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Oladosu VI, Park S, Sauer K. Flip the switch: the role of FleQ in modulating the transition between the free-living and sessile mode of growth in Pseudomonas aeruginosa. J Bacteriol 2024; 206:e0036523. [PMID: 38436566 PMCID: PMC10955856 DOI: 10.1128/jb.00365-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen causing chronic infections that are associated with the sessile/biofilm mode of growth rather than the free-living/planktonic mode of growth. The transcriptional regulator FleQ contributes to both modes of growth by functioning both as an activator and repressor and inversely regulating flagella genes associated with the planktonic mode of growth and genes contributing to the biofilm mode of growth. Here, we review findings that enhance our understanding of the molecular mechanism by which FleQ enables the transition between the two modes of growth. We also explore recent advances in the mechanism of action of FleQ to both activate and repress gene expression from a single promoter. Emphasis will be on the role of sigma factors, cyclic di-GMP, and the transcriptional regulator AmrZ in inversely regulating flagella and biofilm-associated genes and converting FleQ from a repressor to an activator.
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Affiliation(s)
- Victoria I. Oladosu
- Department of Biological Sciences, Binghamton University, Binghamton, New York, USA
| | - Soyoung Park
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, New York, USA
| | - Karin Sauer
- Department of Biological Sciences, Binghamton University, Binghamton, New York, USA
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2
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Blanco-Romero E, Durán D, Garrido-Sanz D, Redondo-Nieto M, Martín M, Rivilla R. Adaption of Pseudomonas ogarae F113 to the Rhizosphere Environment-The AmrZ-FleQ Hub. Microorganisms 2023; 11:microorganisms11041037. [PMID: 37110460 PMCID: PMC10146422 DOI: 10.3390/microorganisms11041037] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/10/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Motility and biofilm formation are two crucial traits in the process of rhizosphere colonization by pseudomonads. The regulation of both traits requires a complex signaling network that is coordinated by the AmrZ-FleQ hub. In this review, we describe the role of this hub in the adaption to the rhizosphere. The study of the direct regulon of AmrZ and the phenotypic analyses of an amrZ mutant in Pseudomonas ogarae F113 has shown that this protein plays a crucial role in the regulation of several cellular functions, including motility, biofilm formation, iron homeostasis, and bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) turnover, controlling the synthesis of extracellular matrix components. On the other hand, FleQ is the master regulator of flagellar synthesis in P. ogarae F113 and other pseudomonads, but its implication in the regulation of multiple traits related with environmental adaption has been shown. Genomic scale studies (ChIP-Seq and RNA-Seq) have shown that in P. ogarae F113, AmrZ and FleQ are general transcription factors that regulate multiple traits. It has also been shown that there is a common regulon shared by the two transcription factors. Moreover, these studies have shown that AmrZ and FleQ form a regulatory hub that inversely regulate traits such as motility, extracellular matrix component production, and iron homeostasis. The messenger molecule c-di-GMP plays an essential role in this hub since its production is regulated by AmrZ and it is sensed by FleQ and required for its regulatory role. This regulatory hub is functional both in culture and in the rhizosphere, indicating that the AmrZ-FleQ hub is a main player of P. ogarae F113 adaption to the rhizosphere environment.
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Affiliation(s)
- Esther Blanco-Romero
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - David Durán
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Daniel Garrido-Sanz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Miguel Redondo-Nieto
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Rafael Rivilla
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
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3
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AIDmut-Seq: a Three-Step Method for Detecting Protein-DNA Binding Specificity. Microbiol Spectr 2023; 11:e0378322. [PMID: 36533916 PMCID: PMC9927353 DOI: 10.1128/spectrum.03783-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Transcriptional factors (TFs) and their regulons make up the gene regulatory networks. Here, we developed a method based on TF-directed activation-induced cytidine deaminase (AID) mutagenesis in combination with genome sequencing, called AIDmut-Seq, to detect TF targets on the genome. AIDmut-Seq involves only three simple steps, including the expression of the AID-TF fusion protein, whole-genome sequencing, and single nucleotide polymorphism (SNP) profiling, making it easy for junior and interdisciplinary researchers to use. Using AIDmut-Seq for the major quorum sensing regulator LasR in Pseudomonas aeruginosa, we confirmed that a few TF-guided C-T (or G-A) conversions occurred near their binding boxes on the genome, and a number of previously characterized and uncharacterized LasR-binding sites were detected. Further verification of AIDmut-Seq using various transcriptional regulators demonstrated its high efficiency for most transcriptional activators (FleQ, ErdR, GacA, ExsA). We confirmed the binding of LasR, FleQ, and ErdR to 100%, 50%, and 86% of their newly identified promoters by using in vitro protein-DNA binding assay. And real-time RT-PCR data validated the intracellular activity of these TFs to regulate the transcription of those newly found target promoters. However, AIDmut-Seq exhibited low efficiency for some small transcriptional repressors such as RsaL and AmrZ, with possible reasons involving fusion-induced TF dysfunction as well as low transcription rates of target promoters. Although there are false-positive and false-negative results in the AIDmut-Seq data, preliminary results have demonstrated the value of AIDmut-Seq to act as a complementary tool for existing methods. IMPORTANCE Protein-DNA interactions (PDI) play a central role in gene regulatory networks (GRNs). However, current techniques for studying genome-wide PDI usually involve complex experimental procedures, which prevent their broad use by scientific researchers. In this study, we provide a in vivo method called AIDmut-Seq. AIDmut-Seq involves only three simple steps that are easy to operate for researchers with basic skills in molecular biology. The efficiency of AIDmut-Seq was tested and confirmed using multiple transcription factors in Pseudomonas aeruginosa. Although there are still some defects regarding false-positive and false-negative results, AIDmut-Seq will be a good choice in the early stage of PDI study.
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4
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Chautrand T, Depayras S, Souak D, Bouteiller M, Kondakova T, Barreau M, Ben Mlouka MA, Hardouin J, Konto-Ghiorghi Y, Chevalier S, Merieau A, Orange N, Duclairoir-Poc C. Detoxification Response of Pseudomonas fluorescens MFAF76a to Gaseous Pollutants NO 2 and NO. Microorganisms 2022; 10:microorganisms10081576. [PMID: 36013994 PMCID: PMC9414441 DOI: 10.3390/microorganisms10081576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Bacteria are often exposed to nitrosative stress from their environment, from atmospheric pollution or from the defense mechanisms of other organisms. Reactive nitrogen species (RNS), which mediate nitrosative stress, are notably involved in the mammalian immune response through the production of nitric oxide (NO) by the inducible NO synthase iNOS. RNS are highly reactive and can alter various biomolecules such as lipids, proteins and DNA, making them toxic for biological organisms. Resistance to RNS is therefore important for the survival of bacteria in various environments, and notably to successfully infect their host. The fuel combustion processes used in industries and transports are responsible for the emission of important quantities of two major RNS, NO and the more toxic nitrogen dioxide (NO2). Human exposure to NO2 is notably linked to increases in lung infections. While the response of bacteria to NO in liquid medium is well-studied, few data are available on their exposure to gaseous NO and NO2. This study showed that NO2 is much more toxic than NO at similar concentrations for the airborne bacterial strain Pseudomonas fluorescens MFAF76a. The response to NO2 involves a wide array of effectors, while the response to NO seemingly focuses on the Hmp flavohemoprotein. Results showed that NO2 induces the production of other RNS, unlike NO, which could explain the differences between the effects of these two molecules.
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Affiliation(s)
- Thibault Chautrand
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Ségolène Depayras
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
- Praxens, Normandy Health Security Center, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Djouhar Souak
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Mathilde Bouteiller
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Tatiana Kondakova
- LPS-BIOSCIENCES SAS, Domaine de l’Université Paris Sud, Bâtiment 430, Université Paris Saclay, 91400 Orsay, France
| | - Magalie Barreau
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Mohamed Amine Ben Mlouka
- Polymers, Biopolymers, Surface Laboratory, University of Rouen Normandy, INSA, CNRS, Bâtiment DULONG—Bd Maurice de Broglie, CEDEX, F-76821 Mont-Saint-Aignan, France
- PISSARO Proteomic Facility, IRIB, F-76820 Mont-Saint-Aignan, France
| | - Julie Hardouin
- Polymers, Biopolymers, Surface Laboratory, University of Rouen Normandy, INSA, CNRS, Bâtiment DULONG—Bd Maurice de Broglie, CEDEX, F-76821 Mont-Saint-Aignan, France
- PISSARO Proteomic Facility, IRIB, F-76820 Mont-Saint-Aignan, France
| | - Yoan Konto-Ghiorghi
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Sylvie Chevalier
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Annabelle Merieau
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Nicole Orange
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Cécile Duclairoir-Poc
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
- Correspondence:
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5
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Regulation of extracellular matrix components by AmrZ is mediated by c-di-GMP in Pseudomonas ogarae F113. Sci Rep 2022; 12:11914. [PMID: 35831472 PMCID: PMC9279365 DOI: 10.1038/s41598-022-16162-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 07/05/2022] [Indexed: 12/04/2022] Open
Abstract
The AmrZ/FleQ hub has been identified as a central node in the regulation of environmental adaption in the plant growth-promoting rhizobacterium and model for rhizosphere colonization Pseudomonas ogarae F113. AmrZ is involved in the regulation of motility, biofilm formation, and bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) turnover, among others, in this bacterium. The mutants in amrZ have a pleiotropic phenotype with distinguishable colony morphology, reduced biofilm formation, increased motility, and are severely impaired in competitive rhizosphere colonization. Here, RNA-Seq and qRT-PCR gene expression analyses revealed that AmrZ regulates many genes related to the production of extracellular matrix (ECM) components at the transcriptional level. Furthermore, overproduction of c-di-GMP in an amrZ mutant, by ectopic production of the Caulobacter crescentus constitutive diguanylate cyclase PleD*, resulted in increased expression of many genes implicated in the synthesis of ECM components. The overproduction of c-di-GMP in the amrZ mutant also suppressed the biofilm formation and motility phenotypes, but not the defect in competitive rhizosphere colonization. These results indicate that although biofilm formation and motility are mainly regulated indirectly by AmrZ, through the modulation of c-di-GMP levels, the implication of AmrZ in rhizosphere competitive colonization occurs in a c-di-GMP-independent manner.
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6
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Anti-Virulence Activity of 3,3′-Diindolylmethane (DIM): A Bioactive Cruciferous Phytochemical with Accelerated Wound Healing Benefits. Pharmaceutics 2022; 14:pharmaceutics14050967. [PMID: 35631553 PMCID: PMC9144697 DOI: 10.3390/pharmaceutics14050967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/24/2022] [Accepted: 04/28/2022] [Indexed: 01/27/2023] Open
Abstract
Antimicrobial resistance is among the top global health problems with antibacterial resistance currently representing the major threat both in terms of occurrence and complexity. One reason current treatments of bacterial diseases are ineffective is the occurrence of protective and resistant biofilm structures. Phytochemicals are currently being reviewed for newer anti-virulence agents. In the present study, we aimed to investigate the anti-virulence activity of 3,3′-diindolylmethane (DIM), a bioactive cruciferous phytochemical. Using a series of in vitro assays on major Gram-negative pathogens, including transcriptomic analysis, and in vivo porcine wound studies as well as in silico experiments, we show that DIM has anti-biofilm activity. Following DIM treatment, our findings show that biofilm formation of two of the most prioritized bacterial pathogens Acinetobacter baumannii and Pseudomonas aeruginosa was inhibited respectively by 65% and 70%. Combining the antibiotic tobramycin with DIM enabled a high inhibition (94%) of P. aeruginosa biofilm. A DIM-based formulation, evaluated for its wound-healing efficacy on P. aeruginosa-infected wounds, showed a reduction in its bacterial bioburden, and wound size. RNA-seq was used to evaluate the molecular mechanism underlying the bacterial response to DIM. The gene expression profile encompassed shifts in virulence and biofilm-associated genes. A network regulation analysis showed the downregulation of 14 virulence-associated super-regulators. Quantitative real-time PCR verified and supported the transcriptomic results. Molecular docking and interaction profiling indicate that DIM can be accommodated in the autoinducer- or DNA-binding pockets of the virulence regulators making multiple non-covalent interactions with the key residues that are involved in ligand binding. DIM treatment prevented biofilm formation and destroyed existing biofilm without affecting microbial death rates. This study provides evidence for bacterial virulence attenuation by DIM.
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7
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Blanco-Romero E, Durán D, Garrido-Sanz D, Rivilla R, Martín M, Redondo-Nieto M. Transcriptomic analysis of Pseudomonas ogarae F113 reveals the antagonistic roles of AmrZ and FleQ during rhizosphere adaption. Microb Genom 2022; 8. [PMID: 35012704 PMCID: PMC8914362 DOI: 10.1099/mgen.0.000750] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Rhizosphere colonization by bacteria involves molecular and cellular mechanisms, such as motility and chemotaxis, biofilm formation, metabolic versatility, or biosynthesis of secondary metabolites, among others. Nonetheless, there is limited knowledge concerning the main regulatory factors that drive the rhizosphere colonization process. Here we show the importance of the AmrZ and FleQ transcription factors for adaption in the plant growth-promoting rhizobacterium (PGPR) and rhizosphere colonization model Pseudomonas ogarae F113. RNA-Seq analyses of P. ogarae F113 grown in liquid cultures either in exponential and stationary growth phase, and rhizosphere conditions, revealed that rhizosphere is a key driver of global changes in gene expression in this bacterium. Regarding the genetic background, this work has revealed that a mutation in fleQ causes considerably more alterations in the gene expression profile of this bacterium than a mutation in amrZ under rhizosphere conditions. The functional analysis has revealed that in P. ogarae F113, the transcription factors AmrZ and FleQ regulate genes involved in diverse bacterial functions. Notably, in the rhizosphere, these transcription factors antagonistically regulate genes related to motility, biofilm formation, nitrogen, sulfur, and amino acid metabolism, transport, signalling, and secretion, especially the type VI secretion systems. These results define the regulon of two important bifunctional transcriptional regulators in pseudomonads during the process of rhizosphere colonization.
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Affiliation(s)
- Esther Blanco-Romero
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - David Durán
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Daniel Garrido-Sanz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain.,Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Rafael Rivilla
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
| | - Miguel Redondo-Nieto
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain
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8
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Mukhi M, Vishwanathan AS. Identifying potential inhibitors of biofilm-antagonistic proteins to promote biofilm formation: a virtual screening and molecular dynamics simulations approach. Mol Divers 2021; 26:2135-2147. [PMID: 34546549 DOI: 10.1007/s11030-021-10320-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 09/14/2021] [Indexed: 12/16/2022]
Abstract
Microbial biofilms play a critical role in environmental biotechnology and associated applications. Biofilm production can be enhanced by inhibiting the function of proteins that negatively regulate their formation. With this objective, an in silico approach was adopted to identify competitive inhibitors of eight biofilm-antagonistic proteins, namely AbrB and SinR (from Bacillus subtilis) and AmrZ, PDE (EAL), PslG, RetS, ShrA and TpbA (from Pseudomonas aeruginosa). Fifteen inhibitors that structurally resembled the natural ligand of each protein were shortlisted using ligand-based and structure-based virtual screening. The top four inhibitors obtained from molecular docking using Autodock Vina were further docked using SwissDock and DOCK 6.9 to obtain a consensus hit for each protein based on different scoring functions. Further analysis of the protein-ligand complexes revealed that these top inhibitors formed significant non-covalent interactions with their respective protein binding sites. The eight protein-ligand complexes were then subjected to molecular dynamics simulations for 30 ns using GROMACS. RMSD and radius of gyration values of 0.1-0.4 nm and 1.0-3.5 nm, respectively, along with hydrogen bond formation throughout the trajectory indicated that all the complexes remained stable, compact and intact during the simulation period. Binding energy values between -20 and -77 kJ/mol obtained from MM-PBSA calculations further confirmed the high affinities of the eight inhibitors for their respective receptors. The outcome of this study holds great promise to enhance biofilms that are central to biotechnological processes associated with microbial electrochemical technologies, wastewater treatment, bioremediation and the industrial production of value-added products.
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Affiliation(s)
- Mayur Mukhi
- WATER Laboratory, Department of Biosciences, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam, Puttaparthi, Andhra Pradesh, 515134, India
| | - A S Vishwanathan
- WATER Laboratory, Department of Biosciences, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam, Puttaparthi, Andhra Pradesh, 515134, India.
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9
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Specific and Global RNA Regulators in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:ijms22168632. [PMID: 34445336 PMCID: PMC8395346 DOI: 10.3390/ijms22168632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/05/2021] [Accepted: 08/08/2021] [Indexed: 01/20/2023] Open
Abstract
Pseudomonas aeruginosa (Pae) is an opportunistic pathogen showing a high intrinsic resistance to a wide variety of antibiotics. It causes nosocomial infections that are particularly detrimental to immunocompromised individuals and to patients suffering from cystic fibrosis. We provide a snapshot on regulatory RNAs of Pae that impact on metabolism, pathogenicity and antibiotic susceptibility. Different experimental approaches such as in silico predictions, co-purification with the RNA chaperone Hfq as well as high-throughput RNA sequencing identified several hundreds of regulatory RNA candidates in Pae. Notwithstanding, using in vitro and in vivo assays, the function of only a few has been revealed. Here, we focus on well-characterized small base-pairing RNAs, regulating specific target genes as well as on larger protein-binding RNAs that sequester and thereby modulate the activity of translational repressors. As the latter impact large gene networks governing metabolism, acute or chronic infections, these protein-binding RNAs in conjunction with their cognate proteins are regarded as global post-transcriptional regulators.
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10
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Amemiya HM, Schroeder J, Freddolino PL. Nucleoid-associated proteins shape chromatin structure and transcriptional regulation across the bacterial kingdom. Transcription 2021; 12:182-218. [PMID: 34499567 PMCID: PMC8632127 DOI: 10.1080/21541264.2021.1973865] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/15/2021] [Accepted: 08/18/2021] [Indexed: 01/21/2023] Open
Abstract
Genome architecture has proven to be critical in determining gene regulation across almost all domains of life. While many of the key components and mechanisms of eukaryotic genome organization have been described, the interplay between bacterial DNA organization and gene regulation is only now being fully appreciated. An increasing pool of evidence has demonstrated that the bacterial chromosome can reasonably be thought of as chromatin, and that bacterial chromosomes contain transcriptionally silent and transcriptionally active regions analogous to heterochromatin and euchromatin, respectively. The roles played by histones in eukaryotic systems appear to be shared across a range of nucleoid-associated proteins (NAPs) in bacteria, which function to compact, structure, and regulate large portions of bacterial chromosomes. The broad range of extant NAPs, and the extent to which they differ from species to species, has raised additional challenges in identifying and characterizing their roles in all but a handful of model bacteria. Here we review the regulatory roles played by NAPs in several well-studied bacteria and use the resulting state of knowledge to provide a working definition for NAPs, based on their function, binding pattern, and expression levels. We present a screening procedure which can be applied to any species for which transcriptomic data are available. Finally, we note that NAPs tend to play two major regulatory roles - xenogeneic silencers and developmental regulators - and that many unrecognized potential NAPs exist in each bacterial species examined.
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Affiliation(s)
- Haley M. Amemiya
- University of Michigan Medical School, Ann Arbor, MI, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jeremy Schroeder
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L. Freddolino
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
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11
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CdbA is a DNA-binding protein and c-di-GMP receptor important for nucleoid organization and segregation in Myxococcus xanthus. Nat Commun 2020; 11:1791. [PMID: 32286293 PMCID: PMC7156744 DOI: 10.1038/s41467-020-15628-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/19/2020] [Indexed: 01/04/2023] Open
Abstract
Cyclic di-GMP (c-di-GMP) is a second messenger that modulates multiple responses to environmental and cellular signals in bacteria. Here we identify CdbA, a DNA-binding protein of the ribbon-helix-helix family that binds c-di-GMP in Myxococcus xanthus. CdbA is essential for viability, and its depletion causes defects in chromosome organization and segregation leading to a block in cell division. The protein binds to the M. xanthus genome at multiple sites, with moderate sequence specificity; however, its depletion causes only modest changes in transcription. The interactions of CdbA with c-di-GMP and DNA appear to be mutually exclusive and residue substitutions in CdbA regions important for c-di-GMP binding abolish binding to both c-di-GMP and DNA, rendering these protein variants non-functional in vivo. We propose that CdbA acts as a nucleoid-associated protein that contributes to chromosome organization and is modulated by c-di-GMP, thus revealing a link between c-di-GMP signaling and chromosome biology. The second messenger c-di-GMP modulates multiple responses to environmental and cellular signals in bacteria. Here, Skotnicka et al. identify a protein that binds c-di-GMP and contributes to chromosome organization and segregation in Myxococcus xanthus, with DNA-binding activity regulated by c-di-GMP.
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12
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Xu A, Zhang M, Du W, Wang D, Ma LZ. A molecular mechanism for how sigma factor AlgT and transcriptional regulator AmrZ inhibit twitching motility in Pseudomonas aeruginosa. Environ Microbiol 2020; 23:572-587. [PMID: 32162778 DOI: 10.1111/1462-2920.14985] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/27/2020] [Accepted: 03/10/2020] [Indexed: 11/28/2022]
Abstract
Pseudomonas aeruginosa isolates from cystic fibrosis patients are often mucoid (due to the overexpression of exopolysaccharide alginate) yet lost motility. It remains unclear about how P. aeruginosa coordinately regulates alginate production and the type IV pili-driven twitching motility. Here we showed that sigma 22 factor (AlgT/U), an activator of alginate biosynthesis, repressed twitching motility by inhibiting the expression of pilin (PilA) through the intermediate transcriptional regulator AmrZ, which directly bound to the promoter region of pilA in both mucoid strain FRD1 and non-mucoid strain PAO1. Four conserved AmrZ-binding sites were found in pilA promoters among 10 P. aeruginosa strains although their entire pilA promoters had low identity. AmrZ has been reported to be essential for twitching in PAO1. We found that AmrZ was also required for twitching in mucoid FRD1, yet a high level of AmrZ inhibited twitching motility. This result was consistent with the phenomenon that twitching is frequently repressed in mucoid strains, in which the expression of AmrZ was highly activated by AlgT. Additionally, AlgT also inhibited the transcription of pilMNOP operon, which is involved in efficient pilus assembly. Our data elucidated a mechanism for how AlgT and AmrZ coordinately controlled twitching motility in P. aeruginosa.
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Affiliation(s)
- Anming Xu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Miaokun Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Weili Du
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Di Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Luyan Z Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
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13
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Bacterial alginate regulators and phage homologs repress CRISPR-Cas immunity. Nat Microbiol 2020; 5:679-687. [PMID: 32203410 PMCID: PMC7190418 DOI: 10.1038/s41564-020-0691-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022]
Abstract
CRISPR-Cas systems are adaptive immune systems that protect bacteria from bacteriophage (phage) infection1. To provide immunity, RNA-guided protein surveillance complexes recognize foreign nucleic acids, triggering their destruction by Cas nucleases2. While the essential requirements for immune activity are well understood, the physiological cues that regulate CRISPR-Cas expression are not. Here, a forward genetic screen identifies a two-component system (KinB/AlgB), previously characterized in regulating Pseudomonas aeruginosa alginate biosynthesis3,4, as a regulator of the expression and activity of the P. aeruginosa Type I-F CRISPR-Cas system. Downstream of KinB/AlgB, activators of alginate production AlgU (a σE orthologue) and AlgR, repress CRISPR-Cas activity during planktonic and surface-associated growth5. AmrZ, another alginate regulator6, is triggered to repress CRISPR-Cas immunity during surface-association. Pseudomonas phages and plasmids have taken advantage of this regulatory scheme, and carry hijacked homologs of AmrZ that repress CRISPR-Cas expression and activity. This suggests that while CRISPR-Cas regulation may be important to limit self-toxicity, endogenous repressive pathways represent a vulnerability for parasite manipulation.
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14
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Kutnowski N, Shmulevich F, Davidov G, Shahar A, Bar-Zvi D, Eichler J, Zarivach R, Shaanan B. Specificity of protein-DNA interactions in hypersaline environment: structural studies on complexes of Halobacterium salinarum oxidative stress-dependent protein hsRosR. Nucleic Acids Res 2019; 47:8860-8873. [PMID: 31310308 PMCID: PMC7145548 DOI: 10.1093/nar/gkz604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/13/2019] [Accepted: 07/02/2019] [Indexed: 12/21/2022] Open
Abstract
Interactions between proteins and DNA are crucial for all biological systems. Many studies have shown the dependence of protein–DNA interactions on the surrounding salt concentration. How these interactions are maintained in the hypersaline environments that halophiles inhabit remains puzzling. Towards solving this enigma, we identified the DNA motif recognized by the Halobactrium salinarum ROS-dependent transcription factor (hsRosR), determined the structure of several hsRosR–DNA complexes and investigated the DNA-binding process under extreme high-salt conditions. The picture that emerges from this work contributes to our understanding of the principles underlying the interplay between electrostatic interactions and salt-mediated protein–DNA interactions in an ionic environment characterized by molar salt concentrations.
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Affiliation(s)
- Nitzan Kutnowski
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel
| | - Fania Shmulevich
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel
| | - Geula Davidov
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel.,National Institute of Biotechnology in the Negev, Ben-Gurion University, Beer Sheva 8410510, Israel
| | - Anat Shahar
- Macromolecular Crystallography Research Center, National Institute of Biotechnology in the Negev, Ben-Gurion University, Beer Sheva 8410510, Israel
| | - Dudy Bar-Zvi
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel.,National Institute of Biotechnology in the Negev, Ben-Gurion University, Beer Sheva 8410510, Israel
| | - Boaz Shaanan
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel
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15
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Hou L, Debru A, Chen Q, Bao Q, Li K. AmrZ Regulates Swarming Motility Through Cyclic di-GMP-Dependent Motility Inhibition and Controlling Pel Polysaccharide Production in Pseudomonas aeruginosa PA14. Front Microbiol 2019; 10:1847. [PMID: 31474950 PMCID: PMC6707383 DOI: 10.3389/fmicb.2019.01847] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 07/26/2019] [Indexed: 11/16/2022] Open
Abstract
Swarming is a surface-associated motile behavior that plays an important role in the rapid spread, colonization, and subsequent establishment of bacterial communities. In Pseudomonas aeruginosa, swarming is dependent upon a functional flagella and aided by the production of biosurfactants. AmrZ, a conserved transcription factor across pseudomonads, has been shown to be a global regulator of multiple genes important for virulence and ecological fitness. In this study, we expand this concept of global control to swarming motility by showing that deletion of amrZ results in a severe defect in swarming, while multicopy expression of this gene stimulates swarming of P. aeruginosa. Mechanistic studies showed that the swarming defect of an amrZ mutant does not involve changes of biosurfactant production but is associated with flagellar malfunction. The ∆amrZ mutant exhibits increased levels of the second messenger cyclic di-GMP (c-di-GMP) compared to the wild-type strain, under swarming conditions. We found that the diguanylate cyclase GcbA was the main contributor to the increased accumulation of c-di-GMP observed in the ∆amrZ mutant and was a strong inhibitor of flagellar-dependent motility. Our results revealed that the GcbA-dependent inhibition of motility required the presence of two c-di-GMP receptors containing a PilZ domain: FlgZ and PA14_56180. Furthermore, the ∆amrZ mutant exhibits enhanced production of Pel polysaccharide. Epistasis analysis revealed that GcbA and the Pel polysaccharide act independently to limit swarming in ΔamrZ. Our results support a role for AmrZ in controlling swarming motility, yet another social behavior besides biofilm formation that is crucial for the ability of P. aeruginosa to colonize a variety of surfaces. The central role of AmrZ in controlling these behaviors makes it a good target for the development of treatments directed to combat P. aeruginosa infections.
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Affiliation(s)
- Lingli Hou
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.,Scientific Research Center of Wenzhou Medical University, Wenzhou, China
| | - Alexander Debru
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qianqian Chen
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qiyu Bao
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Kewei Li
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
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16
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Tandon H, Sharma A, Sandhya S, Srinivasan N, Singh R. Mycobacterium tuberculosis Rv0366c-Rv0367c encodes a non-canonical PezAT-like toxin-antitoxin pair. Sci Rep 2019; 9:1163. [PMID: 30718534 PMCID: PMC6362051 DOI: 10.1038/s41598-018-37473-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 11/27/2018] [Indexed: 11/29/2022] Open
Abstract
Toxin-antitoxin (TA) systems are ubiquitously existing addiction modules with essential roles in bacterial persistence and virulence. The genome of Mycobacterium tuberculosis encodes approximately 79 TA systems. Through computational and experimental investigations, we report for the first time that Rv0366c-Rv0367c is a non-canonical PezAT-like toxin-antitoxin system in M. tuberculosis. Homology searches with known PezT homologues revealed that residues implicated in nucleotide, antitoxin-binding and catalysis are conserved in Rv0366c. Unlike canonical PezA antitoxins, the N-terminal of Rv0367c is predicted to adopt the ribbon-helix-helix (RHH) motif for deoxyribonucleic acid (DNA) recognition. Further, the modelled complex predicts that the interactions between PezT and PezA involve conserved residues. We performed a large-scale search in sequences encoded in 101 mycobacterial and 4500 prokaryotic genomes and show that such an atypical PezAT organization is conserved in 20 other mycobacterial organisms and in families of class Actinobacteria. We also demonstrate that overexpression of Rv0366c induces bacteriostasis and this growth defect could be restored upon co-expression of cognate antitoxin, Rv0367c. Further, we also observed that inducible expression of Rv0366c in Mycobacterium smegmatis results in decreased cell-length and enhanced tolerance against a front-line tuberculosis (TB) drug, ethambutol. Taken together, we have identified and functionally characterized a novel non-canonical TA system from M. tuberculosis.
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Affiliation(s)
- Himani Tandon
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Arun Sharma
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, PO Box #4, Faridabad, Haryana, 121001, India
| | - Sankaran Sandhya
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | | | - Ramandeep Singh
- Tuberculosis Research Laboratory, Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, PO Box #4, Faridabad, Haryana, 121001, India.
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17
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Liu H, Yan H, Xiao Y, Nie H, Huang Q, Chen W. The exopolysaccharide gene cluster pea is transcriptionally controlled by RpoS and repressed by AmrZ in Pseudomonas putida KT2440. Microbiol Res 2018; 218:1-11. [PMID: 30454651 DOI: 10.1016/j.micres.2018.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/29/2018] [Accepted: 09/05/2018] [Indexed: 10/28/2022]
Abstract
In Pseudomonas putida KT2440, the exopolysaccharide Pea is associated with biofilm stability and pellicle formation; however, little is known about its regulatory pathway. In this study, we identified that the gene cluster pea was transcribed from 25 bp upstream of the operon and the stationary phase alternative sigma factor RpoS regulated the transcription of pea. When RpoS was absent, another sigma factor, likely the housekeeping sigma factor RpoD, could also mediate pea transcription but at a low level. The function of Pea polysaccharide was further confirmed to be necessary for full production of biofilm, formation of pellicle and c-di-GMP-dependent wrinkly colony morphology. Additionally, evidences were provided to demonstrate that the transcriptional regulator AmrZ was a negative regulator for pea expression. DNase I footprinting studies verified that AmrZ bound directly to the site overlapping the pea promoter, which might interfere with the binding of RNA polymerase to the promoter and resulted in inhibition of transcription initiation.
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Affiliation(s)
- Huizhong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Huaduo Yan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yujie Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Hailing Nie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
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18
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Evolutionary Plasticity of AmrZ Regulation in Pseudomonas. mSphere 2018; 3:3/2/e00132-18. [PMID: 29669886 PMCID: PMC5907648 DOI: 10.1128/msphere.00132-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 03/26/2018] [Indexed: 11/20/2022] Open
Abstract
amrZ encodes a master regulator protein conserved across pseudomonads, which can be either a positive or negative regulator of swimming motility depending on the species examined. To better understand plasticity in the regulatory function of AmrZ, we characterized the mode of regulation for this protein for two different motility-related phenotypes in Pseudomonas stutzeri As in Pseudomonas syringae, AmrZ functions as a positive regulator of swimming motility within P. stutzeri, which suggests that the functions of this protein with regard to swimming motility have switched at least twice across pseudomonads. Shifts in mode of regulation cannot be explained by changes in AmrZ sequence alone. We further show that AmrZ acts as a positive regulator of colony spreading within this strain and that this regulation is at least partially independent of swimming motility. Closer investigation of mechanistic shifts in dual-function regulators like AmrZ could provide unique insights into how transcriptional pathways are rewired between closely related species.IMPORTANCE Microbes often display finely tuned patterns of gene regulation across different environments, with major regulatory changes controlled by a small group of "master" regulators within each cell. AmrZ is a master regulator of gene expression across pseudomonads and can be either a positive or negative regulator for a variety of pathways depending on the strain and genomic context. Here, we demonstrate that the phenotypic outcomes of regulation of swimming motility by AmrZ have switched at least twice independently in pseudomonads, so that AmrZ promotes increased swimming motility in P. stutzeri and P. syringae but represses this phenotype in Pseudomonas fluorescens and Pseudomonas aeruginosa Since examples of switches in regulatory mode are relatively rare, further investigation into the mechanisms underlying shifts in regulator function for AmrZ could provide unique insights into the evolution of bacterial regulatory proteins.
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19
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The Novel Transcriptional Regulator LmbU Promotes Lincomycin Biosynthesis through Regulating Expression of Its Target Genes in Streptomyces lincolnensis. J Bacteriol 2017; 200:JB.00447-17. [PMID: 29038257 DOI: 10.1128/jb.00447-17] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022] Open
Abstract
Lincomycin A is a clinically important antimicrobial agent produced by Streptomyces lincolnensis In this study, a new regulator designated LmbU (GenBank accession no. ABX00623.1) was identified and characterized to regulate lincomycin biosynthesis in S. lincolnensis wild-type strain NRRL 2936. Both inactivation and overexpression of lmbU resulted in significant influences on lincomycin production. Transcriptional analysis and in vivo neomycin resistance (Neor) reporter assays demonstrated that LmbU activates expression of the lmbA, lmbC, lmbJ, and lmbW genes and represses expression of the lmbK and lmbU genes. Electrophoretic mobility shift assays (EMSAs) demonstrated that LmbU can bind to the regions upstream of the lmbA and lmbW genes through the consensus and palindromic sequence 5'-CGCCGGCG-3'. However, LmbU cannot bind to the regions upstream of the lmbC, lmbJ, lmbK, and lmbU genes as they lack this motif. These data indicate a complex transcriptional regulatory mechanism of LmbU. LmbU homologues are present in the biosynthetic gene clusters of secondary metabolites of many other actinomycetes. Furthermore, the LmbU homologue from Saccharopolyspora erythraea (GenBank accession no. WP_009944629.1) also binds to the regions upstream of lmbA and lmbW, which suggests widespread activity for this regulator. LmbU homologues have no significant structural similarities to other known cluster-situated regulators (CSRs), which indicates that they belong to a new family of regulatory proteins. In conclusion, the present report identifies LmbU as a novel transcriptional regulator and provides new insights into regulation of lincomycin biosynthesis in S. lincolnensisIMPORTANCE Although lincomycin biosynthesis has been extensively studied, its regulatory mechanism remains elusive. Here, a novel regulator, LmbU, which regulates transcription of its target genes in the lincomycin biosynthetic gene cluster (lmb gene cluster) and therefore promotes lincomycin biosynthesis, was identified in S. lincolnensis strain NRRL 2936. Importantly, we show that this new regulatory element is relatively widespread across diverse actinomycetes species. In addition, our findings provide a new strategy for improvement of yield of lincomycin through manipulation of LmbU, and this approach could also be evaluated in other secondary metabolite gene clusters containing this regulatory protein.
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20
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RsmA and AmrZ orchestrate the assembly of all three type VI secretion systems in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2017; 114:7707-7712. [PMID: 28673999 DOI: 10.1073/pnas.1700286114] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The type VI secretion system (T6SS) is a weapon of bacterial warfare and host cell subversion. The Gram-negative pathogen Pseudomonas aeruginosa has three T6SSs involved in colonization, competition, and full virulence. H1-T6SS is a molecular gun firing seven toxins, Tse1-Tse7, challenging survival of other bacteria and helping P. aeruginosa to prevail in specific niches. The H1-T6SS characterization was facilitated through studying a P. aeruginosa strain lacking the RetS sensor, which has a fully active H1-T6SS, in contrast to the parent. However, study of H2-T6SS and H3-T6SS has been neglected because of a poor understanding of the associated regulatory network. Here we performed a screen to identify H2-T6SS and H3-T6SS regulatory elements and found that the posttranscriptional regulator RsmA imposes a concerted repression on all three T6SS clusters. A higher level of complexity could be observed as we identified a transcriptional regulator, AmrZ, which acts as a negative regulator of H2-T6SS. Overall, although the level of T6SS transcripts is fine-tuned by AmrZ, all T6SS mRNAs are silenced by RsmA. We expanded this concept of global control by RsmA to VgrG spike and T6SS toxin transcripts whose genes are scattered on the chromosome. These observations triggered the characterization of a suite of H2-T6SS toxins and their implication in direct bacterial competition. Our study thus unveils a central mechanism that modulates the deployment of all T6SS weapons that may be simultaneously produced within a single cell.
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21
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Pseudomonas aeruginosa AmrZ Binds to Four Sites in the algD Promoter, Inducing DNA-AmrZ Complex Formation and Transcriptional Activation. J Bacteriol 2016; 198:2673-81. [PMID: 27185826 DOI: 10.1128/jb.00259-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/09/2016] [Indexed: 11/20/2022] Open
Abstract
During late stages of cystic fibrosis pulmonary infections, Pseudomonas aeruginosa often overproduces the exopolysaccharide alginate, protecting the bacterial community from host immunity and antimicrobials. The transcription of the alginate biosynthesis operon is under tight control by a number of factors, including AmrZ, the focus of this study. Interestingly, multiple transcription factors interact with the far-upstream region of this promoter (PalgD), in which one AmrZ binding site has been identified previously. The mechanisms of AmrZ binding and subsequent activation remain unclear and require more-detailed investigation. In this study, in-depth examinations elucidated four AmrZ binding sites, and their disruption eliminated AmrZ binding and promoter activation. Furthermore, our in vitro fluorescence resonance energy transfer experiments suggest that AmrZ holds together multiple binding sites in PalgD and thereafter induces the formation of higher-order DNA-AmrZ complexes. To determine the importance of interactions between those AmrZ oligomers in the cell, a DNA phasing experiment was performed. PalgD transcription was significantly impaired when the relative phase between AmrZ binding sites was reversed (5 bp), while a full-DNA-turn insertion (10 bp) restored promoter activity. Taken together, the investigations presented here provide a deeper mechanistic understanding of AmrZ-mediated binding to PalgD IMPORTANCE: Overproduction of the exopolysaccharide alginate provides protection to Pseudomonas aeruginosa against antimicrobial treatments and is associated with chronic P. aeruginosa infections in the lungs of cystic fibrosis patients. In this study, we combined a variety of microbiological, genetic, biochemical, and biophysical approaches to investigate the activation of the alginate biosynthesis operon promoter by a key transcription factor named AmrZ. This study has provided important new information on the mechanism of activation of this extremely complex promoter.
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22
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Hobbs ET, Pereira T, O’Neill PK, Erill I. A Bayesian inference method for the analysis of transcriptional regulatory networks in metagenomic data. Algorithms Mol Biol 2016; 11:19. [PMID: 27398089 PMCID: PMC4938975 DOI: 10.1186/s13015-016-0082-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 06/30/2016] [Indexed: 11/13/2022] Open
Abstract
Background Metagenomics enables the analysis of bacterial population composition and the study of emergent population features, such as shared metabolic pathways. Recently, we have shown that metagenomics datasets can be leveraged to characterize population-wide transcriptional regulatory networks, or meta-regulons, providing insights into how bacterial populations respond collectively to specific triggers. Here we formalize a Bayesian inference framework to analyze the composition of transcriptional regulatory networks in metagenomes by determining the probability of regulation of orthologous gene sequences. We assess the performance of this approach on synthetic datasets and we validate it by analyzing the copper-homeostasis network of Firmicutes species in the human gut microbiome. Results Assessment on synthetic datasets shows that our method provides a robust and interpretable metric for assessing putative regulation by a transcription factor on sets of promoter sequences mapping to an orthologous gene cluster. The inference framework integrates the regulatory contribution of secondary sites and can discern false positives arising from multiple instances of a clonal sequence. Posterior probabilities for orthologous gene clusters decline sharply when less than 20 % of mapped promoters have binding sites, but we introduce a sensitivity adjustment procedure to speed up computation that enhances regulation assessment in heterogeneous ortholog clusters. Analysis of the copper-homeostasis regulon governed by CsoR in the human gut microbiome Firmicutes reveals that CsoR controls itself and copper-translocating P-type ATPases, but not CopZ-type copper chaperones. Our analysis also indicates that CsoR frequently targets promoters with dual CsoR-binding sites, suggesting that it exploits higher-order binding conformations to fine-tune its activity. Conclusions We introduce and validate a method for the analysis of transcriptional regulatory networks from metagenomic data that enables inference of meta-regulons in a systematic and interpretable way. Validation of this method on the CsoR meta-regulon of gut microbiome Firmicutes illustrates the usefulness of the approach, revealing novel properties of the copper-homeostasis network in poorly characterized bacterial species and putting forward evidence of new mechanisms of DNA binding for this transcriptional regulator. Our approach will enable the comparative analysis of regulatory networks across metagenomes, yielding novel insights into the evolution of transcriptional regulatory networks. Electronic supplementary material The online version of this article (doi:10.1186/s13015-016-0082-8) contains supplementary material, which is available to authorized users.
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23
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Temperate phages both mediate and drive adaptive evolution in pathogen biofilms. Proc Natl Acad Sci U S A 2016; 113:8266-71. [PMID: 27382184 DOI: 10.1073/pnas.1520056113] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Temperate phages drive genomic diversification in bacterial pathogens. Phage-derived sequences are more common in pathogenic than nonpathogenic taxa and are associated with changes in pathogen virulence. High abundance and mobilization of temperate phages within hosts suggests that temperate phages could promote within-host evolution of bacterial pathogens. However, their role in pathogen evolution has not been experimentally tested. We experimentally evolved replicate populations of Pseudomonas aeruginosa with or without a community of three temperate phages active in cystic fibrosis (CF) lung infections, including the transposable phage, ɸ4, which is closely related to phage D3112. Populations grew as free-floating biofilms in artificial sputum medium, mimicking sputum of CF lungs where P. aeruginosa is an important pathogen and undergoes evolutionary adaptation and diversification during chronic infection. Although bacterial populations adapted to the biofilm environment in both treatments, population genomic analysis revealed that phages altered both the trajectory and mode of evolution. Populations evolving with phages exhibited a greater degree of parallel evolution and faster selective sweeps than populations without phages. Phage ɸ4 integrated randomly into the bacterial chromosome, but integrations into motility-associated genes and regulators of quorum sensing systems essential for virulence were selected in parallel, strongly suggesting that these insertional inactivation mutations were adaptive. Temperate phages, and in particular transposable phages, are therefore likely to facilitate adaptive evolution of bacterial pathogens within hosts.
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Xu B, Ju Y, Soukup RJ, Ramsey DM, Fishel R, Wysocki VH, Wozniak DJ. The Pseudomonas aeruginosa AmrZ C-terminal domain mediates tetramerization and is required for its activator and repressor functions. ENVIRONMENTAL MICROBIOLOGY REPORTS 2016; 8:85-90. [PMID: 26549743 PMCID: PMC4769699 DOI: 10.1111/1758-2229.12354] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/01/2015] [Indexed: 05/14/2023]
Abstract
Pseudomonas aeruginosa is an important bacterial opportunistic pathogen, presenting a significant threat towards individuals with underlying diseases such as cystic fibrosis. The transcription factor AmrZ regulates expression of multiple P. aeruginosa virulence factors. AmrZ belongs to the ribbon-helix-helix protein superfamily, in which many members function as dimers, yet others form higher order oligomers. In this study, four independent approaches were undertaken and demonstrated that the primary AmrZ form in solution is tetrameric. Deletion of the AmrZ C-terminal domain leads to loss of tetramerization and reduced DNA binding to both activated and repressed target promoters. Additionally, the C-terminal domain is essential for efficient AmrZ-mediated activation and repression of its targets.
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Affiliation(s)
- Binjie Xu
- Department of Microbiology, The Ohio State University, Columbus, Ohio, 43210
- Department of Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, 43210
| | - Yue Ju
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210
| | - Randal J. Soukup
- Department of Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, Ohio, 43210
| | - Deborah M. Ramsey
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Richard Fishel
- Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University Wexner Medical Center and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, 43210
| | - Vicki H. Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210
| | - Daniel J. Wozniak
- Department of Microbiology, The Ohio State University, Columbus, Ohio, 43210
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, 43210
- Department of Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, 43210
- All correspondence should be addressed to Daniel J. Wozniak, . Address: BRT 704, 460 W. 12 Ave, Columbus, OH, 43210. Phone: 614-247-7629; Fax: 614-2929-616
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Prada-Ramírez HA, Pérez-Mendoza D, Felipe A, Martínez-Granero F, Rivilla R, Sanjuán J, Gallegos MT. AmrZ regulates cellulose production in Pseudomonas syringae pv. tomato DC3000. Mol Microbiol 2015; 99:960-77. [PMID: 26564578 DOI: 10.1111/mmi.13278] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2015] [Indexed: 11/27/2022]
Abstract
In Pseudomonas syringae pv. tomato DC3000, the second messenger c-di-GMP has been previously shown to stimulate pellicle formation and cellulose biosynthesis. A screen for genes involved in cellulose production under high c-di-GMP intracellular levels led to the identification of insertions in two genes, wssB and wssE, belonging to the Pto DC3000 cellulose biosynthesis operon wssABCDEFGHI. Interestingly, beside cellulose-deficient mutants, colonies with a rougher appearance than the wild type also arouse among the transposants. Those mutants carry insertions in amrZ, a gene encoding a transcriptional regulator in different Pseudomonas. Here, we provide evidence that AmrZ is involved in the regulation of bacterial cellulose production at transcriptional level by binding to the promoter region of the wssABCDEFGHI operon and repressing cellulose biosynthesis genes. Mutation of amrZ promotes wrinkly colony morphology, increased cellulose production and loss of motility in Pto DC3000. AmrZ regulon includes putative c-di-GMP metabolising proteins, like AdcA and MorA, which may also impact those phenotypes. Furthermore, an amrZ but not a cellulose-deficient mutant turned out to be impaired in pathogenesis, indicating that AmrZ is a key regulator of Pto DC3000 virulence probably by controlling bacterial processes other than cellulose production.
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Affiliation(s)
- Harold A Prada-Ramírez
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | - Daniel Pérez-Mendoza
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | - Antonia Felipe
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | | | - Rafael Rivilla
- Department of Biology, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Juan Sanjuán
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
| | - María-Trinidad Gallegos
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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Davis RR, Shaban NM, Perrino FW, Hollis T. Crystal structure of RNA-DNA duplex provides insight into conformational changes induced by RNase H binding. Cell Cycle 2015; 14:668-73. [PMID: 25664393 DOI: 10.4161/15384101.2014.994996] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
RNA-DNA hybrids play essential roles in a variety of biological processes, including DNA replication, transcription, and viral integration. Ribonucleotides incorporated within DNA are hydrolyzed by RNase H enzymes in a removal process that is necessary for maintaining genomic stability. In order to understand the structural determinants involved in recognition of a hybrid substrate by RNase H we have determined the crystal structure of a dodecameric non-polypurine/polypyrimidine tract RNA-DNA duplex. A comparison to the same sequence bound to RNase H, reveals structural changes to the duplex that include widening of the major groove to 12.5 Å from 4.2 Å and decreasing the degree of bending along the axis which may play a crucial role in the ribonucleotide recognition and cleavage mechanism within RNase H. This structure allows a direct comparison to be made about the conformational changes induced in RNA-DNA hybrids upon binding to RNase H and may provide insight into how dysfunction in the endonuclease causes disease.
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Affiliation(s)
- Ryan R Davis
- a Department of Biochemistry; Center for Structural Biology ; Wake Forest School of Medicine ; Winston-Salem , NC USA
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27
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Volante A, Carrasco B, Tabone M, Alonso JC. The interaction of ω2 with the RNA polymerase β' subunit functions as an activation to repression switch. Nucleic Acids Res 2015; 43:9249-61. [PMID: 26243774 PMCID: PMC4627068 DOI: 10.1093/nar/gkv788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 07/23/2015] [Indexed: 12/03/2022] Open
Abstract
The ω gene is encoded in broad-host range and low-copy plasmids. It is genetically linked to antibiotic resistance genes of the major human pathogens of phylum Firmicutes. The homodimeric forms of ω (ω2) coordinate the plasmid copy number control, faithful partition (ω2 and δ2) and better-than-random segregation (ζϵ2ζ) systems. The promoter (P) of the ωϵζ operon (Pω) transiently interacts with ω2. Adding δ2 facilitates the formation of stable ω2·Pω complexes. Here we show that limiting ω2 interacts with the N-terminal domain of the β’ subunit of the Bacillus subtilis RNA polymerase (RNAP-σA) vegetative holoenzyme. In this way ω2 recruits RNAP-σA onto Pω DNA. Partial Pω occupancy by ω2 increases the rate at which RNAP-σA complex shifts from its closed (RPC) to open (RPO) form. This shift increases transcription activation. Adding δ2 further increases the rate of Pω transcription initiation, perhaps by stabilizing the ω2·Pω complex. In contrast, full operator occupancy by ω2 facilitates RPC formation, but it blocks RPO isomerization and represses Pω utilization. The stimulation and inhibition of RPO formation is the mechanism whereby ω2 mediates copy number fluctuation and stable plasmid segregation. By this mechanism, ω2 also indirectly influences the acquisition of antibiotic resistance genes.
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Affiliation(s)
- Andrea Volante
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Mariangela Tabone
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
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Leighton TL, Buensuceso RNC, Howell PL, Burrows LL. Biogenesis of Pseudomonas aeruginosa type IV pili and regulation of their function. Environ Microbiol 2015; 17:4148-63. [PMID: 25808785 DOI: 10.1111/1462-2920.12849] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 03/13/2015] [Accepted: 03/14/2015] [Indexed: 12/27/2022]
Abstract
Type IV pili (T4P) are bacterial virulence factors involved in a wide variety of functions including deoxyribonucleic acid uptake, surface attachment, biofilm formation and twitching motility. While T4P are common surface appendages, the systems that assemble them and the regulation of their function differ between species. Pseudomonas aeruginosa, Neisseria spp. and Myxococcus xanthus are common model systems used to study T4P biology. This review focuses on recent advances in P. aeruginosa T4P structural biology, and the regulatory pathways controlling T4P biogenesis and function.
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Affiliation(s)
- Tiffany L Leighton
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Ryan N C Buensuceso
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - P Lynne Howell
- Program in Molecular Structure & Function, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
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Okkotsu Y, Little AS, Schurr MJ. The Pseudomonas aeruginosa AlgZR two-component system coordinates multiple phenotypes. Front Cell Infect Microbiol 2014; 4:82. [PMID: 24999454 PMCID: PMC4064291 DOI: 10.3389/fcimb.2014.00082] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/02/2014] [Indexed: 01/28/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes a multitude of infections. These infections can occur at almost any site in the body and are usually associated with a breach of the innate immune system. One of the prominent sites where P. aeruginosa causes chronic infections is within the lungs of cystic fibrosis patients. P. aeruginosa uses two-component systems that sense environmental changes to differentially express virulence factors that cause both acute and chronic infections. The P. aeruginosa AlgZR two component system is one of its global regulatory systems that affects the organism's fitness in a broad manner. This two-component system is absolutely required for two P. aeruginosa phenotypes: twitching motility and alginate production, indicating its importance in both chronic and acute infections. Additionally, global transcriptome analyses indicate that it regulates the expression of many different genes, including those associated with quorum sensing, type IV pili, type III secretion system, anaerobic metabolism, cyanide and rhamnolipid production. This review examines the complex AlgZR regulatory network, what is known about the structure and function of each protein, and how it relates to the organism's ability to cause infections.
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Affiliation(s)
- Yuta Okkotsu
- Department of Microbiology, University of Colorado School of Medicine Aurora, CO, USA
| | - Alexander S Little
- Department of Microbiology, University of Colorado School of Medicine Aurora, CO, USA
| | - Michael J Schurr
- Department of Microbiology, University of Colorado School of Medicine Aurora, CO, USA
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Martínez-Granero F, Redondo-Nieto M, Vesga P, Martín M, Rivilla R. AmrZ is a global transcriptional regulator implicated in iron uptake and environmental adaption in P. fluorescens F113. BMC Genomics 2014; 15:237. [PMID: 24670089 PMCID: PMC3986905 DOI: 10.1186/1471-2164-15-237] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 03/21/2014] [Indexed: 12/04/2022] Open
Abstract
Background AmrZ, a RHH transcriptional regulator, regulates motility and alginate production in pseudomonads. Expression of amrZ depends on the environmental stress sigma factor AlgU. amrZ and algU mutants have been shown to be impaired in environmental fitness in different pseudomonads with different lifestyles. Considering the importance of AmrZ for the ecological fitness of pseudomonads and taking advantage of the full sequencing and annotation of the Pseudomonas fluorescens F113 genome, we have carried out a ChIP-seq analysis from a pool of eight independent ChIP assays in order to determine the AmrZ binding sites and its implication in the regulation of genes involved in environmental adaption. Results 154 enriched regions (AmrZ binding sites) were detected in this analysis, being 76% of them located in putative promoter regions. 18 of these peaks were validated in an independent ChIP assay by qPCR. The 154 peaks were assigned to genes involved in several functional classes such as motility and chemotaxis, iron homeostasis, and signal transduction and transcriptional regulators, including genes encoding proteins implicated in the turn-over of c-diGMP. A putative AmrZ binding site was also observed by aligning the 154 regions with the MEME software. This motif was present in 75% of the peaks and was similar to that described in the amrZ and algD promoters in P. aeruginosa. We have analyzed the role of AmrZ in the regulation of iron uptake genes, to find that AmrZ represses their expression under iron limiting conditions. Conclusions The results presented here show that AmrZ is an important global transcriptional regulator involved in environmental sensing and adaption. It is also a new partner in the complex iron homeostasis regulation.
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Affiliation(s)
| | | | | | | | - Rafael Rivilla
- Departamento de Biología, Universidad Autónoma de Madrid, C/Darwin, 2, 28049 Madrid Spain.
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Jones CJ, Newsom D, Kelly B, Irie Y, Jennings LK, Xu B, Limoli DH, Harrison JJ, Parsek MR, White P, Wozniak DJ. ChIP-Seq and RNA-Seq reveal an AmrZ-mediated mechanism for cyclic di-GMP synthesis and biofilm development by Pseudomonas aeruginosa. PLoS Pathog 2014; 10:e1003984. [PMID: 24603766 PMCID: PMC3946381 DOI: 10.1371/journal.ppat.1003984] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 01/23/2014] [Indexed: 11/28/2022] Open
Abstract
The transcription factor AmrZ regulates genes important for P. aeruginosa virulence, including type IV pili, extracellular polysaccharides, and the flagellum; however, the global effect of AmrZ on gene expression remains unknown, and therefore, AmrZ may directly regulate many additional genes that are crucial for infection. Compared to the wild type strain, a ΔamrZ mutant exhibits a rugose colony phenotype, which is commonly observed in variants that accumulate the intracellular second messenger cyclic diguanylate (c-di-GMP). Cyclic di-GMP is produced by diguanylate cyclases (DGC) and degraded by phosphodiesterases (PDE). We hypothesized that AmrZ limits the intracellular accumulation of c-di-GMP through transcriptional repression of gene(s) encoding a DGC. In support of this, we observed elevated c-di-GMP in the ΔamrZ mutant compared to the wild type strain. Consistent with other strains that accumulate c-di-GMP, when grown as a biofilm, the ΔamrZ mutant formed larger microcolonies than the wild-type strain. This enhanced biofilm formation was abrogated by expression of a PDE. To identify potential target DGCs, a ChIP-Seq was performed and identified regions of the genome that are bound by AmrZ. RNA-Seq experiments revealed the entire AmrZ regulon, and characterized AmrZ as an activator or repressor at each binding site. We identified an AmrZ-repressed DGC-encoding gene (PA4843) from this cohort, which we named AmrZ dependent cyclase A (adcA). PAO1 overexpressing adcA accumulates 29-fold more c-di-GMP than the wild type strain, confirming the cyclase activity of AdcA. In biofilm reactors, a ΔamrZ ΔadcA double mutant formed smaller microcolonies than the single ΔamrZ mutant, indicating adcA is responsible for the hyper biofilm phenotype of the ΔamrZ mutant. This study combined the techniques of ChIP-Seq and RNA-Seq to define the comprehensive regulon of a bifunctional transcriptional regulator. Moreover, we identified a c-di-GMP mediated mechanism for AmrZ regulation of biofilm formation and chronicity. Pathogenic bacteria such as Pseudomonas aeruginosa utilize a wide variety of systems to sense and respond to the changing conditions during an infection. When a stress is sensed, signals are transmitted to impact expression of many genes that allow the bacterium to adapt to the changing conditions. AmrZ is a protein that regulates production of several virulence-associated gene products, though we predicted that its role in virulence was more expansive than previously described. Transcription factors such as AmrZ often affect the expression of a gene by binding and promoting or inhibiting expression of the target gene. Two global techniques were utilized to determine where AmrZ binds in the genome, and what effect AmrZ has once bound. This approach revealed that AmrZ represses the production of a signaling molecule called cyclic diguanylate, which is known to induce the formation of difficult to treat communities of bacteria called biofilms. This study also identified many novel targets of AmrZ to promote future studies of this regulator. Collectively, these data can be utilized to develop treatments to inhibit biofilm formation during devastating chronic infections.
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Affiliation(s)
- Christopher J. Jones
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America
- Department of Infection and Immunity and Center for Microbial Interface Biology, Ohio State University, Columbus, Ohio, United States of America
| | - David Newsom
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Benjamin Kelly
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Yasuhiko Irie
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Laura K. Jennings
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Binjie Xu
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
| | - Dominique H. Limoli
- Department of Infection and Immunity and Center for Microbial Interface Biology, Ohio State University, Columbus, Ohio, United States of America
| | - Joe J. Harrison
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Peter White
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Daniel J. Wozniak
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America
- Department of Microbiology, Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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32
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Hay ID, Wang Y, Moradali MF, Rehman ZU, Rehm BHA. Genetics and regulation of bacterial alginate production. Environ Microbiol 2014; 16:2997-3011. [DOI: 10.1111/1462-2920.12389] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 12/18/2013] [Accepted: 12/22/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Iain D. Hay
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Yajie Wang
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Mohammed F. Moradali
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Zahid U. Rehman
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Bernd H. A. Rehm
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology; Massey University; Palmerston North 4442 New Zealand
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Isom CE, Turner JL, Lessner DJ, Karr EA. Redox-sensitive DNA binding by homodimeric Methanosarcina acetivorans MsvR is modulated by cysteine residues. BMC Microbiol 2013; 13:163. [PMID: 23865844 PMCID: PMC3729527 DOI: 10.1186/1471-2180-13-163] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 07/12/2013] [Indexed: 11/16/2022] Open
Abstract
Background Methanoarchaea are among the strictest known anaerobes, yet they can survive exposure to oxygen. The mechanisms by which they sense and respond to oxidizing conditions are unknown. MsvR is a transcription regulatory protein unique to the methanoarchaea. Initially identified and characterized in the methanogen Methanothermobacter thermautotrophicus (Mth), MthMsvR displays differential DNA binding under either oxidizing or reducing conditions. Since MthMsvR regulates a potential oxidative stress operon in M. thermautotrophicus, it was hypothesized that the MsvR family of proteins were redox-sensitive transcription regulators. Results An MsvR homologue from the methanogen Methanosarcina acetivorans, MaMsvR, was overexpressed and purified. The two MsvR proteins bound the same DNA sequence motif found upstream of all known MsvR encoding genes, but unlike MthMsvR, MaMsvR did not bind the promoters of select genes involved in the oxidative stress response. Unlike MthMsvR that bound DNA under both non-reducing and reducing conditions, MaMsvR bound DNA only under reducing conditions. MaMsvR appeared as a dimer in gel filtration chromatography analysis and site-directed mutagenesis suggested that conserved cysteine residues within the V4R domain were involved in conformational rearrangements that impact DNA binding. Conclusions Results presented herein suggest that homodimeric MaMsvR acts as a transcriptional repressor by binding Ma PmsvR under non-reducing conditions. Changing redox conditions promote conformational changes that abrogate binding to Ma PmsvR which likely leads to de-repression.
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Affiliation(s)
- Catherine E Isom
- Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK, 73019, USA
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AmrZ modulates Pseudomonas aeruginosa biofilm architecture by directly repressing transcription of the psl operon. J Bacteriol 2013; 195:1637-44. [PMID: 23354748 DOI: 10.1128/jb.02190-12] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Pseudomonas aeruginosa strains recovered from chronic pulmonary infections in cystic fibrosis patients are frequently mucoid. Such strains express elevated levels of alginate but reduced levels of the aggregative polysaccharide Psl; however, the mechanistic basis for this regulation is not completely understood. Elevated pslA expression was observed in an amrZ null mutant and in strains expressing a DNA-binding-deficient AmrZ. AmrZ is a transcription factor that positively regulates twitching motility and alginate synthesis, two phenotypes involved in P. aeruginosa biofilm development. AmrZ bound directly to the pslA promoter in vitro, and molecular analyses indicate that AmrZ represses psl expression by binding to a site overlapping the promoter. Altered expression of amrZ in nonmucoid strains impacted biofilm structure and architecture, as structured microcolonies were observed with low AmrZ production and flat biofilms with amrZ overexpression. These biofilm phenotypes correlated with Psl levels, since we observed elevated Psl production in amrZ mutants and lower Psl production in amrZ-overexpressing strains. These observations support the hypothesis that AmrZ is a multifunctional regulator mediating transition of P. aeruginosa biofilm infections from colonizing to chronic biofilms through repression of the psl operon while activating the algD operon.
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Structure and function of AvtR, a novel transcriptional regulator from a hyperthermophilic archaeal lipothrixvirus. J Virol 2012; 87:124-36. [PMID: 23055559 DOI: 10.1128/jvi.01306-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The structural and functional analysis of the protein AvtR encoded by Acidianus filamentous virus 6 (AFV6), which infects the archaeal genus Acidianus, revealed its unusual structure and involvement in transcriptional regulation of several viral genes. The crystal structure of AvtR (100 amino acids) at 2.6-Å resolution shows that it is constituted of a repeated ribbon-helix-helix (RHH) motif, which is found in a large family of bacterial transcriptional regulators. The known RHH proteins form dimers that interact with DNA using their ribbon to create a central β-sheet. The repeated RHH motifs of AvtR superpose well on such dimers, but its central sheet contains an extra strand, suggesting either conformational changes or a different mode of DNA binding. Systematic evolution of ligands by exponential enrichment (SELEX) experiments combined with systematic mutational and computational analysis of the predicted site revealed 8 potential AvtR targets in the AFV6 genome. Two of these targets were studied in detail, and the complex role of AvtR in the transcriptional regulation of viral genes was established. Repressing transcription from its own gene, gp29, AvtR can also act as an activator of another gene, gp30. Its binding sites are distant from both genes' TATA boxes, and the mechanism of AvtR-dependent regulation appears to include protein oligomerization starting from the protein's initial binding sites. Many RHH transcriptional regulators of archaeal viruses could share this regulatory mechanism.
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