1
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Smith EL, Goley ED. House of CarDs: Functional insights into the transcriptional regulator CdnL. Mol Microbiol 2024. [PMID: 38664995 DOI: 10.1111/mmi.15268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/12/2024] [Accepted: 04/11/2024] [Indexed: 07/07/2024]
Abstract
Regulation of bacterial transcription is a complex and multi-faceted phenomenon that is critical for growth and adaptation. Proteins in the CarD_CdnL_TRCF family are widespread, often essential, regulators of transcription of genes required for growth and metabolic homeostasis. Research in the last decade has described the mechanistic and structural bases of CarD-CdnL-mediated regulation of transcription initiation. More recently, studies in a range of bacteria have begun to elucidate the physiological roles of CarD-CdnL proteins as well as mechanisms by which these proteins, themselves, are regulated. A theme has emerged wherein regulation of CarD-CdnL proteins is central to bacterial adaptation to stress and/or changing environmental conditions.
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Affiliation(s)
- Erika L Smith
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Erin D Goley
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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2
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Pérez-Castaño R, Bastida-Martínez E, Fernández Zapata J, Polanco MDC, Galbis-Martínez ML, Iniesta AA, Fontes M, Padmanabhan S, Elías-Arnanz M. Coenzyme B 12 -dependent and independent photoregulation of carotenogenesis across Myxococcales. Environ Microbiol 2022; 24:1865-1886. [PMID: 35005822 PMCID: PMC9304148 DOI: 10.1111/1462-2920.15895] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/27/2021] [Accepted: 01/01/2022] [Indexed: 11/28/2022]
Abstract
Light-induced carotenogenesis in Myxococcus xanthus is controlled by the B12 -based CarH repressor and photoreceptor, and by a separate intricate pathway involving singlet oxygen, the B12 -independent CarH paralog CarA and various other proteins, some eukaryotic-like. Whether other myxobacteria conserve these pathways and undergo photoregulated carotenogenesis is unknown. Here, comparative analyses across 27 Myxococcales genomes identified carotenogenic genes, albeit arranged differently, with carH often in their genomic vicinity, in all three Myxococcales suborders. However, CarA and its associated factors were found exclusively in suborder Cystobacterineae, with carA-carH invariably in tandem in a syntenic carotenogenic operon, except for Cystobacter/Melittangium, which lack CarA but retain all other factors. We experimentally show B12 -mediated photoregulated carotenogenesis in representative myxobacteria, and a remarkably plastic CarH operator design and DNA binding across Myxococcales. Unlike the two characterized CarH from other phyla, which are tetrameric, Cystobacter CarH (the first myxobacterial homolog amenable to analysis in vitro) is a dimer that combines direct CarH-like B12 -based photoregulation with CarA-like DNA-binding and inhibition by an antirepressor. This study provides new molecular insights into B12 -dependent photoreceptors. It further establishes the B12 -dependent pathway for photoregulated carotenogenesis as broadly prevalent across myxobacteria and its evolution, exclusively in one suborder, into a parallel complex B12 -independent circuit. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ricardo Pérez-Castaño
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - Eva Bastida-Martínez
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - Jesús Fernández Zapata
- Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas, 28006, Madrid, Spain
| | - María Del Carmen Polanco
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - María Luisa Galbis-Martínez
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - Antonio A Iniesta
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - Marta Fontes
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - S Padmanabhan
- Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas, 28006, Madrid, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
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3
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Light-Triggered Carotenogenesis in Myxococcus xanthus: New Paradigms in Photosensory Signaling, Transduction and Gene Regulation. Microorganisms 2021; 9:microorganisms9051067. [PMID: 34063365 PMCID: PMC8156234 DOI: 10.3390/microorganisms9051067] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 11/17/2022] Open
Abstract
Myxobacteria are Gram-negative δ-proteobacteria found predominantly in terrestrial habitats and often brightly colored due to the biosynthesis of carotenoids. Carotenoids are lipophilic isoprenoid pigments that protect cells from damage and death by quenching highly reactive and toxic oxidative species, like singlet oxygen, generated upon growth under light. The model myxobacterium Myxococcus xanthus turns from yellow in the dark to red upon exposure to light because of the photoinduction of carotenoid biosynthesis. How light is sensed and transduced to bring about regulated carotenogenesis in order to combat photooxidative stress has been extensively investigated in M. xanthus using genetic, biochemical and high-resolution structural methods. These studies have unearthed new paradigms in bacterial light sensing, signal transduction and gene regulation, and have led to the discovery of prototypical members of widely distributed protein families with novel functions. Major advances have been made over the last decade in elucidating the molecular mechanisms underlying the light-dependent signaling and regulation of the transcriptional response leading to carotenogenesis in M. xanthus. This review aims to provide an up-to-date overview of these findings and their significance.
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Bernal-Bernal D, Abellón-Ruiz J, Iniesta AA, Pajares-Martínez E, Bastida-Martínez E, Fontes M, Padmanabhan S, Elías-Arnanz M. Multifactorial control of the expression of a CRISPR-Cas system by an extracytoplasmic function σ/anti-σ pair and a global regulatory complex. Nucleic Acids Res 2019; 46:6726-6745. [PMID: 29893914 PMCID: PMC6061681 DOI: 10.1093/nar/gky475] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 05/15/2018] [Indexed: 12/19/2022] Open
Abstract
Expression of CRISPR-Cas systems is a prerequisite for their defensive role against invading genetic elements. Yet, much remains unknown about how this crucial step is regulated. We describe a new mechanism controlling CRISPR-cas expression, which requires an extracytoplasmic function (ECF) σ factor (DdvS), its membrane-bound anti-σ (DdvA) and a global regulatory complex (CarD–CarG). Transcriptomic analyses revealed that the DdvS/CarD/CarG-dependent regulon comprises a type III-B CRISPR-Cas system in Myxococcus xanthus. We mapped four DdvS-driven CarD/CarG-dependent promoters, with one lying immediately upstream of the cas cluster. Consistent with direct action, DdvS and CarD–CarG localize at these promoters in vivo. The cas genes are transcribed as a polycistronic mRNA that reads through the leader into the CRISPR array, a putative σA-dependent promoter in the leader having negligible activity in vivo. Consequently, expression of the entire CRISPR-Cas system and mature CRISPR-RNA (crRNA) production is DdvS/CarD/CarG-dependent. DdvA likely uses its large C-terminal domain to sense and transduce the extracytoplasmic signal triggering CRISPR-cas expression, which we show is not starvation-induced multicellular development. An ECF-σ/anti-σ pair and a global regulatory complex provide an effective mechanism to coordinate signal-sensing with production of precursor crRNA, its processing Cas6 endoribonuclease and other Cas proteins for mature crRNA biogenesis and interference.
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Affiliation(s)
- Diego Bernal-Bernal
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Javier Abellón-Ruiz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Antonio A Iniesta
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Elena Pajares-Martínez
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Eva Bastida-Martínez
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Marta Fontes
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - S Padmanabhan
- Instituto de Química Física 'Rocasolano', Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
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5
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Bernal-Bernal D, Abellón-Ruiz J, Iniesta AA, Pajares-Martínez E, Bastida-Martínez E, Fontes M, Padmanabhan S, Elías-Arnanz M. Multifactorial control of the expression of a CRISPR-Cas system by an extracytoplasmic function σ/anti-σ pair and a global regulatory complex. Nucleic Acids Res 2018. [PMID: 29893914 DOI: 10.1093/nar/gky475.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Expression of CRISPR-Cas systems is a prerequisite for their defensive role against invading genetic elements. Yet, much remains unknown about how this crucial step is regulated. We describe a new mechanism controlling CRISPR-cas expression, which requires an extracytoplasmic function (ECF) σ factor (DdvS), its membrane-bound anti-σ (DdvA) and a global regulatory complex (CarD-CarG). Transcriptomic analyses revealed that the DdvS/CarD/CarG-dependent regulon comprises a type III-B CRISPR-Cas system in Myxococcus xanthus. We mapped four DdvS-driven CarD/CarG-dependent promoters, with one lying immediately upstream of the cas cluster. Consistent with direct action, DdvS and CarD-CarG localize at these promoters in vivo. The cas genes are transcribed as a polycistronic mRNA that reads through the leader into the CRISPR array, a putative σA-dependent promoter in the leader having negligible activity in vivo. Consequently, expression of the entire CRISPR-Cas system and mature CRISPR-RNA (crRNA) production is DdvS/CarD/CarG-dependent. DdvA likely uses its large C-terminal domain to sense and transduce the extracytoplasmic signal triggering CRISPR-cas expression, which we show is not starvation-induced multicellular development. An ECF-σ/anti-σ pair and a global regulatory complex provide an effective mechanism to coordinate signal-sensing with production of precursor crRNA, its processing Cas6 endoribonuclease and other Cas proteins for mature crRNA biogenesis and interference.
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Affiliation(s)
- Diego Bernal-Bernal
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Javier Abellón-Ruiz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Antonio A Iniesta
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Elena Pajares-Martínez
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Eva Bastida-Martínez
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Marta Fontes
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - S Padmanabhan
- Instituto de Química Física 'Rocasolano', Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
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6
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Caulobacter crescentus CdnL is a non-essential RNA polymerase-binding protein whose depletion impairs normal growth and rRNA transcription. Sci Rep 2017; 7:43240. [PMID: 28233804 PMCID: PMC5324124 DOI: 10.1038/srep43240] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 01/23/2017] [Indexed: 12/22/2022] Open
Abstract
CdnL is an essential RNA polymerase (RNAP)-binding activator of rRNA transcription in mycobacteria and myxobacteria but reportedly not in Bacillus. Whether its function and mode of action are conserved in other bacteria thus remains unclear. Because virtually all alphaproteobacteria have a CdnL homolog and none of these have been characterized, we studied the homolog (CdnLCc) of the model alphaproteobacterium Caulobacter crescentus. We show that CdnLCc is not essential for viability but that its absence or depletion causes slow growth and cell filamentation. CdnLCc is degraded in vivo in a manner dependent on its C-terminus, yet excess CdnLCc resulting from its stabilization did not adversely affect growth. We find that CdnLCc interacts with itself and with the RNAP β subunit, and localizes to at least one rRNA promoter in vivo, whose activity diminishes upon depletion of CdnLCc. Interestingly, cells expressing CdnLCc mutants unable to interact with the RNAP were cold-sensitive, suggesting that CdnLCc interaction with RNAP is especially required at lower than standard growth temperatures in C. crescentus. Our study indicates that despite limited sequence similarities and regulatory differences compared to its myco/myxobacterial homologs, CdnLCc may share similar biological functions, since it affects rRNA synthesis, probably by stabilizing open promoter-RNAP complexes.
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7
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Goldberg T, Rost B, Bromberg Y. Computational prediction shines light on type III secretion origins. Sci Rep 2016; 6:34516. [PMID: 27713481 PMCID: PMC5054392 DOI: 10.1038/srep34516] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/15/2016] [Indexed: 01/27/2023] Open
Abstract
Type III secretion system is a key bacterial symbiosis and pathogenicity mechanism responsible for a variety of infectious diseases, ranging from food-borne illnesses to the bubonic plague. In many Gram-negative bacteria, the type III secretion system transports effector proteins into host cells, converting resources to bacterial advantage. Here we introduce a computational method that identifies type III effectors by combining homology-based inference with de novo predictions, reaching up to 3-fold higher performance than existing tools. Our work reveals that signals for recognition and transport of effectors are distributed over the entire protein sequence instead of being confined to the N-terminus, as was previously thought. Our scan of hundreds of prokaryotic genomes identified previously unknown effectors, suggesting that type III secretion may have evolved prior to the archaea/bacteria split. Crucially, our method performs well for short sequence fragments, facilitating evaluation of microbial communities and rapid identification of bacterial pathogenicity – no genome assembly required. pEffect and its data sets are available at http://services.bromberglab.org/peffect.
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Affiliation(s)
- Tatyana Goldberg
- Department of Informatics, Bioinformatics &Computational Biology - I12, TUM, Garching, Germany.,Graduate School, Center of Doctoral Studies in Informatics and its Applications (CeDoSIA), TUM, Garching, Germany
| | - Burkhard Rost
- Department of Informatics, Bioinformatics &Computational Biology - I12, TUM, Garching, Germany.,Institute for Advanced Study (TUM-IAS), Garching, Germany.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Yana Bromberg
- Institute for Advanced Study (TUM-IAS), Garching, Germany.,Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ, USA
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Structure-function dissection of Myxococcus xanthus CarD N-terminal domain, a defining member of the CarD_CdnL_TRCF family of RNA polymerase interacting proteins. PLoS One 2015; 10:e0121322. [PMID: 25811865 PMCID: PMC4374960 DOI: 10.1371/journal.pone.0121322] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/30/2015] [Indexed: 01/08/2023] Open
Abstract
Two prototypes of the large CarD_CdnL_TRCF family of bacterial RNA polymerase (RNAP)-binding proteins, Myxococcus xanthus CarD and CdnL, have distinct functions whose molecular basis remain elusive. CarD, a global regulator linked to the action of several extracytoplasmic function (ECF) σ-factors, binds to the RNAP β subunit (RNAP-β) and to protein CarG via an N-terminal domain, CarDNt, and to DNA via an intrinsically unfolded C-terminal domain resembling eukaryotic high-mobility-group A (HMGA) proteins. CdnL, a CarDNt-like protein that is essential for cell viability, is implicated in σA-dependent rRNA promoter activation and interacts with RNAP-β but not with CarG. While the HMGA-like domain of CarD by itself is inactive, we find that CarDNt has low but observable ability to activate ECF σ-dependent promoters in vivo, indicating that the C-terminal DNA-binding domain is required to maximize activity. Our structure-function dissection of CarDNt reveals an N-terminal, five-stranded β -sheet Tudor-like domain, CarD1-72, whose structure and contacts with RNAP-β mimic those of CdnL. Intriguingly, and in marked contrast to CdnL, CarD mutations that disrupt its interaction with RNAP-β did not annul activity. Our data suggest that the CarDNt C-terminal segment, CarD61-179, may be structurally distinct from its CdnL counterpart, and that it houses at least two distinct and crucial function determinants: (a) CarG-binding, which is specific to CarD; and (b) a basic residue stretch, which is also conserved and functionally required in CdnL. This study highlights the evolution of shared and divergent interactions in similar protein modules that enable the distinct activities of two related members of a functionally important and widespread bacterial protein family.
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9
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Gallego-García A, Mirassou Y, García-Moreno D, Elías-Arnanz M, Jiménez MA, Padmanabhan S. Structural insights into RNA polymerase recognition and essential function of Myxococcus xanthus CdnL. PLoS One 2014; 9:e108946. [PMID: 25272012 PMCID: PMC4182748 DOI: 10.1371/journal.pone.0108946] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/28/2014] [Indexed: 11/18/2022] Open
Abstract
CdnL and CarD are two functionally distinct members of the CarD_CdnL_TRCF family of bacterial RNA polymerase (RNAP)-interacting proteins, which co-exist in Myxococcus xanthus. While CarD, found exclusively in myxobacteria, has been implicated in the activity of various extracytoplasmic function (ECF) σ-factors, the function and mode of action of the essential CdnL, whose homologs are widespread among bacteria, remain to be elucidated in M. xanthus. Here, we report the NMR solution structure of CdnL and present a structure-based mutational analysis of its function. An N-terminal five-stranded β-sheet Tudor-like module in the two-domain CdnL mediates binding to RNAP-β, and mutations that disrupt this interaction impair cell growth. The compact CdnL C-terminal domain consists of five α-helices folded as in some tetratricopeptide repeat-like protein-protein interaction domains, and contains a patch of solvent-exposed nonpolar and basic residues, among which a set of basic residues is shown to be crucial for CdnL function. We show that CdnL, but not its loss-of-function mutants, stabilizes formation of transcriptionally competent, open complexes by the primary σA-RNAP holoenzyme at an rRNA promoter in vitro. Consistent with this, CdnL is present at rRNA promoters in vivo. Implication of CdnL in RNAP-σA activity and of CarD in ECF-σ function in M. xanthus exemplifies how two related members within a widespread bacterial protein family have evolved to enable distinct σ-dependent promoter activity.
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Affiliation(s)
- Aránzazu Gallego-García
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Yasmina Mirassou
- Instituto de Química Física ‘Rocasolano’, Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Madrid, Spain
| | - Diana García-Moreno
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
- * E-mail: (MEA); (MAJ); (SP)
| | - María Angeles Jiménez
- Instituto de Química Física ‘Rocasolano’, Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Madrid, Spain
- * E-mail: (MEA); (MAJ); (SP)
| | - S. Padmanabhan
- Instituto de Química Física ‘Rocasolano’, Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Madrid, Spain
- * E-mail: (MEA); (MAJ); (SP)
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10
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Sarmadian H, Nazari R, Zolfaghari M, Pirayandeh M, Sadrnia M, Arjomandzadegan M, Titov L, Rajabi F, Ahmadi A, Shojapoor M. Study of carD gene sequence in clinical isolates of Mycobacterium tuberculosis. Acta Microbiol Immunol Hung 2014; 61:1-10. [PMID: 24631749 DOI: 10.1556/amicr.61.2014.1.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mycobacterium tuberculosis growth rate is closely coupled to rRNA transcription which is regulated through carD gene. The aim of this study was to determine the sequence of carD gene in drug susceptible and resistant clinical isolates of M. tuberculosis and designing of a PCR assay based on carD sequence for rapid detection of this bacterium.Specific primers for amplification of carD gene were carefully designed, so that whole sequence of gene could be amplified; therefore primers were positioned at the upstream (promoter of this gene and ispD gene) and downstream (in ispD gene). DNA from 41 clinical isolates of M. tuberculosis with different pattern of drug resistance was used in the study. PCR conditions and annealing temperature were designed by means of online programs. PCR products were sequenced by ABI system.PCR product of carD gene was a 524 bp fragment. This method could detect all resistant and susceptible strains of M. tuberculosis. The size of amplified fragment was similar in all investigated samples. Sequence analysis showed that there was similar sequence in all of our isolates therefore probably this gene is considered to be conservative. Translation of nucleotide mode to amino acids was showed that TRCF domain in N-terminal of protein CarD was found to be fully conservative.This is the first study on the sequence of carD gene in clinical isolates of M. tuberculosis. This conservative gene is recommended for use as a target for designing of suitable inhibitors as anti-tuberculosis drug because its importance for life of MTB. In the other hand, a PCR detection method based on detection of carD gene was recommended for rapid detection in routine test.
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Affiliation(s)
- Hossein Sarmadian
- 1 Arak University of Medical Sciences Tuberculosis and Pediatric Infectious Research Center Arak Iran
| | - Razieh Nazari
- 2 Islamic Azad University Department of Microbiology, Faculty of Basic Sciences, Qom Branch Qom Iran
| | - Mohammad Zolfaghari
- 2 Islamic Azad University Department of Microbiology, Faculty of Basic Sciences, Qom Branch Qom Iran
| | - Mina Pirayandeh
- 2 Islamic Azad University Department of Microbiology, Faculty of Basic Sciences, Qom Branch Qom Iran
| | - Maryam Sadrnia
- 3 Payame Noor University Department of Biology P.O. Box 19395-4697 Tehran Iran
| | - Mohammad Arjomandzadegan
- 1 Arak University of Medical Sciences Tuberculosis and Pediatric Infectious Research Center Arak Iran
| | - Leonid Titov
- 4 Belarusian Research Institute for Epidemiology and Microbiology Minsk Belarus
| | - Fariba Rajabi
- 1 Arak University of Medical Sciences Tuberculosis and Pediatric Infectious Research Center Arak Iran
| | - Azam Ahmadi
- 1 Arak University of Medical Sciences Tuberculosis and Pediatric Infectious Research Center Arak Iran
| | - Mana Shojapoor
- 5 Arak University of Medical Sciences Research Center of Molecular Medicine Arak Iran
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11
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Abellón-Ruiz J, Bernal-Bernal D, Abellán M, Fontes M, Padmanabhan S, Murillo FJ, Elías-Arnanz M. The CarD/CarG regulatory complex is required for the action of several members of the large set of Myxococcus xanthus extracytoplasmic function σ factors. Environ Microbiol 2014; 16:2475-90. [PMID: 24428729 DOI: 10.1111/1462-2920.12386] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 12/27/2013] [Indexed: 11/25/2022]
Abstract
Extracytoplasmic function (ECF) σ factors are critical players in signal transduction networks involved in bacterial response to environmental changes. The Myxococcus xanthus genome reveals ∼45 putative ECF-σ factors, but for the overwhelming majority, the specific signals or mechanisms for selective activation and regulation remain unknown. One well-studied ECF-σ, CarQ, binds to its anti-σ, CarR, and is inactive in the dark but drives its own expression from promoter P(QRS) on illumination. This requires the CarD/CarG complex, the integration host factor (IHF) and a specific CarD-binding site upstream of P(QRS). Here, we show that DdvS, a previously uncharacterized ECF-σ, activates its own expression in a CarD/CarG-dependent manner but is inhibited when specifically bound to the N-terminal zinc-binding anti-σ domain of its cognate anti-σ, DdvA. Interestingly, we find that the autoregulatory action of 11 other ECF-σ factors studied here depends totally or partially on CarD/CarG but not IHF. In silico analysis revealed possible CarD-binding sites that may be involved in direct regulation by CarD/CarG of target promoter activity. CarD/CarG-linked ECF-σ regulation likely recurs in other myxobacteria with CarD/CarG orthologous pairs and could underlie, at least in part, the global regulatory effect of the complex on M. xanthus gene expression.
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Affiliation(s)
- Javier Abellón-Ruiz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
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12
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Kaur G, Dutta D, Thakur KG. Crystal structure of Mycobacterium tuberculosis CarD, an essential RNA polymerase binding protein, reveals a quasidomain-swapped dimeric structural architecture. Proteins 2013; 82:879-84. [PMID: 24115125 DOI: 10.1002/prot.24419] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/28/2013] [Accepted: 09/03/2013] [Indexed: 01/22/2023]
Abstract
Mycobacterium tuberculosis (Mtb) CarD is an essential transcriptional regulator that binds RNA polymerase and plays an important role in reprogramming transcription machinery under diverse stress conditions. Here, we report the crystal structure of CarD at 2.3 Å resolution, that represents the first structural description of CarD/CdnL-Like family of proteins. CarD adopts an overall bi-lobed structural architecture where N-terminal domain resembles 'tudor-like' domain and C-terminal domain adopts a novel five helical fold that lacks the predicted leucine zipper structural motif. The structure reveals dimeric state of CarD resulting from β-strand swapping between the N-terminal domains of each individual subunits. The structure provides crucial insights into the possible mode(s) of CarD/RNAP interactions.
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Affiliation(s)
- Gundeep Kaur
- Structural Biology Laboratory, G. N. Ramachandran Protein Centre, CSIR-Institute of Microbial Technology, Chandigarh, 160036, India
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13
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Ramón-García S, Ng C, Jensen PR, Dosanjh M, Burian J, Morris RP, Folcher M, Eltis LD, Grzesiek S, Nguyen L, Thompson CJ. WhiB7, an Fe-S-dependent transcription factor that activates species-specific repertoires of drug resistance determinants in actinobacteria. J Biol Chem 2013; 288:34514-28. [PMID: 24126912 DOI: 10.1074/jbc.m113.516385] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
WhiB-like (Wbl) proteins are well known for their diverse roles in actinobacterial morphogenesis, cell division, virulence, primary and secondary metabolism, and intrinsic antibiotic resistance. Gene disruption experiments showed that three different Actinobacteria (Mycobacterium smegmatis, Streptomyces lividans, and Rhodococcus jostii) each exhibited a different whiB7-dependent resistance profile. Heterologous expression of whiB7 genes showed these resistance profiles reflected the host's repertoire of endogenous whiB7-dependent genes. Transcriptional activation of two resistance genes in the whiB7 regulon, tap (a multidrug transporter) and erm(37) (a ribosomal methyltransferase), required interaction of WhiB7 with their promoters. Furthermore, heterologous expression of tap genes isolated from Mycobacterium species demonstrated that divergencies in drug specificity of homologous structural proteins contribute to the variation of WhiB7-dependent drug resistance. WhiB7 has a specific tryptophan/glycine-rich region and four conserved cysteine residues; it also has a peptide sequence (AT-hook) at its C terminus that binds AT-rich DNA sequence motifs upstream of the promoters it activates. Targeted mutagenesis showed that these motifs were required to provide antibiotic resistance in vivo. Anaerobically purified WhiB7 from S. lividans was dimeric and contained 2.1 ± 0.3 and 2.2 ± 0.3 mol of iron and sulfur, respectively, per protomer (consistent with the presence of a 2Fe-2S cluster). However, the properties of the dimer's absorption spectrum were most consistent with the presence of an oxygen-labile 4Fe-4S cluster, suggesting 50% occupancy. These data provide the first insights into WhiB7 iron-sulfur clusters as they exist in vivo, a major unresolved issue in studies of Wbl proteins.
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Affiliation(s)
- Santiago Ramón-García
- From the Department of Microbiology and Immunology, Centre for Tuberculosis Research, Life Sciences Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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14
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Comparative RNA-sequencing of the acarbose producer Actinoplanes sp. SE50/110 cultivated in different growth media. J Biotechnol 2013; 167:166-77. [DOI: 10.1016/j.jbiotec.2012.10.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 09/18/2012] [Accepted: 10/28/2012] [Indexed: 12/14/2022]
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15
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Mirassou Y, Elías-Arnanz M, Padmanabhan S, Jiménez MA. (1)H, (13)C and (15)N assignments of CdnL, an essential protein in Myxococcus xanthus. BIOMOLECULAR NMR ASSIGNMENTS 2013; 7:51-55. [PMID: 22392343 DOI: 10.1007/s12104-012-9375-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 02/25/2012] [Indexed: 05/31/2023]
Abstract
CdnL, an essential protein in Myxococcus xanthus and several other bacteria, is a member of the large CarD_TRCF family of bacterial proteins that interact with RNA polymerase. Structural analyses of the 164-residue M. xanthus CdnL by NMR is complicated because of broadening, and hence overlap, of the signals due to the self-association and the monomer-dimer equilibrium that occurs in solution. Here, we report (1)H, (13)C and (15)N assignments for CdnL achieved by analyzing its NMR spectra on the basis of the complete assignment obtained in this study for the 68-residue N-terminal fragment of CdnL (CdnLNt) together with those we described previously for the stable, protease-resistant, 110-residue C-terminal domain (CdnLCt). This approach relied on our observation that many of the CdnLNt and CdnLCt chemical shifts matched closely with those of the equivalent residues in the full-length protein. Our assignments provide the crucial first step in the structural analysis of CdnL and this functionally important family of bacterial proteins.
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Affiliation(s)
- Yasmina Mirassou
- Instituto de Química Física Rocasolano, CSIC, 28006, Madrid, Spain
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16
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High-mobility-group a-like CarD binds to a DNA site optimized for affinity and position and to RNA polymerase to regulate a light-inducible promoter in Myxococcus xanthus. J Bacteriol 2012; 195:378-88. [PMID: 23144251 DOI: 10.1128/jb.01766-12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The CarD-CarG complex controls various cellular processes in the bacterium Myxococcus xanthus including fruiting body development and light-induced carotenogenesis. The CarD N-terminal domain, which defines the large CarD_CdnL_TRCF protein family, binds to CarG, a zinc-associated protein that does not bind DNA. The CarD C-terminal domain resembles eukaryotic high-mobility-group A (HMGA) proteins, and its DNA binding AT hooks specifically recognize the minor groove of appropriately spaced AT-rich tracts. Here, we investigate the determinants of the only known CarD binding site, the one crucial in CarD-CarG regulation of the promoter of the carQRS operon (P(QRS)), a light-inducible promoter dependent on the extracytoplasmic function (ECF) σ factor CarQ. In vitro, mutating either of the 3-bp AT tracts of this CarD recognition site (TTTCCAGAGCTTT) impaired DNA binding, shifting the AT tracts relative to P(QRS) had no effect or marginally lowered DNA binding, and replacing the native site by the HMGA1a binding one at the human beta interferon promoter (with longer AT tracts) markedly enhanced DNA binding. In vivo, however, all of these changes deterred P(QRS) activation in wild-type M. xanthus, as well as in a strain with the CarD-CarG pair replaced by the Anaeromyxobacter dehalogenans CarD-CarG (CarD(Ad)-CarG(Ad)). CarD(Ad)-CarG(Ad) is functionally equivalent to CarD-CarG despite the lower DNA binding affinity in vitro of CarD(Ad), whose C-terminal domain resembles histone H1 rather than HMGA. We show that CarD physically associates with RNA polymerase (RNAP) specifically via interactions with the RNAP β subunit. Our findings suggest that CarD regulates a light-inducible, ECF σ-dependent promoter by coupling RNAP recruitment and binding to a specific DNA site optimized for affinity and position.
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17
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Gallego-García A, Mirassou Y, Elías-Arnanz M, Padmanabhan S, Jiménez MA. NMR structure note: N-terminal domain of Thermus thermophilus CdnL. JOURNAL OF BIOMOLECULAR NMR 2012; 53:355-363. [PMID: 22782235 DOI: 10.1007/s10858-012-9648-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/19/2012] [Indexed: 06/01/2023]
Affiliation(s)
- Aranzazu Gallego-García
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", 30100 Murcia, Spain
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18
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Westblade LF, Campbell EA, Pukhrambam C, Padovan JC, Nickels BE, Lamour V, Darst SA. Structural basis for the bacterial transcription-repair coupling factor/RNA polymerase interaction. Nucleic Acids Res 2010; 38:8357-69. [PMID: 20702425 PMCID: PMC3001067 DOI: 10.1093/nar/gkq692] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The transcription-repair coupling factor (TRCF, the product of the mfd gene) is a widely conserved bacterial protein that mediates transcription-coupled DNA repair. TRCF uses its ATP-dependent DNA translocase activity to remove transcription complexes stalled at sites of DNA damage, and stimulates repair by recruiting components of the nucleotide excision repair pathway to the site. A protein/protein interaction between TRCF and the β-subunit of RNA polymerase (RNAP) is essential for TRCF function. CarD (also called CdnL), an essential regulator of rRNA transcription in Mycobacterium tuberculosis, shares a homologous RNAP interacting domain with TRCF and also interacts with the RNAP β-subunit. We determined the 2.9-Å resolution X-ray crystal structure of the RNAP interacting domain of TRCF complexed with the RNAP-β1 domain, which harbors the TRCF interaction determinants. The structure reveals details of the TRCF/RNAP protein/protein interface, providing a basis for the design and interpretation of experiments probing TRCF, and by homology CarD, function and interactions with the RNAP.
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Affiliation(s)
- Lars F Westblade
- Laboratory of Molecular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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19
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Elías-Arnanz M, Padmanabhan S, Murillo FJ. The regulatory action of the myxobacterial CarD/CarG complex: a bacterial enhanceosome? FEMS Microbiol Rev 2010; 34:764-78. [PMID: 20561058 DOI: 10.1111/j.1574-6976.2010.00235.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A global regulatory complex made up of two unconventional transcriptional factors, CarD and CarG, is implicated in the control of various processes in Myxococcus xanthus, a Gram-negative bacterium that serves as a prokaryotic model system for multicellular development and the response to blue light. CarD has a unique two-domain architecture composed of: (1) a C-terminal DNA-binding domain that resembles eukaryotic high mobility group A (HMGA) proteins, which are relatively abundant, nonhistone components of chromatin that remodel DNA and prime it for the assembly of multiprotein-DNA complexes essential for various DNA transactions, and (2) an N-terminal domain involved in interactions with CarG and RNA polymerase, which is also the founding member of the large CarD_TRCF family of bacterial proteins. CarG, which does not bind DNA directly, has a zinc-binding motif of the type found in the archaemetzincin class of metalloproteases that, in CarG, appears to play a purely structural role. This review aims to provide an overview of the known molecular details and insights emerging from the study of the singular CarD-CarG prokaryotic regulatory complex and its parallels with enhanceosomes, the higher order, nucleoprotein transcription complexes in eukaryotes.
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Affiliation(s)
- Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Area de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
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20
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García-Moreno D, Abellón-Ruiz J, García-Heras F, Murillo FJ, Padmanabhan S, Elías-Arnanz M. CdnL, a member of the large CarD-like family of bacterial proteins, is vital for Myxococcus xanthus and differs functionally from the global transcriptional regulator CarD. Nucleic Acids Res 2010; 38:4586-98. [PMID: 20371514 PMCID: PMC2919716 DOI: 10.1093/nar/gkq214] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
CarD, a global transcriptional regulator in Myxococcus xanthus, interacts with CarG via CarDNter, its N-terminal domain, and with DNA via a eukaryotic HMGA-type C-terminal domain. Genomic analysis reveals a large number of standalone proteins resembling CarDNter. These constitute, together with the RNA polymerase (RNAP) interacting domain, RID, of transcription–repair coupling factors, the CarD_TRCF protein family. We show that one such CarDNter-like protein, M. xanthus CdnL, cannot functionally substitute CarDNter (or vice versa) nor interact with CarG. Unlike CarD, CdnL is vital for growth, and lethality due to its absence is not rescued by homologs from various other bacteria. In mycobacteria, with no endogenous DksA, the function of the CdnL homolog mirrors that of Escherichia coli DksA. Our finding that CdnL, like DksA, is indispensable in M. xanthus implies that they are not functionally redundant. Cells are normal on CdnL overexpression, but divide aberrantly on CdnL depletion. CdnL localizes to the nucleoid, suggesting piggyback recruitment by factors such as RNAP, which we show interacts with CdnL, CarDNter and RID. Our study highlights a complex network of interactions involving these factors and RNAP, and points to a vital role for M. xanthus CdnL in an essential DNA transaction that affects cell division.
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Affiliation(s)
- Diana García-Moreno
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain
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21
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Functional equivalence of HMGA- and histone H1-like domains in a bacterial transcriptional factor. Proc Natl Acad Sci U S A 2009; 106:13546-51. [PMID: 19666574 DOI: 10.1073/pnas.0902233106] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Histone H1 and high-mobility group A (HMGA) proteins compete dynamically to modulate chromatin structure and regulate DNA transactions in eukaryotes. In prokaryotes, HMGA-like domains are known only in Myxococcus xanthus CarD and its Stigmatella aurantiaca ortholog. These have an N-terminal module absent in HMGA that interacts with CarG (a zinc-associated factor that does not bind DNA) to form a stable complex essential in regulating multicellular development, light-induced carotenogenesis, and other cellular processes. An analogous pair, CarD(Ad) and CarG(Ad), exists in another myxobacterium, Anaeromyxobacter dehalogenans. Intriguingly, the CarD(Ad) C terminus lacks the hallmark HMGA DNA-binding AT-hooks and instead resembles the C-terminal region (CTR) of histone H1. We find that CarD(Ad) alone could not replace CarD in M. xanthus. By contrast, when introduced with CarG(Ad), CarD(Ad) functionally replaced CarD in regulating not just 1 but 3 distinct processes in M. xanthus, despite the lower DNA-binding affinity of CarD(Ad) versus CarD in vitro. The ability of the cognate CarD(Ad)-CarG(Ad) pair to interact, but not the noncognate CarD(Ad)-CarG, rationalizes these data. Thus, in chimeras that conserve CarD-CarG interactions, the H1-like CTR of CarD(Ad) could replace the CarD HMGA AT-hooks with no loss of function in vivo. More tellingly, even chimeras with the CarD AT-hook region substituted by human histone H1 CTR or full-length H1 functioned in M. xanthus. Our domain-swap analyses showing functional equivalence of HMGA AT-hooks and H1 CTR in prokaryotic transcriptional regulation provide molecular insights into possible modes of action underlying their biological roles.
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22
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Stallings CL, Stephanou NC, Chu L, Hochschild A, Nickels BE, Glickman MS. CarD is an essential regulator of rRNA transcription required for Mycobacterium tuberculosis persistence. Cell 2009; 138:146-59. [PMID: 19596241 DOI: 10.1016/j.cell.2009.04.041] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 02/01/2009] [Accepted: 04/13/2009] [Indexed: 12/14/2022]
Abstract
Mycobacterium tuberculosis is arguably the world's most successful infectious agent because of its ability to control its own cell growth within the host. Bacterial growth rate is closely coupled to rRNA transcription, which in E. coli is regulated through DksA and (p)ppGpp. The mechanisms of rRNA transcriptional control in mycobacteria, which lack DksA, are undefined. Here we identify CarD as an essential mycobacterial protein that controls rRNA transcription. Loss of CarD is lethal for mycobacteria in culture and during infection of mice. CarD depletion leads to sensitivity to killing by oxidative stress, starvation, and DNA damage, accompanied by failure to reduce rRNA transcription. CarD can functionally replace DksA for stringent control of rRNA transcription, even though CarD associates with a different site on RNA polymerase. These findings highlight a distinct molecular mechanism for regulating rRNA transcription in mycobacteria that is critical for M. tuberculosis pathogenesis.
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23
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Mirassou Y, García-Moreno D, Santiveri CM, Santoro J, Elías-Arnanz M, Padmanabhan S, Jiménez MA. 1H, 13C and 15N backbone and side chain resonance assignments of the C-terminal domain of CdnL from Myxococcus xanthus. BIOMOLECULAR NMR ASSIGNMENTS 2009; 3:9-12. [PMID: 19636935 DOI: 10.1007/s12104-008-9128-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 10/31/2008] [Indexed: 05/28/2023]
Abstract
CdnL, a 164-residue protein essential for Myxococcus xanthus viability, is a member of a large family of bacterial proteins of unknown structure and function. Here, we report the (1)H, (13)C and (15)N backbone and side chain assignments for the stable C-terminal domain of CdnL identified by limited proteolysis.
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Affiliation(s)
- Yasmina Mirassou
- Instituto de Química Física Rocasolano, CSIC, 28006, Madrid, Spain
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24
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Galbis-Martínez L, Galbis-Martínez M, Murillo FJ, Fontes M. An anti-antisigma factor in the response of the bacterium Myxococcus xanthus to blue light. MICROBIOLOGY-SGM 2008; 154:895-904. [PMID: 18310035 DOI: 10.1099/mic.0.2007/013359-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cells of the Gram-negative bacterium Myxococcus xanthus respond to blue light by producing carotenoids, pigments that play a protective role against the oxidative effects of light. Blue light triggers a network of regulatory actions that lead to the transcriptional activation of the structural genes for carotenoid synthesis. The product of carF, similar to a family of proteins of unknown function called Kua, is an early regulator of this process. Previous genetic data indicate that CarF participates in the light-dependent inactivation of the antisigma factor CarR. In the dark, CarR sequesters the ECF-sigma factor CarQ to the membrane, thereby preventing the activation of the structural genes for carotenoid synthesis. Using a bacterial two-hybrid system, we show here that both CarF and CarQ physically interact with CarR. These results, together with the finding that CarF is located at the membrane, support the hypothesis that CarF acts as an anti-antisigma factor. Comparison of CarF with other Kua proteins shows a remarkable conservation of a number of histidine residues. The effects on CarF function of several histidine to alanine substitutions and of the truncation of specific CarF domains are also reported here.
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Affiliation(s)
- Lilian Galbis-Martínez
- Departamento de Genética y Microbiología (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Marisa Galbis-Martínez
- Departamento de Genética y Microbiología (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Francisco J Murillo
- Departamento de Genética y Microbiología (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
| | - Marta Fontes
- Departamento de Genética y Microbiología (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
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25
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Pérez-Marín MC, Padmanabhan S, Polanco MC, Murillo FJ, Elías-Arnanz M. Vitamin B12 partners the CarH repressor to downregulate a photoinducible promoter in Myxococcus xanthus. Mol Microbiol 2008; 67:804-19. [PMID: 18315685 DOI: 10.1111/j.1365-2958.2007.06086.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A light-inducible promoter, P(B), drives expression of the carB operon in Myxococcus xanthus. Repressed by CarA in the dark, P(B) is activated when CarS, produced in the light, sequesters CarA to prevent operator-CarA binding. The MerR-type, N-terminal domain of CarA, which mediates interactions with both operator and CarS, is linked to a C-terminal oligomerization module with a predicted cobalamin-binding motif. Here, we show that although CarA does bind vitamin B12, mutating the motif involved has no effect on its ability to repress P(B). Intriguingly, P(B) could be repressed in the dark even with no CarA, so long as B12 and an intact CarA operator were present. We have discovered that this effect of B12 depends on the gene immediately downstream of carA. Its product, CarH, also consists of a MerR-type, N-terminal domain that specifically recognizes the CarA operator and CarS, linked to a predicted B12-binding C-terminal oligomerization module. The B12-mediated repression of P(B) in the dark is relieved by deleting carH, by mutating the DNA- or B12-binding residues of CarH, or by illumination. Our findings unveil parallel regulatory circuits that control a light-inducible promoter using a transcriptional factor repertoire that includes a paralogous gene pair and vitamin B12.
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Affiliation(s)
- Mari Cruz Pérez-Marín
- Departamento de Genética y Microbiología, Area de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia 30100, Spain
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26
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Navarro-Avilés G, Jiménez MA, Pérez-Marín MC, González C, Rico M, Murillo FJ, Elías-Arnanz M, Padmanabhan S. Structural basis for operator and antirepressor recognition by Myxococcus xanthus CarA repressor. Mol Microbiol 2007; 63:980-94. [PMID: 17233828 DOI: 10.1111/j.1365-2958.2006.05567.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Blue light induces carotenogenesis in Myxococcus xanthus. The carB operon encodes all but one of the structural genes involved, and its expression is regulated by the CarA-CarS repressor-antirepressor pair. In the dark, CarA-operator binding represses carB. CarS, produced on illumination, interacts physically with CarA to dismantle the CarA-operator complex and activate carB. Both operator and CarS bind to the autonomously folded N-terminal domain of CarA, CarA(Nter), which in excess represses carB. Here, we report the NMR structure of CarA(Nter), and map residues that interact with operator and CarS by NMR chemical shift perturbations, and in vivo and in vitro analyses of site-directed mutants. We show CarA(Nter) adopts the winged-helix topology of MerR-family DNA-binding domains, and conserves the majority of the helix-turn-helix and wing contacts with DNA. Tellingly, helix alpha2 in CarA, a key element in operator DNA recognition, is also critical for interaction with CarS, implying that the CarA-CarS protein-protein and the CarA-operator protein-DNA interfaces overlap. Thus, binding of CarA to operator and to antirepressor are mutually exclusive, and CarA may discern structural features in the acidic CarS protein that resemble operator DNA. Repressor inactivation by occluding the DNA-binding region may be a recurrent mechanism of action for acidic antirepressors.
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Affiliation(s)
- Gloria Navarro-Avilés
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain
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27
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Weselake RJ, Madhavji M, Szarka SJ, Patterson NA, Wiehler WB, Nykiforuk CL, Burton TL, Boora PS, Mosimann SC, Foroud NA, Thibault BJ, Moloney MM, Laroche A, Furukawa-Stoffer TL. Acyl-CoA-binding and self-associating properties of a recombinant 13.3 kDa N-terminal fragment of diacylglycerol acyltransferase-1 from oilseed rape. BMC BIOCHEMISTRY 2006; 7:24. [PMID: 17192193 PMCID: PMC1764880 DOI: 10.1186/1471-2091-7-24] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Accepted: 12/27/2006] [Indexed: 12/01/2022]
Abstract
Background Diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the acyl-CoA-dependent acylation of sn-1, 2-diacylglycerol to generate triacylglycerol and CoA. The deduced amino acid sequence of cDNAs encoding DGAT1 from plants and mammals exhibit a hydrophilic N-terminal region followed by a number of potential membrane-spanning segments, which is consistent with the membrane-bound nature of this enzyme family. In order to gain insight into the structure/function properties of DGAT1 from Brassica napus (BnDGAT1), we produced and partially characterized a recombinant polyHis-tagged N-terminal fragment of the enzyme, BnDGAT1(1–116)His6, with calculated molecular mass of 13,278 Da. Results BnDGAT1(1–116)His6 was highly purified from bacterial lysate and plate-like monoclinic crystals were grown using this preparation. Lipidex-1000 binding assays and gel electrophoresis indicated that BnDGAT1(1–116)His6 interacts with long chain acyl-CoA. The enzyme fragment displayed enhanced affinity for erucoyl (22:1cisΔ13)-CoA over oleoyl (18:1cisΔ9)-CoA, and the binding process displayed positive cooperativity. Gel filtration chromatography and cross-linking studies indicated that BnDGAT1(1–116)His6 self-associated to form a tetramer. Polyclonal antibodies raised against a peptide of 15 amino acid residues representing a segment of BnDGAT1(1–116)His6 failed to react with protein in microsomal vesicles following treatment with proteinase K, suggesting that the N-terminal fragment of BnDGAT1 was localized to the cytosolic side of the ER. Conclusion Collectively, these results suggest that BnDGAT1 may be allosterically modulated by acyl-CoA through the N-terminal region and that the enzyme self-associates via interactions on the cytosolic side of the ER.
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Affiliation(s)
- Randall J Weselake
- Department of Agricultural, Food and Nutritional Science, 4-10 Agriculture/Forestry Centre, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada
| | - Milan Madhavji
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Steve J Szarka
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
- Present address : SemBioSys Genetics Inc., 110, 2985 23 Avenue N.E., Calgary, AB T1Y 7L3, Canada
| | - Nii A Patterson
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
- Present address: Metabolix Inc., 21 Erie Street, Cambridge, MA 02139, USA
| | - William B Wiehler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Cory L Nykiforuk
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
- Present address : SemBioSys Genetics Inc., 110, 2985 23 Avenue N.E., Calgary, AB T1Y 7L3, Canada
| | - Tracy L Burton
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Parveen S Boora
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Steven C Mosimann
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Nora A Foroud
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Benjamin J Thibault
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
| | - Maurice M Moloney
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - André Laroche
- Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta P.O. Box 3000 Main, Lethbridge, Alberta, T1J 4B1, Canada
| | - Tara L Furukawa-Stoffer
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, T1K 3M4, Canada
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Peñalver-Mellado M, García-Heras F, Padmanabhan S, García-Moreno D, Murillo FJ, Elías-Arnanz M. Recruitment of a novel zinc-bound transcriptional factor by a bacterial HMGA-type protein is required for regulating multiple processes in Myxococcus xanthus. Mol Microbiol 2006; 61:910-26. [PMID: 16879646 DOI: 10.1111/j.1365-2958.2006.05289.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enhanceosome assembly in eukaryotes often requires high mobility group A (HMGA) proteins. In prokaryotes, the only known transcriptional regulator with HMGA-like physical, structural and DNA-binding properties is Myxococcus xanthus CarD. Here, we report that every CarD-regulated process analysed also requires the product of gene carG, located immediately downstream of and transcriptionally coupled to carD. CarG has the zinc-binding H/C-rich metallopeptidase motif found in archaemetzincins, but with Q replacing a catalytically essential E. CarG, a monomer, binds two zinc atoms, shows no apparent metallopeptidase activity, and its stability in vivo absolutely requires the cysteines. This indicates a strictly structural role for zinc-binding. In vivo CarG localizes to the nucleoid but only if CarD is also present. In vitro CarG shows no DNA-binding but physically interacts with CarD via its N-terminal and not HMGA domain. CarD and CarG thus work as a single, physically linked, transcriptional regulatory unit, and if one exists in a bacterium so does the other. Like zinc-associated eukaryotic transcriptional adaptors in enhanceosome assembly, CarG regulates by interacting not with DNA but with another transcriptional factor.
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Affiliation(s)
- Marcos Peñalver-Mellado
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia 30100, Spain
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29
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Stafford GP, Ogi T, Hughes C. Binding and transcriptional activation of non-flagellar genes by the Escherichia coli flagellar master regulator FlhD2C2. MICROBIOLOGY-SGM 2005; 151:1779-1788. [PMID: 15941987 PMCID: PMC2528288 DOI: 10.1099/mic.0.27879-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The gene hierarchy directing biogenesis of peritrichous flagella on the surface of Escherichia coli and other enterobacteria is controlled by the heterotetrameric master transcriptional regulator FlhD(2)C(2). To assess the extent to which FlhD(2)C(2) directly activates promoters of a wider regulon, a computational screen of the E. coli genome was used to search for gene-proximal DNA sequences similar to the 42-44 bp inverted repeat FlhD(2)C(2) binding consensus. This identified the binding sequences upstream of all eight flagella class II operons, and also putative novel FlhD(2)C(2) binding sites in the promoter regions of 39 non-flagellar genes. Nine representative non-flagellar promoter regions were all bound in vitro by active reconstituted FlhD(2)C(2) over the K(D) range 38-356 nM, and of the nine corresponding chromosomal promoter-lacZ fusions, those of the four genes b1904, b2446, wzz(fepE) and gltI showed up to 50-fold dependence on FlhD(2)C(2) in vivo. In comparison, four representative flagella class II promoters bound FlhD(2)C(2) in the K(D) range 12-43 nM and were upregulated in vivo 30- to 990-fold. The FlhD(2)C(2)-binding sites of the four regulated non-flagellar genes overlap by 1 or 2 bp the predicted -35 motif of the FlhD(2)C(2)-activated sigma(70) promoters, as is the case with FlhD(2)C(2)-dependent class II flagellar promoters. The data indicate a wider FlhD(2)C(2) regulon, in which non-flagellar genes are bound and activated directly, albeit less strongly, by the same mechanism as that regulating the flagella gene hierarchy.
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Affiliation(s)
- Graham P. Stafford
- University of Cambridge, Department of Pathology, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Tomoo Ogi
- Genome Damage and Stability Centre, University of Sussex, Science Park Road, Falmer, Brighton BN1 9QG, UK
| | - Colin Hughes
- University of Cambridge, Department of Pathology, Tennis Court Road, Cambridge CB2 1QP, UK
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30
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Galbis-Martínez M, Fontes M, Murillo FJ. The high-mobility group A-type protein CarD of the bacterium Myxococcus xanthus as a transcription factor for several distinct vegetative genes. Genetics 2005; 167:1585-95. [PMID: 15342500 PMCID: PMC1471020 DOI: 10.1534/genetics.104.029207] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CarD is the only reported prokaryotic protein showing structural and functional features typical of eukaryotic high-mobility group A transcription factors. In prokaryotes, proteins similar to CarD appear to be confined primarily to myxobacteria. In Myxococcus xanthus, CarD has been previously shown to act as a positive element in two different regulatory networks: one for light-induced synthesis of carotenoids and the other for starvation-induced fruiting body formation. We have now tested the effect of a loss-of-function mutation in the carD gene (carD1) on the expression of a random collection of lacZ-tagged genes, which are normally expressed in the dark during vegetative growth in rich medium. Our results indicate that CarD plays a significant role in the transcriptional regulation of various indicated genes. The carD1 mutation downregulates some genes and upregulates others. Also reported here is the isolation of several mutations that suppress the strong effect of carD1 on the expression of a particular vegetative gene. One of them (sud-2) also suppresses the effect of carD1 on other vegetative genes and on fruiting-body formation. Thus, CarD and the sud-2 gene product appear to participate in a single mechanism, which underlies various apparently diverse regulatory phenomena ascribed to CarD.
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Affiliation(s)
- Marisa Galbis-Martínez
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain
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31
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Pérez-Marín MC, López-Rubio JJ, Murillo FJ, Elías-Arnanz M, Padmanabhan S. The N terminus of Myxococcus xanthus CarA repressor is an autonomously folding domain that mediates physical and functional interactions with both operator DNA and antirepressor protein. J Biol Chem 2004; 279:33093-103. [PMID: 15163666 DOI: 10.1074/jbc.m405225200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of the Myxococcus xanthus carB operon, which encodes the majority of the enzymes involved in light-induced carotenogenesis, is down-regulated in the dark by the CarA repressor binding to its bipartite operator. CarS, produced on illumination, relieves repression of carB by physically interacting with CarA to dis-mantle CarA-DNA complexes. Here, we demonstrate that the N- and C-terminal portions of CarA are organized as distinct structural and functional domains. Specifically, we show that the 78 N-terminal residues of CarA, CarA(Nter), form a monomeric, highly helical, autonomously folding unit with significant structural stability. Significantly, CarA(Nter) houses both the operator and CarS binding specificity determinants of CarA. CarA(Nter) binds operator with a lower affinity than whole CarA, and the CarA(Nter)-CarS complex has a 1:1 stoichiometry. In vitro, sufficiently high concentrations of CarA(Nter) block M. xanthus RNA polymerase-promoter binding, and this is relieved by CarS. In vivo, substitution of the gene carA by that for CarA(Nter) results in constitutive expression of carB just as in a carA-deleted background. However, re-engineering the latter strain to overexpress CarA(Nter) restores repression of carB. Thus, the 78-residue N-terminal portion of CarA is an autonomously folded, dual function domain that orchestrates specific DNA-protein and protein-protein interactions and, when overexpressed, can be functionally competent in vivo.
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Affiliation(s)
- Mari Cruz Pérez-Marín
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia 30071, Spain
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32
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López-Rubio JJ, Padmanabhan S, Lázaro JM, Salas M, Murillo FJ, Elías-Arnanz M. Operator design and mechanism for CarA repressor-mediated down-regulation of the photoinducible carB operon in Myxococcus xanthus. J Biol Chem 2004; 279:28945-53. [PMID: 15123730 DOI: 10.1074/jbc.m403459200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The carB operon encodes all except one of the enzymes involved in light-induced carotenogenesis in Myxococcus xanthus. Expression of its promoter (P(B)) is repressed in the dark by sequence-specific DNA binding of CarA to a palindrome (pI) located between positions -47 and -64 relative to the transcription start site. This promotes subsequent binding of CarA to additional sites that remain to be defined. CarS, produced in the light, interacts physically with CarA, abrogates CarA-DNA binding, and thereby derepresses P(B). In this study, we delineate the operator design that exists for CarA by precisely mapping out the second operator element. For this, we examined how stepwise deletions and site-directed mutagenesis in the region between the palindrome and the transcription start site affect CarA binding around P(B) in vitro and expression of P(B) in vivo. These revealed the second operator element to be an imperfect interrupted palindrome (pII) spanning positions -26 to -40. In vitro assays using purified M. xanthus RNA polymerase showed that CarA abolishes P(B)-RNA polymerase binding and runoff transcription and that both were restored by CarS, thus rationalizing the observations in vivo. CarA binding to pII (after association with pI) effectively occludes RNA polymerase from P(B) and so provides the operative mechanism for the repression of the carB operon by CarA. The bipartite operator design, whereby transcription is blocked by the low affinity CarA-pII binding and is readily restored by CarS, may have evolved to match the needs for a rapid and an effective response to light.
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Affiliation(s)
- José Juan López-Rubio
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia 30071
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