1
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Mueller AU, Chen J, Wu M, Chiu C, Nixon BT, Campbell EA, Darst SA. A general mechanism for transcription bubble nucleation in bacteria. Proc Natl Acad Sci U S A 2023; 120:e2220874120. [PMID: 36972428 PMCID: PMC10083551 DOI: 10.1073/pnas.2220874120] [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: 12/08/2022] [Accepted: 03/01/2023] [Indexed: 03/29/2023] Open
Abstract
Bacterial transcription initiation requires σ factors for nucleation of the transcription bubble. The canonical housekeeping σ factor, σ70, nucleates DNA melting via recognition of conserved bases of the promoter -10 motif, which are unstacked and captured in pockets of σ70. By contrast, the mechanism of transcription bubble nucleation and formation during the unrelated σN-mediated transcription initiation is poorly understood. Herein, we combine structural and biochemical approaches to establish that σN, like σ70, captures a flipped, unstacked base in a pocket formed between its N-terminal region I (RI) and extra-long helix features. Strikingly, RI inserts into the nascent bubble to stabilize the nucleated bubble prior to engagement of the obligate ATPase activator. Our data suggest a general paradigm of transcription initiation that requires σ factors to nucleate an early melted intermediate prior to productive RNA synthesis.
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Affiliation(s)
- Andreas U. Mueller
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - James Chen
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - Mengyu Wu
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - Courtney Chiu
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
| | - B. Tracy Nixon
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA16802
| | | | - Seth A. Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY10065
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2
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Ye F, Gao F, Liu X, Buck M, Zhang X. Mechanisms of DNA opening revealed in AAA+ transcription complex structures. SCIENCE ADVANCES 2022; 8:eadd3479. [PMID: 36542713 PMCID: PMC9770992 DOI: 10.1126/sciadv.add3479] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 11/07/2022] [Indexed: 06/17/2023]
Abstract
Gene transcription is carried out by RNA polymerase (RNAP) and requires the conversion of the initial closed promoter complex, where DNA is double stranded, to a transcription-competent open promoter complex, where DNA is opened up. In bacteria, RNAP relies on σ factors for its promoter specificities. Using a special form of sigma factor (σ54), which forms a stable closed complex and requires its activator that belongs to the AAA+ ATPases (ATPases associated with diverse cellular activities), we obtained cryo-electron microscopy structures of transcription initiation complexes that reveal a previously unidentified process of DNA melting opening. The σ54 amino terminus threads through the locally opened up DNA and then becomes enclosed by the AAA+ hexameric ring in the activator-bound intermediate complex. Our structures suggest how ATP hydrolysis by the AAA+ activator could remove the σ54 inhibition while helping to open up DNA, using σ54 amino-terminal peptide as a pry bar.
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Affiliation(s)
- Fuzhou Ye
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College London, South Kensington SW7 2AZ, UK
| | - Forson Gao
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College London, South Kensington SW7 2AZ, UK
| | - Xiaojiao Liu
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College London, South Kensington SW7 2AZ, UK
| | - Martin Buck
- Department of Life Sciences, Imperial College London, South Kensington SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College London, South Kensington SW7 2AZ, UK
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3
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Kozlova MI, Shalaeva DN, Dibrova DV, Mulkidjanian AY. Common Mechanism of Activated Catalysis in P-loop Fold Nucleoside Triphosphatases-United in Diversity. Biomolecules 2022; 12:1346. [PMID: 36291556 PMCID: PMC9599734 DOI: 10.3390/biom12101346] [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: 07/09/2022] [Revised: 08/20/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
To clarify the obscure hydrolysis mechanism of ubiquitous P-loop-fold nucleoside triphosphatases (Walker NTPases), we analysed the structures of 3136 catalytic sites with bound Mg-NTP complexes or their analogues. Our results are presented in two articles; here, in the second of them, we elucidated whether the Walker A and Walker B sequence motifs-common to all P-loop NTPases-could be directly involved in catalysis. We found that the hydrogen bonds (H-bonds) between the strictly conserved, Mg-coordinating Ser/Thr of the Walker A motif ([Ser/Thr]WA) and aspartate of the Walker B motif (AspWB) are particularly short (even as short as 2.4 ångströms) in the structures with bound transition state (TS) analogues. Given that a short H-bond implies parity in the pKa values of the H-bond partners, we suggest that, in response to the interactions of a P-loop NTPase with its cognate activating partner, a proton relocates from [Ser/Thr]WA to AspWB. The resulting anionic [Ser/Thr]WA alkoxide withdraws a proton from the catalytic water molecule, and the nascent hydroxyl attacks the gamma phosphate of NTP. When the gamma-phosphate breaks away, the trapped proton at AspWB passes by the Grotthuss relay via [Ser/Thr]WA to beta-phosphate and compensates for its developing negative charge that is thought to be responsible for the activation barrier of hydrolysis.
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Affiliation(s)
- Maria I. Kozlova
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
| | - Daria N. Shalaeva
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
| | - Daria V. Dibrova
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
| | - Armen Y. Mulkidjanian
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
- Center of Cellular Nanoanalytics, Osnabrueck University, D-49069 Osnabrueck, Germany
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4
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Kozlova MI, Shalaeva DN, Dibrova DV, Mulkidjanian AY. Common Patterns of Hydrolysis Initiation in P-loop Fold Nucleoside Triphosphatases. Biomolecules 2022; 12:1345. [PMID: 36291554 PMCID: PMC9599529 DOI: 10.3390/biom12101345] [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: 07/09/2022] [Revised: 08/20/2022] [Accepted: 09/14/2022] [Indexed: 11/24/2022] Open
Abstract
The P-loop fold nucleoside triphosphate (NTP) hydrolases (also known as Walker NTPases) function as ATPases, GTPases, and ATP synthases, are often of medical importance, and represent one of the largest and evolutionarily oldest families of enzymes. There is still no consensus on their catalytic mechanism. To clarify this, we performed the first comparative structural analysis of more than 3100 structures of P-loop NTPases that contain bound substrate Mg-NTPs or their analogues. We proceeded on the assumption that structural features common to these P-loop NTPases may be essential for catalysis. Our results are presented in two articles. Here, in the first, we consider the structural elements that stimulate hydrolysis. Upon interaction of P-loop NTPases with their cognate activating partners (RNA/DNA/protein domains), specific stimulatory moieties, usually Arg or Lys residues, are inserted into the catalytic site and initiate the cleavage of gamma phosphate. By analyzing a plethora of structures, we found that the only shared feature was the mechanistic interaction of stimulators with the oxygen atoms of gamma-phosphate group, capable of causing its rotation. One of the oxygen atoms of gamma phosphate coordinates the cofactor Mg ion. The rotation must pull this oxygen atom away from the Mg ion. This rearrangement should affect the properties of the other Mg ligands and may initiate hydrolysis according to the mechanism elaborated in the second article.
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Affiliation(s)
- Maria I. Kozlova
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
| | - Daria N. Shalaeva
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
| | - Daria V. Dibrova
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
| | - Armen Y. Mulkidjanian
- School of Physics, Osnabrueck University, D-49069 Osnabrueck, Germany
- Center of Cellular Nanoanalytics, Osnabrueck University, D-49069 Osnabrueck, Germany
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5
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Bacterial Enhancer Binding Proteins-AAA + Proteins in Transcription Activation. Biomolecules 2020; 10:biom10030351. [PMID: 32106553 PMCID: PMC7175178 DOI: 10.3390/biom10030351] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/12/2020] [Accepted: 02/20/2020] [Indexed: 01/24/2023] Open
Abstract
Bacterial enhancer-binding proteins (bEBPs) are specialised transcriptional activators. bEBPs are hexameric AAA+ ATPases and use ATPase activities to remodel RNA polymerase (RNAP) complexes that contain the major variant sigma factor, σ54 to convert the initial closed complex to the transcription competent open complex. Earlier crystal structures of AAA+ domains alone have led to proposals of how nucleotide-bound states are sensed and propagated to substrate interactions. Recently, the structure of the AAA+ domain of a bEBP bound to RNAP-σ54-promoter DNA was revealed. Together with structures of the closed complex, an intermediate state where DNA is partially loaded into the RNAP cleft and the open promoter complex, a mechanistic understanding of how bEBPs use ATP to activate transcription can now be proposed. This review summarises current structural models and the emerging understanding of how this special class of AAA+ proteins utilises ATPase activities to allow σ54-dependent transcription initiation.
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6
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Danson AE, Jovanovic M, Buck M, Zhang X. Mechanisms of σ 54-Dependent Transcription Initiation and Regulation. J Mol Biol 2019; 431:3960-3974. [PMID: 31029702 PMCID: PMC7057263 DOI: 10.1016/j.jmb.2019.04.022] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 02/02/2023]
Abstract
Cellular RNA polymerase is a multi-subunit macromolecular assembly responsible for gene transcription, a highly regulated process conserved from bacteria to humans. In bacteria, sigma factors are employed to mediate gene-specific expression in response to a variety of environmental conditions. The major variant σ factor, σ54, has a specific role in stress responses. Unlike σ70-dependent transcription, which often can spontaneously proceed to initiation, σ54-dependent transcription requires an additional ATPase protein for activation. As a result, structures of a number of distinct functional states during the dynamic process of transcription initiation have been captured using the σ54 system with both x-ray crystallography and cryo electron microscopy, furthering our understanding of σ54-dependent transcription initiation and DNA opening. Comparisons with σ70 and eukaryotic polymerases reveal unique and common features during transcription initiation.
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Affiliation(s)
- Amy E Danson
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Milija Jovanovic
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Martin Buck
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK.
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7
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Boël G, Danot O, de Lorenzo V, Danchin A. Omnipresent Maxwell's demons orchestrate information management in living cells. Microb Biotechnol 2019; 12:210-242. [PMID: 30806035 PMCID: PMC6389857 DOI: 10.1111/1751-7915.13378] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The development of synthetic biology calls for accurate understanding of the critical functions that allow construction and operation of a living cell. Besides coding for ubiquitous structures, minimal genomes encode a wealth of functions that dissipate energy in an unanticipated way. Analysis of these functions shows that they are meant to manage information under conditions when discrimination of substrates in a noisy background is preferred over a simple recognition process. We show here that many of these functions, including transporters and the ribosome construction machinery, behave as would behave a material implementation of the information-managing agent theorized by Maxwell almost 150 years ago and commonly known as Maxwell's demon (MxD). A core gene set encoding these functions belongs to the minimal genome required to allow the construction of an autonomous cell. These MxDs allow the cell to perform computations in an energy-efficient way that is vastly better than our contemporary computers.
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Affiliation(s)
- Grégory Boël
- UMR 8261 CNRS‐University Paris DiderotInstitut de Biologie Physico‐Chimique13 rue Pierre et Marie Curie75005ParisFrance
| | - Olivier Danot
- Institut Pasteur25‐28 rue du Docteur Roux75724Paris Cedex 15France
| | - Victor de Lorenzo
- Molecular Environmental Microbiology LaboratorySystems Biology ProgrammeCentro Nacional de BiotecnologiaC/Darwin n° 3, Campus de Cantoblanco28049MadridEspaña
| | - Antoine Danchin
- Institute of Cardiometabolism and NutritionHôpital de la Pitié‐Salpêtrière47 Boulevard de l'Hôpital75013ParisFrance
- The School of Biomedical SciencesLi Kashing Faculty of MedicineHong Kong University21, Sassoon RoadPokfulamSAR Hong Kong
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8
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Abstract
Transcription initiation is highly regulated in bacterial cells, allowing adaptive gene regulation in response to environment cues. One class of promoter specificity factor called sigma54 enables such adaptive gene expression through its ability to lock the RNA polymerase down into a state unable to melt out promoter DNA for transcription initiation. Promoter DNA opening then occurs through the action of specialized transcription control proteins called bacterial enhancer-binding proteins (bEBPs) that remodel the sigma54 factor within the closed promoter complexes. The remodelling of sigma54 occurs through an ATP-binding and hydrolysis reaction carried out by the bEBPs. The regulation of bEBP self-assembly into typically homomeric hexamers allows regulated gene expression since the self-assembly is required for bEBP ATPase activity and its direct engagement with the sigma54 factor during the remodelling reaction. Crystallographic studies have now established that in the closed promoter complex, the sigma54 factor occupies the bacterial RNA polymerase in ways that will physically impede promoter DNA opening and the loading of melted out promoter DNA into the DNA-binding clefts of the RNA polymerase. Large-scale structural re-organizations of sigma54 require contact of the bEBP with an amino-terminal glutamine and leucine-rich sequence of sigma54, and lead to domain movements within the core RNA polymerase necessary for making open promoter complexes and synthesizing the nascent RNA transcript.
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9
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Structures of RNA Polymerase Closed and Intermediate Complexes Reveal Mechanisms of DNA Opening and Transcription Initiation. Mol Cell 2017; 67:106-116.e4. [PMID: 28579332 PMCID: PMC5505868 DOI: 10.1016/j.molcel.2017.05.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/29/2017] [Accepted: 05/05/2017] [Indexed: 01/25/2023]
Abstract
Gene transcription is carried out by RNA polymerases (RNAPs). For transcription to occur, the closed promoter complex (RPc), where DNA is double stranded, must isomerize into an open promoter complex (RPo), where the DNA is melted out into a transcription bubble and the single-stranded template DNA is delivered to the RNAP active site. Using a bacterial RNAP containing the alternative σ54 factor and cryoelectron microscopy, we determined structures of RPc and the activator-bound intermediate complex en route to RPo at 3.8 and 5.8 Å. Our structures show how RNAP-σ54 interacts with promoter DNA to initiate the DNA distortions required for transcription bubble formation, and how the activator interacts with RPc, leading to significant conformational changes in RNAP and σ54 that promote RPo formation. We propose that DNA melting is an active process initiated in RPc and that the RNAP conformations of intermediates are significantly different from that of RPc and RPo. RNA polymerase closed complex (RPc) structure reveals DNA distortions by σ Intermediate complex (RPi) structure reveals the roles of AAA activator DNA distortion and opening are initiated in RPc and RPi before entering the RNAP RNAP conformation in RPi is significantly different from closed or open complex
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10
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Crystal structure of Aquifex aeolicus σ N bound to promoter DNA and the structure of σ N-holoenzyme. Proc Natl Acad Sci U S A 2017; 114:E1805-E1814. [PMID: 28223493 DOI: 10.1073/pnas.1619464114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bacterial σ factors confer promoter specificity to the RNA polymerase (RNAP). One alternative σ factor, σN, is unique in its structure and functional mechanism, forming transcriptionally inactive promoter complexes that require activation by specialized AAA+ ATPases. We report a 3.4-Å resolution X-ray crystal structure of a σN fragment in complex with its cognate promoter DNA, revealing the molecular details of promoter recognition by σN The structure allowed us to build and refine an improved σN-holoenzyme model based on previously published 3.8-Å resolution X-ray data. The improved σN-holoenzyme model reveals a conserved interdomain interface within σN that, when disrupted by mutations, leads to transcription activity without activator intervention (so-called bypass mutants). Thus, the structure and stability of this interdomain interface are crucial for the role of σN in blocking transcription activity and in maintaining the activator sensitivity of σN.
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11
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Siegel AR, Wemmer DE. Role of the σ 54 Activator Interacting Domain in Bacterial Transcription Initiation. J Mol Biol 2016; 428:4669-4685. [PMID: 27732872 DOI: 10.1016/j.jmb.2016.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/03/2016] [Accepted: 10/04/2016] [Indexed: 01/05/2023]
Abstract
Bacterial sigma factors are subunits of RNA polymerase that direct the holoenzyme to specific sets of promoters in the genome and are a central element of regulating transcription. Most polymerase holoenzymes open the promoter and initiate transcription rapidly after binding. However, polymerase containing the members of the σ54 family must be acted on by a transcriptional activator before DNA opening and initiation occur. A key domain in these transcriptional activators forms a hexameric AAA+ ATPase that acts through conformational changes brought on by ATP hydrolysis. Contacts between the transcriptional activator and σ54 are primarily made through an N-terminal σ54 activator interacting domain (AID). To better understand this mechanism of bacterial transcription initiation, we characterized the σ54 AID by NMR spectroscopy and other biophysical methods and show that it is an intrinsically disordered domain in σ54 alone. We identified a minimal construct of the Aquifex aeolicus σ54 AID that consists of two predicted helices and retains native-like binding affinity for the transcriptional activator NtrC1. Using the NtrC1 ATPase domain, bound with the non-hydrolyzable ATP analog ADP-beryllium fluoride, we studied the NtrC1-σ54 AID complex using NMR spectroscopy. We show that the σ54 AID becomes structured after associating with the core loops of the transcriptional activators in their ATP state and that the primary site of the interaction is the first predicted helix. Understanding this complex, formed as the first step toward initiation, will help unravel the mechanism of σ54 bacterial transcription initiation.
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Affiliation(s)
- Alexander R Siegel
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
| | - David E Wemmer
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA; Department of Chemistry, University of California, Berkeley, CA 94720, USA.
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12
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Zhang N, Jovanovic G, McDonald C, Ces O, Zhang X, Buck M. Transcription Regulation and Membrane Stress Management in Enterobacterial Pathogens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 915:207-30. [DOI: 10.1007/978-3-319-32189-9_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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13
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Lundgren BR, Connolly MP, Choudhary P, Brookins-Little TS, Chatterjee S, Raina R, Nomura CT. Defining the Metabolic Functions and Roles in Virulence of the rpoN1 and rpoN2 Genes in Ralstonia solanacearum GMI1000. PLoS One 2015; 10:e0144852. [PMID: 26659655 PMCID: PMC4676750 DOI: 10.1371/journal.pone.0144852] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 11/24/2015] [Indexed: 11/18/2022] Open
Abstract
The alternative sigma factor RpoN is a unique regulator found among bacteria. It controls numerous processes that range from basic metabolism to more complex functions such as motility and nitrogen fixation. Our current understanding of RpoN function is largely derived from studies on prototypical bacteria such as Escherichia coli. Bacillus subtilis and Pseudomonas putida. Although the extent and necessity of RpoN-dependent functions differ radically between these model organisms, each bacterium depends on a single chromosomal rpoN gene to meet the cellular demands of RpoN regulation. The bacterium Ralstonia solanacearum is often recognized for being the causative agent of wilt disease in crops, including banana, peanut and potato. However, this plant pathogen is also one of the few bacterial species whose genome possesses dual rpoN genes. To determine if the rpoN genes in this bacterium are genetically redundant and interchangeable, we constructed and characterized ΔrpoN1, ΔrpoN2 and ΔrpoN1 ΔrpoN2 mutants of R. solanacearum GMI1000. It was found that growth on a small range of metabolites, including dicarboxylates, ethanol, nitrate, ornithine, proline and xanthine, were dependent on only the rpoN1 gene. Furthermore, the rpoN1 gene was required for wilt disease on tomato whereas rpoN2 had no observable role in virulence or metabolism in R. solanacearum GMI1000. Interestingly, plasmid-based expression of rpoN2 did not fully rescue the metabolic deficiencies of the ΔrpoN1 mutants; full recovery was specific to rpoN1. In comparison, only rpoN2 was able to genetically complement a ΔrpoN E. coli mutant. These results demonstrate that the RpoN1 and RpoN2 proteins are not functionally equivalent or interchangeable in R. solanacearum GMI1000.
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Affiliation(s)
- Benjamin R. Lundgren
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
| | - Morgan P. Connolly
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
| | - Pratibha Choudhary
- Department of Biology, Syracuse University, Syracuse, New York, United States of America
| | - Tiffany S. Brookins-Little
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
| | - Snigdha Chatterjee
- Department of Biology, Syracuse University, Syracuse, New York, United States of America
| | - Ramesh Raina
- Department of Biology, Syracuse University, Syracuse, New York, United States of America
| | - Christopher T. Nomura
- Department of Chemistry, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
- Center for Applied Microbiology, State University of New York–College of Environmental Science and Forestry, Syracuse, New York, United States of America
- * E-mail:
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14
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Zhang N, Schäfer J, Sharma A, Rayner L, Zhang X, Tuma R, Stockley P, Buck M. Mutations in RNA Polymerase Bridge Helix and Switch Regions Affect Active-Site Networks and Transcript-Assisted Hydrolysis. J Mol Biol 2015; 427:3516-3526. [PMID: 26365052 PMCID: PMC4641871 DOI: 10.1016/j.jmb.2015.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 09/02/2015] [Accepted: 09/03/2015] [Indexed: 11/21/2022]
Abstract
In bacterial RNA polymerase (RNAP), the bridge helix and switch regions form an intricate network with the catalytic active centre and the main channel. These interactions are important for catalysis, hydrolysis and clamp domain movement. By targeting conserved residues in Escherichia coli RNAP, we are able to show that functions of these regions are differentially required during σ70-dependent and the contrasting σ54-dependent transcription activations and thus potentially underlie the key mechanistic differences between the two transcription paradigms. We further demonstrate that the transcription factor DksA directly regulates σ54-dependent activation both positively and negatively. This finding is consistent with the observed impacts of DksA on σ70-dependent promoters. DksA does not seem to significantly affect RNAP binding to a pre-melted promoter DNA but affects extensively activity at the stage of initial RNA synthesis on σ54-regulated promoters. Strikingly, removal of the σ54 Region I is sufficient to invert the action of DksA (from stimulation to inhibition or vice versa) at two test promoters. The RNAP mutants we generated also show a strong propensity to backtrack. These mutants increase the rate of transcript-hydrolysis cleavage to a level comparable to that seen in the Thermus aquaticus RNAP even in the absence of a non-complementary nucleotide. These novel phenotypes imply an important function of the bridge helix and switch regions as an anti-backtracking ratchet and an RNA hydrolysis regulator. The bridge helix and switch regions form an intricate network in RNAP. The σ70 and σ54 transcription systems differentially use this interaction network. Transcription factor DksA and σ54 Region I also contribute to this network. Disruption of this network enhances backtracking and intrinsic RNA hydrolysis.
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Affiliation(s)
- Nan Zhang
- Division of Cell and Molecular Biology, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, United Kingdom.
| | - Jorrit Schäfer
- Division of Cell and Molecular Biology, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Amit Sharma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Lucy Rayner
- Division of Cell and Molecular Biology, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Xiaodong Zhang
- Division of Macromolecular Structure and Function, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Peter Stockley
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Martin Buck
- Division of Cell and Molecular Biology, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, United Kingdom.
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15
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Osadnik H, Schöpfel M, Heidrich E, Mehner D, Lilie H, Parthier C, Risselada HJ, Grubmüller H, Stubbs MT, Brüser T. PspF-binding domain PspA1-144and the PspA·F complex: New insights into the coiled-coil-dependent regulation of AAA+ proteins. Mol Microbiol 2015; 98:743-59. [DOI: 10.1111/mmi.13154] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2015] [Indexed: 02/05/2023]
Affiliation(s)
- Hendrik Osadnik
- Institute of Microbiology; Leibniz Universität Hannover; Herrenhäuser Str. 2 Hannover 30419 Germany
| | - Michael Schöpfel
- Institute of Biochemistry and Biotechnology; Martin-Luther University Halle-Wittenberg; Kurt-Mothes-Straße 3 Halle (Saale) 06120 Germany
| | - Eyleen Heidrich
- Institute of Microbiology; Leibniz Universität Hannover; Herrenhäuser Str. 2 Hannover 30419 Germany
| | - Denise Mehner
- Institute of Microbiology; Leibniz Universität Hannover; Herrenhäuser Str. 2 Hannover 30419 Germany
| | - Hauke Lilie
- Institute of Biochemistry and Biotechnology; Martin-Luther University Halle-Wittenberg; Kurt-Mothes-Straße 3 Halle (Saale) 06120 Germany
| | - Christoph Parthier
- Institute of Biochemistry and Biotechnology; Martin-Luther University Halle-Wittenberg; Kurt-Mothes-Straße 3 Halle (Saale) 06120 Germany
| | - H. Jelger Risselada
- Max Planck Institute for Biophysical Chemistry; Am Fassberg 11 Göttingen 37077 Germany
| | - Helmut Grubmüller
- Max Planck Institute for Biophysical Chemistry; Am Fassberg 11 Göttingen 37077 Germany
| | - Milton T. Stubbs
- Institute of Biochemistry and Biotechnology; Martin-Luther University Halle-Wittenberg; Kurt-Mothes-Straße 3 Halle (Saale) 06120 Germany
| | - Thomas Brüser
- Institute of Microbiology; Leibniz Universität Hannover; Herrenhäuser Str. 2 Hannover 30419 Germany
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16
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Schaefer J, Engl C, Zhang N, Lawton E, Buck M. Genome wide interactions of wild-type and activator bypass forms of σ54. Nucleic Acids Res 2015; 43:7280-91. [PMID: 26082500 PMCID: PMC4551910 DOI: 10.1093/nar/gkv597] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/25/2015] [Indexed: 01/05/2023] Open
Abstract
Enhancer-dependent transcription involving the promoter specificity factor σ54 is widely distributed amongst bacteria and commonly associated with cell envelope function. For transcription initiation, σ54-RNA polymerase yields open promoter complexes through its remodelling by cognate AAA+ ATPase activators. Since activators can be bypassed in vitro, bypass transcription in vivo could be a source of emergent gene expression along evolutionary pathways yielding new control networks and transcription patterns. At a single test promoter in vivo bypass transcription was not observed. We now use genome-wide transcription profiling, genome-wide mutagenesis and gene over-expression strategies in Escherichia coli, to (i) scope the range of bypass transcription in vivo and (ii) identify genes which might alter bypass transcription in vivo. We find little evidence for pervasive bypass transcription in vivo with only a small subset of σ54 promoters functioning without activators. Results also suggest no one gene limits bypass transcription in vivo, arguing bypass transcription is strongly kept in check. Promoter sequences subject to repression by σ54 were evident, indicating loss of rpoN (encoding σ54) rather than creating rpoN bypass alleles would be one evolutionary route for new gene expression patterns. Finally, cold-shock promoters showed unusual σ54-dependence in vivo not readily correlated with conventional σ54 binding-sites.
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Affiliation(s)
- Jorrit Schaefer
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Christoph Engl
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK Institute for Global Food Security, Queen's University Belfast, Belfast BT9 5BN, UK
| | - Nan Zhang
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Edward Lawton
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Martin Buck
- Faculty of Natural Sciences, Division of Cell & Molecular Biology, Imperial College London, London SW7 2AZ, UK
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17
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Rifampicin-resistance, rpoB polymorphism and RNA polymerase genetic engineering. J Biotechnol 2015; 202:60-77. [DOI: 10.1016/j.jbiotec.2014.11.024] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/22/2014] [Accepted: 11/26/2014] [Indexed: 01/22/2023]
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18
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Han H, Monroe N, Votteler J, Shakya B, Sundquist WI, Hill CP. Binding of Substrates to the Central Pore of the Vps4 ATPase Is Autoinhibited by the Microtubule Interacting and Trafficking (MIT) Domain and Activated by MIT Interacting Motifs (MIMs). J Biol Chem 2015; 290:13490-9. [PMID: 25833946 DOI: 10.1074/jbc.m115.642355] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Indexed: 12/21/2022] Open
Abstract
The endosomal sorting complexes required for transport (ESCRT) pathway drives reverse topology membrane fission events within multiple cellular pathways, including cytokinesis, multivesicular body biogenesis, repair of the plasma membrane, nuclear membrane vesicle formation, and HIV budding. The AAA ATPase Vps4 is recruited to membrane necks shortly before fission, where it catalyzes disassembly of the ESCRT-III lattice. The N-terminal Vps4 microtubule-interacting and trafficking (MIT) domains initially bind the C-terminal MIT-interacting motifs (MIMs) of ESCRT-III subunits, but it is unclear how the enzyme then remodels these substrates in response to ATP hydrolysis. Here, we report quantitative binding studies that demonstrate that residues from helix 5 of the Vps2p subunit of ESCRT-III bind to the central pore of an asymmetric Vps4p hexamer in a manner that is dependent upon the presence of flexible nucleotide analogs that can mimic multiple states in the ATP hydrolysis cycle. We also find that substrate engagement is autoinhibited by the Vps4p MIT domain and that this inhibition is relieved by binding of either Type 1 or Type 2 MIM elements, which bind the Vps4p MIT domain through different interfaces. These observations support the model that Vps4 substrates are initially recruited by an MIM-MIT interaction that activates the Vps4 central pore to engage substrates and generate force, thereby triggering ESCRT-III disassembly.
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Affiliation(s)
- Han Han
- From the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Nicole Monroe
- From the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Jörg Votteler
- From the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Binita Shakya
- From the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Wesley I Sundquist
- From the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Christopher P Hill
- From the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
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19
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Schmidt H. Dynein motors: How AAA+ ring opening and closing coordinates microtubule binding and linker movement. Bioessays 2015; 37:532-43. [DOI: 10.1002/bies.201400215] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Helgo Schmidt
- Medical Research Council Laboratory of Molecular Biology; Division of Structural Studies; Cambridge UK
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20
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Darbari VC, Lawton E, Lu D, Burrows PC, Wiesler S, Joly N, Zhang N, Zhang X, Buck M. Molecular basis of nucleotide-dependent substrate engagement and remodeling by an AAA+ activator. Nucleic Acids Res 2014; 42:9249-61. [PMID: 25063294 PMCID: PMC4132715 DOI: 10.1093/nar/gku588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Binding and hydrolysis of ATP is universally required by AAA+ proteins to underpin their mechano-chemical work. Here we explore the roles of the ATPase site in an AAA+ transcriptional activator protein, the phage shock protein F (PspF), by specifically altering the Walker B motif sequence required in catalyzing ATP hydrolysis. One such mutant, the E108Q variant, is defective in ATP hydrolysis but fully remodels target transcription complexes, the RNAP-σ54 holoenzyme, in an ATP dependent manner. Structural analysis of the E108Q variant reveals that unlike wild-type protein, which has distinct conformations for E108 residue in the ATP and ADP bound forms, E108Q adapts the same conformation irrespective of nucleotide bound. Our data show that the remodeling activities of E108Q are strongly favored on pre-melted DNA and engagement with RNAP-σ54 using ATP binding can be sufficient to convert the inactive holoenzyme to an active form, while hydrolysis per se is required for nucleic acid remodeling that leads to transcription bubble formation. Furthermore, using linked dimer constructs, we show that RNAP-σ54 engagement by adjacent subunits within a hexamer are required for this protein remodeling activity while DNA remodeling activity can tolerate defective ATP hydrolysis of alternating subunits.
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Affiliation(s)
- Vidya C Darbari
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Ed Lawton
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Duo Lu
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Patricia C Burrows
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Simone Wiesler
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Nicolas Joly
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Nan Zhang
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Xiaodong Zhang
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Martin Buck
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
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21
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Sharma A, Leach RN, Gell C, Zhang N, Burrows PC, Shepherd DA, Wigneshweraraj S, Smith DA, Zhang X, Buck M, Stockley PG, Tuma R. Domain movements of the enhancer-dependent sigma factor drive DNA delivery into the RNA polymerase active site: insights from single molecule studies. Nucleic Acids Res 2014; 42:5177-90. [PMID: 24553251 PMCID: PMC4005640 DOI: 10.1093/nar/gku146] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recognition of bacterial promoters is regulated by two distinct classes of sequence-specific sigma factors, σ70 or σ54, that differ both in their primary sequence and in the requirement of the latter for activation via enhancer-bound upstream activators. The σ54 version controls gene expression in response to stress, often mediating pathogenicity. Its activator proteins are members of the AAA+ superfamily and use adenosine triphosphate (ATP) hydrolysis to remodel initially auto-inhibited holoenzyme promoter complexes. We have mapped this remodeling using single-molecule fluorescence spectroscopy. Initial remodeling is nucleotide-independent and driven by binding both ssDNA during promoter melting and activator. However, DNA loading into the RNA polymerase active site depends on co-operative ATP hydrolysis by the activator. Although the coupled promoter recognition and melting steps may be conserved between σ70 and σ54, the domain movements of the latter have evolved to require an activator ATPase.
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Affiliation(s)
- Amit Sharma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Robert N. Leach
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Christopher Gell
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Nan Zhang
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Patricia C. Burrows
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Dale A. Shepherd
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Sivaramesh Wigneshweraraj
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - David Alastair Smith
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Xiaodong Zhang
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Martin Buck
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
| | - Peter G. Stockley
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
- *To whom correspondence should be addressed. Tel: +44 1133 433092; Fax: +44 1133 437897;
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK, Department of Life Sciences, Sir Alexander Fleming Building, Imperial College, London SW72AZ, UK and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
- Correspondence may also be addressed to Roman Tuma. Tel: +44 1133 433080; Fax: +44 1133 437897;
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22
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Zhang YT, Jiang F, Tian ZX, Huo YX, Sun YC, Wang YP. CRP-cyclic AMP dependent inhibition of the xylene-responsive σ(54)-promoter Pu in Escherichia coli. PLoS One 2014; 9:e86727. [PMID: 24466213 PMCID: PMC3900584 DOI: 10.1371/journal.pone.0086727] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
The expression of σ(54)-dependent Pseudomonas putida Pu promoter is activated by XylR activator when cells are exposed to a variety of aromatic inducers. In this study, the transcriptional activation of the P. putida Pu promoter was recreated in the heterologous host Escherichia coli. Here we show that the cAMP receptor protein (CRP), a well-known carbon utilization regulator, had an inhibitory effect on the expression of Pu promoter in a cAMP-dependent manner. The inhibitory effect was not activator specific. In vivo KMnO4 and DMS footprinting analysis indicated that CRP-cAMP poised the RNA polymerase at Pu promoter, inhibiting the isomerization step of the transcription initiation even in the presence of an activator. Therefore, the presence of PTS-sugar, which eliminates cAMP, could activate the poised RNA polymerase at Pu promoter to transcribe. Moreover, the activation region 1 (AR1) of CRP, which interacts directly with the αCTD (C-terminal domain of α-subunit) of RNA polymerase, was found essential for the CRP-mediated inhibition at Pu promoter. A model for the above observations is discussed.
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Affiliation(s)
- Yuan-Tao Zhang
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
| | - Feng Jiang
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
- Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zhe-Xian Tian
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
| | - Yi-Xin Huo
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
| | - Yi-Cheng Sun
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
- Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, China
- * E-mail:
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23
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Determination of the self-association residues within a homomeric and a heteromeric AAA+ enhancer binding protein. J Mol Biol 2014; 426:1692-710. [PMID: 24434682 DOI: 10.1016/j.jmb.2014.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/17/2013] [Accepted: 01/06/2014] [Indexed: 11/24/2022]
Abstract
The σ(54)-dependent transcription in bacteria requires specific activator proteins, bacterial enhancer binding protein (bEBP), members of the AAA+ (ATPases Associated with various cellular Activities) protein family. The bEBPs usually form oligomers in order to hydrolyze ATP and make open promoter complexes. The bEBP formed by HrpR and HrpS activates transcription from the σ(54)-dependent hrpL promoter responsible for triggering the Type Three Secretion System in Pseudomonas syringae pathovars. Unlike other bEBPs that usually act as homohexamers, HrpR and HrpS operate as a highly co-dependent heterohexameric complex. To understand the organization of the HrpRS complex and the HrpR and HrpS strict co-dependence, we have analyzed the interface between subunits using the random and directed mutagenesis and available crystal structures of several closely related bEBPs. We identified key residues required for the self-association of HrpR (D32, E202 and K235) with HrpS (D32, E200 and K233), showed that the HrpR D32 and HrpS K233 residues form interacting pairs directly involved in an HrpR-HrpS association and that the change in side-chain length at position 233 in HrpS affects self-association and interaction with the HrpR and demonstrated that the HrpS D32, E200 and K233 are not involved in negative regulation imposed by HrpV. We established that the equivalent residues K30, E200 and E234 in a homo-oligomeric bEBP, PspF, are required for the subunit communication and formation of an oligomeric lock that cooperates with the ATP γ-phosphate sensing PspF residue R227, providing insights into their roles in the heteromeric HrpRS co-complex.
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24
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Sysoeva TA, Yennawar N, Allaire M, Nixon BT. Crystallization and preliminary X-ray analysis of the ATPase domain of the σ(54)-dependent transcription activator NtrC1 from Aquifex aeolicus bound to the ATP analog ADP-BeFx. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1384-8. [PMID: 24316836 PMCID: PMC3855726 DOI: 10.1107/s174430911302976x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 10/30/2013] [Indexed: 11/10/2022]
Abstract
One way that bacteria regulate the transcription of specific genes to adapt to environmental challenges is to use different σ factors that direct the RNA polymerase holoenzyme to distinct promoters. Unlike σ(70) RNA polymerase (RNAP), σ(54) RNAP is unable to initiate transcription without an activator: enhancer-binding protein (EBP). All EBPs contain one ATPase domain that belongs to the family of ATPases associated with various cellular activities (AAA+ ATPases). AAA+ ATPases use the energy of ATP hydrolysis to remodel different target macromolecules to perform distinct functions. These mechanochemical enzymes are known to form ring-shaped oligomers whose conformations strongly depend upon nucleotide status. Here, the crystallization of the AAA+ ATPase domain of an EBP from Aquifex aeolicus, NtrC1, in the presence of the non-hydrolyzable ATP analog ADP-BeFx is reported. X-ray diffraction data were collected from two crystals from two different protein fractions of the NtrC1 ATPase domain. Previously, this domain was co-crystallized with ADP and ATP, but the latter crystals were grown from the Walker B substitution variant E239A. Therefore, the new data sets are the first for a wild-type EBP ATPase domain co-crystallized with an ATP analog and they reveal a new crystal form. The resulting structure(s) will shed light on the mechanism of EBP-type transcription activators.
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Affiliation(s)
- Tatyana A. Sysoeva
- Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA
| | - Neela Yennawar
- Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA
| | - Marc Allaire
- NLSL, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - B. Tracy Nixon
- Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA
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25
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Zhang N, Gordiyenko Y, Joly N, Lawton E, Robinson CV, Buck M. Subunit dynamics and nucleotide-dependent asymmetry of an AAA(+) transcription complex. J Mol Biol 2013; 426:71-83. [PMID: 24055699 DOI: 10.1016/j.jmb.2013.08.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/21/2013] [Accepted: 08/24/2013] [Indexed: 01/22/2023]
Abstract
Bacterial enhancer binding proteins (bEBPs) are transcription activators that belong to the AAA(+) protein family. They form higher-order self-assemblies to regulate transcription initiation at stress response and pathogenic promoters. The precise mechanism by which these ATPases utilize ATP binding and hydrolysis energy to remodel their substrates remains unclear. Here we employed mass spectrometry of intact complexes to investigate subunit dynamics and nucleotide occupancy of the AAA(+) domain of one well-studied bEBP in complex with its substrate, the σ(54) subunit of RNA polymerase. Our results demonstrate that the free AAA(+) domain undergoes significant changes in oligomeric states and nucleotide occupancy upon σ(54) binding. Such changes likely correlate with one transition state of ATP and are associated with an open spiral ring formation that is vital for asymmetric subunit function and interface communication. We confirmed that the asymmetric subunit functionality persists for open promoter complex formation using single-chain forms of bEBP lacking the full complement of intact ATP hydrolysis sites. Outcomes reconcile low- and high-resolution structures and yield a partial sequential ATP hydrolysis model for bEBPs.
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Affiliation(s)
- Nan Zhang
- Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
| | - Yuliya Gordiyenko
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Nicolas Joly
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Batiment Buffon, 15 rue Helene Brion, 75205 Paris Cedex 13, France
| | - Edward Lawton
- Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London SW7 2AZ, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, UK.
| | - Martin Buck
- Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
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26
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A key hydrophobic patch identified in an AAA⁺ protein essential for its in trans inhibitory regulation. J Mol Biol 2013; 425:2656-69. [PMID: 23659791 PMCID: PMC3791423 DOI: 10.1016/j.jmb.2013.04.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/11/2013] [Accepted: 04/20/2013] [Indexed: 11/22/2022]
Abstract
Bacterial enhancer binding proteins (bEBPs) are a subclass of the AAA+ (ATPases Associated with various cellular Activities) protein family. They are responsible for σ54-dependent transcription activation during infection and function under many stressful growth conditions. The majority of bEBPs are regulated in their formation of ring-shaped hexameric self-assemblies via an amino-terminal domain through its phosphorylation or ligand binding. In contrast, the Escherichia coli phage shock protein F (PspF) is negatively regulated in trans by phage shock protein A (PspA). Up to six PspA subunits suppress PspF hexamer action. Here, we present biochemical evidence that PspA engages across the side of a PspF hexameric ring. We identify three key binding determinants located in a surface-exposed ‘W56 loop’ of PspF, which form a tightly packed hydrophobic cluster, the ‘YLW’ patch. We demonstrate the profound impact of the PspF W56 loop residues on ATP hydrolysis, the σ54 binding loop 1, and the self-association interface. We infer from single-chain studies that for complete PspF inhibition to occur, more than three PspA subunits need to bind a PspF hexamer with at least two binding to adjacent PspF subunits. By structural modelling, we propose that PspA binds to PspF via its first two helical domains. After PspF binding-induced conformational changes, PspA may then share structural similarities with a bEBP regulatory domain. What is the mechanism of in trans inhibition of oligomeric self-assemblies? Inhibitor initially docks on the AAA+ domain at a hydrophobic patch. Consequently, ATPase and self-association of the AAA+ domain are altered. Inhibitor’s structure mimics the evolutionarily divergent in cis regulatory domain. In trans inhibition of oligomeric AAA+ domains requires multiple contacts.
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27
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Wiesler SC, Weinzierl ROJ, Buck M. An aromatic residue switch in enhancer-dependent bacterial RNA polymerase controls transcription intermediate complex activity. Nucleic Acids Res 2013; 41:5874-86. [PMID: 23609536 PMCID: PMC3675486 DOI: 10.1093/nar/gkt271] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The formation of the open promoter complex (RPo) in which the melted DNA containing the transcription start site is located at the RNA polymerase (RNAP) catalytic centre is an obligatory step in the transcription of DNA into RNA catalyzed by RNAP. In the RPo, an extensive network of interactions is established between DNA, RNAP and the σ-factor and the formation of functional RPo occurs via a series of transcriptional intermediates (collectively 'RPi'). A single tryptophan is ideally positioned to directly engage with the flipped out base of the non-template strand at the +1 site. Evidence suggests that this tryptophan (i) is involved in either forward translocation or DNA scrunching and (ii) in σ(54)-regulated promoters limits the transcription activity of at least one intermediate complex (RPi) before the formation of a fully functional RPo. Limiting RPi activity may be important in preventing the premature synthesis of abortive transcripts, suggesting its involvement in a general mechanism driving the RPi to RPo transition for transcription initiation.
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Affiliation(s)
- Simone C Wiesler
- Division of Cell and Molecular Biology, Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.
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28
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Weber M, Gawanbacht A, Habjan M, Rang A, Borner C, Schmidt AM, Veitinger S, Jacob R, Devignot S, Kochs G, García-Sastre A, Weber F. Incoming RNA virus nucleocapsids containing a 5'-triphosphorylated genome activate RIG-I and antiviral signaling. Cell Host Microbe 2013; 13:336-46. [PMID: 23498958 PMCID: PMC5515363 DOI: 10.1016/j.chom.2013.01.012] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 10/12/2012] [Accepted: 01/25/2013] [Indexed: 12/24/2022]
Abstract
Host defense to RNA viruses depends on rapid intracellular recognition of viral RNA by two cytoplasmic RNA helicases: RIG-I and MDA5. RNA transfection experiments indicate that RIG-I responds to naked double-stranded RNAs (dsRNAs) with a triphosphorylated 5' (5'ppp) terminus. However, the identity of the RIG-I stimulating viral structures in an authentic infection context remains unresolved. We show that incoming viral nucleocapsids containing a 5'ppp dsRNA "panhandle" structure trigger antiviral signaling that commences with RIG-I, is mediated through the adaptor protein MAVS, and terminates with transcription factor IRF-3. Independent of mammalian cofactors or viral polymerase activity, RIG-I bound to viral nucleocapsids, underwent a conformational switch, and homo-oligomerized. Enzymatic probing and superresolution microscopy suggest that RIG-I interacts with the panhandle structure of the viral nucleocapsids. These results define cytoplasmic entry of nucleocapsids as the proximal RIG-I-sensitive step during infection and establish viral nucleocapsids with a 5'ppp dsRNA panhandle as a RIG-I activator.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Ali Gawanbacht
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
| | - Matthias Habjan
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
| | - Andreas Rang
- Institute of Virology, Helmut-Ruska-Haus, University Hospital Charité, Charité Campus Mitte, Berlin, Germany
| | - Christoph Borner
- Institute of Molecular Medicine, Stefan-Meier-Strasse 17, D-79104 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs University Freiburg, Germany
| | - Anna Mareike Schmidt
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs University Freiburg, Germany
| | - Sophie Veitinger
- Department of Cell Biology and Cell Pathology, Philipps-University Marburg, Marburg, Germany
| | - Ralf Jacob
- Department of Cell Biology and Cell Pathology, Philipps-University Marburg, Marburg, Germany
| | - Stéphanie Devignot
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Georg Kochs
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
| | - Adolfo García-Sastre
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY-10029, USA
- Department of Medicine, Division of Infectious Diseases, Mount Sinai School of Medicine, New York, NY-10029, USA
- Global Health and Emerging Pathogens Institute, Mount Sinai School of Medicine, New York, NY-10029, USA
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs University Freiburg, Germany
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Sabbatini M, Vezzoli A, Milani M, Bertoni G. Evidence for self-association of the alternative sigma factor σ 54. FEBS J 2013; 280:1371-8. [DOI: 10.1111/febs.12129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 12/21/2012] [Accepted: 01/11/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Massimo Sabbatini
- Department of Life Sciences; Università degli Studi di Milano; Milan; Italy
| | - Alessandro Vezzoli
- Department of Life Sciences; Università degli Studi di Milano; Milan; Italy
| | | | - Giovanni Bertoni
- Department of Life Sciences; Università degli Studi di Milano; Milan; Italy
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30
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Joyet P, Bouraoui H, Aké FMD, Derkaoui M, Zébré AC, Cao TN, Ventroux M, Nessler S, Noirot-Gros MF, Deutscher J, Milohanic E. Transcription regulators controlled by interaction with enzyme IIB components of the phosphoenolpyruvate: sugar phosphotransferase system. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1415-24. [PMID: 23318733 DOI: 10.1016/j.bbapap.2013.01.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 12/27/2012] [Accepted: 01/04/2013] [Indexed: 11/16/2022]
Abstract
Numerous bacteria possess transcription activators and antiterminators composed of regulatory domains phosphorylated by components of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). These domains, called PTS regulation domains (PRDs), usually contain two conserved histidines as potential phosphorylation sites. While antiterminators possess two PRDs with four phosphorylation sites, transcription activators contain two PRDs plus two regulatory domains resembling PTS components (EIIA and EIIB). The activity of these transcription regulators is controlled by up to five phosphorylations catalyzed by PTS proteins. Phosphorylation by the general PTS components EI and HPr is usually essential for the activity of PRD-containing transcription regulators, whereas phosphorylation by the sugar-specific components EIIA or EIIB lowers their activity. For a specific regulator, for example the Bacillus subtilis mtl operon activator MtlR, the functional phosphorylation sites can be different in other bacteria and consequently the detailed mode of regulation varies. Some of these transcription regulators are also controlled by an interaction with a sugar-specific EIIB PTS component. The EIIBs are frequently fused to the membrane-spanning EIIC and EIIB-mediated membrane sequestration is sometimes crucial for the control of a transcription regulator. This is also true for the Escherichia coli repressor Mlc, which does not contain a PRD but nevertheless interacts with the EIIB domain of the glucose-specific PTS. In addition, some PRD-containing transcription activators interact with a distinct EIIB protein located in the cytoplasm. The phosphorylation state of the EIIB components, which changes in response to the presence or absence of the corresponding carbon source, affects their interaction with transcription regulators. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).
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Affiliation(s)
- Philippe Joyet
- Institut National de la Recherche Agronomique, UMR1319 Microbiologie de l'alimentation au service de la santé humaine Micalis, F-78350 Jouy-en-Josas, France; AgroParisTech, UMR Micalis, F-78350 Jouy-en-Josas, France
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31
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The role of bacterial enhancer binding proteins as specialized activators of σ54-dependent transcription. Microbiol Mol Biol Rev 2013; 76:497-529. [PMID: 22933558 DOI: 10.1128/mmbr.00006-12] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial enhancer binding proteins (bEBPs) are transcriptional activators that assemble as hexameric rings in their active forms and utilize ATP hydrolysis to remodel the conformation of RNA polymerase containing the alternative sigma factor σ(54). We present a comprehensive and detailed summary of recent advances in our understanding of how these specialized molecular machines function. The review is structured by introducing each of the three domains in turn: the central catalytic domain, the N-terminal regulatory domain, and the C-terminal DNA binding domain. The role of the central catalytic domain is presented with particular reference to (i) oligomerization, (ii) ATP hydrolysis, and (iii) the key GAFTGA motif that contacts σ(54) for remodeling. Each of these functions forms a potential target of the signal-sensing N-terminal regulatory domain, which can act either positively or negatively to control the activation of σ(54)-dependent transcription. Finally, we focus on the DNA binding function of the C-terminal domain and the enhancer sites to which it binds. Particular attention is paid to the importance of σ(54) to the bacterial cell and its unique role in regulating transcription.
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32
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Wiesler SC, Burrows PC, Buck M. A dual switch controls bacterial enhancer-dependent transcription. Nucleic Acids Res 2012; 40:10878-92. [PMID: 22965125 PMCID: PMC3505966 DOI: 10.1093/nar/gks844] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/13/2012] [Accepted: 08/13/2012] [Indexed: 12/31/2022] Open
Abstract
Bacterial RNA polymerases (RNAPs) are targets for antibiotics. Myxopyronin binds to the RNAP switch regions to block structural rearrangements needed for formation of open promoter complexes. Bacterial RNAPs containing the major variant σ(54) factor are activated by enhancer-binding proteins (bEBPs) and transcribe genes whose products are needed in pathogenicity and stress responses. We show that (i) enhancer-dependent RNAPs help Escherichia coli to survive in the presence of myxopyronin, (ii) enhancer-dependent RNAPs partially resist inhibition by myxopyronin and (iii) ATP hydrolysis catalysed by bEBPs is obligatory for functional interaction of the RNAP switch regions with the transcription start site. We demonstrate that enhancer-dependent promoters contain two barriers to full DNA opening, allowing tight regulation of transcription initiation. bEBPs engage in a dual switch to (i) allow propagation of nucleated DNA melting from an upstream DNA fork junction and (ii) complete the formation of the transcription bubble and downstream DNA fork junction at the RNA synthesis start site, resulting in switch region-dependent RNAP clamp closure and open promoter complex formation.
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Affiliation(s)
- Simone C. Wiesler
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | | | - Martin Buck
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
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33
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Zhang N, Joly N, Buck M. A common feature from different subunits of a homomeric AAA+ protein contacts three spatially distinct transcription elements. Nucleic Acids Res 2012; 40:9139-52. [PMID: 22772990 PMCID: PMC3467059 DOI: 10.1093/nar/gks661] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Initiation of σ(54)-dependent transcription requires assistance to melt DNA at the promoter site but is impeded by numerous protein-protein and nucleo-protein interactions. To alleviate these inhibitory interactions, hexameric bacterial enhancer binding proteins (bEBP), a subset of the ATPases associated with various cellular activities (AAA+) protein family, are required to remodel the transcription complex using energy derived from ATP hydrolysis. However, neither the process of energy conversion nor the internal architecture of the closed promoter complex is well understood. Escherichia coli Phage shock protein F (PspF), a well-studied bEBP, contains a surface-exposed loop 1 (L1). L1 is key to the energy coupling process by interacting with Region I of σ(54) (σ(54)(RI)) in a nucleotide dependent manner. Our analyses uncover new levels of complexity in the engagement of a multimeric bEBP with a basal transcription complex via several L1s. The mechanistic implications for these multivalent L1 interactions are elaborated in the light of available structures for the bEBP and its target complexes.
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Affiliation(s)
- Nan Zhang
- Division of Biology, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
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34
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Joly N, Buck M. Single chain forms of the enhancer binding protein PspF provide insights into geometric requirements for gene activation. J Biol Chem 2011; 286:12734-42. [PMID: 21300807 DOI: 10.1074/jbc.m110.203554] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Genetic information in the DNA is accessed by the molecular machine RNA polymerase following a highly conserved process, invariably involving the transition between double-stranded and single-stranded DNA states. In the case of the bacterial enhancer-dependent RNA polymerase (which is essential for adaptive responses and bacterial pathogenesis), the DNA melting event depends on specialized hexameric AAA+ ATPase activators. Involvement of such factors in transcription was demonstrated 25 years ago, but why these activators need to be hexameric, whether all the subunits operate identically, what is the contribution of each of the six subunits within the hexamer (structural, functional, or both), and how many active subunits are required for transcription activation remain open questions. Using engineered single-chain polypeptides covalently linking two or three subunits of the activator (allowing the subunit distribution within a hexamer to be fixed), we now show that (i) individual subunits have differential contributions to the activities of the oligomer and (ii) only a fraction of the subunits within the hexameric ATPase is directly required for gene activation. We establish that nucleotide-dependent coordination across three subunits of the hexameric bacterial enhancer binding proteins (bEBPs) is necessary for engagement and remodeling of the closed complex (RPc). Outcomes revealed features of bEBP, distinguishing their mode of action from fully processive AAA+ proteins or from simple bimodal switches. We now propose that the hexamer functions with asymmetric organization, potentially involving a split planar (open ring) or spiral character.
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Affiliation(s)
- Nicolas Joly
- Division of Biology, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
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35
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Jovanovic M, James EH, Burrows PC, Rego FGM, Buck M, Schumacher J. Regulation of the co-evolved HrpR and HrpS AAA+ proteins required for Pseudomonas syringae pathogenicity. Nat Commun 2011; 2:177. [PMID: 21285955 PMCID: PMC3105312 DOI: 10.1038/ncomms1177] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 01/05/2011] [Indexed: 11/26/2022] Open
Abstract
The bacterial AAA+ enhancer-binding proteins (EBPs) HrpR and HrpS (HrpRS) of Pseudomonas syringae (Ps) activate σ54-dependent transcription at the hrpL promoter; triggering type-three secretion system-mediated pathogenicity. In contrast with singly acting EBPs, the evolution of the strictly co-operative HrpRS pair raises questions of potential benefits and mechanistic differences this transcription control system offers. Here, we show distinct properties of HrpR and HrpS variants, indicating functional specialization of these non-redundant, tandemly arranged paralogues. Activities of HrpR, HrpS and their control proteins HrpV and HrpG from Ps pv. tomato DC3000 in vitro establish that HrpRS forms a transcriptionally active hetero-hexamer, that there is a direct negative regulatory role for HrpV through specific binding to HrpS and that HrpG suppresses HrpV. The distinct HrpR and HrpS functionalities suggest how partial paralogue degeneration has potentially led to a novel control mechanism for EBPs and indicate subunit-specific roles for EBPs in σ54-RNA polymerase activation. HrpR and HrpS enhancer-binding proteins of Pseudomonas syringae activate σ54-dependent transcription of the HrpL promoter and are required for type-three secretion pathogenicity. Here, the authors demonstrate that, despite being co-regulated, HrpR and HrpS each have distinct functions for activating σ54.
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Affiliation(s)
- Milija Jovanovic
- Division of Biology, Faculty of Natural Sciences, Sir Alexander Fleming Building, Imperial College London, London SW7 2AZ, UK
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36
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Joly N, Engl C, Jovanovic G, Huvet M, Toni T, Sheng X, Stumpf MPH, Buck M. Managing membrane stress: the phage shock protein (Psp) response, from molecular mechanisms to physiology. FEMS Microbiol Rev 2010; 34:797-827. [PMID: 20636484 DOI: 10.1111/j.1574-6976.2010.00240.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The bacterial phage shock protein (Psp) response functions to help cells manage the impacts of agents impairing cell membrane function. The system has relevance to biotechnology and to medicine. Originally discovered in Escherichia coli, Psp proteins and homologues are found in Gram-positive and Gram-negative bacteria, in archaea and in plants. Study of the E. coli and Yersinia enterocolitica Psp systems provides insights into how membrane-associated sensory Psp proteins might perceive membrane stress, signal to the transcription apparatus and use an ATP-hydrolysing transcription activator to produce effector proteins to overcome the stress. Progress in understanding the mechanism of signal transduction by the membrane-bound Psp proteins, regulation of the psp gene-specific transcription activator and the cell biology of the system is presented and discussed. Many features of the action of the Psp system appear to be dominated by states of self-association of the master effector, PspA, and the transcription activator, PspF, alongside a signalling pathway that displays strong conditionality in its requirement.
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Affiliation(s)
- Nicolas Joly
- Division of Biology, Imperial College London, South Kensington, London, UK
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37
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Abstract
Gene transcription is a fundamental cellular process carried out by RNA polymerase (RNAP) enzymes and is highly regulated through the action of gene regulatory complexes. Important mechanistic insights have been gained from structural studies on multisubunit RNAP from bacteria, yeast and archaea, although the initiation process that involves the conversion of the inactive transcription complex to an active one has yet to be fully understood. RNAPs are unambiguously closely related in structure and function across all kingdoms of life and have conserved mechanisms. In bacteria, sigma (sigma) factors direct RNAP to specific promoter sites and the RNAP/sigma holoenzyme can either form a stable closed complex that is incompetent for transcription (as in the case of sigma(54)) or can spontaneously proceed to an open complex that is competent for transcription (as in the case of sigma(70)). The conversion of the RNAP/sigma(54) closed complex to an open complex requires ATP hydrolysis by enhancer-binding proteins, hence providing an ideal model system for studying the initiation process biochemically and structurally. In this review, we present recent structural studies of the two major bacterial RNAP holoenzymes and focus on mechanistic advances in the transcription initiation process via enhancer-binding proteins.
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Affiliation(s)
- Tamaswati Ghosh
- Department of Life Sciences, Centre for Structural Biology, Division of Molecular Biosciences, Imperial College London, London, UK
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38
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A prehydrolysis state of an AAA+ ATPase supports transcription activation of an enhancer-dependent RNA polymerase. Proc Natl Acad Sci U S A 2010; 107:9376-81. [PMID: 20439713 DOI: 10.1073/pnas.1001188107] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ATP hydrolysis-dependent molecular machines and motors often drive regulated conformational transformations in cell signaling and gene regulation complexes. Conformational reorganization of a gene regulation complex containing the major variant form of bacterial RNA polymerase (RNAP), Esigma(54), requires engagement with its cognate ATP-hydrolyzing activator protein. Importantly, this activated RNAP is essential for a number of adaptive responses, including those required for bacterial pathogenesis. Here we characterize the initial encounter between the enhancer-dependent Esigma(54) and its cognate activator AAA+ ATPase protein, before ADP+P(i) formation, using a small primed RNA (spRNA) synthesis assay. The results show that in a prehydrolysis state, sufficient activator-dependent rearrangements in Esigma(54) have occurred to allow engagement of the RNAP active site with single-stranded promoter DNA to support spRNA synthesis, but not to melt the promoter DNA. This catalytically competent transcription intermediate has similarity with the open promoter complex, in that the RNAP dynamics required for DNA scrunching should be occurring. Significantly, this work highlights that prehydrolysis states of ATPases are functionally important in the molecular transformations they drive.
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39
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Joly N, Buck M. Engineered interfaces of an AAA+ ATPase reveal a new nucleotide-dependent coordination mechanism. J Biol Chem 2010; 285:15178-15186. [PMID: 20197281 DOI: 10.1074/jbc.m110.103150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homohexameric ring AAA(+) ATPases are found in all kingdoms of life and are involved in all cellular processes. To accommodate the large spectrum of substrates, the conserved AAA(+) core has become specialized through the insertion of specific substrate-binding motifs. Given their critical roles in cellular function, understanding the nucleotide-driven mechanisms of action is of wide importance. For one type of member AAA(+) protein (phage shock protein F, PspF), we identified and established the functional significance of strategically placed arginine and glutamate residues that form interacting pairs in response to nucleotide binding. We show that these interactions are critical for "cis" and "trans" subunit communication, which support coordination between subunits for nucleotide-dependent substrate remodeling. Using an allele-specific suppression approach for ATPase and substrate remodeling, we demonstrate that the targeted residues directly interact and are unlikely to make any other pairwise critical interactions. We then propose a mechanistic rationale by which the nucleotide-bound state of adjacent subunits can be sensed without direct involvement of R-finger residues. As the structural AAA(+) core is conserved, we propose that the functional networks established here could serve as a template to identify similar residue pairs in other AAA(+) proteins.
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Affiliation(s)
- Nicolas Joly
- Division of Biology, Imperial College London, London SW7 2AZ, United Kingdom.
| | - Martin Buck
- Division of Biology, Imperial College London, London SW7 2AZ, United Kingdom.
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40
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Bröcker MJ, Wätzlich D, Saggu M, Lendzian F, Moser J, Jahn D. Biosynthesis of (bacterio)chlorophylls: ATP-dependent transient subunit interaction and electron transfer of dark operative protochlorophyllide oxidoreductase. J Biol Chem 2010; 285:8268-77. [PMID: 20075073 DOI: 10.1074/jbc.m109.087874] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dark operative protochlorophyllide oxidoreductase (DPOR) catalyzes the light-independent two-electron reduction of protochlorophyllide a to form chlorophyllide a, the last common precursor of chlorophyll a and bacteriochlorophyll a biosynthesis. During ATP-dependent DPOR catalysis the homodimeric ChlL(2) subunit carrying a [4Fe-4S] cluster transfers electrons to the corresponding heterotetrameric catalytic subunit (ChlN/ChlB)(2), which also possesses a redox active [4Fe-4S] cluster. To investigate the transient interaction of both subcomplexes and the resulting electron transfer reactions, the ternary DPOR enzyme holocomplex comprising subunits ChlN, ChlB, and ChlL from the cyanobacterium Prochlorococcus marinus was trapped as an octameric (ChlN/ChlB)(2)(ChlL(2))(2) complex after incubation with the nonhydrolyzable ATP analogs adenosine 5'-(gamma-thio)triphosphate, adenosine 5'-(beta,gamma-imido)triphosphate, or MgADP in combination with AlF(4)(-). Additionally, a mutant ChlL(2) protein, with a deleted Leu(153) in the switch II region also allowed for the formation of a stable octameric complex. Furthermore, efficient complex formation required the presence of protochlorophyllide. Electron paramagnetic resonance spectroscopy of ternary DPOR complexes revealed a reduced [4Fe-4S] cluster located on ChlL(2), indicating that complete ATP hydrolysis is a prerequisite for intersubunit electron transfer. Circular dichroism spectroscopic experiments indicated nucleotide-dependent conformational changes for ChlL(2) after ATP binding. A nucleotide-dependent switch mechanism triggering ternary complex formation and electron transfer was concluded. From these results a detailed redox cycle for DPOR catalysis was deduced.
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Affiliation(s)
- Markus J Bröcker
- Institut für Mikrobiologie, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany
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41
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Joly N, Burrows PC, Engl C, Jovanovic G, Buck M. A lower-order oligomer form of phage shock protein A (PspA) stably associates with the hexameric AAA(+) transcription activator protein PspF for negative regulation. J Mol Biol 2009; 394:764-75. [PMID: 19804784 PMCID: PMC3128695 DOI: 10.1016/j.jmb.2009.09.055] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Accepted: 09/22/2009] [Indexed: 12/02/2022]
Abstract
To survive and colonise their various environments, including those used during infection, bacteria have developed a variety of adaptive systems. Amongst these is phage shock protein (Psp) response, which can be induced in Escherichia coli upon filamentous phage infection (specifically phage secretin pIV) and by other membrane-damaging agents. The E. coli Psp system comprises seven proteins, of which PspA is the central component. PspA is a bifunctional protein that is directly involved in (i) the negative regulation of the psp-specific transcriptional activator PspF and (ii) the maintenance of membrane integrity in a mechanism proposed to involve the formation of a 36-mer ring complex. Here we established that the PspA negative regulation of PspF ATPase activity is the result of a cooperative inhibition. We present biochemical evidence showing that an inhibitory PspA–PspF regulatory complex, which has significantly reduced PspF ATPase activity, is composed of around six PspF subunits and six PspA subunits, suggesting that PspA exists in at least two different oligomeric assemblies. We now establish that all four putative helical domains of PspA are critical for the formation of the 36-mer. In contrast, not all four helical domains are required for the formation of the inhibitory PspA–PspF complex. Since a range of initial PspF oligomeric states permit formation of the apparent PspA–PspF dodecameric assembly, we conclude that PspA and PspF demonstrate a strong propensity to self-assemble into a single defined heteromeric regulatory complex.
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Affiliation(s)
- Nicolas Joly
- Division of Biology, Sir Alexander Fleming Building, Imperial College London, Exhibition Road, London SW7 2AZ, UK
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42
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Zhang N, Joly N, Burrows PC, Jovanovic M, Wigneshweraraj SR, Buck M. The role of the conserved phenylalanine in the sigma54-interacting GAFTGA motif of bacterial enhancer binding proteins. Nucleic Acids Res 2009; 37:5981-92. [PMID: 19692583 PMCID: PMC2764435 DOI: 10.1093/nar/gkp658] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
σ54-dependent transcription requires activation by bacterial enhancer binding proteins (bEBPs). bEBPs are members of the AAA+ (ATPases associated with various cellular activities) protein family and typically form hexameric structures that are crucial for their ATPase activity. The precise mechanism by which the energy derived from ATP hydrolysis is coupled to biological output has several unknowns. Here we use Escherichia coli PspF, a model bEBP involved in the transcription of stress response genes (psp operon), to study determinants of its contact features with the closed promoter complex. We demonstrate that substitution of a highly conserved phenylalanine (F85) residue within the L1 loop GAFTGA motif affects (i) the ATP hydrolysis rate of PspF, demonstrating the link between L1 and the nucleotide binding pocket; (ii) the internal organization of the hexameric ring; and (iii) σ54 interactions. Importantly, we provide evidence for a close relationship between F85 and the −12 DNA fork junction structure, which may contribute to key interactions during the energy coupling step and the subsequent remodelling of the Eσ54 closed complex. The functionality of F85 is distinct from that of other GAFTGA residues, especially T86 where in contrast to F85 a clean uncoupling phenotype is observed.
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Affiliation(s)
- Nan Zhang
- Division of Biology, Sir Alexander Fleming Building, and Centre for Molecular Microbiology and Infection, Flowers Building, Imperial College London, London SW7 2AZ, UK
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43
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Burrows PC, Joly N, Nixon BT, Buck M. Comparative analysis of activator-Esigma54 complexes formed with nucleotide-metal fluoride analogues. Nucleic Acids Res 2009; 37:5138-50. [PMID: 19553192 PMCID: PMC2731916 DOI: 10.1093/nar/gkp541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bacterial RNA polymerase (RNAP) containing the major variant σ54 factor forms open promoter complexes in a reaction in which specialized activator proteins hydrolyse ATP. Here we probe binding interactions between σ54-RNAP (Eσ54) and the ATPases associated with various cellular activities (AAA+) domain of the Escherichia coli activator protein, PspF, using nucleotide-metal fluoride (BeF and AlF) analogues representing ground and transition states of ATP, which allow complexes (that are otherwise too transient with ATP) to be captured. We show that the organization and functionality of the ADP–BeF- and ADP–AlF-dependent complexes greatly overlap. Our data support an activation pathway in which the initial ATP-dependent binding of the activator to the Eσ54 closed complex results in the re-organization of Eσ54 with respect to the transcription start-site. However, the nucleotide-dependent binding interactions between the activator and the Eσ54 closed complex are in themselves insufficient for forming open promoter complexes when linear double-stranded DNA is present in the initial closed complex.
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Affiliation(s)
- Patricia C Burrows
- Department of Life Sciences, Division of Biology, Faculty of Natural Sciences, Sir Alexander Fleming Building, Imperial College London, London SW7 2AZ, UK
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44
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Xiao Y, Wigneshweraraj SR, Weinzierl R, Wang YP, Buck M. Construction and functional analyses of a comprehensive sigma54 site-directed mutant library using alanine-cysteine mutagenesis. Nucleic Acids Res 2009; 37:4482-97. [PMID: 19474350 PMCID: PMC2715252 DOI: 10.1093/nar/gkp419] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The sigma(54) factor associates with core RNA polymerase (RNAP) to form a holoenzyme that is unable to initiate transcription unless acted on by an activator protein. sigma(54) is closely involved in many steps of activator-dependent transcription, such as core RNAP binding, promoter recognition, activator interaction and open complex formation. To systematically define sigma(54) residues that contribute to each of these functions and to generate a resource for site specific protein labeling, a complete mutant library of sigma(54) was constructed by alanine-cysteine scanning mutagenesis. Amino acid residues from 3 to 476 of Cys(-)sigma(54) were systematically mutated to alanine and cysteine in groups of two adjacent residues at a time. The influences of each substitution pair upon the functions of sigma(54) were analyzed in vivo and in vitro and the functions of many residues were revealed for the first time. Increased sigma(54) isomerization activity seldom corresponded with an increased transcription activity of the holoenzyme, suggesting the steps after sigma(54) isomerization, likely to be changes in core RNAP structure, are also strictly regulated or rate limiting to open complex formation. A linkage between core RNAP-binding activity and activator responsiveness indicates that the sigma(54)-core RNAP interface changes upon activation.
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Affiliation(s)
- Yan Xiao
- National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
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Burrows PC, Schumacher J, Amartey S, Ghosh T, Burgis TA, Zhang X, Nixon BT, Buck M. Functional roles of the pre-sensor I insertion sequence in an AAA+ bacterial enhancer binding protein. Mol Microbiol 2009; 73:519-33. [PMID: 19486295 PMCID: PMC2745333 DOI: 10.1111/j.1365-2958.2009.06744.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular machines belonging to the AAA+ superfamily of ATPases use NTP hydrolysis to remodel their versatile substrates. The presence of an insertion sequence defines the major phylogenetic pre-sensor I insertion (pre-SIi) AAA+ superclade. In the bacterial σ54-dependent enhancer binding protein phage shock protein F (PspF) the pre-SIi loop adopts different conformations depending on the nucleotide-bound state. Single amino acid substitutions within the dynamic pre-SIi loop of PspF drastically change the ATP hydrolysis parameters, indicating a structural link to the distant hydrolysis site. We used a site-specific protein–DNA proximity assay to measure the contribution of the pre-SIi loop in σ54-dependent transcription and demonstrate that the pre-SIi loop is a major structural feature mediating nucleotide state-dependent differential engagement with Eσ54. We suggest that much, if not all, of the action of the pre-SIi loop is mediated through the L1 loop and relies on a conserved molecular switch, identified in a crystal structure of one pre-SIi variant and in accordance with the high covariance between some pre-SIi residues and distinct residues outside the pre-SIi sequence.
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Affiliation(s)
- Patricia C Burrows
- Department of Life Sciences, Division of Biology, Imperial College London, London, UK
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Peña-Sánchez J, Poggio S, Flores-Pérez U, Osorio A, Domenzain C, Dreyfus G, Camarena L. Identification of the binding site of the σ
54 hetero-oligomeric FleQ/FleT activator in the flagellar promoters of Rhodobacter sphaeroides. Microbiology (Reading) 2009; 155:1669-1679. [DOI: 10.1099/mic.0.024455-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Expression of the flagellar genes in Rhodobacter sphaeroides is dependent on one of the four sigma-54 factors present in this bacterium and on the enhancer binding proteins (EBPs) FleQ and FleT. These proteins, in contrast to other well-characterized EBPs, carry out activation as a hetero-oligomeric complex. To further characterize the molecular properties of this complex we mapped the binding sites or upstream activation sequences (UASs) of six different flagellar promoters. In most cases the UASs were identified at approximately 100 bp upstream from the promoter. However, the activity of the divergent promoters flhAp-flgAp, which are separated by only 53 bp, is mainly dependent on a UAS located approximately 200 bp downstream from each promoter. Interestingly, a significant amount of activation mediated by the upstream or contralateral UAS was also detected, suggesting that the architecture of this region is important for the correct regulation of these promoters. Sequence analysis of the regions carrying the potential FleQ/FleT binding sites revealed a conserved motif. In vivo footprinting experiments with the motAp promoter allowed us to identify a protected region that overlaps with this motif. These results allow us to propose a consensus sequence that represents the binding site of the FleQ/FleT activating complex.
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Affiliation(s)
- J. Peña-Sánchez
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - S. Poggio
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - U. Flores-Pérez
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - A. Osorio
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - C. Domenzain
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - G. Dreyfus
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - L. Camarena
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
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Burrows PC, Joly N, Cannon WV, Cámara BP, Rappas M, Zhang X, Dawes K, Nixon BT, Wigneshweraraj SR, Buck M. Coupling sigma factor conformation to RNA polymerase reorganisation for DNA melting. J Mol Biol 2009; 387:306-19. [PMID: 19356588 DOI: 10.1016/j.jmb.2009.01.052] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 01/24/2009] [Accepted: 01/26/2009] [Indexed: 11/18/2022]
Abstract
ATP-driven remodelling of initial RNA polymerase (RNAP) promoter complexes occurs as a major post recruitment strategy used to control gene expression. Using a model-enhancer-dependent bacterial system (sigma54-RNAP, Esigma54) and a slowly hydrolysed ATP analogue (ATPgammaS), we provide evidence for a nucleotide-dependent temporal pathway leading to DNA melting involving a small set of sigma54-DNA conformational states. We demonstrate that the ATP hydrolysis-dependent remodelling of Esigma54 occurs in at least two distinct temporal steps. The first detected remodelling phase results in changes in the interactions between the promoter specificity sigma54 factor and the promoter DNA. The second detected remodelling phase causes changes in the relationship between the promoter DNA and the core RNAP catalytic beta/beta' subunits, correlating with the loading of template DNA into the catalytic cleft of RNAP. It would appear that, for Esigma54 promoters, loading of template DNA within the catalytic cleft of RNAP is dependent on fast ATP hydrolysis steps that trigger changes in the beta' jaw domain, thereby allowing acquisition of the open complex status.
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Affiliation(s)
- Patricia C Burrows
- Division of Biology, Department of Life Sciences, Faculty of Natural Sciences, Sir Alexander Fleming Building, Imperial College London, London SW7 2AZ, UK
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48
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Organization of an activator-bound RNA polymerase holoenzyme. Mol Cell 2008; 32:337-46. [PMID: 18995832 PMCID: PMC2680985 DOI: 10.1016/j.molcel.2008.09.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 05/30/2008] [Accepted: 09/05/2008] [Indexed: 12/31/2022]
Abstract
Transcription initiation involves the conversion from closed promoter complexes, comprising RNA polymerase (RNAP) and double-stranded promoter DNA, to open complexes, in which the enzyme is able to access the DNA template in a single-stranded form. The complex between bacterial RNAP and its major variant sigma factor σ54 remains as a closed complex until ATP hydrolysis-dependent remodeling by activator proteins occurs. This remodeling facilitates DNA melting and allows the transition to the open complex. Here we present cryoelectron microscopy reconstructions of bacterial RNAP in complex with σ54 alone, and of RNAP-σ54 with an AAA+ activator. Together with photo-crosslinking data that establish the location of promoter DNA within the complexes, we explain why the RNAP-σ54 closed complex is unable to access the DNA template and propose how the structural changes induced by activator binding can initiate conformational changes that ultimately result in formation of the open complex.
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Zhang X, Wigley DB. The 'glutamate switch' provides a link between ATPase activity and ligand binding in AAA+ proteins. Nat Struct Mol Biol 2008; 15:1223-7. [PMID: 18849995 PMCID: PMC2806578 DOI: 10.1038/nsmb.1501] [Citation(s) in RCA: 93] [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: 05/01/2008] [Accepted: 09/23/2008] [Indexed: 11/25/2022]
Abstract
AAA+ proteins carry out diverse functions in cells. In most cases, their ATPase activity is tightly regulated by protein partners and target ligands, but the mechanism for this control has remained unclear. We have identified a conserved link between the ligand binding and ATPase sites in AAA+ proteins. This link, which we call the 'glutamate switch', regulates ATPase activity directly in response to the binding of target ligands by controlling the orientation of the conserved glutamate residue in the DExx motif, switching it between active and inactive conformations. The reasons for this level of control of the ATPase activity are discussed in the context of the biological processes catalyzed by AAA+ proteins.
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Affiliation(s)
- Xiaodong Zhang
- Division of Molecular Biosciences, Centre for Structural Biology, Dept. of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Dale B. Wigley
- Cancer Research UK Clare Hall Laboratories, The London Research Institute, Blanche Lane, South Mimms, Potters Bar, Herts EN6 3LD,U.K
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Visualizing the organization and reorganization of transcription complexes for gene expression. Biochem Soc Trans 2008; 36:776-9. [PMID: 18631157 DOI: 10.1042/bst0360776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Regulated gene expression requires control of the transcription machinery, frequently through the establishment of different functional states of the transcribing enzyme RNA polymerase and its attendant activator proteins. In bacteria, major adaptive responses use an enhancer-dependent RNA polymerase, activated for transcription by a class of ATPases that remodel initial promoter complexes to form transcriptionally proficient open promoter complexes. In the present article, we summarize the integrated use of site-specific protein cleavage and DNA cross-linking methods, as well as FRET (fluorescence resonance energy transfer) in combination with X-ray crystallography and cryo-electron microscopy to gain insight into the organization of the enhancer-dependent sigma 54-RNA polymerase and the ATPase-driven activation mechanism.
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