1
|
Pandiyan A, Mallikarjun J, Maheshwari H, Gowrishankar J. Pathological R-loops in bacteria from engineered expression of endogenous antisense RNAs whose synthesis is ordinarily terminated by Rho. Nucleic Acids Res 2024:gkae839. [PMID: 39373509 DOI: 10.1093/nar/gkae839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 08/13/2024] [Accepted: 09/12/2024] [Indexed: 10/08/2024] Open
Abstract
In many bacteria, the essential factors Rho and NusG mediate termination of synthesis of nascent transcripts (including antisense RNAs) that are not being simultaneously translated. It has been proposed that in Rho's absence toxic RNA-DNA hybrids (R-loops) may be generated from nascent untranslated transcripts, and genome-wide mapping studies in Escherichia coli have identified putative loci of R-loop formation from more than 100 endogenous antisense transcripts that are synthesized only in a Rho-deficient strain. Here we provide evidence that engineered expression in wild-type E. coli of several such individual antisense regions on a plasmid or the chromosome generates R-loops that, in an RNase H-modulated manner, serve to disrupt genome integrity. Rho inhibition was associated with increased prevalence of antisense R-loops also in Xanthomonas oryzae pv. oryzae and Caulobacter crescentus. Our results confirm the essential role of Rho in several bacterial genera for prevention of toxic R-loops from pervasive yet cryptic endogenous antisense transcripts. Engineered antisense R-looped regions may be useful for studies on both site-specific impediments to bacterial chromosomal replication and the mechanisms of their resolution.
Collapse
Affiliation(s)
- Apuratha Pandiyan
- Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar 140306, Punjab, India
| | - Jillella Mallikarjun
- Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar 140306, Punjab, India
- Centre for DNA Fingerprinting and Diagnostics, Uppal Road, Hyderabad 500039, Telengana, India
| | - Himanshi Maheshwari
- Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar 140306, Punjab, India
| | - Jayaraman Gowrishankar
- Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar 140306, Punjab, India
| |
Collapse
|
2
|
Moreira S, Chyou TY, Wade J, Brown C. Diversification of the Rho transcription termination factor in bacteria. Nucleic Acids Res 2024; 52:8979-8997. [PMID: 38966992 PMCID: PMC11347177 DOI: 10.1093/nar/gkae582] [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: 10/26/2023] [Revised: 06/17/2024] [Accepted: 06/24/2024] [Indexed: 07/06/2024] Open
Abstract
Correct termination of transcription is essential for gene expression. In bacteria, factor-dependent termination relies on the Rho factor, that classically has three conserved domains. Some bacteria also have a functional insertion region. However, the variation in Rho structure among bacteria has not been analyzed in detail. This study determines the distribution, sequence conservation, and predicted features of Rho factors with diverse domain architectures by analyzing 2730 bacterial genomes. About half (49.8%) of the species analyzed have the typical Escherichia coli like Rho while most of the other species (39.8%) have diverse, atypical forms of Rho. Besides conservation of the main domains, we describe a duplicated RNA-binding domain present in specific species and novel variations in the bicyclomycin binding pocket. The additional regions observed in Rho proteins exhibit remarkable diversity. Commonly, however, they have exceptional amino acid compositions and are predicted to be intrinsically disordered, to undergo phase separation, or have prion-like behavior. Phase separation has recently been shown to play roles in Rho function and bacterial fitness during harsh conditions in one species and this study suggests a more widespread role. In conclusion, diverse atypical Rho factors are broadly distributed among bacteria, suggesting additional cellular roles.
Collapse
Affiliation(s)
- Sofia M Moreira
- Department of Biochemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Te-yuan Chyou
- Department of Biochemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Joseph T Wade
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY 12222, USA
| | - Chris M Brown
- Department of Biochemistry, University of Otago, Dunedin, Otago 9054, New Zealand
- Genetics Otago, University of Otago, Dunedin, Otago 9054, New Zealand
| |
Collapse
|
3
|
Zheng Y, Chai R, Wang T, Xu Z, He Y, Shen P, Liu J. RNA polymerase stalling-derived genome instability underlies ribosomal antibiotic efficacy and resistance evolution. Nat Commun 2024; 15:6579. [PMID: 39097616 PMCID: PMC11297953 DOI: 10.1038/s41467-024-50917-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 07/24/2024] [Indexed: 08/05/2024] Open
Abstract
Bacteria often evolve antibiotic resistance through mutagenesis. However, the processes causing the mutagenesis have not been fully resolved. Here, we find that a broad range of ribosome-targeting antibiotics cause mutations through an underexplored pathway. Focusing on the clinically important aminoglycoside gentamicin, we find that the translation inhibitor causes genome-wide premature stalling of RNA polymerase (RNAP) in a loci-dependent manner. Further analysis shows that the stalling is caused by the disruption of transcription-translation coupling. Anti-intuitively, the stalled RNAPs subsequently induce lesions to the DNA via transcription-coupled repair. While most of the bacteria are killed by genotoxicity, a small subpopulation acquires mutations via SOS-induced mutagenesis. Given that these processes are triggered shortly after antibiotic addition, resistance rapidly emerges in the population. Our work reveals a mechanism of action of ribosomal antibiotics, illustrates the importance of dissecting the complex interplay between multiple molecular processes in understanding antibiotic efficacy, and suggests new strategies for countering the development of resistance.
Collapse
Affiliation(s)
- Yayun Zheng
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China
| | - Ruochen Chai
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China
| | - Tianmin Wang
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China.
- Tsinghua-Peking Center for Life Sciences, Beijing, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
| | - Zeqi Xu
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China
| | - Yihui He
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China
| | - Ping Shen
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China
| | - Jintao Liu
- Center for Infection Biology, School of Basic Medical Sciences, Tsinghua University, Beijing, China.
- Tsinghua-Peking Center for Life Sciences, Beijing, China.
- SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Shanxi Medical University, Taiyuan, Shanxi Province, China.
| |
Collapse
|
4
|
Hustmyer CM, Landick R. Bacterial chromatin proteins, transcription, and DNA topology: Inseparable partners in the control of gene expression. Mol Microbiol 2024; 122:81-112. [PMID: 38847475 PMCID: PMC11260248 DOI: 10.1111/mmi.15283] [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: 01/11/2024] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 06/15/2024]
Abstract
DNA in bacterial chromosomes is organized into higher-order structures by DNA-binding proteins called nucleoid-associated proteins (NAPs) or bacterial chromatin proteins (BCPs). BCPs often bind to or near DNA loci transcribed by RNA polymerase (RNAP) and can either increase or decrease gene expression. To understand the mechanisms by which BCPs alter transcription, one must consider both steric effects and the topological forces that arise when DNA deviates from its fully relaxed double-helical structure. Transcribing RNAP creates DNA negative (-) supercoils upstream and positive (+) supercoils downstream whenever RNAP and DNA are unable to rotate freely. This (-) and (+) supercoiling generates topological forces that resist forward translocation of DNA through RNAP unless the supercoiling is constrained by BCPs or relieved by topoisomerases. BCPs also may enhance topological stress and overall can either inhibit or aid transcription. Here, we review current understanding of how RNAP, BCPs, and DNA topology interplay to control gene expression.
Collapse
Affiliation(s)
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison
- Department of Bacteriology, University of Wisconsin-Madison
| |
Collapse
|
5
|
Zhang J, Zhang S, Zhou W, Zhang X, Li G, Li R, Lin X, Chen Z, Liu F, Shen P, Zhou X, Gao Y, Chen Z, Chao Y, Wang C. A widely conserved protein Rof inhibits transcription termination factor Rho and promotes Salmonella virulence program. Nat Commun 2024; 15:3187. [PMID: 38622116 PMCID: PMC11018607 DOI: 10.1038/s41467-024-47438-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/18/2024] [Indexed: 04/17/2024] Open
Abstract
Transcription is crucial for the expression of genetic information and its efficient and accurate termination is required for all living organisms. Rho-dependent termination could rapidly terminate unwanted premature RNAs and play important roles in bacterial adaptation to changing environments. Although Rho has been discovered for about five decades, the regulation mechanisms of Rho-dependent termination are still not fully elucidated. Here we report that Rof is a conserved antiterminator and determine the cryogenic electron microscopy structure of Rho-Rof antitermination complex. Rof binds to the open-ring Rho hexamer and inhibits the initiation of Rho-dependent termination. Rof's N-terminal α-helix undergoes conformational changes upon binding with Rho, and is key in facilitating Rof-Rho interactions. Rof binds to Rho's primary binding site (PBS) and excludes Rho from binding with PBS ligand RNA at the initiation step. Further in vivo analyses in Salmonella Typhimurium show that Rof is required for virulence gene expression and host cell invasion, unveiling a physiological function of Rof and transcription termination in bacterial pathogenesis.
Collapse
Affiliation(s)
- Jing Zhang
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
| | - Shuo Zhang
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wei Zhou
- Department of Pharmaceutical Sciences, Beijing Institute of Radiation Medicine, Beijing, China
| | - Xiang Zhang
- The Fifth People's Hospital, Institutes of Biomedical Sciences, School of Public Health, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Guanjin Li
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ruoxuan Li
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xingyu Lin
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ziying Chen
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
- The Fifth People's Hospital, Institutes of Biomedical Sciences, School of Public Health, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Fang Liu
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China
| | - Pan Shen
- Department of Pharmaceutical Sciences, Beijing Institute of Radiation Medicine, Beijing, China
| | - Xiaogen Zhou
- College of Information Engineering, Zhejiang University of Technology, Hangzhou, China
| | - Yue Gao
- Department of Pharmaceutical Sciences, Beijing Institute of Radiation Medicine, Beijing, China.
| | - Zhenguo Chen
- The Fifth People's Hospital, Institutes of Biomedical Sciences, School of Public Health, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Yanjie Chao
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
| | - Chengyuan Wang
- CAS Key Laboratory of Molecular Virology and Immunology, Center for Microbes, Development and Health (CMDH), Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
| |
Collapse
|
6
|
Bhardwaj K, Kalita A, Verma N, Prakash A, Thakur R, Dutta D. Rho-dependent termination enables cellular pH homeostasis. J Bacteriol 2024; 206:e0035623. [PMID: 38169297 PMCID: PMC10810219 DOI: 10.1128/jb.00356-23] [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: 10/28/2023] [Accepted: 12/05/2023] [Indexed: 01/05/2024] Open
Abstract
The termination factor Rho, an ATP-dependent RNA translocase, preempts pervasive transcription processes, thereby rendering genome integrity in bacteria. Here, we show that the loss of Rho function raised the intracellular pH to >8.0 in Escherichia coli. The loss of Rho function upregulates tryptophanase-A (TnaA), an enzyme that catabolizes tryptophan to produce indole, pyruvate, and ammonia. We demonstrate that the enhanced TnaA function had produced the conjugate base ammonia, raising the cellular pH in the Rho-dependent termination defective strains. On the other hand, the constitutively overexpressed Rho lowered the cellular pH to about 6.2, independent of cellular ammonia levels. Since Rho overexpression may increase termination activities, the decrease in cellular pH could result from an excess H+ ion production during ATP hydrolysis by overproduced Rho. Furthermore, we performed in vivo termination assays to show that the efficiency of Rho-dependent termination was increased at both acidic and basic pH ranges. Given that the Rho level remained unchanged, the alkaline pH increases the termination efficiency by stimulating Rho's catalytic activity. We conducted the Rho-mediated RNA release assay from a stalled elongation complex to show an efficient RNA release at alkaline pH, compared to the neutral or acidic pH, that supports our in vivo observation. Whereas acidic pH appeared to increase the termination function by elevating the cellular level of Rho. This study is the first to link Rho function to the cellular pH homeostasis in bacteria. IMPORTANCE The current study shows that the loss or gain of Rho-dependent termination alkalizes or acidifies the cytoplasm, respectively. In the case of loss of Rho function, the tryptophanase-A enzyme is upregulated, and degrades tryptophan, producing ammonia to alkalize cytoplasm. We hypothesize that Rho overproduction by deleting its autoregulatory DNA portion increases termination function, causing excessive ATP hydrolysis to produce H+ ions and cytoplasmic acidification. Therefore, this study is the first to unravel a relationship between Rho function and intrinsic cellular pH homeostasis. Furthermore, the Rho level increases in the absence of autoregulation, causing cytoplasmic acidification. As intracellular pH plays a critical role in enzyme function, such a connection between Rho function and alkalization will have far-reaching implications for bacterial physiology.
Collapse
Affiliation(s)
- Kanika Bhardwaj
- CSIR Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Arunima Kalita
- CSIR Institute of Microbial Technology, Chandigarh, India
| | - Neha Verma
- CSIR Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Anand Prakash
- CSIR Institute of Microbial Technology, Chandigarh, India
| | - Ruchika Thakur
- CSIR Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Dipak Dutta
- CSIR Institute of Microbial Technology, Chandigarh, India
| |
Collapse
|
7
|
Falchi FA, Forti F, Carnelli C, Genco A, Pizzoccheri R, Manzari C, Pavesi G, Briani F. Human PNPase causes RNA stabilization and accumulation of R-loops in the Escherichia coli model system. Sci Rep 2023; 13:11771. [PMID: 37479726 PMCID: PMC10362022 DOI: 10.1038/s41598-023-38924-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 07/17/2023] [Indexed: 07/23/2023] Open
Abstract
Polyribonucleotide phosphorylase (PNPase) is a phosphorolytic RNA exonuclease highly conserved throughout evolution. In Escherichia coli, PNPase controls complex phenotypic traits like biofilm formation and growth at low temperature. In human cells, PNPase is located in mitochondria, where it is implicated in the RNA import from the cytoplasm, the mitochondrial RNA degradation and the processing of R-loops, namely stable RNA-DNA hybrids displacing a DNA strand. In this work, we show that the human PNPase (hPNPase) expressed in E. coli causes oxidative stress, SOS response activation and R-loops accumulation. Hundreds of E. coli RNAs are stabilized in presence of hPNPase, whereas only few transcripts are destabilized. Moreover, phenotypic traits typical of E. coli strains lacking PNPase are strengthened in presence of the human enzyme. We discuss the hypothesis that hPNPase expressed in E. coli may bind, but not degrade, the RNA, in agreement with previous in vitro data showing that phosphate concentrations in the range of those found in the bacterial cytoplasm and, more relevant, in the mitochondria, inhibit its activity.
Collapse
Affiliation(s)
- Federica A Falchi
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy
| | - Francesca Forti
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy
| | - Cristina Carnelli
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy
| | - Aurelia Genco
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy
| | - Roberto Pizzoccheri
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy
| | - Caterina Manzari
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", 70121, Bari, Italy
| | - Giulio Pavesi
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy.
| | - Federica Briani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133, Milan, Italy.
| |
Collapse
|
8
|
FinO/ProQ-family proteins: an evolutionary perspective. Biosci Rep 2023; 43:232566. [PMID: 36787218 PMCID: PMC9977716 DOI: 10.1042/bsr20220313] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 02/02/2023] [Accepted: 02/14/2023] [Indexed: 02/15/2023] Open
Abstract
RNA-binding proteins are key actors of post-transcriptional networks. Almost exclusively studied in the light of their interactions with RNA ligands and the associated functional events, they are still poorly understood as evolutionary units. In this review, we discuss the FinO/ProQ family of bacterial RNA chaperones, how they evolve and spread across bacterial populations and what properties and opportunities they provide to their host cells. We reflect on major conserved and divergent themes within the family, trying to understand how the same ancestral RNA-binding fold, augmented with additional structural elements, could yield either highly specialised proteins or, on the contrary, globally acting regulatory hubs with a pervasive impact on gene expression. We also consider dominant convergent evolutionary trends that shaped their RNA chaperone activity and recurrently implicated the FinO/ProQ-like proteins in bacterial DNA metabolism, translation and virulence. Finally, we offer a new perspective in which FinO/ProQ-family regulators emerge as active evolutionary players with both negative and positive roles, significantly impacting the evolutionary modes and trajectories of their bacterial hosts.
Collapse
|
9
|
Kumar S, Sau S, Agnivesh PK, Roy A, Kalia NP. Role of transcription termination factor Rho in anti-tuberculosis drug discovery. Drug Discov Today 2023; 28:103490. [PMID: 36638880 DOI: 10.1016/j.drudis.2023.103490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 12/26/2022] [Accepted: 01/05/2023] [Indexed: 01/11/2023]
Abstract
Mycobacterial infections, including multidrug and extreme drug-resistant (MDR and XDR) infections, are a severe challenge and create a virtual antibiotic-deficient era. Bacterial transcription is an established antimicrobial drug target. In mycobacteria, efficient transcription termination relies on the ATP-dependent RNA helicase factor Rho. Rho factor is essential for Mycobacterium tuberculosis (Mtb) survival, and is a valid antibacterial drug target with no homolog in eukaryotes. Rho maintains genomic stability and virulence and prevents pervasive transcription in Mtb. In this review, we provide an overview of the essentiality of Rho in Mtb, which makes it an attractive drug target for inhibitor discovery.
Collapse
Affiliation(s)
- Sunil Kumar
- Department of Biological Sciences, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, Telangana 500 037, India
| | - Shashikanta Sau
- Department of Biological Sciences, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, Telangana 500 037, India
| | - Puja Kumari Agnivesh
- Department of Biological Sciences, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, Telangana 500 037, India
| | - Arnab Roy
- Department of Biological Sciences, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, Telangana 500 037, India
| | - Nitin Pal Kalia
- Department of Biological Sciences, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, Telangana 500 037, India.
| |
Collapse
|
10
|
YihE is a novel binding partner of Rho and regulates Rho-dependent transcription termination in the Cpx stress response. iScience 2022; 25:105483. [DOI: 10.1016/j.isci.2022.105483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/21/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022] Open
|
11
|
Abstract
In bacteria, transcription and translation take place in the same cellular compartment. Therefore, a messenger RNA can be translated as it is being transcribed, a process known as transcription-translation coupling. This process was already recognized at the dawn of molecular biology, yet the interplay between the two key players, the RNA polymerase and ribosome, remains elusive. Genetic data indicate that an RNA sequence can be translated shortly after it has been transcribed. The closer both processes are in time, the less accessible the RNA sequence is between the RNA polymerase and ribosome. This temporal coupling has important consequences for gene regulation. Biochemical and structural studies have detailed several complexes between the RNA polymerase and ribosome. The in vivo relevance of this physical coupling has not been formally demonstrated. We discuss how both temporal and physical coupling may mesh to produce the phenomenon we know as transcription-translation coupling.
Collapse
Affiliation(s)
- Gregor M Blaha
- Department of Biochemistry, University of California, Riverside, California, USA;
| | - Joseph T Wade
- Wadsworth Center, New York State Department of Health, Albany, New York, USA;
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, USA
| |
Collapse
|
12
|
Portela R, A. Faria N, Mwangi M, Miragaia M, de Lencastre H, Tomasz A, Gonçalves Sobral R. Analysis of a Cell Wall Mutant Highlights Rho-Dependent Genome Amplification Events in Staphylococcus aureus. Microbiol Spectr 2022; 10:e0248321. [PMID: 36094182 PMCID: PMC9603463 DOI: 10.1128/spectrum.02483-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 08/06/2022] [Indexed: 01/04/2023] Open
Abstract
In a study of antibiotic resistance in Staphylococcus aureus, specific cell wall mutants were previously generated for the peptidoglycan biosynthesis gene murF, by the insertion of an integrative plasmid. A collection of 30 independent mutants was obtained, and all harbored a variable number of copies of the inserted plasmid, arranged in tandem in the chromosome. Of the 30 mutants, only 3, F9, F20 and F26, with a lower number of plasmid copies, showed an altered peptidoglycan structure, lower resistance to β-lactams and a different loss-of-function mutation in rho gene, that encodes a transcription termination factor. The rho mutations were found to correlate with the level of oxacillin resistance, since genetic complementation with rho gene reestablished the resistance and cell wall parental profile in F9, F20 and F26 strains. Furthermore, complementation with rho resulted in the amplification of the number of plasmid tandem repeats, suggesting that Rho enabled events of recombination that favored a rearrangement in the chromosome in the region of the impaired murF gene. Although the full mechanism of reversion of the cell wall damage was not fully elucidated, we showed that Rho is involved in the recombination process that mediates the tandem amplification of exogeneous DNA fragments inserted into the chromosome. IMPORTANCE The cell wall of bacteria, namely, peptidoglycan, is the target of several antibiotic classes such as β-lactams. Staphylococcus aureus is well known for its capacity to adapt to antibiotic stress and develop resistance strategies, namely, to β-lactams. In this context, the construction of cell wall mutants provides useful models to study the development of such resistance mechanisms. Here, we characterized a collection of independent mutants, impaired in the same peptidoglycan biosynthetic step, obtained through the insertion of a plasmid in the coding region of murF gene. S. aureus demonstrated the capacity to overcome the cell wall damage by amplifying the copy number of the inserted plasmid, through an undescribed mechanism that involves the Rho transcription termination factor.
Collapse
Affiliation(s)
- Raquel Portela
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- Laboratory of Molecular Microbiology of Bacterial Pathogens, UCIBIO – Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Nuno A. Faria
- Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
| | - Michael Mwangi
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, USA
| | - Maria Miragaia
- Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
| | - Hermínia de Lencastre
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, USA
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
| | - Alexander Tomasz
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, USA
| | - Rita Gonçalves Sobral
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- Laboratory of Molecular Microbiology of Bacterial Pathogens, UCIBIO – Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| |
Collapse
|
13
|
McLean EK, Nye TM, Lowder FC, Simmons LA. The Impact of RNA-DNA Hybrids on Genome Integrity in Bacteria. Annu Rev Microbiol 2022; 76:461-480. [PMID: 35655343 PMCID: PMC9527769 DOI: 10.1146/annurev-micro-102521-014450] [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] [Indexed: 09/10/2023]
Abstract
During the essential processes of DNA replication and transcription, RNA-DNA hybrid intermediates are formed that pose significant risks to genome integrity when left unresolved. To manage RNA-DNA hybrids, all cells rely on RNase H family enzymes that specifically cleave the RNA portion of the many different types of hybrids that form in vivo. Recent experimental advances have provided new insight into how RNA-DNA hybrids form and the consequences to genome integrity that ensue when persistent hybrids remain unresolved. Here we review the types of RNA-DNA hybrids, including R-loops, RNA primers, and ribonucleotide misincorporations, that form during DNA replication and transcription and discuss how each type of hybrid can contribute to genome instability in bacteria. Further, we discuss how bacterial RNase HI, HII, and HIII and bacterial FEN enzymes contribute to genome maintenance through the resolution of hybrids.
Collapse
Affiliation(s)
- Emma K McLean
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
| | - Taylor M Nye
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
- Current affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Frances C Lowder
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
| | - Lyle A Simmons
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
| |
Collapse
|
14
|
Miropolskaya N, Petushkov I, Esyunina D, Kulbachinskiy A. Suppressor mutations in Escherichia coli RNA polymerase alter transcription initiation but do not affect translesion RNA synthesis in vitro. J Biol Chem 2022; 298:102099. [PMID: 35667439 PMCID: PMC9254596 DOI: 10.1016/j.jbc.2022.102099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 11/19/2022] Open
Abstract
Bacterial RNA polymerase (RNAP) coordinates transcription with DNA repair and replication. Many RNAP mutations have pleiotropic phenotypes with profound effects on transcription-coupled processes. One class of RNAP mutations (rpo*) has been shown to suppress mutations in regulatory factors responsible for changes in gene expression during stationary phase or starvation, as well as in factors involved in the restoration of replication forks after DNA damage. These mutations were suggested to affect the ability of RNAP to transcribe damaged DNA and to decrease the stability of transcription complexes, thus facilitating their dislodging during DNA replication and repair, although this was not explicitly demonstrated. Here, we obtained nine mutations of this class located around the DNA/RNA binding cleft of E. coli RNAP and analyzed their transcription properties in vitro. We found that these mutations decreased promoter complex stability to varying degrees and all decreased the activity of rRNA promoters. However, they did not have strong effects on elongation complex stability. Some mutations were shown to stimulate transcriptional pauses or decrease intrinsic RNA cleavage by RNAP, but none altered the ability of RNAP to transcribe DNA templates containing damaged nucleotides. Thus, we conclude that the suppressor phenotypes of the mutations are unlikely to result from direct effects on DNA lesion recognition by RNAP but may be primarily explained by changes in transcription initiation. Further analysis of the effects of these mutations on the genomic distribution of RNAP and its interactions with regulatory factors will be essential for understanding their diverse phenotypes in vivo.
Collapse
Affiliation(s)
- Nataliya Miropolskaya
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia
| | - Ivan Petushkov
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia
| | - Daria Esyunina
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia.
| | - Andrey Kulbachinskiy
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia.
| |
Collapse
|
15
|
Parize E, Gerhardt EC, Oliveira AC, Pedrosa FO, Souza EM, Huergo LF, Steffens MB. Expression, purification and characterization of the transcription termination factor Rho from Azospirillum brasilense. Protein Expr Purif 2022; 198:106114. [DOI: 10.1016/j.pep.2022.106114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/10/2022] [Accepted: 05/24/2022] [Indexed: 11/25/2022]
|
16
|
Fleurier S, Dapa T, Tenaillon O, Condon C, Matic I. rRNA operon multiplicity as a bacterial genome stability insurance policy. Nucleic Acids Res 2022; 50:12601-12620. [PMID: 35552441 PMCID: PMC9825170 DOI: 10.1093/nar/gkac332] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 04/12/2022] [Accepted: 04/21/2022] [Indexed: 01/29/2023] Open
Abstract
Quick growth restart after upon encountering favourable environmental conditions is a major fitness contributor in natural environment. It is widely assumed that the time required to restart growth after nutritional upshift is determined by how long it takes for cells to synthesize enough ribosomes to produce the proteins required to reinitiate growth. Here we show that a reduction in the capacity to synthesize ribosomes by reducing number of ribosomal RNA (rRNA) operons (rrn) causes a longer transition from stationary phase to growth of Escherichia coli primarily due to high mortality rates. Cell death results from DNA replication blockage and massive DNA breakage at the sites of the remaining rrn operons that become overloaded with RNA polymerases (RNAPs). Mortality rates and growth restart duration can be reduced by preventing R-loop formation and improving DNA repair capacity. The same molecular mechanisms determine the duration of the recovery phase after ribosome-damaging stresses, such as antibiotics, exposure to bile salts or high temperature. Our study therefore suggests that a major function of rrn operon multiplicity is to ensure that individual rrn operons are not saturated by RNAPs, which can result in catastrophic chromosome replication failure and cell death during adaptation to environmental fluctuations.
Collapse
Affiliation(s)
- Sebastien Fleurier
- Department of Infection, Immunity and Inflammation, Institut Cochin, Inserm U1016, CNRS UMR8104, Université de Paris, 75014 Paris, France
| | - Tanja Dapa
- Department of Infection, Immunity and Inflammation, Institut Cochin, Inserm U1016, CNRS UMR8104, Université de Paris, 75014 Paris, France
| | | | - Ciarán Condon
- Institut de Biologie Physico-Chimique, CNRS UMR8261, Université de Paris, 75005 Paris, France
| | - Ivan Matic
- To whom correspondence should be addressed.
| |
Collapse
|
17
|
Rho-dependent transcription termination proceeds via three routes. Nat Commun 2022; 13:1663. [PMID: 35351884 PMCID: PMC8964686 DOI: 10.1038/s41467-022-29321-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 03/09/2022] [Indexed: 01/26/2023] Open
Abstract
Rho is a general transcription termination factor in bacteria, but many aspects of its mechanism of action are unclear. Diverse models have been proposed for the initial interaction between the RNA polymerase (RNAP) and Rho (catch-up and stand-by pre-terminational models); for the terminational release of the RNA transcript (RNA shearing, RNAP hyper-translocation or displacing, and allosteric models); and for the post-terminational outcome (whether the RNAP dissociates or remains bound to the DNA). Here, we use single-molecule fluorescence assays to study those three steps in transcription termination mediated by E. coli Rho. We find that different mechanisms previously proposed for each step co-exist, but apparently occur on various timescales and tend to lead to specific outcomes. Our results indicate that three kinetically distinct routes take place: (1) the catch-up mode leads first to RNA shearing for RNAP recycling on DNA, and (2) later to RNAP displacement for decomposition of the transcriptional complex; (3) the last termination usually follows the stand-by mode with displacing for decomposing. This three-route model would help reconcile current controversies on the mechanisms. Rho is a general transcription termination factor in bacteria. Here, Song et al. use single-molecule fluorescence assays to provide evidence that Rho-mediated transcription termination can occur via three kinetically different routes.
Collapse
|
18
|
Modulation of RecFORQ- and RecA-Mediated Homologous Recombination in Escherichia coli by Isoforms of Translation Initiation Factor IF2. J Bacteriol 2022; 204:e0056921. [PMID: 35343793 DOI: 10.1128/jb.00569-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Homologous recombination (HR) is critically important for chromosomal replication, as well as DNA damage repair in all life forms. In Escherichia coli, the process of HR comprises (i) two parallel presynaptic pathways that are mediated, respectively, by proteins RecB/C/D and RecF/O/R/Q; (ii) a synaptic step mediated by RecA that leads to generation of Holliday junctions (HJs); and (iii) postsynaptic steps mediated sequentially by HJ-acting proteins RuvA/B/C followed by proteins PriA/B/C of replication restart. Combined loss of RuvA/B/C and a DNA helicase UvrD is synthetically lethal, which is attributed to toxicity caused by accumulated HJs since viability in these double mutant strains is restored by removal of the presynaptic or synaptic proteins RecF/O/R/Q or RecA, respectively. Here we show that, as in ΔuvrD strains, ruv mutations confer synthetic lethality in cells deficient for transcription termination factor Rho, and that loss of RecFORQ presynaptic pathway proteins or of RecA suppresses this lethality. Furthermore, loss of IF2-1 (which is one of three isoforms [IF2-1, IF2-2, and IF2-3] of the essential translation initiation factor IF2 that are synthesized from three in-frame initiation codons in infB) also suppressed uvrD-ruv and rho-ruv lethalities, whereas deficiency of IF2-2 and IF2-3 exacerbated the synthetic defects. Our results suggest that Rho deficiency is associated with an increased frequency of HR that is mediated by the RecFORQ pathway along with RecA. They also lend support to earlier reports that IF2 isoforms participate in DNA transactions, and we propose that they do so by modulation of HR functions. IMPORTANCE The process of homologous recombination (HR) is important for maintenance of genome integrity in all cells. In Escherichia coli, the RecA protein is a critical participant in HR, which acts at a step common to and downstream of two HR pathways mediated by the RecBCD and RecFOR proteins, respectively. In this study, an isoform (IF2-1) of the translation initiation factor IF2 has been identified as a novel facilitator of RecA's function in vivo during HR.
Collapse
|
19
|
Pham P, Shao Y, Cox MM, Goodman MF. Genomic landscape of single-stranded DNA gapped intermediates in Escherichia coli. Nucleic Acids Res 2021; 50:937-951. [PMID: 34951472 PMCID: PMC8789085 DOI: 10.1093/nar/gkab1269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/08/2021] [Accepted: 12/13/2021] [Indexed: 12/22/2022] Open
Abstract
Single-stranded (ss) gapped regions in bacterial genomes (gDNA) are formed on W- and C-strands during replication, repair, and recombination. Using non-denaturing bisulfite treatment to convert C to U on ssDNA, combined with deep sequencing, we have mapped gDNA gap locations, sizes, and distributions in Escherichia coli for cells grown in mid-log phase in the presence and absence of UV irradiation, and in stationary phase cells. The fraction of ssDNA on gDNA is similar for W- and C-strands, ∼1.3% for log phase cells, ∼4.8% for irradiated log phase cells, and ∼8.5% for stationary phase cells. After UV irradiation, gaps increased in numbers and average lengths. A monotonic reduction in ssDNA occurred symmetrically between the DNA replication origin of (OriC) and terminus (Ter) for log phase cells with and without UV, a hallmark feature of DNA replication. Stationary phase cells showed no OriC → Ter ssDNA gradient. We have identified a spatially diverse gapped DNA landscape containing thousands of highly enriched ‘hot’ ssDNA regions along with smaller numbers of ‘cold’ regions. This analysis can be used for a wide variety of conditions to map ssDNA gaps generated when DNA metabolic pathways have been altered, and to identify proteins bound in the gaps.
Collapse
Affiliation(s)
- Phuong Pham
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089-2910, USA
| | - Yijun Shao
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089-2910, USA
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
| | - Myron F Goodman
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089-2910, USA
| |
Collapse
|
20
|
Kim A, Wang GG. R-loop and its functions at the regulatory interfaces between transcription and (epi)genome. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2021; 1864:194750. [PMID: 34461314 PMCID: PMC8627470 DOI: 10.1016/j.bbagrm.2021.194750] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/10/2021] [Accepted: 08/19/2021] [Indexed: 01/08/2023]
Abstract
R-loop represents a prevalent and specialized chromatin structure critically involved in a wide range of biological processes. In particular, co-transcriptional R-loops, produced often due to RNA polymerase pausing or RNA biogenesis malfunction, can initiate molecular events to context-dependently regulate local gene transcription and crosstalk with chromatin modifications. Cellular "readers" of R-loops are identified, exerting crucial impacts on R-loop homeostasis and gene regulation. Mounting evidence also supports R-loop deregulation as a frequent, sometimes initiating, event during the development of human pathologies, notably cancer and neurological disorder. The purpose of this review is to cover recent advances in understanding the fundamentals of R-loop biology, which have started to unveil complex interplays of R-loops with factors involved in various biological processes such as transcription, RNA processing and epitranscriptomic modification (such as N6-methyladenosine), DNA damage sensing and repair, and epigenetic regulation.
Collapse
Affiliation(s)
- Arum Kim
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Gang Greg Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA.
| |
Collapse
|
21
|
Brüning JG, Marians KJ. Bypass of complex co-directional replication-transcription collisions by replisome skipping. Nucleic Acids Res 2021; 49:9870-9885. [PMID: 34469567 PMCID: PMC8464059 DOI: 10.1093/nar/gkab760] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 12/27/2022] Open
Abstract
Collisions between the replisome and RNA polymerases [RNAP(s)] are the main obstacle to DNA replication. These collisions can occur either head-on or co-directionally with respect to the direction of translocation of both complexes. Whereas head-on collisions require additional factors to be resolved, co-directional collisions are thought to be overcome by the replisome itself using the mRNA transcript as a primer. We show that mRNA takeover is utilized primarily after collisions with single RNAP complexes with short transcripts. Bypass of more complex transcription complexes requires the synthesis of a new primer downstream of the RNAP for the replisome to resume leading-strand synthesis. In both cases, bypass proceeds with displacement of the RNAP. Rep, Mfd, UvrD and RNase H can process the RNAP block and facilitate replisome bypass by promoting the formation of continuous leading strands. Bypass of co-directional RNAP(s) and/or R-loops is determined largely by the length of the obstacle that the replisome needs to traverse: R-loops are about equally as potent obstacles as RNAP arrays if they occupy the same length of the DNA template.
Collapse
Affiliation(s)
- Jan-Gert Brüning
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Kenneth J Marians
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| |
Collapse
|
22
|
Uruci S, Lo CSY, Wheeler D, Taneja N. R-Loops and Its Chro-Mates: The Strange Case of Dr. Jekyll and Mr. Hyde. Int J Mol Sci 2021; 22:ijms22168850. [PMID: 34445553 PMCID: PMC8396322 DOI: 10.3390/ijms22168850] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/04/2021] [Accepted: 08/12/2021] [Indexed: 12/22/2022] Open
Abstract
Since their discovery, R-loops have been associated with both physiological and pathological functions that are conserved across species. R-loops are a source of replication stress and genome instability, as seen in neurodegenerative disorders and cancer. In response, cells have evolved pathways to prevent R-loop accumulation as well as to resolve them. A growing body of evidence correlates R-loop accumulation with changes in the epigenetic landscape. However, the role of chromatin modification and remodeling in R-loops homeostasis remains unclear. This review covers various mechanisms precluding R-loop accumulation and highlights the role of chromatin modifiers and remodelers in facilitating timely R-loop resolution. We also discuss the enigmatic role of RNA:DNA hybrids in facilitating DNA repair, epigenetic landscape and the potential role of replication fork preservation pathways, active fork stability and stalled fork protection pathways, in avoiding replication-transcription conflicts. Finally, we discuss the potential role of several Chro-Mates (chromatin modifiers and remodelers) in the likely differentiation between persistent/detrimental R-loops and transient/benign R-loops that assist in various physiological processes relevant for therapeutic interventions.
Collapse
Affiliation(s)
- Sidrit Uruci
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands; (S.U.); (C.S.Y.L.)
| | - Calvin Shun Yu Lo
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands; (S.U.); (C.S.Y.L.)
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA;
| | - Nitika Taneja
- Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands; (S.U.); (C.S.Y.L.)
- Correspondence:
| |
Collapse
|
23
|
Topoisomerase I Essentiality, DnaA-Independent Chromosomal Replication, and Transcription-Replication Conflict in Escherichia coli. J Bacteriol 2021; 203:e0019521. [PMID: 34124945 DOI: 10.1128/jb.00195-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Topoisomerase I (Topo I) of Escherichia coli, encoded by topA, acts to relax negative supercoils in DNA. Topo I deficiency results in hypernegative supercoiling, formation of transcription-associated RNA-DNA hybrids (R-loops), and DnaA- and oriC-independent constitutive stable DNA replication (cSDR), but some uncertainty persists as to whether topA is essential for viability in E. coli and related enterobacteria. Here, we show that several topA alleles, including ΔtopA, confer lethality in derivatives of wild-type E. coli strain MG1655. Viability in the absence of Topo I was restored with two perturbations, neither of which reversed the hypernegative supercoiling phenotype: (i) in a reduced-genome strain (MDS42) or (ii) by an RNA polymerase (RNAP) mutation, rpoB*35, that has been reported to alleviate the deleterious consequences of RNAP backtracking and transcription-replication conflicts. Four phenotypes related to cSDR were identified for topA mutants: (i) one of the topA alleles rescued ΔdnaA lethality; (ii) in dnaA+ derivatives, Topo I deficiency generated a characteristic copy number peak in the terminus region of the chromosome; (iii) topA was synthetically lethal with rnhA (encoding RNase HI, whose deficiency also confers cSDR); and (iv) topA rnhA synthetic lethality was itself rescued by ΔdnaA. We propose that the terminal lethal consequence of hypernegative DNA supercoiling in E. coli topA mutants is RNAP backtracking during transcription elongation and associated R-loop formation, which in turn leads to transcription-replication conflicts and to cSDR. IMPORTANCE In all life forms, double-helical DNA exists in a topologically supercoiled state. The enzymes DNA gyrase and topoisomerase I act, respectively, to introduce and to relax negative DNA supercoils in Escherichia coli. That gyrase deficiency leads to bacterial death is well established, but the essentiality of topoisomerase I for viability has been less certain. This study confirms that topoisomerase I is essential for E. coli viability and suggests that in its absence, aberrant chromosomal DNA replication and excessive transcription-replication conflicts occur that are responsible for lethality.
Collapse
|
24
|
Muskhelishvili G, Sobetzko P, Mehandziska S, Travers A. Composition of Transcription Machinery and Its Crosstalk with Nucleoid-Associated Proteins and Global Transcription Factors. Biomolecules 2021; 11:biom11070924. [PMID: 34206477 PMCID: PMC8301835 DOI: 10.3390/biom11070924] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 11/24/2022] Open
Abstract
The coordination of bacterial genomic transcription involves an intricate network of interdependent genes encoding nucleoid-associated proteins (NAPs), DNA topoisomerases, RNA polymerase subunits and modulators of transcription machinery. The central element of this homeostatic regulatory system, integrating the information on cellular physiological state and producing a corresponding transcriptional response, is the multi-subunit RNA polymerase (RNAP) holoenzyme. In this review article, we argue that recent observations revealing DNA topoisomerases and metabolic enzymes associated with RNAP supramolecular complex support the notion of structural coupling between transcription machinery, DNA topology and cellular metabolism as a fundamental device coordinating the spatiotemporal genomic transcription. We analyse the impacts of various combinations of RNAP holoenzymes and global transcriptional regulators such as abundant NAPs, on genomic transcription from this viewpoint, monitoring the spatiotemporal patterns of couplons—overlapping subsets of the regulons of NAPs and RNAP sigma factors. We show that the temporal expression of regulons is by and large, correlated with that of cognate regulatory genes, whereas both the spatial organization and temporal expression of couplons is distinctly impacted by the regulons of NAPs and sigma factors. We propose that the coordination of the growth phase-dependent concentration gradients of global regulators with chromosome configurational dynamics determines the spatiotemporal patterns of genomic expression.
Collapse
Affiliation(s)
- Georgi Muskhelishvili
- School of Natural Sciences, Agricultural University of Georgia, David Aghmashenebeli Alley 24, Tbilisi 0159, Georgia
- Correspondence:
| | - Patrick Sobetzko
- Department of Chromosome Biology, Philipps-Universität Marburg, LOEWE-Zentrum für Synthetische Mikrobiologie, Hans-Meerwein-Straße, 35043 Marburg, Germany;
| | - Sanja Mehandziska
- School of Engineering and Science, Campus Ring 1, Jacobs University Bremen, 28759 Bremen, Germany;
| | - Andrew Travers
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| |
Collapse
|
25
|
Simon I, Delaleau M, Schwartz A, Boudvillain M. A Large Insertion Domain in the Rho Factor From a Low G + C, Gram-negative Bacterium is Critical for RNA Binding and Transcription Termination Activity. J Mol Biol 2021; 433:167060. [PMID: 34023400 DOI: 10.1016/j.jmb.2021.167060] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/30/2021] [Accepted: 05/16/2021] [Indexed: 10/21/2022]
Abstract
Rho-dependent termination of transcription (RDTT) is a critical regulatory mechanism specific to bacteria. In a subset of species including most Actinobacteria and Bacteroidetes, the Rho factor contains a large, poorly conserved N-terminal insertion domain (NID) of cryptic function. To date, only two NID-bearing Rho factors from high G + C Actinobacteria have been thoroughly characterized. Both can trigger RDTT at promoter-proximal sites or with structurally constrained transcripts that are unsuitable for the archetypal, NID-less Rho factor of Escherichia coli (EcRho). Here, we provide the first biochemical characterization of a NID-bearing Rho factor from a low G + C bacterium. We show that Bacteroides fragilis Rho (BfRho) is a bona fide RNA-dependent NTPase motor able to unwind long RNA:DNA duplexes and to disrupt transcription complexes. The large NID (~40% of total mass) strongly increases BfRho affinity for RNA, is strictly required for RDTT, but does not promote RDTT at promoter-proximal sites or with a structurally constrained transcript. Furthermore, the NID does not preclude modulation of RDTT by transcription factors NusA and NusG or by the Rho inhibitor bicyclomycin. Although the NID contains a prion-like Q/N-rich motif, it does not spontaneously trigger formation of β-amyloids. Thus, despite its unusually large RNA binding domain, BfRho behaves more like the NID-less EcRho than NID-bearing counterparts from high G + C Actinobacteria. Our data highlight the evolutionary plasticity of Rho's N-terminal region and illustrate how RDTT is adapted to distinct genomic contents.
Collapse
Affiliation(s)
- Isabelle Simon
- Centre de Biophysique Moléculaire, CNRS UPR4301, Rue Charles Sadron, 45071 Orléans cedex 2, France; ED 549, Santé, Sciences Biologiques & Chimie du Vivant, Université d'Orléans, France
| | - Mildred Delaleau
- Centre de Biophysique Moléculaire, CNRS UPR4301, Rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Annie Schwartz
- Centre de Biophysique Moléculaire, CNRS UPR4301, Rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Marc Boudvillain
- Centre de Biophysique Moléculaire, CNRS UPR4301, Rue Charles Sadron, 45071 Orléans cedex 2, France.
| |
Collapse
|
26
|
Kouzminova EA, Kuzminov A. Ultraviolet-induced RNA:DNA hybrids interfere with chromosomal DNA synthesis. Nucleic Acids Res 2021; 49:3888-3906. [PMID: 33693789 PMCID: PMC8053090 DOI: 10.1093/nar/gkab147] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 02/14/2021] [Accepted: 02/23/2021] [Indexed: 12/28/2022] Open
Abstract
Ultraviolet (UV) induces pyrimidine dimers (PDs) in DNA and replication-dependent fragmentation in chromosomes. The rnhAB mutants in Escherichia coli, accumulating R-loops and single DNA-rNs, are generally resistant to DNA damage, but are surprisingly UV-sensitive, even though they remove PDs normally, suggesting irreparable chromosome lesions. We show here that the RNase H defect does not cause additional chromosome fragmentation after UV, but inhibits DNA synthesis after replication restart. Genetic analysis implies formation of R-loop-anchored transcription elongation complexes (R-loop-aTECs) in UV-irradiated rnhAB mutants, predicting that their chromosomal DNA will accumulate: (i) RNA:DNA hybrids; (ii) a few slow-to-remove PDs. We confirm both features and also find that both, surprisingly, depend on replication restart. Finally, enriching for the UV-induced RNA:DNA hybrids in the rnhAB uvrA mutants also co-enriches for PDs, showing their co-residence in the same structures. We propose that PD-triggered R-loop-aTECs block head-on replication in RNase H-deficient mutants.
Collapse
Affiliation(s)
- Elena A Kouzminova
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Andrei Kuzminov
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| |
Collapse
|
27
|
Villa TG, Abril AG, Sánchez-Pérez A. Mastering the control of the Rho transcription factor for biotechnological applications. Appl Microbiol Biotechnol 2021; 105:4053-4071. [PMID: 33963893 DOI: 10.1007/s00253-021-11326-7] [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: 03/19/2021] [Revised: 04/22/2021] [Accepted: 04/27/2021] [Indexed: 12/25/2022]
Abstract
The present review represents an update on the fundamental role played by the Rho factor, which facilitates the process of Rho-dependent transcription termination in the prokaryotic world; it also provides a summary of relevant mutations in the Rho factor and the insights they provide into the functions carried out by this protein. Furthermore, a section is dedicated to the putative future use of Rho (the 'taming' of Rho) to facilitate biotechnological processes and adapt them to different technological contexts. Novel bacterial strains can be designed, containing mutations in the rho gene, that are better suited for different biotechnological applications. This process can obtain novel microbial strains that are adapted to lower temperatures of fermentation, shorter production times, exhibit better nutrient utilization, or display other traits that are beneficial in productive Biotechnology. Additional important issues reviewed here include epistasis, the design of TATA boxes, the role of small RNAs, and the manipulation of clathrin-mediated endocytosis, by some pathogenic bacteria, to invade eukaryotic cells. KEY POINTS: • It is postulated that controlling the action of the prokaryotic Rho factor could generate major biotechnological improvements, such as an increase in bacterial productivity or a reduction of the microbial-specific growth rate. • The review also evaluates the putative impact of epistatic mechanisms on Biotechnology, both as possible responsible for unexpected failures in gene cloning and more important for the genesis of new strains for biotechnological applications • The use of clathrin-coated vesicles by intracellular bacterial microorganisms is included too and proposed as a putative delivery mechanism, for drugs and vaccines.
Collapse
Affiliation(s)
- Tomás G Villa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, La Coruña, 15706, Santiago de Compostela, Spain.
| | - Ana G Abril
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, La Coruña, 15706, Santiago de Compostela, Spain.
| | - Angeles Sánchez-Pérez
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW, 2006, Australia.
| |
Collapse
|
28
|
Wang B, Artsimovitch I. NusG, an Ancient Yet Rapidly Evolving Transcription Factor. Front Microbiol 2021; 11:619618. [PMID: 33488562 PMCID: PMC7819879 DOI: 10.3389/fmicb.2020.619618] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/07/2020] [Indexed: 12/19/2022] Open
Abstract
Timely and accurate RNA synthesis depends on accessory proteins that instruct RNA polymerase (RNAP) where and when to start and stop transcription. Among thousands of transcription factors, NusG/Spt5 stand out as the only universally conserved family of regulators. These proteins interact with RNAP to promote uninterrupted RNA synthesis and with diverse cellular partners to couple transcription to RNA processing, modification or translation, or to trigger premature termination of aberrant transcription. NusG homologs are present in all cells that utilize bacterial-type RNAP, from endosymbionts to plants, underscoring their ancient and essential function. Yet, in stark contrast to other core RNAP components, NusG family is actively evolving: horizontal gene transfer and sub-functionalization drive emergence of NusG paralogs, such as bacterial LoaP, RfaH, and UpxY. These specialized regulators activate a few (or just one) operons required for expression of antibiotics, capsules, secretion systems, toxins, and other niche-specific macromolecules. Despite their common origin and binding site on the RNAP, NusG homologs differ in their target selection, interacting partners and effects on RNA synthesis. Even among housekeeping NusGs from diverse bacteria, some factors promote pause-free transcription while others slow the RNAP down. Here, we discuss structure, function, and evolution of NusG proteins, focusing on unique mechanisms that determine their effects on gene expression and enable bacterial adaptation to diverse ecological niches.
Collapse
Affiliation(s)
- Bing Wang
- Department of Microbiology and the Center for RNA Biology, The Ohio State University, Columbus, OH, United States
| | - Irina Artsimovitch
- Department of Microbiology and the Center for RNA Biology, The Ohio State University, Columbus, OH, United States
| |
Collapse
|
29
|
Yang Z, Li M, Sun Q. RHON1 Co-transcriptionally Resolves R-Loops for Arabidopsis Chloroplast Genome Maintenance. Cell Rep 2021; 30:243-256.e5. [PMID: 31914390 DOI: 10.1016/j.celrep.2019.12.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/24/2019] [Accepted: 12/02/2019] [Indexed: 01/10/2023] Open
Abstract
Preventing transcription-replication head-on conflict (HO-TRC)-triggered R-loop formation is essential for maintaining genome integrity in bacteria, plants, and mammals. The R-loop eraser RNase H can efficiently relax HO-TRCs. However, it is not clear how organisms resist HO-TRC-triggered R-loops when RNase H proteins are deficient. By screening factors that may relieve R-loop accumulation in the Arabidopsis atrnh1c mutant, we find that overexpression of the R-loop helicase RHON1 can rescue the defects of aberrantly accumulated HO-TRC-triggered R-loops co-transcriptionally. In addition, we find that RHON1 interacts with and orchestrates the transcriptional activity of plastid-encoded RNA polymerases to release the conflicts between transcription and replication. Our study illustrates that organisms employ multiple mechanisms to escape HO-TRC-triggered R-loop accumulation and thus maintain genome integrity.
Collapse
Affiliation(s)
- Zhuo Yang
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Mengmeng Li
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qianwen Sun
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| |
Collapse
|
30
|
Said N, Hilal T, Sunday ND, Khatri A, Bürger J, Mielke T, Belogurov GA, Loll B, Sen R, Artsimovitch I, Wahl MC. Steps toward translocation-independent RNA polymerase inactivation by terminator ATPase ρ. Science 2021; 371:eabd1673. [PMID: 33243850 PMCID: PMC7864586 DOI: 10.1126/science.abd1673] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/26/2020] [Indexed: 12/31/2022]
Abstract
Factor-dependent transcription termination mechanisms are poorly understood. We determined a series of cryo-electron microscopy structures portraying the hexameric adenosine triphosphatase (ATPase) ρ on a pathway to terminating NusA/NusG-modified elongation complexes. An open ρ ring contacts NusA, NusG, and multiple regions of RNA polymerase, trapping and locally unwinding proximal upstream DNA. NusA wedges into the ρ ring, initially sequestering RNA. Upon deflection of distal upstream DNA over the RNA polymerase zinc-binding domain, NusA rotates underneath one capping ρ subunit, which subsequently captures RNA. After detachment of NusG and clamp opening, RNA polymerase loses its grip on the RNA:DNA hybrid and is inactivated. Our structural and functional analyses suggest that ρ, and other termination factors across life, may use analogous strategies to allosterically trap transcription complexes in a moribund state.
Collapse
Affiliation(s)
- Nelly Said
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Tarek Hilal
- Research Center of Electron Microscopy and Core Facility BioSupraMol, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Nicholas D Sunday
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Ajay Khatri
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
- Graduate Studies, Regional Centre for Biotechnology, Faridabad, Haryana, India
| | - Jörg Bürger
- Microscopy and Cryo-Electron Microscopy Service Group, Max-Planck-Institut für Molekulare Genetik, Berlin, Germany
- Institute of Medical Physics und Biophysics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Thorsten Mielke
- Microscopy and Cryo-Electron Microscopy Service Group, Max-Planck-Institut für Molekulare Genetik, Berlin, Germany
| | | | - Bernhard Loll
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Ranjan Sen
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Irina Artsimovitch
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| |
Collapse
|
31
|
Hao Z, Epshtein V, Kim KH, Proshkin S, Svetlov V, Kamarthapu V, Bharati B, Mironov A, Walz T, Nudler E. Pre-termination Transcription Complex: Structure and Function. Mol Cell 2020; 81:281-292.e8. [PMID: 33296676 DOI: 10.1016/j.molcel.2020.11.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/11/2020] [Accepted: 11/06/2020] [Indexed: 02/07/2023]
Abstract
Rho is a general transcription termination factor playing essential roles in RNA polymerase (RNAP) recycling, gene regulation, and genomic stability in most bacteria. Traditional models of transcription termination postulate that hexameric Rho loads onto RNA prior to contacting RNAP and then translocates along the transcript in pursuit of the moving RNAP to pull RNA from it. Here, we report the cryoelectron microscopy (cryo-EM) structures of two termination process intermediates. Prior to interacting with RNA, Rho forms a specific "pre-termination complex" (PTC) with RNAP and elongation factors NusA and NusG, which stabilize the PTC. RNA exiting RNAP interacts with NusA before entering the central channel of Rho from the distal C-terminal side of the ring. We map the principal interactions in the PTC and demonstrate their critical role in termination. Our results support a mechanism in which the formation of a persistent PTC is a prerequisite for termination.
Collapse
Affiliation(s)
- Zhitai Hao
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Vitaly Epshtein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Kelly H Kim
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA
| | - Sergey Proshkin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Moscow 119991, Russia
| | - Vladimir Svetlov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Venu Kamarthapu
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Binod Bharati
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Alexander Mironov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Moscow 119991, Russia
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA.
| |
Collapse
|
32
|
Brüning JG, Marians KJ. Replisome bypass of transcription complexes and R-loops. Nucleic Acids Res 2020; 48:10353-10367. [PMID: 32926139 PMCID: PMC7544221 DOI: 10.1093/nar/gkaa741] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/22/2020] [Accepted: 08/25/2020] [Indexed: 12/16/2022] Open
Abstract
The vast majority of the genome is transcribed by RNA polymerases. G+C-rich regions of the chromosomes and negative superhelicity can promote the invasion of the DNA by RNA to form R-loops, which have been shown to block DNA replication and promote genome instability. However, it is unclear whether the R-loops themselves are sufficient to cause this instability or if additional factors are required. We have investigated replisome collisions with transcription complexes and R-loops using a reconstituted bacterial DNA replication system. RNA polymerase transcription complexes co-directionally oriented with the replication fork were transient blockages, whereas those oriented head-on were severe, stable blockages. On the other hand, replisomes easily bypassed R-loops on either template strand. Replication encounters with R-loops on the leading-strand template (co-directional) resulted in gaps in the nascent leading strand, whereas lagging-strand template R-loops (head-on) had little impact on replication fork progression. We conclude that whereas R-loops alone can act as transient replication blocks, most genome-destabilizing replication fork stalling likely occurs because of proteins bound to the R-loops.
Collapse
Affiliation(s)
- Jan-Gert Brüning
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Kenneth J Marians
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| |
Collapse
|
33
|
Ng Kwan Lim E, Sasseville C, Carrier MC, Massé E. Keeping Up with RNA-Based Regulation in Bacteria: New Roles for RNA Binding Proteins. Trends Genet 2020; 37:86-97. [PMID: 33077249 DOI: 10.1016/j.tig.2020.09.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 01/06/2023]
Abstract
RNA binding proteins (RBPs) are ubiquitously found in all kingdoms of life. They are involved in a plethora of regulatory events, ranging from direct regulation of gene expression to guiding modification of RNA molecules. As bacterial regulators, RBPs can act alone or in concert with RNA-based regulators, such as small regulatory RNAs (sRNAs), riboswitches, or clustered regularly interspaced short palindromic repeats (CRISPR) RNAs. Various functions of RBPs, whether dependent or not on an RNA regulator, have been described in the past. However, the past decade has been a fertile ground for the development of novel high-throughput methods. These methods acted as stepping-stones for the discovery of new functions of RBPs and helped in the understanding of the molecular mechanisms behind previously described regulatory events. Here, we present an overview of the recently identified roles of major bacterial RBPs from different model organisms. Moreover, the tight relationship between RBPs and RNA-based regulators will be explored.
Collapse
Affiliation(s)
- Evelyne Ng Kwan Lim
- Faculty of Medicine and Health Sciences, Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, J1H 5N4, QC, Canada
| | - Charles Sasseville
- Faculty of Medicine and Health Sciences, Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, J1H 5N4, QC, Canada
| | - Marie-Claude Carrier
- Faculty of Medicine and Health Sciences, Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, J1H 5N4, QC, Canada
| | - Eric Massé
- Faculty of Medicine and Health Sciences, Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, J1H 5N4, QC, Canada.
| |
Collapse
|
34
|
Wang B, Artsimovitch I. A Growing Gap between the RNAP and the Lead Ribosome. Trends Microbiol 2020; 29:4-5. [PMID: 33046341 DOI: 10.1016/j.tim.2020.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 09/28/2020] [Accepted: 09/29/2020] [Indexed: 11/20/2022]
Abstract
In prokaryotes, transcription-translation coupling is thought to guarantee the synthesis of high-quality mRNAs and surveil foreign genes. Surprisingly, Johnson et al. show that translation is uncoupled from transcription in Bacillus subtilis, arguing that bacteria utilize very diverse gene expression strategies to meet their unique regulatory needs.
Collapse
Affiliation(s)
- Bing Wang
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA; The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Irina Artsimovitch
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA; The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.
| |
Collapse
|
35
|
Trzilova D, Anjuwon-Foster BR, Torres Rivera D, Tamayo R. Rho factor mediates flagellum and toxin phase variation and impacts virulence in Clostridioides difficile. PLoS Pathog 2020; 16:e1008708. [PMID: 32785266 PMCID: PMC7446863 DOI: 10.1371/journal.ppat.1008708] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 08/24/2020] [Accepted: 06/16/2020] [Indexed: 12/17/2022] Open
Abstract
The intestinal pathogen Clostridioides difficile exhibits heterogeneity in motility and toxin production. This phenotypic heterogeneity is achieved through phase variation by site-specific recombination via the DNA recombinase RecV, which reversibly inverts the "flagellar switch" upstream of the flgB operon. A recV mutation prevents flagellar switch inversion and results in phenotypically locked strains. The orientation of the flagellar switch influences expression of the flgB operon post-transcription initiation, but the specific molecular mechanism is unknown. Here, we report the isolation and characterization of spontaneous suppressor mutants in the non-motile, non-toxigenic recV flg OFF background that regained motility and toxin production. The restored phenotypes corresponded with increased expression of flagellum and toxin genes. The motile suppressor mutants contained single-nucleotide polymorphisms (SNPs) in rho, which encodes the bacterial transcription terminator Rho factor. Analyses using transcriptional reporters indicate that Rho contributes to heterogeneity in flagellar gene expression by preferentially terminating transcription of flg OFF mRNA within the 5' leader sequence. Additionally, Rho is important for initial colonization of the intestine in a mouse model of infection, which may in part be due to the sporulation and growth defects observed in the rho mutants. Together these data implicate Rho factor as a regulator of gene expression affecting phase variation of important virulence factors of C. difficile.
Collapse
Affiliation(s)
- Dominika Trzilova
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Brandon R. Anjuwon-Foster
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Dariana Torres Rivera
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| |
Collapse
|
36
|
Syeda AH, Dimude JU, Skovgaard O, Rudolph CJ. Too Much of a Good Thing: How Ectopic DNA Replication Affects Bacterial Replication Dynamics. Front Microbiol 2020; 11:534. [PMID: 32351461 PMCID: PMC7174701 DOI: 10.3389/fmicb.2020.00534] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 03/12/2020] [Indexed: 12/15/2022] Open
Abstract
Each cell division requires the complete and accurate duplication of the entire genome. In bacteria, the duplication process of the often-circular chromosomes is initiated at a single origin per chromosome, resulting in two replication forks that traverse the chromosome in opposite directions. DNA synthesis is completed once the two forks fuse in a region diametrically opposite the origin. In some bacteria, such as Escherichia coli, the region where forks fuse forms a specialized termination area. Polar replication fork pause sites flanking this area can pause the progression of replication forks, thereby allowing forks to enter but not to leave. Transcription of all required genes has to take place simultaneously with genome duplication. As both of these genome trafficking processes share the same template, conflicts are unavoidable. In this review, we focus on recent attempts to add additional origins into various ectopic chromosomal locations of the E. coli chromosome. As ectopic origins disturb the native replichore arrangements, the problems resulting from such perturbations can give important insights into how genome trafficking processes are coordinated and the problems that arise if this coordination is disturbed. The data from these studies highlight that head-on replication–transcription conflicts are indeed highly problematic and multiple repair pathways are required to restart replication forks arrested at obstacles. In addition, the existing data also demonstrate that the replication fork trap in E. coli imposes significant constraints to genome duplication if ectopic origins are active. We describe the current models of how replication fork fusion events can cause serious problems for genome duplication, as well as models of how such problems might be alleviated both by a number of repair pathways as well as the replication fork trap system. Considering the problems associated both with head-on replication-transcription conflicts as well as head-on replication fork fusion events might provide clues of how these genome trafficking issues have contributed to shape the distinct architecture of bacterial chromosomes.
Collapse
Affiliation(s)
- Aisha H Syeda
- Department of Biology, University of York, York, United Kingdom
| | - Juachi U Dimude
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Ole Skovgaard
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Christian J Rudolph
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| |
Collapse
|
37
|
Ali N, Gowrishankar J. Cross-subunit catalysis and a new phenomenon of recessive resurrection in Escherichia coli RNase E. Nucleic Acids Res 2020; 48:847-861. [PMID: 31802130 PMCID: PMC6954427 DOI: 10.1093/nar/gkz1152] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 12/13/2022] Open
Abstract
RNase E is a 472-kDa homo-tetrameric essential endoribonuclease involved in RNA processing and turnover in Escherichia coli. In its N-terminal half (NTH) is the catalytic active site, as also a substrate 5′-sensor pocket that renders enzyme activity maximal on 5′-monophosphorylated RNAs. The protein's non-catalytic C-terminal half (CTH) harbours RNA-binding motifs and serves as scaffold for a multiprotein degradosome complex, but is dispensable for viability. Here, we provide evidence that a full-length hetero-tetramer, composed of a mixture of wild-type and (recessive lethal) active-site mutant subunits, exhibits identical activity in vivo as the wild-type homo-tetramer itself (‘recessive resurrection’). When all of the cognate polypeptides lacked the CTH, the active-site mutant subunits were dominant negative. A pair of C-terminally truncated polypeptides, which were individually inactive because of additional mutations in their active site and 5′-sensor pocket respectively, exhibited catalytic function in combination, both in vivo and in vitro (i.e. intragenic or allelic complementation). Our results indicate that adjacent subunits within an oligomer are separately responsible for 5′-sensing and cleavage, and that RNA binding facilitates oligomerization. We propose also that the CTH mediates a rate-determining initial step for enzyme function, which is likely the binding and channelling of substrate for NTH’s endonucleolytic action.
Collapse
Affiliation(s)
- Nida Ali
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal 576104, India
| | - Jayaraman Gowrishankar
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
| |
Collapse
|
38
|
Chedin F, Benham CJ. Emerging roles for R-loop structures in the management of topological stress. J Biol Chem 2020; 295:4684-4695. [PMID: 32107311 DOI: 10.1074/jbc.rev119.006364] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
R-loop structures are a prevalent class of alternative non-B DNA structures that form during transcription upon invasion of the DNA template by the nascent RNA. R-loops form universally in the genomes of organisms ranging from bacteriophages, bacteria, and yeasts to plants and animals, including mammals. A growing body of work has linked these structures to both physiological and pathological processes, in particular to genome instability. The rising interest in R-loops is placing new emphasis on understanding the fundamental physicochemical forces driving their formation and stability. Pioneering work in Escherichia coli revealed that DNA topology, in particular negative DNA superhelicity, plays a key role in driving R-loops. A clear role for DNA sequence was later uncovered. Here, we review and synthesize available evidence on the roles of DNA sequence and DNA topology in controlling R-loop formation and stability. Factoring in recent developments in R-loop modeling and single-molecule profiling, we propose a coherent model accounting for the interplay between DNA sequence and DNA topology in driving R-loop structure formation. This model reveals R-loops in a new light as powerful and reversible topological stress relievers, an insight that significantly expands the repertoire of R-loops' potential biological roles under both normal and aberrant conditions.
Collapse
Affiliation(s)
- Frederic Chedin
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616 .,Genome Center, University of California, Davis, California 95616
| | - Craig J Benham
- Genome Center, University of California, Davis, California 95616 .,Departments of Mathematics and Biomedical Engineering, University of California, Davis, California 95616
| |
Collapse
|
39
|
Veetil RT, Malhotra N, Dubey A, Seshasayee ASN. Laboratory Evolution Experiments Help Identify a Predominant Region of Constitutive Stable DNA Replication Initiation. mSphere 2020; 5:e00939-19. [PMID: 32102945 PMCID: PMC7045392 DOI: 10.1128/msphere.00939-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/06/2020] [Indexed: 01/06/2023] Open
Abstract
The bacterium Escherichia coli can initiate replication in the absence of the replication initiator protein DnaA and/or the canonical origin of replication oriC in a ΔrnhA background. This phenomenon, which can be primed by R-loops, is called constitutive stable DNA replication (cSDR). Whether DNA replication during cSDR initiates in a stochastic manner through the length of the chromosome or at specific sites and how E. coli can find adaptations to loss of fitness caused by cSDR remain inadequately answered. We use laboratory evolution experiments of ΔrnhA-ΔdnaA strains followed by deep sequencing to show that DNA replication preferentially initiates within a broad region located ∼0.4 to 0.7 Mb clockwise of oriC. This region includes many bisulfite-sensitive sites, which have been previously defined as R-loop-forming regions, and includes a site containing sequence motifs that favor R-loop formation. Initiation from this region would result in head-on replication-transcription conflicts at rRNA loci. Inversions of these rRNA loci, which can partly resolve these conflicts, help the bacterium suppress the fitness defects of cSDR. These inversions partially restore the gene expression changes brought about by cSDR. The inversion, however, increases the possibility of conflicts at essential mRNA genes, which would utilize only a minuscule fraction of RNA polymerase molecules, most of which transcribe rRNA genes. Whether subsequent adaptive strategies would attempt to resolve these conflicts remains an open question.IMPORTANCE The bacterium E. coli can replicate its DNA even in the absence of the molecules that are required for canonical replication initiation. This often requires the formation of RNA-DNA hybrid structures and is referred to as constitutive stable DNA replication (cSDR). Where on the chromosome does cSDR initiate? We answer this question using laboratory evolution experiments and genomics and show that selection favors cSDR initiation predominantly at a region ∼0.6 Mb clockwise of oriC. Initiation from this site will result in more head-on collisions of DNA polymerase with RNA polymerase operating on rRNA loci. The bacterium adapts to this problem by inverting a region of the genome including several rRNA loci such that head-on collisions between the two polymerases are minimized. Understanding such evolutionary strategies in the context of cSDR can provide insights into the potential causes of resistance to antibiotics that target initiation of DNA replication.
Collapse
Affiliation(s)
- Reshma T Veetil
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Gandhi Krishi Vigyan Kendra, Bengaluru, Karnataka, India
- School of Life Science, The University of Trans-Disciplinary Health Sciences & Technology (TDU), Bengaluru, Karnataka, India
| | - Nitish Malhotra
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Gandhi Krishi Vigyan Kendra, Bengaluru, Karnataka, India
| | - Akshara Dubey
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Gandhi Krishi Vigyan Kendra, Bengaluru, Karnataka, India
| | - Aswin Sai Narain Seshasayee
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Gandhi Krishi Vigyan Kendra, Bengaluru, Karnataka, India
| |
Collapse
|
40
|
Abstract
RNA-binding proteins (RBPs) are central to most if not all cellular processes, dictating the fate of virtually all RNA molecules in the cell. Starting with pioneering work on ribosomal proteins, studies of bacterial RBPs have paved the way for molecular studies of RNA-protein interactions. Work over the years has identified major RBPs that act on cellular transcripts at the various stages of bacterial gene expression and that enable their integration into post-transcriptional networks that also comprise small non-coding RNAs. Bacterial RBP research has now entered a new era in which RNA sequencing-based methods permit mapping of RBP activity in a truly global manner in vivo. Moreover, the soaring interest in understudied members of host-associated microbiota and environmental communities is likely to unveil new RBPs and to greatly expand our knowledge of RNA-protein interactions in bacteria.
Collapse
Affiliation(s)
- Erik Holmqvist
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Jörg Vogel
- Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany. .,Institute of Molecular Infection Biology, University of Würzburg, Würzburg, Germany.
| |
Collapse
|
41
|
Nadiras C, Eveno E, Schwartz A, Figueroa-Bossi N, Boudvillain M. A multivariate prediction model for Rho-dependent termination of transcription. Nucleic Acids Res 2019; 46:8245-8260. [PMID: 29931073 PMCID: PMC6144790 DOI: 10.1093/nar/gky563] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/08/2018] [Indexed: 11/13/2022] Open
Abstract
Bacterial transcription termination proceeds via two main mechanisms triggered either by simple, well-conserved (intrinsic) nucleic acid motifs or by the motor protein Rho. Although bacterial genomes can harbor hundreds of termination signals of either type, only intrinsic terminators are reliably predicted. Computational tools to detect the more complex and diversiform Rho-dependent terminators are lacking. To tackle this issue, we devised a prediction method based on Orthogonal Projections to Latent Structures Discriminant Analysis [OPLS-DA] of a large set of in vitro termination data. Using previously uncharacterized genomic sequences for biochemical evaluation and OPLS-DA, we identified new Rho-dependent signals and quantitative sequence descriptors with significant predictive value. Most relevant descriptors specify features of transcript C>G skewness, secondary structure, and richness in regularly-spaced 5'CC/UC dinucleotides that are consistent with known principles for Rho-RNA interaction. Descriptors collectively warrant OPLS-DA predictions of Rho-dependent termination with a ∼85% success rate. Scanning of the Escherichia coli genome with the OPLS-DA model identifies significantly more termination-competent regions than anticipated from transcriptomics and predicts that regions intrinsically refractory to Rho are primarily located in open reading frames. Altogether, this work delineates features important for Rho activity and describes the first method able to predict Rho-dependent terminators in bacterial genomes.
Collapse
Affiliation(s)
- Cédric Nadiras
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France.,ED 549, Sciences Biologiques & Chimie du Vivant, Université d'Orléans, France
| | - Eric Eveno
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Annie Schwartz
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Nara Figueroa-Bossi
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, University of Paris-Sud, University of Paris-Saclay, Gif-sur-Yvette, France
| | - Marc Boudvillain
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France
| |
Collapse
|
42
|
Ragheb M, Merrikh H. The enigmatic role of Mfd in replication-transcription conflicts in bacteria. DNA Repair (Amst) 2019; 81:102659. [PMID: 31311770 PMCID: PMC6892258 DOI: 10.1016/j.dnarep.2019.102659] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Conflicts between replication and transcription can have life-threatening consequences. RNA polymerase (RNAP) is the major impediment to replication progression, and its efficient removal from DNA should mitigate the consequences of collisions with replication. Cells have various proteins that can resolve conflicts by removing stalled (or actively translocating) RNAP from DNA. It would therefore seem logical that RNAP-associated factors, such as the bacterial DNA translocase Mfd, would minimize the effects of conflicts. Despite seemingly conclusive statements in most textbooks, the role of Mfd in conflicts remains an enigma. In this review, we will discuss the different physical states of RNAP during transcription, and how each distinct state can influence conflict severity and potentially trigger the involvement of Mfd. We propose models to explain the contradictory conclusions from published studies on the potential role of Mfd in resolving conflicts.
Collapse
Affiliation(s)
- Mark Ragheb
- Molecular and Cellular Biology Graduate Program and Medical Scientist Training Program, University of Washington, Seattle, WA, USA
| | - Houra Merrikh
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37205, USA; Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
| |
Collapse
|
43
|
Abstract
Bacteria frequently encounter low concentrations of antibiotics. Active antibiotics are commonly detected in soil and water at concentrations much below lethal concentration. Although sub-MICs of antibiotics do not kill bacteria, they can have a major impact on bacterial populations by contributing to the development of antibiotic resistance through mutations in originally sensitive bacteria or acquisition of DNA from resistant bacteria. It was shown that concentrations as low as 100-fold below the MIC can actually lead to the selection of antibiotic-resistant cells. We seek to understand how bacterial cells react to such antibiotic concentrations using E. coli, the Gram-negative bacterial paradigm, and V. cholerae, the causative agent of cholera. Our findings shed light on the processes triggered at the DNA level by antibiotics targeting translation, how damage occurs, and what the bacterial strategies are to respond to such DNA damage. We have previously identified Vibrio cholerae mutants in which the stress response to subinhibitory concentrations of aminoglycoside is altered. One gene identified, VC1636, encodes a putative DNA/RNA helicase, recently named RadD in Escherichia coli. Here we combined extensive genetic characterization and high-throughput approaches in order to identify partners and molecular mechanisms involving RadD. We show that double-strand DNA breaks (DSBs) are formed upon subinhibitory tobramycin treatment in the absence of radD and recBCD and that formation of these DSBs can be overcome by RNase H1 overexpression. Loss of RNase H1, or of the transcription-translation coupling factor EF-P, is lethal in the radD deletion mutant. We propose that R-loops are formed upon sublethal aminoglycoside treatment, leading to the formation of DSBs that can be repaired by the RecBCD homologous recombination pathway, and that RadD counteracts such R-loop accumulation. We discuss how R-loops that can occur upon translation-transcription uncoupling could be the link between tobramycin treatment and DNA break formation.
Collapse
|
44
|
Raghunathan N, Goswami S, Leela JK, Pandiyan A, Gowrishankar J. A new role for Escherichia coli Dam DNA methylase in prevention of aberrant chromosomal replication. Nucleic Acids Res 2019; 47:5698-5711. [PMID: 30957852 PMCID: PMC6582345 DOI: 10.1093/nar/gkz242] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/20/2019] [Accepted: 03/26/2019] [Indexed: 01/20/2023] Open
Abstract
The Dam DNA methylase of Escherichia coli is required for methyl-directed mismatch repair, regulation of chromosomal DNA replication initiation from oriC (which is DnaA-dependent), and regulation of gene expression. Here, we show that Dam suppresses aberrant oriC-independent chromosomal replication (also called constitutive stable DNA replication, or cSDR). Dam deficiency conferred cSDR and, in presence of additional mutations (Δtus, rpoB*35) that facilitate retrograde replication fork progression, rescued the lethality of ΔdnaA mutants. The DinG helicase was required for rescue of ΔdnaA inviability during cSDR. Viability of ΔdnaA dam derivatives was dependent on the mismatch repair proteins, since such viability was lost upon introduction of deletions in mutS, mutH or mutL; thus generation of double strand ends (DSEs) by MutHLS action appears to be required for cSDR in the dam mutant. On the other hand, another DSE-generating agent phleomycin was unable to rescue ΔdnaA lethality in dam+ derivatives (mutS+ or ΔmutS), but it could do so in the dam ΔmutS strain. These results point to a second role for Dam deficiency in cSDR. We propose that in Dam-deficient strains, there is an increased likelihood of reverse replication restart (towards oriC) following recombinational repair of DSEs on the chromosome.
Collapse
Affiliation(s)
- Nalini Raghunathan
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal 576104, India
| | - Sayantan Goswami
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal 576104, India
| | - Jakku K Leela
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
| | - Apuratha Pandiyan
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
| | - Jayaraman Gowrishankar
- Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500039, India
| |
Collapse
|
45
|
Fitzgerald DM, Rosenberg SM. What is mutation? A chapter in the series: How microbes "jeopardize" the modern synthesis. PLoS Genet 2019; 15:e1007995. [PMID: 30933985 PMCID: PMC6443146 DOI: 10.1371/journal.pgen.1007995] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mutations drive evolution and were assumed to occur by chance: constantly, gradually, roughly uniformly in genomes, and without regard to environmental inputs, but this view is being revised by discoveries of molecular mechanisms of mutation in bacteria, now translated across the tree of life. These mechanisms reveal a picture of highly regulated mutagenesis, up-regulated temporally by stress responses and activated when cells/organisms are maladapted to their environments-when stressed-potentially accelerating adaptation. Mutation is also nonrandom in genomic space, with multiple simultaneous mutations falling in local clusters, which may allow concerted evolution-the multiple changes needed to adapt protein functions and protein machines encoded by linked genes. Molecular mechanisms of stress-inducible mutation change ideas about evolution and suggest different ways to model and address cancer development, infectious disease, and evolution generally.
Collapse
Affiliation(s)
- Devon M. Fitzgerald
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- The Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susan M. Rosenberg
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- The Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
| |
Collapse
|
46
|
Nadiras C, Delaleau M, Schwartz A, Margeat E, Boudvillain M. A Fluorogenic Assay To Monitor Rho-Dependent Termination of Transcription. Biochemistry 2019; 58:865-874. [PMID: 30624903 DOI: 10.1021/acs.biochem.8b01216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Transcription termination mediated by the ring-shaped, ATP-dependent Rho motor is a multipurpose regulatory mechanism specific to bacteria and constitutes an interesting target for the development of new antibiotics. Although Rho-dependent termination can punctuate gene expression or contribute to the protection of the genome at hundreds of sites within a given bacterium, its exact perimeter and site- or species-specific features remain insufficiently characterized. New advanced approaches are required to explore thoroughly the diversity of Rho-dependent terminators and the complexity of associated mechanisms. Current in vitro analyses of Rho-dependent termination rely on radiolabeling, gel electrophoresis, and phosphorimaging of transcription reaction products and are thus hazardous, inconvenient, and low-throughput. To address these limitations, we have developed the first in vitro assay using a fluorescence detection modality to study Rho-dependent transcription termination. This powerful experimental tool accurately estimates terminator strengths in a matter of minutes and is optimized for a microplate reader format allowing multiplexed characterization of putative terminator sequences and mechanisms or high-throughput screening of new drugs targeting Rho-dependent termination.
Collapse
Affiliation(s)
- Cédric Nadiras
- Centre de Biophysique Moléculaire , CNRS UPR4301 , rue Charles Sadron , 45071 Orléans cedex 2, France.,ED 549, Sciences Biologiques & Chimie du Vivant , Université d'Orléans , 45100 Orléans , France
| | - Mildred Delaleau
- Centre de Biophysique Moléculaire , CNRS UPR4301 , rue Charles Sadron , 45071 Orléans cedex 2, France
| | - Annie Schwartz
- Centre de Biophysique Moléculaire , CNRS UPR4301 , rue Charles Sadron , 45071 Orléans cedex 2, France
| | - Emmanuel Margeat
- Centre de Biochimie Structurale, INSERM U 1054, CNRS UMR 5048, Université de Montpellier , 29 rue de Navacelles , 34090 Montpellier , France
| | - Marc Boudvillain
- Centre de Biophysique Moléculaire , CNRS UPR4301 , rue Charles Sadron , 45071 Orléans cedex 2, France.,ED 549, Sciences Biologiques & Chimie du Vivant , Université d'Orléans , 45100 Orléans , France
| |
Collapse
|
47
|
Nagel A, Michalik S, Debarbouille M, Hertlein T, Gesell Salazar M, Rath H, Msadek T, Ohlsen K, van Dijl JM, Völker U, Mäder U. Inhibition of Rho Activity Increases Expression of SaeRS-Dependent Virulence Factor Genes in Staphylococcus aureus, Showing a Link between Transcription Termination, Antibiotic Action, and Virulence. mBio 2018; 9:e01332-18. [PMID: 30228237 PMCID: PMC6143737 DOI: 10.1128/mbio.01332-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/16/2018] [Indexed: 12/29/2022] Open
Abstract
Staphylococcus aureus causes various diseases ranging from skin and soft tissue infections to life-threatening infections. Adaptation to the different host niches is controlled by a complex network of transcriptional regulators. Global profiling of condition-dependent transcription revealed adaptation of S. aureus HG001 at the levels of transcription initiation and termination. In particular, deletion of the gene encoding the Rho transcription termination factor triggered a remarkable overall increase in antisense transcription and gene expression changes attributable to indirect regulatory effects. The goal of the present study was a detailed comparative analysis of S. aureus HG001 and its isogenic rho deletion mutant. Proteome analysis revealed significant differences in cellular and extracellular protein profiles, most notably increased amounts of the proteins belonging to the SaeR regulon in the Rho-deficient strain. The SaeRS two-component system acts as a major regulator of virulence gene expression in staphylococci. Higher levels of SaeRS-dependent virulence factors such as adhesins, toxins, and immune evasion proteins in the rho mutant resulted in higher virulence in a murine bacteremia model, which was alleviated in a rho complemented strain. Inhibition of Rho activity by bicyclomycin, a specific inhibitor of Rho activity, also induced the expression of SaeRS-dependent genes, at both the mRNA and protein levels, to the same extent as observed in the rho mutant. Taken together, these findings indicate that activation of the Sae system in the absence of Rho is directly linked to Rho's transcription termination activity and establish a new link between antibiotic action and virulence gene expression in S. aureusIMPORTANCE The major human pathogen Staphylococcus aureus is a widespread commensal bacterium but also the most common cause of nosocomial infections. It adapts to the different host niches through a complex gene regulatory network. We show here that the Rho transcription termination factor, which represses pervasive antisense transcription in various bacteria, including S. aureus, plays a role in controlling SaeRS-dependent virulence gene expression. A Rho-deficient strain produces larger amounts of secreted virulence factors in vitro and shows increased virulence in mice. We also show that treatment of S. aureus with the antibiotic bicyclomycin, which inhibits Rho activity and is effective against Gram-negative bacteria, induces the same changes in the proteome as observed in the Rho-deficient strain. Our results reveal for the first time a link between transcription termination and virulence regulation in S. aureus, which implies a novel mechanism by which an antibiotic can modulate the expression of virulence factors.
Collapse
Affiliation(s)
- Anna Nagel
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Stephan Michalik
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Michel Debarbouille
- Biology of Gram-Positive Pathogens, Department of Microbiology, Institut Pasteur and CNRS ERL 3526, Paris, France
| | - Tobias Hertlein
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany
| | - Manuela Gesell Salazar
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Hermann Rath
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Tarek Msadek
- Biology of Gram-Positive Pathogens, Department of Microbiology, Institut Pasteur and CNRS ERL 3526, Paris, France
| | - Knut Ohlsen
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Ulrike Mäder
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| |
Collapse
|
48
|
Lawson MR, Ma W, Bellecourt MJ, Artsimovitch I, Martin A, Landick R, Schulten K, Berger JM. Mechanism for the Regulated Control of Bacterial Transcription Termination by a Universal Adaptor Protein. Mol Cell 2018; 71:911-922.e4. [PMID: 30122535 DOI: 10.1016/j.molcel.2018.07.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/21/2018] [Accepted: 07/13/2018] [Indexed: 12/14/2022]
Abstract
NusG/Spt5 proteins are the only transcription factors utilized by all cellular organisms. In enterobacteria, NusG antagonizes the transcription termination activity of Rho, a hexameric helicase, during the synthesis of ribosomal and actively translated mRNAs. Paradoxically, NusG helps Rho act on untranslated transcripts, including non-canonical antisense RNAs and those arising from translational stress; how NusG fulfills these disparate functions is unknown. Here, we demonstrate that NusG activates Rho by assisting helicase isomerization from an open-ring, RNA-loading state to a closed-ring, catalytically active translocase. A crystal structure of closed-ring Rho in complex with NusG reveals the physical basis for this activation and further explains how Rho is excluded from translationally competent RNAs. This study demonstrates how a universally conserved transcription factor acts to modulate the activity of a ring-shaped ATPase motor and establishes how the innate sequence bias of a termination factor can be modulated to silence pervasive, aberrant transcription.
Collapse
Affiliation(s)
- Michael R Lawson
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Wen Ma
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Beckman Institute for Advanced Science Technology, Urbana, IL 61801, USA; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Michael J Bellecourt
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Irina Artsimovitch
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Klaus Schulten
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Beckman Institute for Advanced Science Technology, Urbana, IL 61801, USA; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - James M Berger
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| |
Collapse
|
49
|
Kang JG, Lee HW, Ko S, Chae JS. Comparative proteomic analysis of outer membrane protein 43 ( omp43)-deficient Bartonella henselae. J Vet Sci 2018; 19:59-70. [PMID: 28693313 PMCID: PMC5799401 DOI: 10.4142/jvs.2018.19.1.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/09/2017] [Accepted: 06/08/2017] [Indexed: 12/17/2022] Open
Abstract
Outer membrane proteins (OMPs) of Gram-negative bacteria constitute the first line of defense protecting cells against environmental stresses including chemical, biophysical, and biological attacks. Although the 43-kDa OMP (OMP43) is major porin protein among Bartonella henselae-derived OMPs, its function remains unreported. In this study, OMP43-deficient mutant B. henselae (Δomp43) was generated to investigate OMP43 function. Interestingly, Δomp43 exhibited weaker proliferative ability than that of wild-type (WT) B. henselae. To study the differences in proteomic expression between WT and Δomp43, two-dimensional gel electrophoresis-based proteomic analysis was performed. Based on Clusters of Orthologus Groups functional assignments, 12 proteins were associated with metabolism, 7 proteins associated with information storage and processing, and 3 proteins associated with cellular processing and signaling. By semi-quantitative reverse transcriptase polymerase chain reaction, increases in tldD, efp, ntrX, pdhA, purB, and ATPA mRNA expression and decreases in Rho and yfeA mRNA expression were confirmed in Δomp43. In conclusion, this is the first report showing that a loss of OMP43 expression in B. henselae leads to retarded proliferation. Furthermore, our proteomic data provide useful information for the further investigation of mechanisms related to the growth of B. henselae.
Collapse
Affiliation(s)
- Jun-Gu Kang
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Hee-Woo Lee
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Sungjin Ko
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| | - Joon-Seok Chae
- Laboratory of Veterinary Internal Medicine, Research Institute and BK21 Program for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Korea
| |
Collapse
|
50
|
Abstract
ABSTRACT
Although bacterial genomes are usually densely protein-coding, genome-wide mapping approaches of transcriptional start sites revealed that a significant fraction of the identified promoters drive the transcription of noncoding RNAs. These can be
trans
-acting RNAs, mainly originating from intergenic regions and, in many studied examples, possessing regulatory functions. However, a significant fraction of these noncoding RNAs consist of natural antisense transcripts (asRNAs), which overlap other transcriptional units. Naturally occurring asRNAs were first observed to play a role in bacterial plasmid replication and in bacteriophage λ more than 30 years ago. Today’s view is that asRNAs abound in all three domains of life. There are several examples of asRNAs in bacteria with clearly defined functions. Nevertheless, many asRNAs appear to result from pervasive initiation of transcription, and some data point toward global functions of such widespread transcriptional activity, explaining why the search for a specific regulatory role is sometimes futile. In this review, we give an overview about the occurrence of antisense transcription in bacteria, highlight particular examples of functionally characterized asRNAs, and discuss recent evidence pointing at global relevance in RNA processing and transcription-coupled DNA repair.
Collapse
|