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Delbeau M, Omollo EO, Froom R, Koh S, Mooney RA, Lilic M, Brewer JJ, Rock J, Darst SA, Campbell EA, Landick R. Structural and functional basis of the universal transcription factor NusG pro-pausing activity in Mycobacterium tuberculosis. Mol Cell 2023; 83:1474-1488.e8. [PMID: 37116494 PMCID: PMC10231689 DOI: 10.1016/j.molcel.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/08/2023] [Accepted: 04/04/2023] [Indexed: 04/30/2023]
Abstract
Transcriptional pauses mediate regulation of RNA biogenesis. DNA-encoded pause signals trigger pausing by stabilizing RNA polymerase (RNAP) swiveling and inhibiting DNA translocation. The N-terminal domain (NGN) of the only universal transcription factor, NusG/Spt5, modulates pausing through contacts to RNAP and DNA. Pro-pausing NusGs enhance pauses, whereas anti-pausing NusGs suppress pauses. Little is known about pausing and NusG in the human pathogen Mycobacterium tuberculosis (Mtb). We report that MtbNusG is pro-pausing. MtbNusG captures paused, swiveled RNAP by contacts to the RNAP protrusion and nontemplate-DNA wedged between the NGN and RNAP gate loop. In contrast, anti-pausing Escherichia coli (Eco) NGN contacts the MtbRNAP gate loop, inhibiting swiveling and pausing. Using CRISPR-mediated genetics, we show that pro-pausing NGN is required for mycobacterial fitness. Our results define an essential function of mycobacterial NusG and the structural basis of pro- versus anti-pausing NusG activity, with broad implications for the function of all NusG orthologs.
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Affiliation(s)
- Madeleine Delbeau
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Expery O Omollo
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ruby Froom
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA; Laboratory of Host-Pathogen Biology, The Rockefeller University, New York, NY 10065, USA
| | - Steven Koh
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Rachel A Mooney
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Mirjana Lilic
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Joshua J Brewer
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA
| | - Jeremy Rock
- Laboratory of Host-Pathogen Biology, The Rockefeller University, New York, NY 10065, USA
| | - Seth A Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA.
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065, USA.
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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2
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Gong X, Gnanasekaran K, Ma K, Forman CJ, Wang X, Su S, Farha OK, Gianneschi NC. Rapid Generation of Metal-Organic Framework Phase Diagrams by High-Throughput Transmission Electron Microscopy. J Am Chem Soc 2022; 144:6674-6680. [PMID: 35385280 DOI: 10.1021/jacs.2c01095] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Metal-organic frameworks (MOFs) constructed from Zr6 nodes and tetratopic carboxylate linkers display high structural diversity and complexity in which various crystal topologies can result from identical building units. To determine correlations between MOF topologies and experimental parameters, such as solvent choice or modulator identity and concentration, we demonstrate the rapid generation of phase diagrams for Zr6-MOFs with 1,4-dibromo-2,3,5,6-tetrakis(4-carboxyphenyl)benzene linkers under a variety of conditions. We have developed a full set of methods for high-throughput transmission electron microscopy (TEM), including automated sample preparation and data acquisition, to accelerate MOF characterization. The use of acetic acid as a modulator yields amorphous, NU-906, NU-600, and mixed-phase structures depending on the ratio of N,N-dimethylformamide to N,N-diethylformamide solvent and the quantity of the modulator. Notably, the use of formic acid as a modulator enables direct control of crystal growth along the c direction through variation of the modulator quantity, thus realizing aspect ratio control of NU-1008 crystals with different catalytic hydrolysis performance toward a nerve agent simulant.
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Affiliation(s)
- Xinyi Gong
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Karthikeyan Gnanasekaran
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Departments of Biomedical Engineering, Materials Science & Engineering, and Pharmacology, Simpson-Querrey Institute, Chemistry of Life Processes Institute, and Lurie Cancer Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Kaikai Ma
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Christopher J Forman
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Departments of Biomedical Engineering, Materials Science & Engineering, and Pharmacology, Simpson-Querrey Institute, Chemistry of Life Processes Institute, and Lurie Cancer Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xingjie Wang
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Shengyi Su
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Omar K Farha
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Nathan C Gianneschi
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,Departments of Biomedical Engineering, Materials Science & Engineering, and Pharmacology, Simpson-Querrey Institute, Chemistry of Life Processes Institute, and Lurie Cancer Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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3
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Lilic M, Darst SA, Campbell EA. Structural basis of transcriptional activation by the Mycobacterium tuberculosis intrinsic antibiotic-resistance transcription factor WhiB7. Mol Cell 2021; 81:2875-2886.e5. [PMID: 34171296 PMCID: PMC8311663 DOI: 10.1016/j.molcel.2021.05.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/22/2021] [Accepted: 05/12/2021] [Indexed: 01/25/2023]
Abstract
In pathogenic mycobacteria, transcriptional responses to antibiotics result in induced antibiotic resistance. WhiB7 belongs to the Actinobacteria-specific family of Fe-S-containing transcription factors and plays a crucial role in inducible antibiotic resistance in mycobacteria. Here, we present cryoelectron microscopy structures of Mycobacterium tuberculosis transcriptional regulatory complexes comprising RNA polymerase σA-holoenzyme, global regulators CarD and RbpA, and WhiB7, bound to a WhiB7-regulated promoter. The structures reveal how WhiB7 interacts with σA-holoenzyme while simultaneously interacting with an AT-rich sequence element via its AT-hook. Evidently, AT-hooks, rare elements in bacteria yet prevalent in eukaryotes, bind to target AT-rich DNA sequences similarly to the nuclear chromosome binding proteins. Unexpectedly, a subset of particles contained a WhiB7-stabilized closed promoter complex, revealing this intermediate's structure, and we apply kinetic modeling and biochemical assays to rationalize how WhiB7 activates transcription. Altogether, our work presents a comprehensive view of how WhiB7 serves to activate gene expression leading to antibiotic resistance.
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Affiliation(s)
- Mirjana Lilic
- Laboratory of Molecular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Seth A Darst
- Laboratory of Molecular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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4
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Hernando MD, Primeau JO, Young HS. Helical Membrane Protein Crystallization in the New Era of Electron Cryo-Microscopy. Methods Mol Biol 2021; 2302:179-199. [PMID: 33877628 DOI: 10.1007/978-1-0716-1394-8_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Helical assemblies of proteins, which consist of a two-dimensional lattice of identical subunits arranged with helical symmetry, are a common structural motif in nature. For membrane proteins, crystallization protocols can induce helical arrangements and take advantage of the symmetry found in these assemblies for the structural determination of target proteins. Modern advances in the field of electron cryo-microscopy (cryo-EM), in particular the advent of direct electron detectors, have opened the potential for structure determination of membrane proteins in such assemblies at high resolution. The nature of the symmetry in helical crystals of membrane proteins means that a single image potentially contains enough information for three-dimensional structural determination. With the current direct electron detectors, we have never been closer to making this a reality. Here, we present a protocol detailing the preparation of helical crystals, with an emphasis on further cryo-EM analysis and structural determination of the sarco(endo)plasmic reticulum Ca2+-ATPase in the presence of regulatory subunits such as phospholamban.
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Affiliation(s)
- Mary D Hernando
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Joseph O Primeau
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
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5
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Schorb M, Haberbosch I, Hagen WJH, Schwab Y, Mastronarde DN. Software tools for automated transmission electron microscopy. Nat Methods 2019; 16:471-477. [PMID: 31086343 PMCID: PMC7000238 DOI: 10.1038/s41592-019-0396-9] [Citation(s) in RCA: 260] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 03/15/2019] [Indexed: 11/09/2022]
Abstract
The demand for high-throughput data collection in electron microscopy is increasing for applications in structural and cellular biology. Here we present a combination of software tools that enable automated acquisition guided by image analysis for a variety of transmission electron microscopy acquisition schemes. SerialEM controls microscopes and detectors and can trigger automated tasks at multiple positions with high flexibility. Py-EM interfaces with SerialEM to enact specimen-specific image-analysis pipelines that enable feedback microscopy. As example applications, we demonstrate dose reduction in cryo-electron microscopy experiments, fully automated acquisition of every cell in a plastic section and automated targeting on serial sections for 3D volume imaging across multiple grids.
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Affiliation(s)
- Martin Schorb
- Electron Microscopy Core Facility, EMBL, Heidelberg, Germany.
| | - Isabella Haberbosch
- Department of Hematology, Oncology and Rheumatology, University Hospital Heidelberg, Heidelberg Research Center for Molecular Medicine, EMBL, Heidelberg, Germany
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
| | - Wim J H Hagen
- Structural and Computational Biology Unit and Cryo-Electron Microscopy Service Platform, EMBL, Heidelberg, Germany
| | - Yannick Schwab
- Electron Microscopy Core Facility, EMBL, Heidelberg, Germany
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
| | - David N Mastronarde
- Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder, CO, USA.
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6
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Structures of an RNA polymerase promoter melting intermediate elucidate DNA unwinding. Nature 2019; 565:382-385. [PMID: 30626968 DOI: 10.1038/s41586-018-0840-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 11/28/2018] [Indexed: 01/25/2023]
Abstract
A key regulated step of transcription is promoter melting by RNA polymerase (RNAP) to form the open promoter complex1-3. To generate the open complex, the conserved catalytic core of the RNAP combines with initiation factors to locate promoter DNA, unwind 12-14 base pairs of the DNA duplex and load the template-strand DNA into the RNAP active site. Formation of the open complex is a multi-step process during which transient intermediates of unknown structure are formed4-6. Here we present cryo-electron microscopy structures of bacterial RNAP-promoter DNA complexes, including structures of partially melted intermediates. The structures show that late steps of promoter melting occur within the RNAP cleft, delineate key roles for fork-loop 2 and switch 2-universal structural features of RNAP-in restricting access of DNA to the RNAP active site, and explain why clamp opening is required to allow entry of single-stranded template DNA into the active site. The key roles of fork-loop 2 and switch 2 suggest a common mechanism for late steps in promoter DNA opening to enable gene expression across all domains of life.
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Boyaci H, Chen J, Lilic M, Palka M, Mooney RA, Landick R, Darst SA, Campbell EA. Fidaxomicin jams Mycobacterium tuberculosis RNA polymerase motions needed for initiation via RbpA contacts. eLife 2018; 7:34823. [PMID: 29480804 PMCID: PMC5837556 DOI: 10.7554/elife.34823] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/13/2018] [Indexed: 01/22/2023] Open
Abstract
Fidaxomicin (Fdx) is an antimicrobial RNA polymerase (RNAP) inhibitor highly effective against Mycobacterium tuberculosis RNAP in vitro, but clinical use of Fdx is limited to treating Clostridium difficile intestinal infections due to poor absorption. To identify the structural determinants of Fdx binding to RNAP, we determined the 3.4 Å cryo-electron microscopy structure of a complete M. tuberculosis RNAP holoenzyme in complex with Fdx. We find that the actinobacteria general transcription factor RbpA contacts fidaxomycin, explaining its strong effect on M. tuberculosis. Additional structures define conformational states of M. tuberculosis RNAP between the free apo-holoenzyme and the promoter-engaged open complex ready for transcription. The results establish that Fdx acts like a doorstop to jam the enzyme in an open state, preventing the motions necessary to secure promoter DNA in the active site. Our results provide a structural platform to guide development of anti-tuberculosis antimicrobials based on the Fdx binding pocket. Tuberculosis (TB) is an infectious disease that affects over ten million people every year. The Mycobacterium tuberculosis bacteria that cause the disease spread through the air from one person to another and mainly infect the lungs. Although curable, TB is difficult to eradicate because it is remarkably widespread, with one third of the world’s population estimated to carry the bacteria. Treatment for TB involves a mix of antibiotics that should be taken for several months to a year. The number of multidrug-resistant TB cases, where the infection is not treatable by the common cocktail of antibiotics, is rapidly increasing. There is therefore a need to discover new drugs that can kill the M. tuberculosis bacteria. An antibiotic called fidaxomicin is used to treat intestinal infections. Although it can kill Mycobacterium tuberculosis cells in culture, it is not absorbed from the intestines to the blood and thus cannot reach the lungs to kill the bacteria. It may be possible to change the structure of the drug so that it can enter the bloodstream. Before this can be done, researchers need to understand exactly how fidaxomicin kills the bacteria so that they know which parts of the drug they can alter without making it less effective. Fidaxomicin kills bacterial cells by binding to an enzyme called RNA polymerase. The antibiotic prevents the enzyme from reading and ‘transcribing’ DNA to form molecules that are essential for life. To learn more about how fidaxomicin has this effect, Boyaci, Chen et al. used cryo-electron microscopy to look at structures of the M. tuberculosis RNA polymerase in different states, including when it was bound to fidaxomicin. The structures reveal the chemical details of the interactions between the RNA polymerase and the antibiotic. The two molecules bind to each other through a region of the RNA polymerase that is unique to M. tuberculosis and closely related bacteria. Fidaxomicin acts like a doorstop to jam the RNA polymerase in an open state that cannot bind to DNA and transcribe genes. Medicinal chemists could now build on these findings to develop new drugs that might treat TB, either by modifying fidaxomicin or designing new antibiotics that bind to the same region of the RNA polymerase. Because the fidaxomicin-binding region of the RNA polymerase is specific to M. tuberculosis new antibiotics could be tailored towards the bacteria that have a minimal effect on a patient’s normal gut bacteria.
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Affiliation(s)
- Hande Boyaci
- The Rockefeller University, New York, United States
| | - James Chen
- The Rockefeller University, New York, United States
| | | | - Margaret Palka
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Rachel Anne Mooney
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States.,Department of Bacteriology, University of Wisconsin-Madison, Madison, United States
| | - Seth A Darst
- The Rockefeller University, New York, United States
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9
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Tan YZ, Cheng A, Potter CS, Carragher B. Automated data collection in single particle electron microscopy. Microscopy (Oxf) 2015; 65:43-56. [PMID: 26671944 DOI: 10.1093/jmicro/dfv369] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/06/2015] [Indexed: 11/12/2022] Open
Abstract
Automated data collection is an integral part of modern workflows in single particle electron microscopy (EM) research. This review surveys the software packages available for automated single particle EM data collection. The degree of automation at each stage of data collection is evaluated, and the capabilities of the software packages are described. Finally, future trends in automation are discussed.
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Affiliation(s)
- Yong Zi Tan
- The National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY 10027, USA Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Anchi Cheng
- The National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY 10027, USA Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA
| | - Clinton S Potter
- The National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY 10027, USA Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Bridget Carragher
- The National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY 10027, USA Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Ave, New York, NY 10027, USA Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
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