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Vivek Dalvi
- Applied Microbiology Laboratory, Centre for Rural Development and Technology (CRDT), Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Sumit Dhali
- Applied Microbiology Laboratory, Centre for Rural Development and Technology (CRDT), Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Anushree Malik
- Applied Microbiology Laboratory, Centre for Rural Development and Technology (CRDT), Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India; Department of Chemical and Biological Engineering, Princeton University, E-Quad Visitor Office A429, Princeton, NJ 08544, USA.
| | - Kamal Kishore Pant
- Catalytic Reaction Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India; Indian Institute of Technology (IIT) Roorkee, Roorkee, Uttarakhand 247667, India
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3
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Hernández-Ramírez KC, Valle-Maldonado MI, Patiño-Medina JA, Calo S, Jácome-Galarza IE, Garre V, Meza-Carmen V, Ramírez-Díaz MI. Role of PumB antitoxin as a transcriptional regulator of the PumAB type-II toxin-antitoxin system and its endoribonuclease activity on the PumA (toxin) transcript. Mol Genet Genomics 2023; 298:455-472. [PMID: 36604348 DOI: 10.1007/s00438-022-01988-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 12/20/2022] [Indexed: 01/07/2023]
Abstract
The PumAB type-II toxin-antitoxin (TA) system is encoded by pumAB genes that are organized into an operon. This system is encoded by the pUM505 plasmid, isolated from a Pseudomonas aeruginosa clinical strain. The pumA gene encodes a putative RelE toxin protein (toxic component), whereas the pumB gene encodes a putative HTH antitoxin protein. The expression of the PumAB system in Escherichia coli confers plasmid stability. In addition, PumA toxin overexpression in P. aeruginosa possesses the capability to increase bacterial virulence, an effect that is neutralized by the PumB antitoxin. The aim of this study was to establish the mechanism of regulation of the PumAB toxin-antitoxin system from pUM505. By an in silico analysis of the putative regulatory elements, we identified two putative internal promoters, PpumB and PpumB-AlgU (in addition to the already reported PpumAB), located upstream of pumB. By RT-qPCR assays, we determined that the pumAB genes are transcribed differentially, in that the mRNA of pumB is more abundant than the pumA transcript. We also observed that pumB could be expressed individually and that its mRNA levels decreased under oxidative stress, during individual expression as well as co-expression of pumAB. However, under stressful conditions, the pumA mRNA levels were not affected. This suggests the negative regulation of pumB by stressful conditions. The PumB purified protein was found to bind to a DNA region located between the PpumAB and the pumA coding region, and PumA participates in PumB binding, suggesting that a PumA-PumB complex co-regulates the transcription of the pumAB operon. Interestingly, the pumA mRNA levels decreased after incubation in vitro with PumB protein. This effect was repressed by ribonuclease inhibitors, suggesting that PumB could function as an RNAse toward the mRNA of the toxin. Taken together, we conclude that the PumAB TA system possesses multiple mechanisms to regulate its expression, as well as that the PumB antitoxin generates a decrease in the mRNA toxin levels, suggesting an RNase function. Our analysis provides new insights into the understanding of the control of TA systems from mobile plasmid-encoded genes from a human pathogen.
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Affiliation(s)
- K C Hernández-Ramírez
- Laboratorio de Microbiología, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - M I Valle-Maldonado
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico.,Laboratorio Estatal de Salud Pública, Secretaría de Salud Michoacán, Morelia, Mexico
| | - J A Patiño-Medina
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - S Calo
- School of Natural and Exact Sciences, Pontificia Universidad Católica Madre y Maestra, 51033, Santiago de los Caballeros, Dominican Republic
| | - I E Jácome-Galarza
- Laboratorio Estatal de Salud Pública, Secretaría de Salud Michoacán, Morelia, Mexico
| | - V Garre
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - V Meza-Carmen
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - M I Ramírez-Díaz
- Laboratorio de Microbiología, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico.
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4
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Luo Y, Chen L, Lu Z, Zhang W, Liu W, Chen Y, Wang X, Du W, Luo J, Wu H. Genome sequencing of biocontrol strain Bacillus amyloliquefaciens Bam1 and further analysis of its heavy metal resistance mechanism. BIORESOUR BIOPROCESS 2022; 9:74. [PMID: 38647608 PMCID: PMC10991351 DOI: 10.1186/s40643-022-00563-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 07/01/2022] [Indexed: 11/10/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) or Biocontrol strains inevitably encounter heavy metal excess stress during the product's processing and application. Bacillus amyloliquefaciens Bam1 was a potential biocontrol strain with strong heavy metal resistant ability. To understand its heavy metal resistance mechanism, the complete genome of Bam1 had been sequenced, and the comparative genomic analysis of Bam1 and FZB42, an industrialized PGPR and biocontrol strain with relatively lower heavy metal tolerance, was conducted. The comparative genomic analysis of Bam1 and the other nine B. amyloliquefaciens strains as well as one Bacillus velezensis (genetically and physiologically very close to B. amyloliquefaciens) was also performed. Our results showed that the complete genome size of Bam1 was 3.95 Mb, 4219 coding sequences were predicted, and it possessed the highest number of unique genes among the eleven analyzed strains. Nine genes related to heavy metal resistance were detected within the twelve DNA islands of Bam1, while only two of them were detected within the seventeen DNA islands of FZB42. When compared with B. amyloliquefaciens type strain DSM7, Bam1 lacked contig L, whereas FZB42 lacked contig D and I, as well as just possessed contig B with a very small size. Our results could also deduce that Bam1 promoted its essential heavy metal resistance mainly by decreasing the import and increasing the export of heavy metals with the corresponding homeostasis systems, which are regulated by different metalloregulators. While Bam1 promoted its non-essential heavy metal resistance mainly by the activation of some specific or non-specific exporters responding to different heavy metals. The variation of the genes related to heavy metal resistance and the other differences of the genomes, including the different number and arrangement of contigs, as well as the number of the heavy metal resistant genes in Prophages and Genomic islands, led to the significant different resistance of Bam1 and FZB42 to heavy metals.
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Affiliation(s)
- Yuanchan Luo
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Lei Chen
- Department of Plant Quarantine, Shanghai Extension and Service Center of Agriculture Technology, Shanghai, 201103, China
| | - Zhibo Lu
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Weijian Zhang
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Wentong Liu
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Yuwei Chen
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Xinran Wang
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
| | - Wei Du
- Agricultural Technology Extension Station of Ningxia, 2, West Shanghai Road, Yinchuan, 750001, China
| | - Jinyan Luo
- Department of Plant Quarantine, Shanghai Extension and Service Center of Agriculture Technology, Shanghai, 201103, China.
| | - Hui Wu
- Department of Applied Biology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
- Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai, 200237, China.
- Key Laboratory of Bio-Based Material Engineering of China National Light Industry Council, 130 Meilong Road, Shanghai, 200237, China.
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5
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Chromiková Z, Chovanová RK, Tamindžija D, Bártová B, Radnović D, Bernier-Latmani R, Barák I. Implantation of Bacillus pseudomycoides Chromate Transporter Increases Chromate Tolerance in Bacillus subtilis. Front Microbiol 2022; 13:842623. [PMID: 35330768 PMCID: PMC8940164 DOI: 10.3389/fmicb.2022.842623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/14/2022] [Indexed: 11/23/2022] Open
Abstract
Chromium of anthropogenic origin contaminates the environment worldwide. The toxicity of chromium, a group I human carcinogen, is greatest when it is in a hexavalent oxidation state, Cr(VI). Cr(VI) is actively transported into the cell, triggering oxidative damage intracellularly. Due to the abundance of unspecific intracellular reductants, any microbial species is capable of bio-transformation of toxic Cr(VI) to innocuous Cr(III), however, this process is often lethal. Only some bacterial species are capable of sustaining the vegetative growth in the presence of a high concentration of Cr(VI) and thus operate as self-sustainable bioremediation agents. One of the successful microbial Cr(VI) detoxification strategies is the activation of chromate efflux pumps. This work describes transplantation of the chromate efflux pump from the potentially pathogenic but highly Cr resistant Bacillus pseudomycoides environmental strain into non-pathogenic but only transiently Cr tolerant Bacillus subtilis strain. In our study, we compared the two Bacillus spp. strains harboring evolutionarily diverged chromate efflux proteins. We have found that individual cells of the Cr-resistant B. pseudomycoides environmental strain accumulate less Cr than the cells of B. subtilis strain. Further, we found that survival of the B. subtilis strain during the Cr stress can be increased by the introduction of the chromate transporter from the Cr resistant environmental strain into its genome. Additionally, the expression of B. pseudomycoides chromate transporter ChrA in B. subtilis seems to be activated by the presence of chromate, hinting at versatility of Cr-efflux proteins. This study outlines the future direction for increasing the Cr-tolerance of non-pathogenic species and safe bioremediation using soil bacteria.
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Affiliation(s)
- Zuzana Chromiková
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
- *Correspondence: Zuzana Chromiková,
| | - Romana Kalianková Chovanová
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Dragana Tamindžija
- Department of Chemistry, Faculty of Sciences, Biochemistry and Environmental Protection, Novi Sad, Serbia
- Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia
| | - Barbora Bártová
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Dragan Radnović
- Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia
| | - Rizlan Bernier-Latmani
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Imrich Barák
- Department of Microbial Genetics, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
- Imrich Barák,
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6
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Rodríguez-Esperón MC, Eastman G, Sandes L, Garabato F, Eastman I, Iriarte A, Fabiano E, Sotelo-Silveira JR, Platero R. Genomics and transcriptomics insights into luteolin effects on the beta-rhizobial strain Cupriavidus necator UYPR2.512. Environ Microbiol 2021; 24:240-264. [PMID: 34811861 DOI: 10.1111/1462-2920.15845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 11/04/2021] [Accepted: 11/08/2021] [Indexed: 11/28/2022]
Abstract
Cupriavidus necator UYPR2.512 is a rhizobial strain that belongs to the Beta-subclass of proteobacteria, able to establish successful symbiosis with Mimosoid legumes. The initial steps of rhizobium-legumes symbioses involve the reciprocal recognition by chemical signals, being luteolin one of the molecules involved. However, there is a lack of information on the effect of luteolin in beta-rhizobia. In this work, we used long-read sequencing to complete the genome of UYPR2.512 providing evidence for the existence of four closed circular replicons. We used an RNA-Seq approach to analyse the response of UYPR2.512 to luteolin. One hundred and forty-five genes were differentially expressed, with similar numbers of downregulated and upregulated genes. Most repressed genes were mapped to the main chromosome, while the upregulated genes were overrepresented among pCne512e, containing the symbiotic genes. Induced genes included the nod operon and genes implicated in exopolysaccharides and flagellar biosynthesis. We identified many genes involved in iron, copper and other heavy metals metabolism. Among repressed genes, we identified genes involved in basal carbon and nitrogen metabolism. Our results suggest that in response to luteolin, C. necator strain UYPR2.512 reshapes its metabolism in order to be prepared for the forthcoming symbiotic interaction.
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Affiliation(s)
- M C Rodríguez-Esperón
- Laboratorio de Microbiología Ambiental, Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - G Eastman
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - L Sandes
- Laboratorio de Microbiología Ambiental, Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - F Garabato
- Laboratorio de Microbiología Ambiental, Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - I Eastman
- Laboratorio de Microbiología Ambiental, Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - A Iriarte
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Facultad de Medicina, Instituto de Higiene, Montevideo, Uruguay
| | - E Fabiano
- Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - J R Sotelo-Silveira
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - R Platero
- Laboratorio de Microbiología Ambiental, Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
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7
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Ziegler CA, Freddolino PL. The leucine-responsive regulatory proteins/feast-famine regulatory proteins: an ancient and complex class of transcriptional regulators in bacteria and archaea. Crit Rev Biochem Mol Biol 2021; 56:373-400. [PMID: 34151666 DOI: 10.1080/10409238.2021.1925215] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Since the discovery of the Escherichia coli leucine-responsive regulatory protein (Lrp) almost 50 years ago, hundreds of Lrp homologs have been discovered, occurring in 45% of sequenced bacteria and almost all sequenced archaea. Lrp-like proteins are often referred to as the feast/famine regulatory proteins (FFRPs), reflecting their common regulatory roles. Acting as either global or local transcriptional regulators, FFRPs detect the environmental nutritional status by sensing small effector molecules (usually amino acids) and regulate the expression of genes involved in metabolism, virulence, motility, nutrient transport, stress tolerance, and antibiotic resistance to implement appropriate behaviors for the specific ecological niche of each organism. Despite FFRPs' complexity, a significant role in gene regulation, and prevalence throughout prokaryotes, the last comprehensive review on this family of proteins was published about a decade ago. In this review, we integrate recent notable findings regarding E. coli Lrp and other FFRPs across bacteria and archaea with previous observations to synthesize a more complete view on the mechanistic details and biological roles of this ancient class of transcription factors.
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Affiliation(s)
- Christine A Ziegler
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
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Analysis of Haloferax mediterranei Lrp Transcriptional Regulator. Genes (Basel) 2021; 12:genes12060802. [PMID: 34070366 PMCID: PMC8229911 DOI: 10.3390/genes12060802] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/14/2021] [Accepted: 05/21/2021] [Indexed: 12/26/2022] Open
Abstract
Haloferax mediterranei is an extremely halophilic archaeon, able to live in hypersaline environments with versatile nutritional requirements, whose study represents an excellent basis in the field of biotechnology. The transcriptional machinery in Archaea combines the eukaryotic basal apparatus and the bacterial regulation mechanisms. However, little is known about molecular mechanisms of gene expression regulation compared with Bacteria, particularly in Haloarchaea. The genome of Hfx. mediterranei contains a gene, lrp (HFX_RS01210), which encodes a transcriptional factor belonging to Lrp/AsnC family. It is located downstream of the glutamine synthetase gene (HFX_RS01205), an enzyme involved in ammonium assimilation and amino acid metabolism. To study this transcriptional factor more deeply, the lrp gene has been homologously overexpressed and purified under native conditions by two chromatographic steps, namely nickel affinity and gel filtration chromatography, showing that Lrp behaves asa tetrameric protein of approximately 67 kDa. Its promoter region has been characterized under different growth conditions using bgaH as a reporter gene. The amount of Lrp protein was also analyzed by Western blotting in different nitrogen sources and under various stress conditions. To sum up, regarding its involvement in the nitrogen cycle, it has been shown that its expression profile does not change in response to the nitrogen sources tested. Differences in its expression pattern have been observed under different stress conditions, such as in the presence of hydrogen peroxide or heavy metals. According to these results, the Lrp seems to be involved in a general response against stress factors, acting as a first-line transcriptional regulator.
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9
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Liu B, Su G, Yang Y, Yao Y, Huang Y, Hu L, Zhong H, He Z. Vertical distribution of microbial communities in chromium-contaminated soil and isolation of Cr(Ⅵ)-Reducing strains. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 180:242-251. [PMID: 31100590 DOI: 10.1016/j.ecoenv.2019.05.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/06/2019] [Accepted: 05/08/2019] [Indexed: 06/09/2023]
Abstract
Soil ecosystems surrounding chromium slag undergo continuous harsh physicochemical conditions due to multiple heavy metals contamination. Previous studies of soil microbial communities mainly focused on surface soil layer, while little was known about the depth-related distributions of the microbial communities in chromium (Cr)-contaminated soil. In this study, a comprehensive analysis of depth-related distributions of microbial communities in Cr-contaminated soil was carried out by Illumina sequencing of 16s rRNA genes. The results revealed that bacterial diversities at 0 cm depth layer were significantly higher than those below 20 cm depths. And there was a remarkable difference in bacterial compositions along with the sampling depths especially for the dominant phyla of Proteobacteria, Actinobacteria, Chloroflexi and Fimicutes (p < 0.05). While the archaea accounted for a relatively low proportion of the microbes and showed stability in the compositions with the predominant phyla of Thaumarchaeota and Euryarchaeota. The linear discriminate analysis (LDA) and effect size (LEfSe) analysis showed that there were thirty-seven kinds of biomarker microbes existing in the five soil layers with LDA threshold of 4.0, and each layer showed distinct microbial divisions, indicating that microbes with different biological functions might survive along with the sampling depths. The environmental variables including total chromium (Cr), Cr(Ⅵ), Mn, Ni, and Zn had considerable influences on microbial community composition in the contaminated soil. A total of 25 Cr(Ⅵ)-reducing strains were further isolated and identified, which were phylogenetically affiliated to Proteobacteria, Actinobacteria and Firmicutes. Among the isolated Cr(Ⅵ)-reducing strains, Bacillus stratosphericus was the first time to be reported with Cr(Ⅵ) reducing capacity.
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Affiliation(s)
- Bang Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Guirong Su
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Yiran Yang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Yang Yao
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Yongji Huang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Liang Hu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Hui Zhong
- School of Life Science, Central South University, Changsha, 410012, China.
| | - Zhiguo He
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China.
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Enhancement of precursor amino acid supplies for improving bacitracin production by activation of branched chain amino acid transporter BrnQ and deletion of its regulator gene lrp in Bacillus licheniformis. Synth Syst Biotechnol 2018; 3:236-243. [PMID: 30417137 PMCID: PMC6215969 DOI: 10.1016/j.synbio.2018.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/07/2018] [Accepted: 10/24/2018] [Indexed: 11/21/2022] Open
Abstract
Bacitracin, a new type of cyclic peptide antibiotic, is widely used as the feed additive in feed industry. Branched chain amino acids (BCAAs) are the key precursors for bacitracin synthesis. In this research, soybean meal was served as the raw material to supply precursor amino acids for bacitracin synthesis, and enhanced production of bacitracin was attempted by engineering BCAA transporter BrnQ and its regulator Lrp in the bacitracin industrial production strain Bacillus licheniformis DW2. Firstly, our results confirmed that Lrp negatively affected bacitracin synthesis in DW2, and deletion of lrp improved intracellular BCAA accumulations, as well as the expression level of BCAA transporter BrnQ, which further led to a 14.71% increase of bacitracin yield, compared with that of DW2. On the contrary, overexpression of Lrp decreased bacitracin yield by 12.28%. Secondly, it was suggested that BrnQ acted as a BCAA importer in DW2, and overexpression of BrnQ enhanced the intracellular BCAA accumulations and 10.43% of bacitracin yield. While, the bacitracin yield decreased by 18.27% in the brnQ deletion strain DW2△brnQ. Finally, BrnQ was further overexpressed in lrp deletion strain DW2△lrp, and bacitracin yield produced by the final strain DW2△lrp::BrnQ was 965.34 U/mL, increased by 22.42% compared with that of DW2 (788.48 U/mL). Collectively, this research confirmed that Lrp affected bacitracin synthesis via regulating the expression of BCAA transporter BrnQ and BCAA distributions, and provided a promising strain for industrial production of bacitracin.
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