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King RA, Babbs M, Baugh K, Hamilton C. Isolation and Characterization of Phages That Bypass the Requirement for RNA-Mediated Antitermination. PHAGE (NEW ROCHELLE, N.Y.) 2023; 4:82-89. [PMID: 37350996 PMCID: PMC10282786 DOI: 10.1089/phage.2023.0008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Introduction The rpoCY75N mutation in the zinc-binding domain of the β' subunit of Escherichia coli RNA polymerase blocks the RNA-based mechanism of transcription antitermination utilized by bacteriophage HK022. Materials and Methods Mutant phages that overcome the block imposed by the rpoCY75N mutation are described. These phages, designated "orc" (overcomes rpoC), carry mutations that create new promoters. Promoter activity was assessed by cloning the respective regions from the wild-type and orc phages into a promoterless lacZ reporter vector. Results Reporter assays showed that the sequence originating from orc phages had significant promoter activity when compared with the equivalent sequence cloned from the parental phage. Conclusions The newly created promoters facilitate the expression of phage genes that are essential for growth on the rpoCY75N strain by bypassing transcription terminators. The small plaque phenotype of orc phages, when grown on the mutant host, suggests that suppression of the rpoCY75N mutation is incomplete.
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Affiliation(s)
- Rodney A. King
- Biology Department, Western Kentucky University, Bowling Green, Kentucky, USA
| | - Millicent Babbs
- Owensboro Family Medicine, University of Louisville, Owensboro, Kentucky, USA
| | - Kimberly Baugh
- Department of Pharmacy, Franciscan Health Lafayette East, Lafayette, Indiana, USA
| | - Courtney Hamilton
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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2
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Dey S, Batisse C, Shukla J, Webster MW, Takacs M, Saint-André C, Weixlbaumer A. Structural insights into RNA-mediated transcription regulation in bacteria. Mol Cell 2022; 82:3885-3900.e10. [DOI: 10.1016/j.molcel.2022.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/07/2022] [Accepted: 09/19/2022] [Indexed: 11/06/2022]
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3
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Structural basis of transcriptional regulation by a nascent RNA element, HK022 putRNA. Nat Commun 2022; 13:4668. [PMID: 35970830 PMCID: PMC9378689 DOI: 10.1038/s41467-022-32315-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/26/2022] [Indexed: 12/16/2022] Open
Abstract
Transcription, in which RNA polymerases (RNAPs) produce RNA from DNA, is the first step of gene expression. As such, it is highly regulated either by trans-elements like protein factors and/or by cis-elements like specific sequences on the DNA. Lambdoid phage HK022 contains a cis-element, put, which suppresses pausing and termination during transcription of the early phage genes. The putRNA transcript solely performs the anti-pausing/termination activities by interacting directly with the E.coli RNAP elongation complex (EC) by an unknown structural mechanism. In this study, we reconstituted putRNA-associated ECs and determined the structures using cryo-electron microscopy. The determined structures of putRNA-associated EC, putRNA-absent EC, and σ70-bound EC suggest that the putRNA interaction with the EC counteracts swiveling, a conformational change previously identified to promote pausing and σ70 might modulate putRNA folding via σ70-dependent pausing during elongation.
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4
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Roles of zinc-binding domain of bacterial RNA polymerase in transcription. Trends Biochem Sci 2022; 47:710-724. [DOI: 10.1016/j.tibs.2022.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 02/27/2022] [Accepted: 03/07/2022] [Indexed: 01/07/2023]
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5
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Shi W, Zhou W, Zhang B, Huang S, Jiang Y, Schammel A, Hu Y, Liu B. Structural basis of bacterial σ 28 -mediated transcription reveals roles of the RNA polymerase zinc-binding domain. EMBO J 2020; 39:e104389. [PMID: 32484956 DOI: 10.15252/embj.2020104389] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/26/2020] [Accepted: 04/30/2020] [Indexed: 11/09/2022] Open
Abstract
In bacteria, σ28 is the flagella-specific sigma factor that targets RNA polymerase (RNAP) to control the expression of flagella-related genes involving bacterial motility and chemotaxis. However, the structural mechanism of σ28 -dependent promoter recognition remains uncharacterized. Here, we report cryo-EM structures of E. coli σ28 -dependent transcribing complexes on a complete flagella-specific promoter. These structures reveal how σ28 -RNAP recognizes promoter DNA through strong interactions with the -10 element, but weak contacts with the -35 element, to initiate transcription. In addition, we observed a distinct architecture in which the β' zinc-binding domain (ZBD) of RNAP stretches out from its canonical position to interact with the upstream non-template strand. Further in vitro and in vivo assays demonstrate that this interaction has the overall effect of facilitating closed-to-open isomerization of the RNAP-promoter complex by compensating for the weak interaction between σ4 and -35 element. This suggests that ZBD relocation may be a general mechanism employed by σ70 family factors to enhance transcription from promoters with weak σ4/-35 element interactions.
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Affiliation(s)
- Wei Shi
- Section of Transcription & Gene Regulation, The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Wei Zhou
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Baoyue Zhang
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Shaojia Huang
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yanan Jiang
- Section of Transcription & Gene Regulation, The Hormel Institute, University of Minnesota, Austin, MN, USA.,Department of Pathophysiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Abigail Schammel
- Section of Transcription & Gene Regulation, The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Bin Liu
- Section of Transcription & Gene Regulation, The Hormel Institute, University of Minnesota, Austin, MN, USA
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6
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Widom JR, Nedialkov YA, Rai V, Hayes RL, Brooks CL, Artsimovitch I, Walter NG. Ligand Modulates Cross-Coupling between Riboswitch Folding and Transcriptional Pausing. Mol Cell 2019; 72:541-552.e6. [PMID: 30388413 PMCID: PMC6565381 DOI: 10.1016/j.molcel.2018.08.046] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/11/2018] [Accepted: 08/30/2018] [Indexed: 12/31/2022]
Abstract
Numerous classes of riboswitches have been found to regulate bacterial gene expression in response to physiological cues, offering new paths to antibacterial drugs. As common studies of isolated riboswitches lack the functional context of the transcription machinery, we here combine single-molecule, biochemical, and simulation approaches to investigate the coupling between co-transcriptional folding of the pseudoknot-structured preQ1 riboswitch and RNA polymerase (RNAP) pausing. We show that pausing at a site immediately downstream of the riboswitch requires a ligand-free pseudoknot in the nascent RNA, a precisely spaced sequence resembling the pause consensus, and electrostatic and steric interactions with the RNAP exit channel. While interactions with RNAP stabilize the native fold of the riboswitch, binding of the ligand signals RNAP release from the pause. Our results demonstrate that the nascent riboswitch and its ligand actively modulate the function of RNAP and vice versa, a paradigm likely to apply to other cellular RNA transcripts.
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Affiliation(s)
- Julia R Widom
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yuri A Nedialkov
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Victoria Rai
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA; Biophysics Program and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ryan L Hayes
- Biophysics Program and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Charles L Brooks
- Biophysics Program and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Irina Artsimovitch
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA.
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7
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Abstract
This chapter focuses on transition metals. All transition metal cations are toxic-those that are essential for Escherichia coli and belong to the first transition period of the periodic system of the element and also the "toxic-only" metals with higher atomic numbers. Common themes are visible in the metabolism of these ions. First, there is transport. High-rate but low-affinity uptake systems provide a variety of cations and anions to the cells. Control of the respective systems seems to be mainly through regulation of transport activity (flux control), with control of gene expression playing only a minor role. If these systems do not provide sufficient amounts of a needed ion to the cell, genes for ATP-hydrolyzing high-affinity but low-rate uptake systems are induced, e.g., ABC transport systems or P-type ATPases. On the other hand, if the amount of an ion is in surplus, genes for efflux systems are induced. By combining different kinds of uptake and efflux systems with regulation at the levels of gene expression and transport activity, the concentration of a single ion in the cytoplasm and the composition of the cellular ion "bouquet" can be rapidly adjusted and carefully controlled. The toxicity threshold of an ion is defined by its ability to produce radicals (copper, iron, chromate), to bind to sulfide and thiol groups (copper, zinc, all cations of the second and third transition period), or to interfere with the metabolism of other ions. Iron poses an exceptional metabolic problem due its metabolic importance and the low solubility of Fe(III) compounds, combined with the ability to cause dangerous Fenton reactions. This dilemma for the cells led to the evolution of sophisticated multi-channel iron uptake and storage pathways to prevent the occurrence of unbound iron in the cytoplasm. Toxic metals like Cd2+ bind to thiols and sulfide, preventing assembly of iron complexes and releasing the metal from iron-sulfur clusters. In the unique case of mercury, the cation can be reduced to the volatile metallic form. Interference of nickel and cobalt with iron is prevented by the low abundance of these metals in the cytoplasm and their sequestration by metal chaperones, in the case of nickel, or by B12 and its derivatives, in the case of cobalt. The most dangerous metal, copper, catalyzes Fenton-like reactions, binds to thiol groups, and interferes with iron metabolism. E. coli solves this problem probably by preventing copper uptake, combined with rapid efflux if the metal happens to enter the cytoplasm.
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8
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Mishra S, Sen R. N protein from lambdoid phages transforms NusA into an antiterminator by modulating NusA-RNA polymerase flap domain interactions. Nucleic Acids Res 2015; 43:5744-58. [PMID: 25990722 PMCID: PMC4499122 DOI: 10.1093/nar/gkv479] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/29/2015] [Indexed: 11/23/2022] Open
Abstract
Interaction of the lambdoid phage N protein with the bacterial transcription elongation factor NusA is the key component in the process of transcription antitermination. A convex surface of E. coli NusA-NTD, located opposite to its RNA polymerase-binding domain (the β-flap domain), directly interacts with N in the antitermination complex. We hypothesized that this N-NusA interaction induces allosteric effects on the NusA-RNAP interaction leading to transformation of NusA into a facilitator of the antitermination process. Here we showed that mutations in β-flap domain specifically defective for N antitermination exhibited altered NusA-nascent RNA interaction and have widened RNA exit channel indicating an intricate role of flap domain in the antitermination. The presence of N reoriented the RNAP binding surface of NusA-NTD, which changed its interaction pattern with the flap domain. These changes caused significant spatial rearrangement of the β-flap as well as the β′ dock domains to form a more constricted RNA exit channel in the N-modified elongation complex (EC), which might play key role in converting NusA into a facilitator of the N antitermination. We propose that in addition to affecting the RNA exit channel and the active center of the EC, β-flap domain rearrangement is also a mechanistic component in the N antitermination process.
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Affiliation(s)
- Saurabh Mishra
- Laboratory of Transcription, Center for DNA Fingerprinting and Diagnostics, Tuljaguda Complex, 4-1-714 Mozamjahi Road, Nampally, Hyderabad 500 001, India Graduate Studies, Manipal University, India
| | - Ranjan Sen
- Laboratory of Transcription, Center for DNA Fingerprinting and Diagnostics, Tuljaguda Complex, 4-1-714 Mozamjahi Road, Nampally, Hyderabad 500 001, India
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9
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Casjens SR, Hendrix RW. Bacteriophage lambda: Early pioneer and still relevant. Virology 2015; 479-480:310-30. [PMID: 25742714 PMCID: PMC4424060 DOI: 10.1016/j.virol.2015.02.010] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/13/2015] [Accepted: 02/05/2015] [Indexed: 12/14/2022]
Abstract
Molecular genetic research on bacteriophage lambda carried out during its golden age from the mid-1950s to mid-1980s was critically important in the attainment of our current understanding of the sophisticated and complex mechanisms by which the expression of genes is controlled, of DNA virus assembly and of the molecular nature of lysogeny. The development of molecular cloning techniques, ironically instigated largely by phage lambda researchers, allowed many phage workers to switch their efforts to other biological systems. Nonetheless, since that time the ongoing study of lambda and its relatives has continued to give important new insights. In this review we give some relevant early history and describe recent developments in understanding the molecular biology of lambda's life cycle.
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Affiliation(s)
- Sherwood R Casjens
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Emma Eccles Jones Medical Research Building, 15 North Medical Drive East, Salt Lake City, UT 84112, USA; Biology Department, University of Utah, Salt Lake City, UT 84112, USA.
| | - Roger W Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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10
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Distinct pathways of RNA polymerase regulation by a phage-encoded factor. Proc Natl Acad Sci U S A 2015; 112:2017-22. [PMID: 25646468 DOI: 10.1073/pnas.1416330112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Transcription antitermination is a common strategy of gene expression regulation, but only a few transcription antitermination factors have been studied in detail. Here, we dissect the transcription antitermination mechanism of Xanthomonas oryzae virus Xp10 protein p7, which binds host RNA polymerase (RNAP) and regulates both transcription initiation and termination. We show that p7 suppresses intrinsic termination by decreasing RNAP pausing and increasing the transcription complex stability, in cooperation with host-encoded factor NusA. Uniquely, the antitermination activity of p7 depends on the ω subunit of the RNAP core and is modulated by ppGpp. In contrast, the inhibition of transcription initiation by p7 does not require ω but depends on other RNAP sites. Our results suggest that p7, a bifunctional transcription factor, uses distinct mechanisms to control different steps of transcription. We propose that regulatory functions of the ω subunit revealed by our analysis may extend to its homologs in eukaryotic RNAPs.
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11
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Mishra S, Mohan S, Godavarthi S, Sen R. The interaction surface of a bacterial transcription elongation factor required for complex formation with an antiterminator during transcription antitermination. J Biol Chem 2013; 288:28089-103. [PMID: 23913688 DOI: 10.1074/jbc.m113.472209] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bacterial transcription elongation factor, NusA, functions as an antiterminator when it is bound to the lambdoid phage derived antiterminator protein, N. The mode of N-NusA interaction is unknown, knowledge of which is essential to understand the antitermination process. It was reported earlier that in the absence of the transcription elongation complex (EC), N interacts with the C-terminal AR1 domain of NusA. However, the functional significance of this interaction is obscure. Here we identified mutations in NusA N terminus (NTD) specifically defective for N-mediated antitermination. These are located at a convex surface of the NusA-NTD, situated opposite its concave RNA polymerase (RNAP) binding surface. These NusA mutants disrupt the N-nut site interactions on the nascent RNA emerging out of a stalled EC. In the N/NusA-modified EC, a Cys-53 (S53C) from the convex surface of the NusA-NTD forms a specific disulfide (S-S) bridge with a Cys-39 (S39C) of the NusA binding region of the N protein. We conclude that when bound to the EC, the N interaction surface of NusA shifts from the AR1 domain to its NTD domain. This occurred due to a massive away-movement of the adjacent AR2 domain of NusA upon binding to the EC. We propose that the close proximity of this altered N-interaction site of NusA to its RNAP binding surface, enables N to influence the NusA-RNAP interaction during transcription antitermination that in turn facilitates the conversion of NusA into an antiterminator.
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Affiliation(s)
- Saurabh Mishra
- From the Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Tuljaguda Complex, 4-1-714 Mozamjahi Road, Nampally, Hyderabad-500001, India
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12
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Abstract
Antiterminator RNA directly modifies the transcription elongation complex so that it terminates less efficiently at intrinsic and factor-dependent terminators. These unusual RNAs were first discovered in bacteriophage HK022, where the nascent transcripts of the phage put sites promote full expression of phage genes during lytic infection. The activity of antiterminator RNA depends on specific structural elements that form as the transcript exits RNA polymerase. To further our understanding of the critical sequence features that permit RNA to serve as a transcriptional antiterminator, we have identified eight antiterminator RNA sequences in bacteriophages or prophages. There is strong sequence conservation among most of the put sequences, but sequence divergence is tolerated if critical structural elements are preserved. The most diverged antiterminator RNA is found in bacteriophage HK639. The HK639 putL transcript is an efficient antiterminator, and it has a novel structural feature that is critical for its activity. HK639 also displays a unique pattern of sensitivity to amino acid substitutions in the β' subunit zinc binding domain of RNA polymerase, adding to existing evidence that this domain interacts specifically with antiterminator RNA.
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13
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Swapna G, Chakraborty A, Kumari V, Sen R, Nagaraja V. Mutations in β' subunit of Escherichia coli RNA polymerase perturb the activator polymerase functional interaction required for promoter clearance. Mol Microbiol 2011; 80:1169-85. [PMID: 21435034 DOI: 10.1111/j.1365-2958.2011.07636.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Transcription activator C employs a unique mechanism to activate mom gene of bacteriophage Mu. The activation process involves, facilitating the recruitment of RNA polymerase (RNAP) by altering the topology of the promoter and enhancing the promoter clearance by reducing the abortive transcription. To understand the basis of this multi-step activation mechanism, we investigated the nature of the physical interaction between C and RNAP during the process. A variety of assays revealed that only DNA-bound C contacts the β' subunit of RNAP. Consistent to these results, we have also isolated RNAP mutants having mutations in the β' subunit which were compromised in C-mediated activation. Mutant RNAPs show reduced productive transcription and increased abortive initiation specifically at the C-dependent mom promoter. Positive control (pc) mutants of C, defective in interaction with RNAP, retained the property of recruiting RNAP to the promoter but were unable to enhance promoter clearance. These results strongly suggest that the recruitment of RNAP to the mom promoter does not require physical interaction with C, whereas a contact between the β' subunit and the activator, and the subsequent allosteric changes in the active site of the enzyme are essential for the enhancement of promoter clearance.
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Affiliation(s)
- Ganduri Swapna
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
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14
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Irnov I, Winkler WC. A regulatory RNA required for antitermination of biofilm and capsular polysaccharide operons in Bacillales. Mol Microbiol 2010; 76:559-75. [DOI: 10.1111/j.1365-2958.2010.07131.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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15
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Abstract
The elongation phase of transcription by RNA polymerase is highly regulated and modulated. Both general and operon-specific elongation factors determine the local rate and extent of transcription to coordinate the appearance of transcript with its use as a messenger or functional ribonucleoprotein or regulatory element, as well as to provide operon-specific gene regulation.
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Affiliation(s)
- Jeffrey W Roberts
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
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16
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Komissarova N, Velikodvorskaya T, Sen R, King RA, Banik-Maiti S, Weisberg RA. Inhibition of a transcriptional pause by RNA anchoring to RNA polymerase. Mol Cell 2008; 31:683-94. [PMID: 18775328 DOI: 10.1016/j.molcel.2008.06.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 04/04/2008] [Accepted: 06/18/2008] [Indexed: 11/18/2022]
Abstract
We describe a mechanism by which nascent RNA inhibits transcriptional pausing. PutL RNA of bacteriophage HK022 suppresses transcription termination at downstream terminators and pausing within a nearby U-rich sequence. In vitro transcription and footprinting assays reveal that this pausing results from backtracking of RNA polymerase and that binding of nascent putL RNA to polymerase limits backtracking by restricting re-entry of the transcript into the RNA exit channel. The restriction is local and relaxes as the transcript elongates. Our results suggest that putL RNA binds to the surface of polymerase close to the RNA exit channel, a region that includes amino acid residues important for antitermination. Although binding is essential for antipausing and antitermination, these two activities of put differ: antipausing is limited to the immediate vicinity of the putL site, but antitermination is not. We propose that RNA anchoring to the elongation complex is a widespread mechanism of pause regulation.
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Affiliation(s)
- Natalia Komissarova
- Section on Microbial Genetics, Laboratory of Molecular Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892-2785, USA
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17
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Cheeran A, Kolli NR, Sen R. The site of action of the antiterminator protein N from the lambdoid phage H-19B. J Biol Chem 2007; 282:30997-1007. [PMID: 17698847 DOI: 10.1074/jbc.m704864200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription antitermination by N proteins of lambdoid phages involves specific interactions of the C-terminal domain of N with the elongation complex (EC). The interacting surface of N on the EC is unknown, knowledge of which is essential to understand the mechanism of antitermination. Specific cleavage patterns were generated near the active site Mg2+ of the RNA polymerase of an N-modified stalled EC using iron-(S)-1-(p-bromoacetamidobenzyl)ethylenediaminetetraacetate conjugated to the only cysteine residue in the C-terminal domain of N from a lambdoid phage H-19B. Modification of EC by N also induced conformational changes around the same region as revealed from the limited trypsin digestion and in situ Fe-dithiothreitol cleavage pattern of the same EC. These data, together with the previously obtained H-19B N-specific mutations in RNA polymerase, beta (G1045D), and beta' (P251S, P254L, G336S, and R270C) subunits, suggest that the active center cleft of the EC could be the site of action of this antiterminator. H-19B N induced altered interactions in this region of EC, prevented the backtracking of the stalled EC at the ops pause site and destabilized RNA hairpin-beta subunit flap domain interactions at the his pause site. We propose that the physical proximity of the C-terminal domain of H-19B N to the active center cleft of the EC is required for the process of transcription antitermination and that it involves both stabilization of the weak RNA-DNA hybrid at a terminator and destabilization of the interactions of terminator hairpin in the RNA exit channel.
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Affiliation(s)
- Anoop Cheeran
- Laboratory of Transcription Biology, Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, India
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18
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Hardy RW. The role of the 3' terminus of the Sindbis virus genome in minus-strand initiation site selection. Virology 2005; 345:520-31. [PMID: 16297426 DOI: 10.1016/j.virol.2005.10.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 09/28/2005] [Accepted: 10/18/2005] [Indexed: 11/26/2022]
Abstract
Genome replication of plus-strand RNA viruses begins with the generation of a minus-strand copy of the genome. Minus-strand synthesis must initiate at or close to the 3' end of the genome and progress to processive elongation to yield the appropriate template for genomic RNA synthesis. The Sindbis virus genome possesses a 3' polyadenylate tail preceded by a 19 nucleotide conserved sequence element (3' CSE). Analyses of in vitro and in vivo synthesized minus-strand RNA presented in this manuscript identify the cytidylate residue immediately preceding the poly (A) tail as the predominant wild-type initiation site. Mutations in the poly (A) tail and the 3' CSE caused the initiation site to shift to the poly (A) tail. Analysis of the products of non-wild-type initiation events demonstrated that they are not productively elongated. This study indicates that full-length minus-strand RNA synthesis is dependent upon initiation occurring at the appropriate site and suggests a mechanism for selection and maintenance of the wt 3' CSE and poly (A) tail.
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Affiliation(s)
- Richard W Hardy
- Department of Biology, Indiana University, 1001 E. Third Street, Bloomington, 47405, USA.
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19
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Cheeran A, Babu Suganthan R, Swapna G, Bandey I, Achary MS, Nagarajaram HA, Sen R. Escherichia coli RNA polymerase mutations located near the upstream edge of an RNA:DNA hybrid and the beginning of the RNA-exit channel are defective for transcription antitermination by the N protein from lambdoid phage H-19B. J Mol Biol 2005; 352:28-43. [PMID: 16061258 DOI: 10.1016/j.jmb.2005.06.052] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 05/08/2005] [Accepted: 06/20/2005] [Indexed: 12/01/2022]
Abstract
Transcription antitermination is an important mechanism that can control regulation of gene expression. The N protein of lambdoid phages modifies the transcription elongation complex (EC) and helps it to overcome downstream terminators. In this modified EC, the C-terminal domain of N makes specific interactions with RNA polymerase (RNAP). The interacting surface of RNAP for N is unknown. Here, we report five mutations in the beta (G1045D) and beta' (P251S, P254L, R270C and G336S) subunits of RNAP that are specifically defective for antitermination by N protein of the lambdoid phage, H-19B. A mutation in the C-terminal domain of N, L108F, suppresses the defect of beta'-P254L. Purified mutant holoenzymes exhibit less processive antitermination. The amino acid substitutions in the mutant RNAPs cluster very close to the RNA:DNA hybrid at the beginning of the RNA-exit channel of the EC. We suggest that the action of H-19B N is exerted through the region defined by these amino acids. Wild-type N stabilizes the EC at terminator sites and in this modified EC a part of the terminator hairpin may form but appears to be unstable. We propose that the action of N close to the active center alters the RNAP-nucleic acid interactions around the RNA:DNA hybrid, which impairs proper folding of the terminator hairpin or stabilizes the weak RNA:DNA hybrid, or both.
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Affiliation(s)
- Anoop Cheeran
- Laboratory of Transcription Biology, Center for DNA Fingerprinting and Diagnostics, Nacharam, Hyderabad-500076, India
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King RA, Markov D, Sen R, Severinov K, Weisberg RA. A conserved zinc binding domain in the largest subunit of DNA-dependent RNA polymerase modulates intrinsic transcription termination and antitermination but does not stabilize the elongation complex. J Mol Biol 2004; 342:1143-54. [PMID: 15351641 DOI: 10.1016/j.jmb.2004.07.072] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 07/21/2004] [Accepted: 07/21/2004] [Indexed: 11/17/2022]
Abstract
An evolutionarily conserved zinc-binding motif is found close to the amino terminus of the largest subunits of DNA-dependent RNA polymerases from bacteria, archaea, and eukaryotes. In bacterial RNA polymerase, this motif, the zinc binding domain, has been implicated in protein-DNA interactions that stabilize the transcription elongation complex and that occur downstream of the catalytic center. Here, we show that this view is incorrect, and instead, the zinc binding domain interacts with product RNA located upstream of the catalytic center and the RNA-DNA hybrid, a view consistent with structural studies of the elongation complex. We engineered mutations that alter or remove the zinc binding domain of Escherichia coli RNA polymerase. Several mutants, including one that lacked all four zinc ligands and another that lacked the entire domain, produced enzymes that were active in vitro and formed stable elongation complexes. However, they were defective in two functions that require interaction of polymerase with product RNA. First, they terminated less efficiently than the wild-type at intrinsic transcription terminators. Second, enzymes lacking the tip of the zinc binding domain or the zinc ligands did not antiterminate in response to an intrinsic antiterminator encoded by the put site of phage HK022. Termination, but not antitermination, was restored by the bacterial termination factor NusA. Surprisingly, a mutant that lacks the entire zinc binding domain regained a partial response to put. To account for this we suggest that put RNA interacts with an additional site in the elongation complex to mediate antitermination, and that this site is occluded by the wild-type zinc binding domain.
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Affiliation(s)
- Rodney A King
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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Naryshkina T, Bruning A, Gadal O, Severinov K. Role of second-largest RNA polymerase I subunit Zn-binding domain in enzyme assembly. EUKARYOTIC CELL 2003; 2:1046-52. [PMID: 14555487 PMCID: PMC219369 DOI: 10.1128/ec.2.5.1046-1052.2003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2003] [Accepted: 07/26/2003] [Indexed: 11/20/2022]
Abstract
The second-largest subunits of eukaryal RNA polymerases are similar to the beta subunits of prokaryal RNA polymerases throughout much of their lengths. The second-largest subunits from eukaryal RNA polymerases contain a four-cysteine Zn-binding domain at their C termini. The domain is also present in archaeal homologs but is absent from prokaryal homologs. Here, we investigated the role of the C-terminal Zn-binding domain of Rpa135, the second-largest subunit of yeast RNA polymerase I. Analysis of nonfunctional Rpa135 mutants indicated that the Zn-binding domain is required for recruitment of the largest subunit, Rpa190, into the RNA polymerase I complex. Curiously, the essential function of the Rpa135 Zn-binding domain is not related to Zn(2+) binding per se, since replacement of only one of the four cysteine residues with alanine led to the loss of Rpa135 function. Even more strikingly, replacement of all four cysteines with alanines resulted in functional Rpa135.
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Affiliation(s)
- Tatyana Naryshkina
- Waksman Institute, Rutgers, The State University, Piscataway, NJ 08854, USA
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Affiliation(s)
- Catherine L Squires
- Department of Molecular Biology and Microbiology, Tufts University, School of Medicine, Boston, Massachusetts 02111-1800, USA
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