1
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Hasan MK, Jeannine Brady L. Nucleic acid-binding KH domain proteins influence a spectrum of biological pathways including as part of membrane-localized complexes. J Struct Biol X 2024; 10:100106. [PMID: 39040530 PMCID: PMC11261784 DOI: 10.1016/j.yjsbx.2024.100106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 06/18/2024] [Accepted: 06/24/2024] [Indexed: 07/24/2024] Open
Abstract
K-Homology domain (KH domain) proteins bind single-stranded nucleic acids, influence protein-protein interactions of proteins that harbor them, and are found in all kingdoms of life. In concert with other functional protein domains KH domains contribute to a variety of critical biological activities, often within higher order machineries including membrane-localized protein complexes. Eukaryotic KH domain proteins are linked to developmental processes, morphogenesis, and growth regulation, and their aberrant expression is often associated with cancer. Prokaryotic KH domain proteins are involved in integral cellular activities including cell division and protein translocation. Eukaryotic and prokaryotic KH domains share structural features, but are differentiated based on their structural organizations. In this review, we explore the structure/function relationships of known examples of KH domain proteins, and highlight cases in which they function within or at membrane surfaces. We also summarize examples of KH domain proteins that influence bacterial virulence and pathogenesis. We conclude the article by discussing prospective research avenues that could be pursued to better investigate this largely understudied protein category.
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Affiliation(s)
- Md Kamrul Hasan
- Department of Oral Biology, University of Florida, Gainesville, FL 32610, USA
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - L. Jeannine Brady
- Department of Oral Biology, University of Florida, Gainesville, FL 32610, USA
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2
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Warner BR, Fredrick K. Contribution of an alternative 16S rRNA helix to biogenesis of the 30S subunit of the ribosome. RNA (NEW YORK, N.Y.) 2024; 30:770-778. [PMID: 38570183 PMCID: PMC11182017 DOI: 10.1261/rna.079960.124] [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: 01/22/2024] [Accepted: 03/23/2024] [Indexed: 04/05/2024]
Abstract
30S subunits become inactive upon exposure to low Mg2+ concentration, because of a reversible conformational change that entails nucleotides (nt) in the neck helix (h28) and 3' tail of 16S rRNA. This active-to-inactive transition involves partial unwinding of h28 and repairing of nt 921-923 with nt 1532-1534, which requires flipping of the 3' tail by ∼180°. Growing evidence suggests that immature 30S particles adopt the inactive conformation in the cell, and transition to the active state occurs at a late stage of maturation. Here, we target nucleotides that form the alternative helix (hALT) of the inactive state. Using an orthogonal ribosome system, we find that disruption of hALT decreases translation activity in the cell modestly, by approximately twofold, without compromising ribosome fidelity. Ribosomes carrying substitutions at positions 1532-1533 support the growth of Escherichia coli strain Δ7 prrn (which carries a single rRNA operon), albeit at rates 10%-20% slower than wild-type ribosomes. These mutant Δ7 prrn strains accumulate free 30S particles and precursor 17S rRNA, indicative of biogenesis defects. Analysis of purified control and mutant subunits suggests that hALT stabilizes the inactive state by 1.2 kcal/mol with little-to-no impact on the active state or the transition state of conversion.
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Affiliation(s)
- Benjamin R Warner
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Kurt Fredrick
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
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3
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Sarıgül İ, Žukova A, Alparslan E, Remm S, Pihlak M, Kaldalu N, Tenson T, Maiväli Ü. Involvement of Escherichia coli YbeX/CorC in ribosomal metabolism. Mol Microbiol 2024; 121:984-1001. [PMID: 38494741 DOI: 10.1111/mmi.15248] [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: 10/27/2023] [Revised: 02/15/2024] [Accepted: 02/20/2024] [Indexed: 03/19/2024]
Abstract
YbeX of Escherichia coli, a member of the CorC protein family, is encoded in the same operon with ribosome-associated proteins YbeY and YbeZ. Here, we report the involvement of YbeX in ribosomal metabolism. The ΔybeX cells accumulate distinct 16S rRNA degradation intermediates in the 30S particles and the 70S ribosomes. E. coli lacking ybeX has a lengthened lag phase upon outgrowth from the stationary phase. This growth phenotype is heterogeneous at the individual cell level and especially prominent under low extracellular magnesium levels. The ΔybeX strain is sensitive to elevated growth temperatures and to several ribosome-targeting antibiotics that have in common the ability to induce the cold shock response in E. coli. Although generally milder, the phenotypes of the ΔybeX mutant overlap with those caused by ybeY deletion. A genetic screen revealed partial compensation of the ΔybeX growth phenotype by the overexpression of YbeY. These findings indicate an interconnectedness among the ybeZYX operon genes, highlighting their roles in ribosomal assembly and/or degradation.
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Affiliation(s)
- İsmail Sarıgül
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Amata Žukova
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Emel Alparslan
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Sille Remm
- Institute of Technology, University of Tartu, Tartu, Estonia
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland
| | - Margus Pihlak
- Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Niilo Kaldalu
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Tanel Tenson
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Ülo Maiväli
- Institute of Technology, University of Tartu, Tartu, Estonia
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4
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Börner J, Friedrich T, Klug G. RNase III participates in control of quorum sensing, pigmentation and oxidative stress resistance in Rhodobacter sphaeroides. Mol Microbiol 2023; 120:874-892. [PMID: 37823424 DOI: 10.1111/mmi.15181] [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: 07/21/2023] [Revised: 09/21/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023]
Abstract
RNase III is a dsRNA-specific endoribonuclease, highly conserved in bacteria and eukarya. In this study, we analysed the effects of inactivation of RNase III on the transcriptome and the phenotype of the facultative phototrophic α-proteobacterium Rhodobacter sphaeroides. RNA-seq revealed an unexpectedly high amount of genes with increased expression located directly downstream to the rRNA operons. Chromosomal insertion of additional transcription terminators restored wild type-like expression of the downstream genes, indicating that RNase III may modulate the rRNA transcription termination in R. sphaeroides. Furthermore, we identified RNase III as a major regulator of quorum-sensing autoinducer synthesis in R. sphaeroides. It negatively controls the expression of the autoinducer synthase CerI by reducing cerI mRNA stability. In addition, RNase III inactivation caused altered resistance against oxidative stress and impaired formation of photosynthetically active pigment-protein complexes. We also observed an increase in the CcsR small RNAs that were previously shown to promote resistance to oxidative stress. Taken together, our data present interesting insights into RNase III-mediated regulation and expand the knowledge on the function of this important enzyme in bacteria.
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Affiliation(s)
- Janek Börner
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Tobias Friedrich
- Biomedical Informatics and Systems Medicine, Justus-Liebig-University Giessen, Giessen, Germany
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, Justus-Liebig-University Giessen, Giessen, Germany
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5
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Gruffaz C, Smirnov A. GTPase Era at the heart of ribosome assembly. Front Mol Biosci 2023; 10:1263433. [PMID: 37860580 PMCID: PMC10582724 DOI: 10.3389/fmolb.2023.1263433] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/21/2023] [Indexed: 10/21/2023] Open
Abstract
Ribosome biogenesis is a key process in all organisms. It relies on coordinated work of multiple proteins and RNAs, including an array of assembly factors. Among them, the GTPase Era stands out as an especially deeply conserved protein, critically required for the assembly of bacterial-type ribosomes from Escherichia coli to humans. In this review, we bring together and critically analyze a wealth of phylogenetic, biochemical, structural, genetic and physiological data about this extensively studied but still insufficiently understood factor. We do so using a comparative and, wherever possible, synthetic approach, by confronting observations from diverse groups of bacteria and eukaryotic organelles (mitochondria and chloroplasts). The emerging consensus posits that Era intervenes relatively early in the small subunit biogenesis and is essential for the proper shaping of the platform which, in its turn, is a prerequisite for efficient translation. The timing of Era action on the ribosome is defined by its interactions with guanosine nucleotides [GTP, GDP, (p)ppGpp], ribosomal RNA, and likely other factors that trigger or delay its GTPase activity. As a critical nexus of the small subunit biogenesis, Era is subject to sophisticated regulatory mechanisms at the transcriptional, post-transcriptional, and post-translational levels. Failure of these mechanisms or a deficiency in Era function entail dramatic generalized consequences for the protein synthesis and far-reaching, pleiotropic effects on the organism physiology, such as the Perrault syndrome in humans.
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Affiliation(s)
- Christelle Gruffaz
- UMR7156- Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
| | - Alexandre Smirnov
- UMR7156- Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
- University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
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6
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Warner BR, Bundschuh R, Fredrick K. Roles of the leader-trailer helix and antitermination complex in biogenesis of the 30S ribosomal subunit. Nucleic Acids Res 2023; 51:5242-5254. [PMID: 37102690 PMCID: PMC10250234 DOI: 10.1093/nar/gkad316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 04/07/2023] [Accepted: 04/13/2023] [Indexed: 04/28/2023] Open
Abstract
Ribosome biogenesis occurs co-transcriptionally and entails rRNA folding, ribosomal protein binding, rRNA processing, and rRNA modification. In most bacteria, the 16S, 23S and 5S rRNAs are co-transcribed, often with one or more tRNAs. Transcription involves a modified RNA polymerase, called the antitermination complex, which forms in response to cis-acting elements (boxB, boxA and boxC) in the nascent pre-rRNA. Sequences flanking the rRNAs are complementary and form long helices known as leader-trailer helices. Here, we employed an orthogonal translation system to interrogate the functional roles of these RNA elements in 30S subunit biogenesis in Escherichia coli. Mutations that disrupt the leader-trailer helix caused complete loss of translation activity, indicating that this helix is absolutely essential for active subunit formation in the cell. Mutations of boxA also reduced translation activity, but by only 2- to 3-fold, suggesting a smaller role for the antitermination complex. Similarly modest drops in activity were seen upon deletion of either or both of two leader helices, termed here hA and hB. Interestingly, subunits formed in the absence of these leader features exhibited defects in translational fidelity. These data suggest that the antitermination complex and precursor RNA elements help to ensure quality control during ribosome biogenesis.
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Affiliation(s)
- Benjamin R Warner
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Ralf Bundschuh
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus,OH 43210, USA
| | - Kurt Fredrick
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
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7
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Lee J, Jo I, Kwon AR, Ha NC. Crystal Structure of the Metallo-Endoribonuclease YbeY from Staphylococcus aureus. J Microbiol Biotechnol 2023; 33:28-34. [PMID: 36457189 PMCID: PMC9895993 DOI: 10.4014/jmb.2209.09019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022]
Abstract
Endoribonuclease YbeY is specific to the single-stranded RNA of ribosomal RNAs and small RNAs. This enzyme is essential for the maturation and quality control of ribosomal RNA in a wide range of bacteria and for virulence in some pathogenic bacteria. In this study, we determined the crystal structure of YbeY from Staphylococcus aureus at a resolution of 1.9 Å in the presence of zinc chloride. The structure showed a zinc ion at the active site and two molecules of tricarboxylic acid citrate, which were also derived from the crystallization conditions. Our structure showed the zinc ion-bound local environment at the molecular level for the first time. Molecular comparisons were performed between the carboxylic moieties of citrate and the phosphate moiety of the RNA backbone, and a model of YbeY in complex with a single strand of RNA was subsequently constructed. Our findings provide molecular insights into how the YbeY enzyme recognizes single-stranded RNA in bacteria.
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Affiliation(s)
- Jinwook Lee
- Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Department of Agricultural Biotechnology, CALS, Seoul National University, Seoul 08826, Republic of Korea
| | - Inseong Jo
- Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Department of Agricultural Biotechnology, CALS, Seoul National University, Seoul 08826, Republic of Korea,Current address: Infectious Diseases Therapeutic Research Center, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Ae-Ran Kwon
- Department of Beauty Care, College of Medical Science, Daegu Haany University, Gyeongsan 38610, Republic of Korea
| | - Nam-Chul Ha
- Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Department of Agricultural Biotechnology, CALS, Seoul National University, Seoul 08826, Republic of Korea,Corresponding author Phone: +82-2-880-4853 E-mail:
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8
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Labban A, Shibl AA, Calleja ML, Hong PY, Morán XAG. Growth dynamics and transcriptional responses of a Red Sea Prochlorococcus strain to varying temperatures. Environ Microbiol 2022; 25:1007-1021. [PMID: 36567447 DOI: 10.1111/1462-2920.16326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/11/2022] [Indexed: 12/27/2022]
Abstract
Prochlorococcus play a crucial role in the ocean's biogeochemical cycling, but it remains controversial how they will respond to global warming. Here we assessed the response to temperature (22-30°C) of the growth dynamics and gene expression profiles of a Red Sea Prochlorococcus strain (RSP50) in a non-axenic culture. Both the specific growth rate (0.55-0.80 day-1 ) and cell size (0.04-0.07 μm3 ) of Prochlorococcus increased significantly with temperature. The primary production released extracellularly ranged from 20% to 34%, with humic-like fluorescent compounds increasing up to fivefold as Prochlorococcus reached its maximum abundance. At 30°C, genes involved in carbon fixation such as CsoS2 and CsoS3 and photosynthetic electron transport including PTOX were downregulated, suggesting a cellular homeostasis and energy saving mechanism response. In contrast, PTOX was found upregulated at 22°C and 24°C. Similar results were found for transaldolase, related to carbon metabolism, and citrate synthase, an important enzyme in the TCA cycle. Our data suggest that in spite of the currently warm temperatures of the Red Sea, Prochlorococcus can modulate its gene expression profiles to permit growth at temperatures lower than its optimum temperature (28°C) but is unable to cope with temperatures exceeding 30°C.
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Affiliation(s)
- Abbrar Labban
- Marine Science, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia.,Environmental Science and Engineering, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Ahmed A Shibl
- Genetic Heritage Group, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.,Public Health Research Center, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Maria Ll Calleja
- Climate Geochemistry Department, Max Plank Institute for Chemistry, Mainz, Germany
| | - Pei-Ying Hong
- Environmental Science and Engineering, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Xosé Anxelu G Morán
- Marine Science, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia.,Centro Oceanográfico de Gijón/Xixón, Instituto Español de Oceanografía (IEO-CSIC), Gijón/Xixón, Spain
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9
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Naganathan A, Culver GM. Interdependency and Redundancy Add Complexity and Resilience to Biogenesis of Bacterial Ribosomes. Annu Rev Microbiol 2022; 76:193-210. [PMID: 35609945 DOI: 10.1146/annurev-micro-041020-121806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The pace and efficiency of ribosomal subunit production directly impact the fitness of bacteria. Biogenesis demands more than just the union of ribosomal components, including RNA and proteins, to form this functional ribonucleoprotein particle. Extra-ribosomal protein factors play a fundamental role in the efficiency and efficacy of ribosomal subunit biogenesis. A paucity of data on intermediate steps, multiple and overlapping pathways, and the puzzling number of functions that extra-ribosomal proteins appear to play in vivo make unraveling the formation of this macromolecular assemblage difficult. In this review, we outline with examples the multinodal landscape of factor-assisted mechanisms that influence ribosome synthesis in bacteria. We discuss in detail late-stage events that mediate correct ribosome formation and the transition to translation initiation and thereby ensure high-fidelity protein synthesis.
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Affiliation(s)
- Anusha Naganathan
- Department of Biology, University of Rochester, Rochester, New York, USA; ,
| | - Gloria M Culver
- Department of Biology, University of Rochester, Rochester, New York, USA; ,
- Center for RNA Biology and Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York, USA
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10
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Babu VMP, Sankari S, Ghosal A, Walker GC. A Mutant Era GTPase Suppresses Phenotypes Caused by Loss of Highly Conserved YbeY Protein in Escherichia coli. Front Microbiol 2022; 13:896075. [PMID: 35663862 PMCID: PMC9159920 DOI: 10.3389/fmicb.2022.896075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 04/13/2022] [Indexed: 12/03/2022] Open
Abstract
Ribosome assembly is a complex fundamental cellular process that involves assembling multiple ribosomal proteins and several ribosomal RNA species in a highly coordinated yet flexible and resilient manner. The highly conserved YbeY protein is a single-strand specific endoribonuclease, important for ribosome assembly, 16S rRNA processing, and ribosome quality control. In Escherichia coli, ybeY deletion results in pleiotropic phenotypes including slow growth, temperature sensitivity, accumulation of precursors of 16S rRNA, and impaired formation of fully assembled 70S subunits. Era, an essential highly conserved GTPase protein, interacts with many ribosomal proteins, and its depletion results in ribosome assembly defects. YbeY has been shown to interact with Era together with ribosomal protein S11. In this study, we have analyzed a suppressor mutation, era(T99I), that can partially suppress a subset of the multiple phenotypes of ybeY deletion. The era(T99I) allele was able to improve 16S rRNA processing and ribosome assembly at 37°C. However, it failed to suppress the temperature sensitivity and did not improve 16S rRNA stability. The era(T99I) allele was also unable to improve the 16S rRNA processing defects caused by the loss of ribosome maturation factors. We also show that era(T99I) increases the GroEL levels in the 30S ribosome fractions independent of YbeY. We propose that the mechanism of suppression is that the changes in Era's structure caused by the era(T99I) mutation affect its GTP/GDP cycle in a way that increases the half-life of RNA binding to Era, thereby facilitating alternative processing of the 16S RNA precursor. Taken together, this study offers insights into the role of Era and YbeY in ribosome assembly and 16S rRNA processing events.
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Affiliation(s)
| | | | | | - Graham C. Walker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States
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11
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Temporal Transcriptional Responses of a Vibrio alginolyticus Strain to
Podoviridae
Phage HH109 Revealed by RNA-Seq. mSystems 2022; 7:e0010622. [PMID: 35400200 PMCID: PMC9040624 DOI: 10.1128/msystems.00106-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio alginolyticus
is a common opportunistic pathogen that causes mass mortality in cultured marine animals. Phage HH109 lyses pathogenic
V. alginolyticus
strain E110 with high efficiency and thus serves as a useful model to understand the dynamic interplay of a phage and its host.
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12
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Zhang J, Hess WR, Zhang C. "Life is short, and art is long": RNA degradation in cyanobacteria and model bacteria. MLIFE 2022; 1:21-39. [PMID: 38818322 PMCID: PMC10989914 DOI: 10.1002/mlf2.12015] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/03/2022] [Accepted: 03/03/2022] [Indexed: 06/01/2024]
Abstract
RNA turnover plays critical roles in the regulation of gene expression and allows cells to respond rapidly to environmental changes. In bacteria, the mechanisms of RNA turnover have been extensively studied in the models Escherichia coli and Bacillus subtilis, but not much is known in other bacteria. Cyanobacteria are a diverse group of photosynthetic organisms that have great potential for the sustainable production of valuable products using CO2 and solar energy. A better understanding of the regulation of RNA decay is important for both basic and applied studies of cyanobacteria. Genomic analysis shows that cyanobacteria have more than 10 ribonucleases and related proteins in common with E. coli and B. subtilis, and only a limited number of them have been experimentally investigated. In this review, we summarize the current knowledge about these RNA-turnover-related proteins in cyanobacteria. Although many of them are biochemically similar to their counterparts in E. coli and B. subtilis, they appear to have distinct cellular functions, suggesting a different mechanism of RNA turnover regulation in cyanobacteria. The identification of new players involved in the regulation of RNA turnover and the elucidation of their biological functions are among the future challenges in this field.
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Affiliation(s)
- Ju‐Yuan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of HydrobiologyChinese Academy of SciencesWuhanChina
| | - Wolfgang R. Hess
- Genetics and Experimental Bioinformatics, Faculty of BiologyUniversity of FreiburgFreiburgGermany
| | - Cheng‐Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of HydrobiologyChinese Academy of SciencesWuhanChina
- Institut WUT‐AMUAix‐Marseille University and Wuhan University of TechnologyWuhanChina
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13
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Andrews ESV, Patrick WM. The hypothesized role of YbeZ in 16S rRNA maturation. Arch Microbiol 2022; 204:114. [PMID: 34984547 DOI: 10.1007/s00203-021-02739-z] [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: 10/21/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 11/28/2022]
Abstract
Ribosomes are the protein production machines in all living cells. Yet in contrast to our understanding of how the ribosome translates DNA information into life, the steps involved in ribosome biogenesis, the assembly of the ribosomal RNA (rRNA) and protein molecules that make up the ribosome, remain incomplete. YbeY is considered one of the most physiologically critical endoribonucleases and is implicated in numerous roles involving RNA including 16S rRNA maturation, yet our existing knowledge of its biochemical function fails to explain the phenotypes that manifest when it is lost. In bacteria, it is common for functionally associated genes to be found co-localized in the genome. Across phylogenetically diverse bacteria, the gene encoding ybeZ, encoding a PhoH domain protein, sits adjacent to ybeY. Recent experimental evidence has shown that PhoH domains are RNA helicases, suggesting that this is also the role of YbeZ. The role of an RNA helicase to support the function of YbeY would help explain its reported biochemistry; therefore, we propose a model for the function of YbeZ in 16S rRNA maturation, linking it with the most recent hypotheses on the function of YbeY, that YbeY together with other ribosomal proteins, and ribosome-associated proteins, plays a role in the biogenesis of the small ribosomal subunit. Our model provides a testable hypothesis to resolve the outstanding details surrounding ribosome biogenesis in bacteria.
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Affiliation(s)
- Emma S V Andrews
- Centre for Biodiscovery, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand.
| | - Wayne M Patrick
- Centre for Biodiscovery, School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
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14
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Condon C, Pellegrini O, Gilet L, Durand S, Braun F. Walking from E. coli to B. subtilis, one ribonuclease at a time. C R Biol 2021; 344:357-371. [DOI: 10.5802/crbiol.70] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 11/22/2021] [Indexed: 11/24/2022]
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15
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Apura P, Gonçalves LG, Viegas SC, Arraiano CM. The world of ribonucleases from pseudomonads: a short trip through the main features and singularities. Microb Biotechnol 2021; 14:2316-2333. [PMID: 34427985 PMCID: PMC8601179 DOI: 10.1111/1751-7915.13890] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 06/30/2021] [Indexed: 11/27/2022] Open
Abstract
The development of synthetic biology has brought an unprecedented increase in the number molecular tools applicable into a microbial chassis. The exploration of such tools into different bacteria revealed not only the challenges of context dependency of biological functions but also the complexity and diversity of regulatory layers in bacterial cells. Most of the standardized genetic tools and principles/functions have been mostly based on model microorganisms, namely Escherichia coli. In contrast, the non-model pseudomonads lack a deeper understanding of their regulatory layers and have limited molecular tools. They are resistant pathogens and promising alternative bacterial chassis, making them attractive targets for further studies. Ribonucleases (RNases) are key players in the post-transcriptional control of gene expression by degrading or processing the RNA molecules in the cell. These enzymes act according to the cellular requirements and can also be seen as the recyclers of ribonucleotides, allowing a continuous input of these cellular resources. This makes these post-transcriptional regulators perfect candidates to regulate microbial physiology. This review summarizes the current knowledge and unique properties of ribonucleases in the world of pseudomonads, taking into account genomic context analysis, biological function and strategies to use ribonucleases to improve biotechnological processes.
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Affiliation(s)
- Patrícia Apura
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
| | - Luis G. Gonçalves
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
| | - Sandra C. Viegas
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
| | - Cecília M. Arraiano
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da República, EANOeiras2780‐157Portugal
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16
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Naganathan A, Keltz R, Lyon H, Culver GM. Uncovering a delicate balance between endonuclease RNase III and ribosomal protein S15 in E. coli ribosome assembly. Biochimie 2021; 191:104-117. [PMID: 34508826 DOI: 10.1016/j.biochi.2021.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 08/26/2021] [Accepted: 09/02/2021] [Indexed: 12/01/2022]
Abstract
The bacterial ribosomal protein S15 is located in the platform, a functional region of the 30S ribosomal subunit. While S15 is critical for in vitro formation of E. coli small subunits (SSUs), it is dispensable for in vivo biogenesis and growth. In this work, a novel synergistic interaction between rpsO, the gene that encodes S15, and rnc (the gene that encodes RNase III), was uncovered in E. coli. RNase III catalyzes processing of precursor ribosomal RNA (rRNA) transcripts and thus is involved in functional ribosome subunit maturation. Strains lacking S15 (ΔrpsO), RNase III (Δrnc) or both genes were examined to understand the relationship between these two factors and the impact of this double deletion on rRNA processing and SSU maturation. The double deletion of rpsO and rnc partially alleviates the observed cold sensitivity of ΔrpsO alone. A novel 16S rRNA precursor (17S∗ rRNA) that is detected in free 30S subunits of Δrnc is incorporated in 70S-like ribosomes in the double deletion. The stable accumulation of 17S∗ rRNA suggests that timing of processing events is closely coupled with SSU formation events in vivo. The double deletion has a suppressive effect on the cell elongation phenotype of ΔrpsO. The alteration of the phenotypes associated with S15 loss, due to the absence of RNase III, indicates that pre-rRNA processing and improvement of growth, relative to that observed for ΔrpsO, are connected. The characterization of the functional link between the two factors illustrates that there are redundancies and compensatory pathways for SSU maturation.
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Affiliation(s)
| | - Roxanne Keltz
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Hiram Lyon
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Gloria M Culver
- Department of Biology, University of Rochester, Rochester, NY, USA; Center for RNA Biology, University of Rochester, Rochester, NY, USA; Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY, USA.
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17
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Hilander T, Jackson CB, Robciuc M, Bashir T, Zhao H. The roles of assembly factors in mammalian mitoribosome biogenesis. Mitochondrion 2021; 60:70-84. [PMID: 34339868 DOI: 10.1016/j.mito.2021.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 02/08/2023]
Abstract
As ancient bacterial endosymbionts of eukaryotic cells, mitochondria have retained their own circular DNA as well as protein translation system including mitochondrial ribosomes (mitoribosomes). In recent years, methodological advancements in cryoelectron microscopy and mass spectrometry have revealed the extent of the evolutionary divergence of mitoribosomes from their bacterial ancestors and their adaptation to the synthesis of 13 mitochondrial DNA encoded oxidative phosphorylation complex subunits. In addition to the structural data, the first assembly pathway maps of mitoribosomes have started to emerge and concomitantly also the assembly factors involved in this process to achieve fully translational competent particles. These transiently associated factors assist in the intricate assembly process of mitoribosomes by enhancing protein incorporation, ribosomal RNA folding and modification, and by blocking premature or non-native protein binding, for example. This review focuses on summarizing the current understanding of the known mammalian mitoribosome assembly factors and discussing their possible roles in the assembly of small or large mitoribosomal subunits.
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Affiliation(s)
- Taru Hilander
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland.
| | - Christopher B Jackson
- Department of Biochemistry and Developmental Biology, Faculty of Medicine, University of Helsinki, Finland.
| | - Marius Robciuc
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Tanzeela Bashir
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland
| | - Hongxia Zhao
- Faculty of Biological and Environmental Sciences, University of Helsinki, Finland; Key Laboratory of Stem Cell and Biopharmaceutical Technology, School of Life Sciences, Guangxi Normal University, Guangxi, China.
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18
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D’Souza AR, Van Haute L, Powell CA, Mutti CD, Páleníková P, Rebelo-Guiomar P, Rorbach J, Minczuk M. YbeY is required for ribosome small subunit assembly and tRNA processing in human mitochondria. Nucleic Acids Res 2021; 49:5798-5812. [PMID: 34037799 PMCID: PMC8191802 DOI: 10.1093/nar/gkab404] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/20/2021] [Accepted: 05/06/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondria contain their own translation apparatus which enables them to produce the polypeptides encoded in their genome. The mitochondrially-encoded RNA components of the mitochondrial ribosome require various post-transcriptional processing steps. Additional protein factors are required to facilitate the biogenesis of the functional mitoribosome. We have characterized a mitochondrially-localized protein, YbeY, which interacts with the assembling mitoribosome through the small subunit. Loss of YbeY leads to a severe reduction in mitochondrial translation and a loss of cell viability, associated with less accurate mitochondrial tRNASer(AGY) processing from the primary transcript and a defect in the maturation of the mitoribosomal small subunit. Our results suggest that YbeY performs a dual, likely independent, function in mitochondria being involved in precursor RNA processing and mitoribosome biogenesis. Issue Section: Nucleic Acid Enzymes.
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Affiliation(s)
- Aaron R D’Souza
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Lindsey Van Haute
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Christopher A Powell
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Christian D Mutti
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Petra Páleníková
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Pedro Rebelo-Guiomar
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Joanna Rorbach
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Michal Minczuk
- To whom correspondence should be addressed. Tel: +44 122 325 2750;
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19
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YbeY, éminence grise of ribosome biogenesis. Biochem Soc Trans 2021; 49:727-745. [PMID: 33929506 DOI: 10.1042/bst20200669] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/30/2022]
Abstract
YbeY is an ultraconserved small protein belonging to the unique heritage shared by most existing bacteria and eukaryotic organelles of bacterial origin, mitochondria and chloroplasts. Studied in more than a dozen of evolutionarily distant species, YbeY is invariably critical for cellular physiology. However, the exact mechanisms by which it exerts such penetrating influence are not completely understood. In this review, we attempt a transversal analysis of the current knowledge about YbeY, based on genetic, structural, and biochemical data from a wide variety of models. We propose that YbeY, in association with the ribosomal protein uS11 and the assembly GTPase Era, plays a critical role in the biogenesis of the small ribosomal subunit, and more specifically its platform region, in diverse genetic systems of bacterial type.
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20
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Shidal C, Shu X, Wu J, Wang J, Huang S, Long J, Bauer JA, Ping J, Guo X, Zheng W, Shu XO, Cai Q. Functional Genomic Analyses of the 21q22.3 Locus Identifying Functional Variants and Candidate Gene YBEY for Breast Cancer Risk. Cancers (Basel) 2021; 13:cancers13092037. [PMID: 33922500 PMCID: PMC8122893 DOI: 10.3390/cancers13092037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/13/2022] Open
Abstract
Simple Summary Previous research has revealed a genetic predisposition to breast carcinogenesis. Thus, identifying causal genetic variants and their associated gene networks may improve breast cancer diagnostics and risk assessment. Our study investigated YBEY, an uncharacterized gene in humans, and its functions in breast cancer risk and progression. We identified two genetic variants associated with YBEY expression that may have causal functions in breast cancer risk. We performed in vitro functional assays using MCF-7, T47D, and MDA-MB-231 breast cancer cell lines and showed that knockdown of YBEY expression significantly inhibited proliferation, colony formation, and invasion/migration. We utilized RNA sequencing to identify gene networks associated with YBEY knockdown including inflammation and metabolic pathways. Further, we used data available in The Cancer Genome Atlas to explore trends in YBEY expression patterns in normal and tumor tissues. Our study provides a role for YBEY in breast carcinogenesis, and further studies investigating its mechanistic functions are warranted. Abstract We previously identified a locus at 21q22.3, tagged by the single nucleotide polymorphism (SNP) rs35418111, being associated with breast cancer risk at a genome-wide significance level; however, the underlying causal functional variants and gene(s) responsible for this association are unknown. We performed functional genomic analyses to identify potential functional variants and target genes that may mediate this association. Functional annotation for SNPs in high linkage disequilibrium (LD, r2 > 0.8) with rs35418111 in Asians showed evidence of promoter and/or enhancer activities, including rs35418111, rs2078203, rs8134832, rs57385578, and rs8126917. These five variants were assessed for interactions with nuclear proteins by electrophoretic mobility shift assays. Our results showed that the risk alleles for rs2078203 and rs35418111 altered DNA-protein interaction patterns. Cis-expression quantitative loci (cis-eQTL) analysis, using data from the Genotype-Tissue Expression database (GTEx) European-ancestry female normal breast tissue, indicated that the risk allele of rs35418111 was associated with a decreased expression of the YBEY gene, a relatively uncharacterized endoribonuclease in humans. We investigated the biological effects of YBEY on breast cancer cell lines by transient knock-down of YBEY expression in MCF-7, T47D, and MDA-MB-231 cell lines. Knockdown of YBEY mRNA in breast cancer cell lines consistently decreased cell proliferation, colony formation, and migration/invasion, regardless of estrogen receptor status. We performed RNA sequencing in MDA-MB-231 cells transfected with siRNA targeting YBEY and subsequent gene set enrichment analysis to identify gene networks associated with YBEY knockdown. These data indicated YBEY was involved in networks associated with inflammation and metabolism. Finally, we showed trends in YBEY expression patterns in breast tissues from The Cancer Genome Atlas (TCGA); early-stage breast cancers had elevated YBEY expression compared with normal tissue, but significantly decreased expression in late-stage disease. Our study provides evidence of a significant role for the human YBEY gene in breast cancer pathogenesis and the association between the rs35418111/21q22.3 locus and breast cancer risk, which may be mediated through functional SNPs, rs35418111 and rs2078203, that regulate expression of YBEY.
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Affiliation(s)
- Chris Shidal
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Xiang Shu
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
- Memorial Sloan Kettering Cancer Center, Department of Epidemiology & Biostatistics, New York, NY 10075, USA
| | - Jie Wu
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Jifeng Wang
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Shuya Huang
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
- Department of Breast Surgery, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250033, China
| | - Jirong Long
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Joshua A. Bauer
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37203, USA;
| | - Jie Ping
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Xingyi Guo
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Wei Zheng
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Xiao-Ou Shu
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
| | - Qiuyin Cai
- Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Department of Medicine, Division of Epidemiology, Vanderbilt University School of Medicine, Nashville, TN 37203, USA; (C.S.); (X.S.); (J.W.); (J.W.); (S.H.); (J.L.); (J.P.); (X.G.); (W.Z.); (X.-O.S.)
- Correspondence: ; Tel.: +1-615-936-1351; Fax: +1-615-936-8291
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21
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Human Mitoribosome Biogenesis and Its Emerging Links to Disease. Int J Mol Sci 2021; 22:ijms22083827. [PMID: 33917098 PMCID: PMC8067846 DOI: 10.3390/ijms22083827] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/20/2022] Open
Abstract
Mammalian mitochondrial ribosomes (mitoribosomes) synthesize a small subset of proteins, which are essential components of the oxidative phosphorylation machinery. Therefore, their function is of fundamental importance to cellular metabolism. The assembly of mitoribosomes is a complex process that progresses through numerous maturation and protein-binding events coordinated by the actions of several assembly factors. Dysregulation of mitoribosome production is increasingly recognized as a contributor to metabolic and neurodegenerative diseases. In recent years, mutations in multiple components of the mitoribosome assembly machinery have been associated with a range of human pathologies, highlighting their importance to cell function and health. Here, we provide a review of our current understanding of mitoribosome biogenesis, highlighting the key factors involved in this process and the growing number of mutations in genes encoding mitoribosomal RNAs, proteins, and assembly factors that lead to human disease.
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22
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Prossliner T, Gerdes K, Sørensen MA, Winther KS. Hibernation factors directly block ribonucleases from entering the ribosome in response to starvation. Nucleic Acids Res 2021; 49:2226-2239. [PMID: 33503254 PMCID: PMC7913689 DOI: 10.1093/nar/gkab017] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/03/2021] [Accepted: 01/11/2021] [Indexed: 11/18/2022] Open
Abstract
Ribosome hibernation is a universal translation stress response found in bacteria as well as plant plastids. The term was coined almost two decades ago and despite recent insights including detailed cryo-EM structures, the physiological role and underlying molecular mechanism of ribosome hibernation has remained unclear. Here, we demonstrate that Escherichia coli hibernation factors RMF, HPF and RaiA (HFs) concurrently confer ribosome hibernation. In response to carbon starvation and resulting growth arrest, we observe that HFs protect ribosomes at the initial stage of starvation. Consistently, a deletion mutant lacking all three factors (ΔHF) is severely inhibited in regrowth from starvation. ΔHF cells increasingly accumulate 70S ribosomes harbouring fragmented rRNA, while rRNA in wild-type 100S dimers is intact. RNA fragmentation is observed to specifically occur at HF-associated sites in 16S rRNA of assembled 70S ribosomes. Surprisingly, degradation of the 16S rRNA 3′-end is decreased in cells lacking conserved endoribonuclease YbeY and exoribonuclease RNase R suggesting that HFs directly block these ribonucleases from accessing target sites in the ribosome.
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Affiliation(s)
- Thomas Prossliner
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark
| | | | - Michael Askvad Sørensen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark
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23
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YbeY controls the type III and type VI secretion systems and biofilm formation through RetS in Pseudomonas aeruginosa. Appl Environ Microbiol 2021; 87:AEM.02171-20. [PMID: 33310711 PMCID: PMC8090875 DOI: 10.1128/aem.02171-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
YbeY is a highly conserved RNase in bacteria and plays essential roles in the maturation of 16S rRNA, regulation of small RNAs (sRNAs) and bacterial responses to environmental stresses. Previously, we verified the role of YbeY in rRNA processing and ribosome maturation in Pseudomonas aeruginosa and demonstrated YbeY-mediated regulation of rpoS through a sRNA ReaL. In this study, we demonstrate that mutation of the ybeY gene results in upregulation of the type III secretion system (T3SS) genes as well as downregulation of the type VI secretion system (T6SS) genes and reduction of biofilm formation. By examining the expression of the known sRNAs in P. aeruginosa, we found that mutation of the ybeY gene leads to downregulation of the small RNAs RsmY/Z that control the T3SS, the T6SS and biofilm formation. Further studies revealed that the reduced levels of RsmY/Z are due to upregulation of retS Taken together, our results reveal the pleiotropic functions of YbeY and provide detailed mechanisms of YbeY-mediated regulation in P. aeruginosa IMPORTANCE Pseudomonas aeruginosa causes a variety of acute and chronic infections in humans. The type III secretion system (T3SS) plays an important role in acute infection and the type VI secretion system (T6SS) and biofilm formation are associated with chronic infections. Understanding of the mechanisms that control the virulence determinants involved in acute and chronic infections will provide clues for the development of effective treatment strategies. Our results reveal a novel RNase mediated regulation on the T3SS, T6SS and biofilm formation in P. aeruginosa.
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24
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Summer S, Smirnova A, Gabriele A, Toth U, Fasemore AM, Förstner KU, Kuhn L, Chicher J, Hammann P, Mitulović G, Entelis N, Tarassov I, Rossmanith W, Smirnov A. YBEY is an essential biogenesis factor for mitochondrial ribosomes. Nucleic Acids Res 2020; 48:9762-9786. [PMID: 32182356 PMCID: PMC7515705 DOI: 10.1093/nar/gkaa148] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 12/11/2022] Open
Abstract
Ribosome biogenesis requires numerous trans-acting factors, some of which are deeply conserved. In Bacteria, the endoribonuclease YbeY is believed to be involved in 16S rRNA 3′-end processing and its loss was associated with ribosomal abnormalities. In Eukarya, YBEY appears to generally localize to mitochondria (or chloroplasts). Here we show that the deletion of human YBEY results in a severe respiratory deficiency and morphologically abnormal mitochondria as an apparent consequence of impaired mitochondrial translation. Reduced stability of 12S rRNA and the deficiency of several proteins of the small ribosomal subunit in YBEY knockout cells pointed towards a defect in mitochondrial ribosome biogenesis. The specific interaction of mitoribosomal protein uS11m with YBEY suggests that the latter helps to properly incorporate uS11m into the nascent small subunit in its late assembly stage. This scenario shows similarities with final stages of cytosolic ribosome biogenesis, and may represent a late checkpoint before the mitoribosome engages in translation.
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Affiliation(s)
- Sabrina Summer
- Center for Anatomy & Cell Biology, Medical University of Vienna, Vienna A-1090, Austria
| | - Anna Smirnova
- UMR7156 - Molecular Genetics, Genomics, Microbiology, University of Strasbourg, CNRS, Strasbourg F-67000, France
| | - Alessandro Gabriele
- UMR7156 - Molecular Genetics, Genomics, Microbiology, University of Strasbourg, CNRS, Strasbourg F-67000, France
| | - Ursula Toth
- Center for Anatomy & Cell Biology, Medical University of Vienna, Vienna A-1090, Austria
| | | | - Konrad U Förstner
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg 97080, Germany.,TH Köln - University of Applied Sciences, Faculty of Information Science and Communication Studies, Institute of Information Science, Cologne D-50678, Germany.,ZB MED - Information Centre for Life Sciences, Cologne D-50931, Germany
| | - Lauriane Kuhn
- Proteomics Platform Strasbourg-Esplanade, FRC1589, IBMC, CNRS, Strasbourg F-67000, France
| | - Johana Chicher
- Proteomics Platform Strasbourg-Esplanade, FRC1589, IBMC, CNRS, Strasbourg F-67000, France
| | - Philippe Hammann
- Proteomics Platform Strasbourg-Esplanade, FRC1589, IBMC, CNRS, Strasbourg F-67000, France
| | - Goran Mitulović
- Proteomics Core Facility, Clinical Department for Laboratory Medicine, Medical University of Vienna, Vienna A-1090, Austria
| | - Nina Entelis
- UMR7156 - Molecular Genetics, Genomics, Microbiology, University of Strasbourg, CNRS, Strasbourg F-67000, France
| | - Ivan Tarassov
- UMR7156 - Molecular Genetics, Genomics, Microbiology, University of Strasbourg, CNRS, Strasbourg F-67000, France
| | - Walter Rossmanith
- Center for Anatomy & Cell Biology, Medical University of Vienna, Vienna A-1090, Austria
| | - Alexandre Smirnov
- UMR7156 - Molecular Genetics, Genomics, Microbiology, University of Strasbourg, CNRS, Strasbourg F-67000, France
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25
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Abstract
The increasing bacterial antibiotic resistance imposes a severe threat to human health. For the development of effective treatment and prevention strategies, it is critical to understand the mechanisms employed by bacteria to grow in the human body. Posttranscriptional regulation plays an important role in bacterial adaptation to environmental changes. RNases and small RNAs are key players in this regulation. In this study, we demonstrate critical roles of the RNase YbeY in the virulence of the pathogenic bacterium Pseudomonas aeruginosa. We further identify the small RNA ReaL as the direct target of YbeY and elucidate the YbeY-regulated pathway on the expression of bacterial virulence factors. Our results shed light on the complex regulatory network of P. aeruginosa and indicate that inference with the YbeY-mediated regulatory pathway might be a valid strategy for the development of a novel treatment strategy. Posttranscriptional regulation plays an essential role in the quick adaptation of pathogenic bacteria to host environments, and RNases play key roles in this process by modifying small RNAs and mRNAs. We find that the Pseudomonas aeruginosa endonuclease YbeY is required for rRNA processing and the bacterial virulence in a murine acute pneumonia model. Transcriptomic analyses reveal that knocking out the ybeY gene results in downregulation of oxidative stress response genes, including the catalase genes katA and katB. Consistently, the ybeY mutant is more susceptible to H2O2 and neutrophil-mediated killing. Overexpression of katA restores the bacterial tolerance to H2O2 and neutrophil killing as well as virulence. We further find that the downregulation of the oxidative stress response genes is due to defective expression of the stationary-phase sigma factor RpoS. We demonstrate an autoregulatory mechanism of RpoS and find that ybeY mutation increases the level of a small RNA, ReaL, which directly represses the translation of rpoS through the 5′ UTR of its mRNA and subsequently reduces the expression of the oxidative stress response genes. In vitro assays demonstrate direct degradation of ReaL by YbeY. Deletion of reaL or overexpression of rpoS in the ybeY mutant restores the bacterial tolerance to oxidative stress and the virulence. We also demonstrate that YbeZ binds to YbeY and is involved in the 16S rRNA processing and regulation of reaL and rpoS as well as the bacterial virulence. Overall, our results reveal pleiotropic roles of YbeY and the YbeY-mediated regulation of rpoS through ReaL.
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26
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Quendera AP, Seixas AF, Dos Santos RF, Santos I, Silva JPN, Arraiano CM, Andrade JM. RNA-Binding Proteins Driving the Regulatory Activity of Small Non-coding RNAs in Bacteria. Front Mol Biosci 2020; 7:78. [PMID: 32478092 PMCID: PMC7237705 DOI: 10.3389/fmolb.2020.00078] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/06/2020] [Indexed: 12/20/2022] Open
Abstract
Small non-coding RNAs (sRNAs) are critical post-transcriptional regulators of gene expression. Distinct RNA-binding proteins (RBPs) influence the processing, stability and activity of bacterial small RNAs. The vast majority of bacterial sRNAs interact with mRNA targets, affecting mRNA stability and/or its translation rate. The assistance of RNA-binding proteins facilitates and brings accuracy to sRNA-mRNA basepairing and the RNA chaperones Hfq and ProQ are now recognized as the most prominent RNA matchmakers in bacteria. These RBPs exhibit distinct high affinity RNA-binding surfaces, promoting RNA strand interaction between a trans-encoding sRNA and its mRNA target. Nevertheless, some organisms lack ProQ and/or Hfq homologs, suggesting the existence of other RBPs involved in sRNA function. Along this line of thought, the global regulator CsrA was recently shown to facilitate the access of an sRNA to its target mRNA and may represent an additional factor involved in sRNA function. Ribonucleases (RNases) can be considered a class of RNA-binding proteins with nucleolytic activity that are responsible for RNA maturation and/or degradation. Presently RNase E, RNase III, and PNPase appear to be the main players not only in sRNA turnover but also in sRNA processing. Here we review the current knowledge on the most important bacterial RNA-binding proteins affecting sRNA activity and sRNA-mediated networks.
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Affiliation(s)
- Ana P Quendera
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André F Seixas
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Ricardo F Dos Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Inês Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - João P N Silva
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - José M Andrade
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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Abstract
This article describes 20 years of research that investigated a second novel target for ribosomal antibiotics, the biogenesis of the two subunits. Over that period, we have examined the effect of 52 different antibiotics on ribosomal subunit formation in six different microorganisms. Most of the antimicrobials we have studied are specific, preventing the formation of only the subunit to which they bind. A few interesting exceptions have also been observed. Forty-one research publications and a book chapter have resulted from this investigation. This review will describe the methodology we used and the fit of our results to a hypothetical model. The model predicts that inhibition of subunit assembly and translation are equivalent targets for most of the antibiotics we have investigated.
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Affiliation(s)
- W Scott Champney
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
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28
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Sharma IM, Woodson SA. RbfA and IF3 couple ribosome biogenesis and translation initiation to increase stress tolerance. Nucleic Acids Res 2020; 48:359-372. [PMID: 31728529 PMCID: PMC7145577 DOI: 10.1093/nar/gkz1065] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/09/2019] [Accepted: 11/04/2019] [Indexed: 12/12/2022] Open
Abstract
Bacterial ribosome biogenesis and translation occur in the same cellular compartment. Therefore, a biochemical gate-keeping step is required to prevent error-prone immature ribosomes from engaging in protein synthesis. Here, we provide evidence for a previously unknown quality control mechanism in which the abundant ribosome assembly factor, RbfA, suppresses protein synthesis by immature Escherichia coli 30S subunits. After 30S maturation, RbfA is displaced by initiation factor 3 (IF3), which promotes translation initiation. Genetic interactions between RbfA and IF3 show that RbfA release by IF3 is important during logarithmic growth as well as during stress encountered during stationary phase, low nutrition, low temperature, and antibiotics. By gating the transition from 30S biogenesis to translation initiation, RbfA and IF3 maintain the fidelity of bacterial protein synthesis.
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Affiliation(s)
- Indra Mani Sharma
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Sarah A Woodson
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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Babu VMP, Sankari S, Budnick JA, Caswell CC, Walker GC. Sinorhizobium meliloti YbeY is a zinc-dependent single-strand specific endoribonuclease that plays an important role in 16S ribosomal RNA processing. Nucleic Acids Res 2020; 48:332-348. [PMID: 31777930 PMCID: PMC6943124 DOI: 10.1093/nar/gkz1095] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/01/2019] [Accepted: 11/21/2019] [Indexed: 12/19/2022] Open
Abstract
Single-strand specific endoribonuclease YbeY has been shown to play an important role in the processing of the 3' end of the 16S rRNA in Escherichia coli. Lack of YbeY results in the accumulation of the 17S rRNA precursor. In contrast to a previous report, we show that Sinorhizobium meliloti YbeY exhibits endoribonuclease activity on single-stranded RNA substrate but not on the double-stranded substrate. This study also identifies the previously unknown metal ion involved in YbeY function to be Zn2+ and shows that the activity of YbeY is enhanced when the occupancy of zinc is increased. We have identified a pre-16S rRNA precursor that accumulates in the S. meliloti ΔybeY strain. We also show that ΔybeY mutant of Brucella abortus, a mammalian pathogen, also accumulates a similar pre-16S rRNA. The pre-16S species is longer in alpha-proteobacteria than in gamma-proteobacteria. We demonstrate that the YbeY from E. coli and S. meliloti can reciprocally complement the rRNA processing defect in a ΔybeY mutant of the other organism. These results establish YbeY as a zinc-dependent single-strand specific endoribonuclease that functions in 16S rRNA processing in both alpha- and gamma-proteobacteria.
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Affiliation(s)
- Vignesh M P Babu
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Siva Sankari
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - James A Budnick
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
- Department of Microbiology and Molecular Genetics, School of Medicine, University of Pittsburgh, PA, USA
| | - Clayton C Caswell
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Graham C Walker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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30
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Andrews ESV, Arcus VL. PhoH2 proteins couple RNA helicase and RNAse activities. Protein Sci 2020; 29:883-892. [PMID: 31886915 DOI: 10.1002/pro.3814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 01/29/2023]
Abstract
PhoH2 proteins are found in a very diverse range of microorganisms that span bacteria and archaea. These proteins are composed of two domains: an N-terminal PIN-domain fused with a C-terminal PhoH domain. Collectively this fusion functions as an RNA helicase and ribonuclease. In other genomic contexts, PINdomains and PhoHdomains are separate but adjacent suggesting association to achieve similar function. Exclusively among the mycobacteria, PhoH2 proteins are encoded in the genome with an upstream gene, phoAT, which is thought to play the role of an antitoxin (in place of the traditional VapB antitoxin that lies upstream of the 47 other PINdomains in the mycobacterial genome). This review examines PhoH2 proteins as a whole and describes the bioinformatics, biochemical, structural, and biological properties of the two domains that make up PhoH2: PIN and PhoH. We review the transcriptional regulators of phoH2 from two mycobacterial species and speculate on the function of PhoH2 proteins in the context of a Type II toxin-antitoxin system which are thought to play a role in the stress response in bacteria.
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Affiliation(s)
- Emma S V Andrews
- School of Science, Division of Health, Engineering, Computing and Science, University of Waikato, Hamilton, New Zealand
| | - Vickery L Arcus
- School of Science, Division of Health, Engineering, Computing and Science, University of Waikato, Hamilton, New Zealand
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31
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Zuo R, Oliveira A, Bullita E, Torino MI, Padgett‐Pagliai KA, Gardner CL, Harrison NA, da Silva D, Merli ML, Gonzalez CF, Lorca GL. Identification of flavonoids as regulators of YbeY activity in
Liberibacter asiaticus. Environ Microbiol 2019; 21:4822-4835. [DOI: 10.1111/1462-2920.14831] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/02/2019] [Accepted: 10/16/2019] [Indexed: 11/27/2022]
Affiliation(s)
- Ran Zuo
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Aline Oliveira
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Enrica Bullita
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Maria Ines Torino
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Kaylie A. Padgett‐Pagliai
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Christopher L. Gardner
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Natalie A. Harrison
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Danilo da Silva
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Marcelo L. Merli
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Claudio F. Gonzalez
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
| | - Graciela L. Lorca
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural ScienceUniversity of Florida Gainesville Florida USA
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32
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Bennison DJ, Irving SE, Corrigan RM. The Impact of the Stringent Response on TRAFAC GTPases and Prokaryotic Ribosome Assembly. Cells 2019; 8:cells8111313. [PMID: 31653044 PMCID: PMC6912228 DOI: 10.3390/cells8111313] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/17/2019] [Accepted: 10/23/2019] [Indexed: 12/24/2022] Open
Abstract
Many facets of ribosome biogenesis and function, including ribosomal RNA (rRNA) transcription, 70S assembly and protein translation, are negatively impacted upon induction of a nutrient stress-sensing signalling pathway termed the stringent response. This stress response is mediated by the alarmones guanosine tetra- and penta-phosphate ((p)ppGpp), the accumulation of which leads to a massive cellular response that slows growth and aids survival. The 70S bacterial ribosome is an intricate structure, with assembly both complex and highly modular. Presiding over the assembly process is a group of P-loop GTPases within the TRAFAC (Translation Factor Association) superclass that are crucial for correct positioning of both early and late stage ribosomal proteins (r-proteins) onto the rRNA. Often described as 'molecular switches', members of this GTPase superfamily readily bind and hydrolyse GTP to GDP in a cyclic manner that alters the propensity of the GTPase to carry out a function. TRAFAC GTPases are considered to act as checkpoints to ribosome assembly, involved in binding to immature sections in the GTP-bound state, preventing further r-protein association until maturation is complete. Here we review our current understanding of the impact of the stringent response and (p)ppGpp production on ribosome maturation in prokaryotic cells, focusing on the inhibition of (p)ppGpp on GTPase-mediated subunit assembly, but also touching upon the inhibition of rRNA transcription and protein translation.
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Affiliation(s)
- Daniel J Bennison
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
| | - Sophie E Irving
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
| | - Rebecca M Corrigan
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
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33
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Abstract
Gram-negative bacteria in infections, biofilms, and industrial settings often stop growing due to nutrient depletion, immune responses, or environmental stresses. Bacteria in this state tend to be tolerant to antibiotics and are often referred to as dormant. Rhodopseudomonas palustris, a phototrophic alphaproteobacterium, can remain fully viable for more than 4 months when its growth is arrested. Here, we show that protein synthesis, specific proteins involved in translation, and a stringent response are required for this remarkable longevity. Because it can generate ATP from light during growth arrest, R. palustris is an extreme example of a bacterial species that will stay alive for long periods of time as a relatively homogeneous population of cells and it is thus an excellent model organism for studies of bacterial longevity. There is evidence that other Gram-negative species also continue to synthesize proteins during growth arrest and that a stringent response is required for their longevity as well. Our observations challenge the notion that growth-arrested cells are necessarily dormant and metabolically inactive and suggest that such bacteria may have a level of metabolic activity that is higher than many would have assumed. Our results also expand our mechanistic understanding of a crucial but understudied phase of the bacterial life cycle.IMPORTANCE We are surrounded by bacteria, but they do not completely dominate our planet despite the ability of many to grow extremely rapidly in the laboratory. This has been interpreted to mean that bacteria in nature are often in a dormant state. We investigated life in growth arrest of Rhodopseudomonas palustris, a proteobacterium that stays alive for months when it is not growing. We found that cells were metabolically active, and they continued to synthesize proteins and mounted a stringent response, both of which were required for their longevity. Our results suggest that long-lived bacteria are not necessarily inactive but have an active metabolism that is well adjusted to life without growth.
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Baumgardt K, Gilet L, Figaro S, Condon C. The essential nature of YqfG, a YbeY homologue required for 3' maturation of Bacillus subtilis 16S ribosomal RNA is suppressed by deletion of RNase R. Nucleic Acids Res 2019; 46:8605-8615. [PMID: 29873764 PMCID: PMC6144821 DOI: 10.1093/nar/gky488] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 05/18/2018] [Indexed: 11/13/2022] Open
Abstract
Ribosomal RNAs are processed from primary transcripts containing 16S, 23S and 5S rRNAs in most bacteria. Maturation generally occurs in a two-step process, consisting of a first crude separation of the major species by RNase III during transcription, followed by precise trimming of 5′ and 3′ extensions on each species upon accurate completion of subunit assembly. The various endo- and exoribonucleases involved in the final processing reactions are strikingly different in Escherichia coli and Bacillus subtilis, the two best studied representatives of Gram-negative and Gram-positive bacteria, respectively. Here, we show that the one exception to this rule is the protein involved in the maturation of the 3′ end of 16S rRNA. Cells depleted for the essential B. subtilis YqfG protein, a homologue of E. coli YbeY, specifically accumulate 16S rRNA precursors bearing 3′ extensions. Remarkably, the essential nature of YqfG can be suppressed by deleting the ribosomal RNA degrading enzyme RNase R, i.e. a ΔyqfG Δrnr mutant is viable. Our data suggest that 70S ribosomes containing 30S subunits with 3′ extensions of 16S rRNA are functional to a degree, but become substrates for degradation by RNase R and are eliminated.
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Affiliation(s)
- Kathrin Baumgardt
- UMR 8261 (CNRS-Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Laetitia Gilet
- UMR 8261 (CNRS-Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Sabine Figaro
- UMR 8261 (CNRS-Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Ciarán Condon
- UMR 8261 (CNRS-Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
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35
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Bechhofer DH, Deutscher MP. Bacterial ribonucleases and their roles in RNA metabolism. Crit Rev Biochem Mol Biol 2019; 54:242-300. [PMID: 31464530 PMCID: PMC6776250 DOI: 10.1080/10409238.2019.1651816] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/22/2019] [Accepted: 07/31/2019] [Indexed: 12/16/2022]
Abstract
Ribonucleases (RNases) are mediators in most reactions of RNA metabolism. In recent years, there has been a surge of new information about RNases and the roles they play in cell physiology. In this review, a detailed description of bacterial RNases is presented, focusing primarily on those from Escherichia coli and Bacillus subtilis, the model Gram-negative and Gram-positive organisms, from which most of our current knowledge has been derived. Information from other organisms is also included, where relevant. In an extensive catalog of the known bacterial RNases, their structure, mechanism of action, physiological roles, genetics, and possible regulation are described. The RNase complement of E. coli and B. subtilis is compared, emphasizing the similarities, but especially the differences, between the two. Included are figures showing the three major RNA metabolic pathways in E. coli and B. subtilis and highlighting specific steps in each of the pathways catalyzed by the different RNases. This compilation of the currently available knowledge about bacterial RNases will be a useful tool for workers in the RNA field and for others interested in learning about this area.
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Affiliation(s)
- David H. Bechhofer
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Murray P. Deutscher
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA
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36
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The RNase YbeY Is Vital for Ribosome Maturation, Stress Resistance, and Virulence of the Natural Genetic Engineer Agrobacterium tumefaciens. J Bacteriol 2019; 201:JB.00730-18. [PMID: 30885931 DOI: 10.1128/jb.00730-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/12/2019] [Indexed: 12/12/2022] Open
Abstract
Riboregulation involving regulatory RNAs, RNA chaperones, and ribonucleases is fundamental for the rapid adaptation of gene expression to changing environmental conditions. The gene coding for the RNase YbeY belongs to the minimal prokaryotic genome set and has a profound impact on physiology in a wide range of bacteria. Here, we show that the Agrobacterium tumefaciens ybeY gene is not essential. Deletion of the gene in the plant pathogen reduced growth, motility, and stress tolerance. Most interestingly, YbeY is crucial for A. tumefaciens-mediated T-DNA transfer and tumor formation. Comparative proteomics by using isobaric tags for relative and absolute quantitation (iTRAQ) revealed dysregulation of 59 proteins, many of which have previously been found to be dependent on the RNA chaperone Hfq. YbeY and Hfq have opposing effects on production of these proteins. Accumulation of a 16S rRNA precursor in the ybeY mutant suggests that A. tumefaciens YbeY is involved in rRNA processing. RNA coimmunoprecipitation-sequencing (RIP-Seq) showed binding of YbeY to the region immediately upstream of the 16S rRNA. Purified YbeY is an oligomer with RNase activity. It does not physically interact with Hfq and thus plays a partially overlapping but distinct role in the riboregulatory network of the plant pathogen.IMPORTANCE Although ybeY gene belongs to the universal bacterial core genome, its biological function is incompletely understood. Here, we show that YbeY is critical for fitness and host-microbe interaction in the plant pathogen Agrobacterium tumefaciens Consistent with the reported endoribonuclease activity of YbeY, A. tumefaciens YbeY acts as a RNase involved in maturation of 16S rRNA. This report adds a worldwide plant pathogen and natural genetic engineer of plants to the growing list of bacteria that require the conserved YbeY protein for host-microbe interaction.
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37
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Janowski M, Zoschke R, Scharff LB, Martinez Jaime S, Ferrari C, Proost S, Ng Wei Xiong J, Omranian N, Musialak-Lange M, Nikoloski Z, Graf A, Schöttler MA, Sampathkumar A, Vaid N, Mutwil M. AtRsgA from Arabidopsis thaliana is important for maturation of the small subunit of the chloroplast ribosome. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:404-420. [PMID: 30044525 DOI: 10.1111/tpj.14040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 07/12/2018] [Accepted: 07/17/2018] [Indexed: 05/24/2023]
Abstract
Plastid ribosomes are very similar in structure and function to the ribosomes of their bacterial ancestors. Since ribosome biogenesis is not thermodynamically favorable under biological conditions it requires the activity of many assembly factors. Here we have characterized a homolog of bacterial RsgA in Arabidopsis thaliana and show that it can complement the bacterial homolog. Functional characterization of a strong mutant in Arabidopsis revealed that the protein is essential for plant viability, while a weak mutant produced dwarf, chlorotic plants that incorporated immature pre-16S ribosomal RNA into translating ribosomes. Physiological analysis of the mutant plants revealed smaller, but more numerous, chloroplasts in the mesophyll cells, reduction of chlorophyll a and b, depletion of proplastids from the rib meristem and decreased photosynthetic electron transport rate and efficiency. Comparative RNA sequencing and proteomic analysis of the weak mutant and wild-type plants revealed that various biotic stress-related, transcriptional regulation and post-transcriptional modification pathways were repressed in the mutant. Intriguingly, while nuclear- and chloroplast-encoded photosynthesis-related proteins were less abundant in the mutant, the corresponding transcripts were increased, suggesting an elaborate compensatory mechanism, potentially via differentially active retrograde signaling pathways. To conclude, this study reveals a chloroplast ribosome assembly factor and outlines the transcriptomic and proteomic responses of the compensatory mechanism activated during decreased chloroplast function.
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Affiliation(s)
- Marcin Janowski
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Reimo Zoschke
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Lars B Scharff
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Silvia Martinez Jaime
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Camilla Ferrari
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Sebastian Proost
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Jonathan Ng Wei Xiong
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Nooshin Omranian
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | | | - Zoran Nikoloski
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
- Bioinformatics Group, Institute of Biochemistry and Biology, University of Potsdam, Karl- Liebknecht-Strasse 24-25, 14476, Potsdam-Golm, Germany
| | - Alexander Graf
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Mark A Schöttler
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Arun Sampathkumar
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Neha Vaid
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
| | - Marek Mutwil
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Potsdam, Germany
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
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Dos Santos RF, Quendera AP, Boavida S, Seixas AF, Arraiano CM, Andrade JM. Major 3'-5' Exoribonucleases in the Metabolism of Coding and Non-coding RNA. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 159:101-155. [PMID: 30340785 DOI: 10.1016/bs.pmbts.2018.07.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
3'-5' exoribonucleases are key enzymes in the degradation of superfluous or aberrant RNAs and in the maturation of precursor RNAs into their functional forms. The major bacterial 3'-5' exoribonucleases responsible for both these activities are PNPase, RNase II and RNase R. These enzymes are of ancient nature with widespread distribution. In eukaryotes, PNPase and RNase II/RNase R enzymes can be found in the cytosol and in mitochondria and chloroplasts; RNase II/RNase R-like enzymes are also found in the nucleus. Humans express one PNPase (PNPT1) and three RNase II/RNase R family members (Dis3, Dis3L and Dis3L2). These enzymes take part in a multitude of RNA surveillance mechanisms that are critical for translation accuracy. Although active against a wide range of both coding and non-coding RNAs, the different 3'-5' exoribonucleases exhibit distinct substrate affinities. The latest studies on these RNA degradative enzymes have contributed to the identification of additional homologue proteins, the uncovering of novel RNA degradation pathways, and to a better comprehension of several disease-related processes and response to stress, amongst many other exciting findings. Here, we provide a comprehensive and up-to-date overview on the function, structure, regulation and substrate preference of the key 3'-5' exoribonucleases involved in RNA metabolism.
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Affiliation(s)
- Ricardo F Dos Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Ana P Quendera
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Sofia Boavida
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André F Seixas
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - José M Andrade
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
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Elevated Levels of Era GTPase Improve Growth, 16S rRNA Processing, and 70S Ribosome Assembly of Escherichia coli Lacking Highly Conserved Multifunctional YbeY Endoribonuclease. J Bacteriol 2018; 200:JB.00278-18. [PMID: 29914987 DOI: 10.1128/jb.00278-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/04/2018] [Indexed: 01/09/2023] Open
Abstract
YbeY is a highly conserved, multifunctional endoribonuclease that plays a significant role in ribosome biogenesis and has several additional roles. Here we show that overexpression of the conserved GTPase Era in Escherichia coli partially suppresses the growth defect of a ΔybeY strain while improving 16S rRNA processing and 70S ribosome assembly. This suppression requires both the ability of Era to hydrolyze GTP and the function of three exoribonucleases, RNase II, RNase R, and RNase PH, suggesting a model for the action of Era. Overexpression of Vibrio cholerae Era similarly partially suppresses the defects of an E. coli ΔybeY strain, indicating that this property of Era is conserved in bacteria other than E. coliIMPORTANCE This work provides insight into the critical, but still incompletely understood, mechanism of processing of the E. coli 16S rRNA 3' terminus. The highly conserved GTPase Era is known to bind to the precursor of the 16S rRNA near its 3' end. Both the endoribonuclease YbeY, which binds to Era, and four exoribonucleases have been implicated in this 3'-end processing. The results reported here offer additional insights into the role of Era in 16S rRNA 3'-end maturation and into the relationship between the action of the endoribonuclease YbeY and that of the four exoribonucleases. This study also hints at why YbeY is essential only in some bacteria and suggests that YbeY could be a target for a new class of antibiotics in these bacteria.
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40
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Anacker ML, Drecktrah D, LeCoultre RD, Lybecker M, Samuels DS. RNase III Processing of rRNA in the Lyme Disease Spirochete Borrelia burgdorferi. J Bacteriol 2018; 200:e00035-18. [PMID: 29632096 PMCID: PMC5996687 DOI: 10.1128/jb.00035-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/04/2018] [Indexed: 02/08/2023] Open
Abstract
The rRNA genes of Borrelia (Borreliella) burgdorferi are unusually organized; the spirochete has a single 16S rRNA gene that is more than 3 kb from a tandem pair of 23S-5S rRNA operons. We generated an rnc null mutant in B. burgdorferi that exhibits a pleiotropic phenotype, including decreased growth rate and increased cell length. Here, we demonstrate that endoribonuclease III (RNase III) is, as expected, involved in processing the 23S rRNA in B. burgdorferi The 5' and 3' ends of the three rRNAs were determined in the wild type and rncBb mutants; the results suggest that RNase III in B. burgdorferi is required for the full maturation of the 23S rRNA but not for the 5S rRNA nor, curiously, for the 16S rRNA.IMPORTANCE Lyme disease, the most common tick-borne zoonosis in the Northern Hemisphere, is caused by the bacterium Borrelia (Borreliella) burgdorferi, a member of the deeply branching spirochete phylum. B. burgdorferi carries a limited suite of ribonucleases, enzymes that cleave RNA during processing and degradation. Several ribonucleases, including RNase III, are involved in the production of ribosomes, which catalyze translation and are a major target of antibiotics. This is the first study to dissect the role of an RNase in any spirochete. We demonstrate that an RNase III mutant is viable but has altered processing of rRNA.
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MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Borrelia burgdorferi/enzymology
- Borrelia burgdorferi/genetics
- Borrelia burgdorferi/metabolism
- Humans
- Lyme Disease/microbiology
- Operon
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
- RNA, Ribosomal, 5S/genetics
- RNA, Ribosomal, 5S/metabolism
- Ribonuclease III/genetics
- Ribonuclease III/metabolism
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Affiliation(s)
- Melissa L Anacker
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Richard D LeCoultre
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Meghan Lybecker
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Department of Biology, University of Colorado, Colorado Springs, Colorado, USA
| | - D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, USA
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Tang X, Wang Y, Zhang Y, Huang S, Liu Z, Fei D, Feng H. A missense mutation of plastid RPS4 is associated with chlorophyll deficiency in Chinese cabbage (Brassica campestris ssp. pekinensis). BMC PLANT BIOLOGY 2018; 18:130. [PMID: 29940850 PMCID: PMC6019835 DOI: 10.1186/s12870-018-1353-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 06/17/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND Plastome mutants are ideal resources for elucidating the functions of plastid genes. Numerous studies have been conducted for the function of plastid genes in barley and tobacco; however, related information is limited in Chinese cabbage. RESULTS A chlorophyll-deficient mutant of Chinese cabbage that was derived by ethyl methanesulfonate treatment on isolated microspores showed uniformly pale green inner leaves and slow growth compared with that shown by the wild type "Fukuda 50' ('FT'). Genetic analysis revealed that cdm was cytoplasmically inherited. Physiological and ultrastructural analyses of cdm showed impaired photosynthesis and abnormal chloroplast development. Utilizing next generation sequencing, the complete plastomes of cdm and 'FT' were respectively re-mapped to the reference genome of Chinese cabbage, and an A-to-C base substitution with a mutation ratio higher than 99% was detected. The missense mutation of plastid ribosomal protein S4 led to valine substitution for glycine at residue 193. The expression level of rps4 was analyzed using quantitative real-time PCR and found lower in than in 'FT'. RNA gel-blot assays showed that the abundance of mature 23S rRNA, 16S rRNA, 5S rRNA, and 4.5S rRNA significantly decreased and that the processing of 23S, 16S rRNA, and 4.5S rRNA was seriously impaired, affecting the ribosomal function in cdm. CONCLUSIONS These findings indicated that cdm was a plastome mutant and that chlorophyll deficiency might be due to an A-to-C base substitution of the plastome-encoded rps4 that impaired the rRNA processing and affected the ribosomal function.
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Affiliation(s)
- Xiaoyan Tang
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
| | - Yiheng Wang
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
| | - Yun Zhang
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
| | - Shengnan Huang
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
| | - Zhiyong Liu
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
| | - Danli Fei
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
| | - Hui Feng
- College of Horticulture, Liaoning Key Lab of Genetics and Breeding for Cruciferous Vegetable Crops, Shenyang Agricultural University, Shenyang, Liaoning 110866 People’s Republic of China
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42
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Endoribonuclease YbeY Is Linked to Proper Cellular Morphology and Virulence in Brucella abortus. J Bacteriol 2018; 200:JB.00105-18. [PMID: 29632093 DOI: 10.1128/jb.00105-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/03/2018] [Indexed: 12/14/2022] Open
Abstract
The YbeY endoribonuclease is one of the best-conserved proteins across the kingdoms of life. In the present study, we demonstrated that YbeY in Brucella abortus is linked to a variety of important activities, including proper cellular morphology, mRNA transcript levels, and virulence. Deletion of ybeY in B. abortus led to a small-colony phenotype when the bacteria were grown on agar medium, as well as to significant aberrations in the morphology of the bacterial cell as evidenced by electron microscopy. Additionally, compared to the parental strain, the ΔybeY strain was significantly attenuated in both macrophage and mouse models of infection. The ΔybeY strain also showed increased sensitivities to several in vitro-applied stressors, including bile acid, hydrogen peroxide, SDS, and paraquat. Transcriptomic analysis revealed that a multitude of mRNA transcripts are dysregulated in the ΔybeY strain, and many of the identified mRNAs encode proteins involved in metabolism, nutrient transport, transcriptional regulation, and flagellum synthesis. We subsequently constructed gene deletion strains of the most highly dysregulated systems, and several of the YbeY-linked gene deletion strains exhibited defects in the ability of the bacteria to survive and replicate in primary murine macrophages. Taken together, these data establish a clear role for YbeY in the biology and virulence of Brucella; moreover, this work further illuminates the highly varied roles of this widely conserved endoribonuclease in bacteria.IMPORTANCEBrucella spp. are highly efficient bacterial pathogens of animals and humans, causing significant morbidity and economic loss worldwide, and relapse of disease often occurs following antibiotic treatment of human brucellosis. As such, novel therapeutic strategies to combat Brucella infections are needed. Ribonucleases in the brucellae are understudied, and these enzymes represent elements that may be potential targets for future treatment approaches. The present work demonstrates the importance of the YbeY endoribonuclease for cellular morphology, efficient control of mRNA levels, and virulence in B. abortus Overall, the results of this study advance our understanding of the critical roles of YbeY in the pathogenesis of the intracellular brucellae and expand our understanding of this highly conserved RNase.
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43
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McAteer SP, Sy BM, Wong JL, Tollervey D, Gally DL, Tree JJ. Ribosome maturation by the endoribonuclease YbeY stabilizes a type 3 secretion system transcript required for virulence of enterohemorrhagic Escherichia coli. J Biol Chem 2018; 293:9006-9016. [PMID: 29678883 PMCID: PMC5995498 DOI: 10.1074/jbc.ra117.000300] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 04/17/2018] [Indexed: 12/11/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a significant human pathogen that colonizes humans and its reservoir host, cattle. Colonization requires the expression of a type 3 secretion (T3S) system that injects a mixture of effector proteins into host cells to promote bacterial attachment and disease progression. The T3S system is tightly regulated by a complex network of transcriptional and post-transcriptional regulators. Using transposon mutagenesis, here we identified the ybeZYX-Int operon as being required for normal T3S levels. Deletion analyses localized the regulation to the endoribonuclease YbeY, previously linked to 16S rRNA maturation and small RNA (sRNA) function. Loss of ybeY in EHEC had pleiotropic effects on EHEC cells, including reduced motility and growth and cold sensitivity. Using UV cross-linking and RNA-Seq (CRAC) analysis, we identified YbeY-binding sites throughout the transcriptome and discovered specific binding of YbeY to the "neck" and "beak" regions of 16S rRNA but identified no significant association of YbeY with sRNA, suggesting that YbeY modulates T3S by depleting mature ribosomes. In E. coli, translation is strongly linked to mRNA stabilization, and subinhibitory concentrations of the translation-initiation inhibitor kasugamycin provoked rapid degradation of a polycistronic mRNA encoding needle filament and needle tip proteins of the T3S system. We conclude that T3S is particularly sensitive to depletion of initiating ribosomes, explaining the inhibition of T3S in the ΔybeY strain. Accessory virulence transcripts may be preferentially degraded in cells with reduced translational capacity, potentially reflecting prioritization in protein production.
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Affiliation(s)
- Sean P McAteer
- From the Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh EH25 9RG, Scotland, United Kingdom
| | - Brandon M Sy
- School of Biotechnology and Biomolecular Sciences, University of New South Wales Sydney, Sydney 2033, Australia, and
| | - Julia L Wong
- School of Biotechnology and Biomolecular Sciences, University of New South Wales Sydney, Sydney 2033, Australia, and
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, Scotland, United Kingdom
| | - David L Gally
- From the Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Edinburgh EH25 9RG, Scotland, United Kingdom,
| | - Jai J Tree
- School of Biotechnology and Biomolecular Sciences, University of New South Wales Sydney, Sydney 2033, Australia, and
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44
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Smith BA, Gupta N, Denny K, Culver GM. Characterization of 16S rRNA Processing with Pre-30S Subunit Assembly Intermediates from E. coli. J Mol Biol 2018; 430:1745-1759. [PMID: 29660326 DOI: 10.1016/j.jmb.2018.04.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 01/02/2023]
Abstract
Ribosomal RNA (rRNA) is a major component of ribosomes and is fundamental to the process of translation. In bacteria, 16S rRNA is a component of the small ribosomal subunit and plays a critical role in mRNA decoding. rRNA maturation entails the removal of intervening spacer sequences contained within the pre-rRNA transcript by nucleolytic enzymes. Enzymatic activities involved in maturation of the 5'-end of 16S rRNA have been identified, but those involved in 3'-end maturation of 16S rRNA are more enigmatic. Here, we investigate molecular details of 16S rRNA maturation using purified in vivo-formed small subunit (SSU) assembly intermediates (pre-SSUs) from wild-type Escherichia coli that contain precursor 16S rRNA (17S rRNA). Upon incubation of pre-SSUs with E. coli S100 cell extracts or purified enzymes implicated in 16S rRNA processing, the 17S rRNA is processed into additional intermediates and mature 16S rRNA. These results illustrate that exonucleases RNase R, RNase II, PNPase, and RNase PH can process the 3'-end of pre-SSUs in vitro. However, the endonuclease YbeY did not exhibit nucleolytic activity with pre-SSUs under these conditions. Furthermore, these data demonstrate that multiple pathways facilitate 16S rRNA maturation with pre-SSUs in vitro, with the dominant pathways entailing complete processing of the 5'-end of 17S rRNA prior to 3'-end maturation or partial processing of the 5'-end with concomitant processing of the 3'-end. These results reveal the multifaceted nature of SSU biogenesis and suggest that E. coli may be able to escape inactivation of any one enzyme by using an existing complementary pathway.
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Affiliation(s)
- Brian A Smith
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Neha Gupta
- Department of Biology, University of Rochester, Rochester, NY 14627, USA; Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kevin Denny
- Department of Biology, University of Rochester, Rochester, NY 14627, USA; Chemistry and Biochemistry Department, Nazareth College, Pittsford, NY 14618, USA
| | - Gloria M Culver
- Department of Biology, University of Rochester, Rochester, NY 14627, USA; Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD 20892, USA; Center for RNA Biology: from Genome to Therapeutics, University of Rochester Medical Center, Rochester, NY 14627, USA.
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45
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Mohanty BK, Kushner SR. Enzymes Involved in Posttranscriptional RNA Metabolism in Gram-Negative Bacteria. Microbiol Spectr 2018; 6:10.1128/microbiolspec.RWR-0011-2017. [PMID: 29676246 PMCID: PMC5912700 DOI: 10.1128/microbiolspec.rwr-0011-2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Indexed: 02/08/2023] Open
Abstract
Gene expression in Gram-negative bacteria is regulated at many levels, including transcription initiation, RNA processing, RNA/RNA interactions, mRNA decay, and translational controls involving enzymes that alter translational efficiency. In this review, we discuss the various enzymes that control transcription, translation, and RNA stability through RNA processing and degradation. RNA processing is essential to generate functional RNAs, while degradation helps control the steady-state level of each individual transcript. For example, all the pre-tRNAs are transcribed with extra nucleotides at both their 5' and 3' termini, which are subsequently processed to produce mature tRNAs that can be aminoacylated. Similarly, rRNAs that are transcribed as part of a 30S polycistronic transcript are matured to individual 16S, 23S, and 5S rRNAs. Decay of mRNAs plays a key role in gene regulation through controlling the steady-state level of each transcript, which is essential for maintaining appropriate protein levels. In addition, degradation of both translated and nontranslated RNAs recycles nucleotides to facilitate new RNA synthesis. To carry out all these reactions, Gram-negative bacteria employ a large number of endonucleases, exonucleases, RNA helicases, and poly(A) polymerase, as well as proteins that regulate the catalytic activity of particular RNases. Under certain stress conditions, an additional group of specialized endonucleases facilitate the cell's ability to adapt and survive. Many of the enzymes, such as RNase E, RNase III, polynucleotide phosphorylase, RNase R, and poly(A) polymerase I, participate in multiple RNA processing and decay pathways.
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Affiliation(s)
| | - Sidney R Kushner
- Department of Genetics
- Department of Microbiology, University of Georgia, Athens, GA 30602
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46
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Abstract
It is well known that many bacteria can survive in a growth-arrested state for long periods of time, on the order of months or even years, without forming dormant structures like spores or cysts. How is such longevity possible? What is the molecular basis of such longevity? Here we used the Gram-negative phototrophic alphaproteobacterium Rhodopseudomonas palustris to identify molecular determinants of bacterial longevity. R. palustris maintained viability for over a month after growth arrest due to nutrient depletion when it was provided with light as a source of energy. In transposon sequencing (Tn-seq) experiments, we identified 117 genes that were required for long-term viability of nongrowing R. palustris cells. Genes in this longevity gene set are annotated to play roles in a number of cellular processes, including DNA repair, tRNA modification, and the fidelity of protein synthesis. These genes are critically important only when cells are not growing. Three genes annotated to affect translation or posttranslational modifications were validated as bona fide longevity genes by mutagenesis and complementation experiments. These genes and others in the longevity gene set are broadly conserved in bacteria. This raises the possibility that it will be possible to define a core set of longevity genes common to many bacterial species. Bacteria in nature and during infections often exist in a nongrowing quiescent state. However, it has been difficult to define experimentally the molecular characteristics of this crucial element of the bacterial life cycle because bacteria that are not growing tend to die under laboratory conditions. Here we present and validate the phototrophic bacterium Rhodopseudomonas palustris as a model system for identification of genes required for the longevity of nongrowing bacteria. Growth-arrested R. palustris maintained almost full viability for weeks using light as an energy source. Such cells were subjected to large-scale mutagenesis to identify genes required for this striking longevity trait. The results define conserved determinants of survival under nongrowing conditions and create a foundation for more extensive studies to elucidate general molecular mechanisms of bacterial longevity.
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47
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Gagarinova A, Stewart G, Samanfar B, Phanse S, White CA, Aoki H, Deineko V, Beloglazova N, Yakunin AF, Golshani A, Brown ED, Babu M, Emili A. Systematic Genetic Screens Reveal the Dynamic Global Functional Organization of the Bacterial Translation Machinery. Cell Rep 2017; 17:904-916. [PMID: 27732863 DOI: 10.1016/j.celrep.2016.09.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 07/30/2016] [Accepted: 09/14/2016] [Indexed: 12/20/2022] Open
Abstract
Bacterial protein synthesis is an essential, conserved, and environmentally responsive process. Yet, many of its components and dependencies remain unidentified. To address this gap, we used quantitative synthetic genetic arrays to map functional relationships among >48,000 gene pairs in Escherichia coli under four culture conditions differing in temperature and nutrient availability. The resulting data provide global functional insights into the roles and associations of genes, pathways, and processes important for efficient translation, growth, and environmental adaptation. We predict and independently verify the requirement of unannotated genes for normal translation, including a previously unappreciated role of YhbY in 30S biogenesis. Dynamic changes in the patterns of genetic dependencies across the four growth conditions and data projections onto other species reveal overarching functional and evolutionary pressures impacting the translation system and bacterial fitness, underscoring the utility of systematic screens for investigating protein synthesis, adaptation, and evolution.
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Affiliation(s)
- Alla Gagarinova
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Geordie Stewart
- Department of Biochemistry and Biomedical Sciences, M.G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Bahram Samanfar
- Department of Biology and the Ottawa Institute of Systems Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON K1A 0C6, Canada
| | - Sadhna Phanse
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, SK S4S 0A2, Canada
| | - Carl A White
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Hiroyuki Aoki
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, SK S4S 0A2, Canada
| | - Viktor Deineko
- Department of Biochemistry, Research and Innovation Centre, University of Regina, Regina, SK S4S 0A2, Canada
| | - Natalia Beloglazova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| | - Alexander F Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3E5, Canada
| | - Ashkan Golshani
- Department of Biology and the Ottawa Institute of Systems Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Eric D Brown
- Department of Biochemistry and Biomedical Sciences, M.G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Mohan Babu
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON K1A 0C6, Canada
| | - Andrew Emili
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.
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Saramago M, Peregrina A, Robledo M, Matos RG, Hilker R, Serrania J, Becker A, Arraiano CM, Jiménez-Zurdo JI. Sinorhizobium meliloti YbeY is an endoribonuclease with unprecedented catalytic features, acting as silencing enzyme in riboregulation. Nucleic Acids Res 2017; 45:1371-1391. [PMID: 28180335 PMCID: PMC5388416 DOI: 10.1093/nar/gkw1234] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 11/22/2016] [Accepted: 11/24/2016] [Indexed: 01/23/2023] Open
Abstract
Structural and biochemical features suggest that the almost ubiquitous bacterial YbeY protein may serve catalytic and/or Hfq-like protective functions central to small RNA (sRNA)-mediated regulation and RNA metabolism. We have biochemically and genetically characterized the YbeY ortholog of the legume symbiont Sinorhizobium meliloti (SmYbeY). Co-immunoprecipitation (CoIP) with a FLAG-tagged SmYbeY yielded a poor enrichment in RNA species, compared to Hfq CoIP-RNA uncovered previously by a similar experimental setup. Purified SmYbeY behaved as a monomer that indistinctly cleaved single- and double-stranded RNA substrates, a unique ability among bacterial endoribonucleases. SmYbeY-mediated catalysis was supported by the divalent metal ions Mg2+, Mn2+ and Ca2+, which influenced in a different manner cleavage efficiency and reactivity patterns, with Ca2+ specifically blocking activity on double-stranded and some structured RNA molecules. SmYbeY loss-of-function compromised expression of core energy and RNA metabolism genes, whilst promoting accumulation of motility, late symbiotic and transport mRNAs. Some of the latter transcripts are known Hfq-binding sRNA targets and might be SmYbeY substrates. Genetic reporter and in vitro assays confirmed that SmYbeY is required for sRNA-mediated down-regulation of the amino acid ABC transporter prbA mRNA. We have thus discovered a bacterial endoribonuclease with unprecedented catalytic features, acting also as gene silencing enzyme.
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Affiliation(s)
- Margarida Saramago
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157 Oeiras, Portugal
- These authors contributed equally to the work as the first authors
| | - Alexandra Peregrina
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
- These authors contributed equally to the work as the first authors
| | - Marta Robledo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
- These authors contributed equally to the work as the first authors
| | - Rute G. Matos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157 Oeiras, Portugal
| | - Rolf Hilker
- LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-University Marburg, 35043 Marburg, Germany
| | - Javier Serrania
- LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-University Marburg, 35043 Marburg, Germany
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-University Marburg, 35043 Marburg, Germany
| | - Cecilia M. Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República, 2780-157 Oeiras, Portugal
| | - José I. Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
- To whom correspondence should be addressed. Tel: +34 958181600; Fax: +34 958181609;
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49
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Jiménez-Zurdo JI, Robledo M. RNA silencing in plant symbiotic bacteria: Insights from a protein-centric view. RNA Biol 2017; 14:1672-1677. [PMID: 28805544 DOI: 10.1080/15476286.2017.1356565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Extensive work in model enterobacteria has evidenced that the RNA chaperone Hfq and several endoribonucleases, such as RNase E or RNase III, serve pivotal roles in small RNA-mediated post-transcriptional silencing of gene expression. Characterization of these protein hubs commonly provide global functional and mechanistic insights into complex sRNA regulatory networks. The legume endosymbiont Sinorhizobium meliloti is a non-classical model bacterium with a very complex lifestyle in which riboregulation is expected to play important adaptive functions. Here, we discuss current knowledge about RNA silencing in S. meliloti from the perspective of the activity of Hfq and a recently discovered endoribonuclease (YbeY) exhibiting unprecedented catalytic versatility for the cleavage of single- and double-stranded RNA molecules.
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Affiliation(s)
- José I Jiménez-Zurdo
- a Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín , Consejo Superior de Investigaciones Científicas (CSIC) , Granada , Spain
| | - Marta Robledo
- a Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín , Consejo Superior de Investigaciones Científicas (CSIC) , Granada , Spain
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50
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A 6-Nucleotide Regulatory Motif within the AbcR Small RNAs of Brucella abortus Mediates Host-Pathogen Interactions. mBio 2017; 8:mBio.00473-17. [PMID: 28588127 PMCID: PMC5461406 DOI: 10.1128/mbio.00473-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Brucella abortus, two small RNAs (sRNAs), AbcR1 and AbcR2, are responsible for regulating transcripts encoding ABC-type transport systems. AbcR1 and AbcR2 are required for Brucella virulence, as a double chromosomal deletion of both sRNAs results in attenuation in mice. Although these sRNAs are responsible for targeting transcripts for degradation, the mechanism utilized by the AbcR sRNAs to regulate mRNA in Brucella has not been described. Here, two motifs (M1 and M2) were identified in AbcR1 and AbcR2, and complementary motif sequences were defined in AbcR-regulated transcripts. Site-directed mutagenesis of M1 or M2 or of both M1 and M2 in the sRNAs revealed transcripts to be targeted by one or both motifs. Electrophoretic mobility shift assays revealed direct, concentration-dependent binding of both AbcR sRNAs to a target mRNA sequence. These experiments genetically and biochemically characterized two indispensable motifs within the AbcR sRNAs that bind to and regulate transcripts. Additionally, cellular and animal models of infection demonstrated that only M2 in the AbcR sRNAs is required for Brucella virulence. Furthermore, one of the M2-regulated targets, BAB2_0612, was found to be critical for the virulence of B. abortus in a mouse model of infection. Although these sRNAs are highly conserved among Alphaproteobacteria, the present report displays how gene regulation mediated by the AbcR sRNAs has diverged to meet the intricate regulatory requirements of each particular organism and its unique biological niche. Small RNAs (sRNAs) are important components of bacterial regulation, allowing organisms to quickly adapt to changes in their environments. The AbcR sRNAs are highly conserved throughout the Alphaproteobacteria and negatively regulate myriad transcripts, many encoding ABC-type transport systems. In Brucella abortus, AbcR1 and AbcR2 are functionally redundant, as only a double abcR1 abcR2 (abcR1/2) deletion results in attenuation in vitro and in vivo. In the present study, we confirmed that the AbcR sRNAs have redundant regulatory functions and defined two six-nucleotide motifs, M1 and M2, that the AbcR sRNAs utilize to control gene expression. Importantly, only M2 was linked to B. abortus virulence. Further investigation of M2-regulated targets identified BAB2_0612 as critical for colonization of B. abortus in mice, highlighting the significance of AbcR M2-regulated transcripts for Brucella infection. Overall, our findings define the molecular mechanism of the virulence-associated AbcR system in the pathogenic bacterium B. abortus.
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