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Chowdhury-Paul S, Martínez-Ortíz IC, Pando-Robles V, Moreno S, Espín G, Merino E, Núñez C. The Azotobacter vinelandii AlgU regulon during vegetative growth and encysting conditions: A proteomic approach. PLoS One 2023; 18:e0286440. [PMID: 37967103 PMCID: PMC10651043 DOI: 10.1371/journal.pone.0286440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/24/2023] [Indexed: 11/17/2023] Open
Abstract
In the Pseduomonadacea family, the extracytoplasmic function sigma factor AlgU is crucial to withstand adverse conditions. Azotobacter vinelandii, a closed relative of Pseudomonas aeruginosa, has been a model for cellular differentiation in Gram-negative bacteria since it forms desiccation-resistant cysts. Previous work demonstrated the essential role of AlgU to withstand oxidative stress and on A. vinelandii differentiation, particularly for the positive control of alginate production. In this study, the AlgU regulon was dissected by a proteomic approach under vegetative growing conditions and upon encystment induction. Our results revealed several molecular targets that explained the requirement of this sigma factor during oxidative stress and extended its role in alginate production. Furthermore, we demonstrate that AlgU was necessary to produce alkyl resorcinols, a type of aromatic lipids that conform the cell membrane of the differentiated cell. AlgU was also found to positively regulate stress resistance proteins such as OsmC, LEA-1, or proteins involved in trehalose synthesis. A position-specific scoring-matrix (PSSM) was generated based on the consensus sequence recognized by AlgU in P. aeruginosa, which allowed the identification of direct AlgU targets in the A. vinelandii genome. This work further expands our knowledge about the function of the ECF sigma factor AlgU in A. vinelandii and contributes to explains its key regulatory role under adverse conditions.
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Affiliation(s)
- Sangita Chowdhury-Paul
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Iliana C. Martínez-Ortíz
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Victoria Pando-Robles
- Instituto Nacional de Salud Pública, Centro de Investigación Sobre Enfermedades Infecciosas, Cuernavaca, Morelos, México
| | - Soledad Moreno
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Enrique Merino
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Cinthia Núñez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
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2
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Sundar S, Piramanayagam S, Natarajan J. A comprehensive review on human disease-causing bacterial proteases and their impeding agents. Arch Microbiol 2023; 205:276. [PMID: 37414902 DOI: 10.1007/s00203-023-03618-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/20/2023] [Accepted: 06/24/2023] [Indexed: 07/08/2023]
Abstract
Proteases are enzymes that catalyze the amide bond dissociation in polypeptide and protein peptide units. They are categorized into seven families and are responsible for a wide spectrum of human ailments, such as various types of cancers, skin infections, urinary tract infections etc. Specifically, the bacterial proteases cause a huge impact in the disease progression. Extracellular bacterial proteases break down the host defense proteins, while intracellular proteases are essential for pathogens virulence. Due to its involvement in disease pathogenesis and virulence, bacterial proteases are considered to be potential drug targets. Several studies have reported potential bacterial protease inhibitors in both Gram-positive and Gram-negative disease causing pathogens. In this study, we have comprehensively reviewed about the various human disease-causing cysteine, metallo, and serine bacterial proteases as well as their potential inhibitors.
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Affiliation(s)
- Shobana Sundar
- Department of Biotechnology, PSG College of Technology, Coimbatore, India
| | | | - Jeyakumar Natarajan
- Data Mining and Text Mining Laboratory, Department of Bioinformatics, Bharathiar University, Coimbatore, Tamil Nadu, India.
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3
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Kristensen SS, Diep DB, Kjos M, Mathiesen G. The role of site-2-proteases in bacteria: a review on physiology, virulence, and therapeutic potential. MICROLIFE 2023; 4:uqad025. [PMID: 37223736 PMCID: PMC10202637 DOI: 10.1093/femsml/uqad025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/21/2023] [Accepted: 05/02/2023] [Indexed: 05/25/2023]
Abstract
Site-2-proteases are a class of intramembrane proteases involved in regulated intramembrane proteolysis. Regulated intramembrane proteolysis is a highly conserved signaling mechanism that commonly involves sequential digestion of an anti-sigma factor by a site-1- and site-2-protease in response to external stimuli, resulting in an adaptive transcriptional response. Variation of this signaling cascade continues to emerge as the role of site-2-proteases in bacteria continues to be explored. Site-2-proteases are highly conserved among bacteria and play a key role in multiple processes, including iron uptake, stress response, and pheromone production. Additionally, an increasing number of site-2-proteases have been found to play a pivotal role in the virulence properties of multiple human pathogens, such as alginate production in Pseudomonas aeruginosa, toxin production in Vibrio cholerae, resistance to lysozyme in enterococci and antimicrobials in several Bacillus spp, and cell-envelope lipid composition in Mycobacterium tuberculosis. The prominent role of site-2-proteases in bacterial pathogenicity highlights the potential of site-2-proteases as novel targets for therapeutic intervention. In this review, we summarize the role of site-2-proteases in bacterial physiology and virulence, as well as evaluate the therapeutic potential of site-2-proteases.
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Affiliation(s)
- Sofie S Kristensen
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), 1433 Ås, Norway
| | | | - Morten Kjos
- Corresponding author. NMBU, P.O. Box 5003, 1433 Ås, Norway. E-mail:
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Xia M, Yu D, Chen H, Dai J, Gao N, Li S, Bi X, Qiu D. An RpoN-dependent PEP-CTERM gene is involved in floc formation of an Aquincola tertiaricarbonis strain. BMC Microbiol 2023; 23:20. [PMID: 36658495 PMCID: PMC9850573 DOI: 10.1186/s12866-022-02745-1] [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] [Received: 01/18/2022] [Accepted: 12/21/2022] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The floc is a characteristic of microbial aggregate growth, displaying cloudy suspensions in water. Floc formation has been demonstrated in a series of bacteria and the floc-forming bacteria play a crucial role in activated sludge (AS) process widely used for municipal sewage and industrial wastewater treatment over a century. It has been demonstrated that some exopolysaccharide biosynthesis genes and the sigma factor (sigma54 or rpoN) were required for floc forming in some bacteria. However, the mechanism underlying the floc formation stills need to be elucidated. RESULTS In this study, we demonstrate that a TPR (Tetratricopeptide repeats) protein-encoding gene prsT is required for floc formation of Aquincola tertiaricarbonis RN12 and an upstream PEP-CTERM gene (designated pepA), regulated by RpoN1, is involved in its floc formation but not swarming motility and biofilm formation. Overexpression of PepA could rescue the floc-forming phenotype of the rpoN1 mutant by decreasing the released soluble exopolysaccharides and increasing the bound polymers. CONCLUSION Our results indicate that the wide-spread PEP-CTERM proteins play an important role in the self-flocculation of bacterial cells and may be a component of extracellular polymeric substances required for floc-formation.
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Affiliation(s)
- Ming Xia
- grid.411854.d0000 0001 0709 0000School of Life Sciences, Hubei Engineering Research Center for Protection and Utilization of Special Biological Resources in the Hanjiang River Basin, Jianghan University, Wuhan, 430056 China ,grid.411854.d0000 0001 0709 0000Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, Jianghan University, Wuhan, 430056 China
| | - Dianzhen Yu
- grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.419092.70000 0004 0467 2285Institute for Nutritional Sciences, SIBS, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Han Chen
- grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.429211.d0000 0004 1792 6029Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072 Hubei Province China
| | - Jingcheng Dai
- grid.429211.d0000 0004 1792 6029Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072 Hubei Province China
| | - Na Gao
- grid.469521.d0000 0004 1756 0127Fisheries Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031 China
| | - Shuyang Li
- grid.429211.d0000 0004 1792 6029Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072 Hubei Province China
| | - Xuezhi Bi
- grid.452198.30000 0004 0485 9218Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, 138668 Singapore
| | - Dongru Qiu
- grid.429211.d0000 0004 1792 6029Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072 Hubei Province China
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Aljghami ME, Barghash MM, Majaesic E, Bhandari V, Houry WA. Cellular functions of the ClpP protease impacting bacterial virulence. Front Mol Biosci 2022; 9:1054408. [PMID: 36533084 PMCID: PMC9753991 DOI: 10.3389/fmolb.2022.1054408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 11/15/2022] [Indexed: 09/28/2023] Open
Abstract
Proteostasis mechanisms significantly contribute to the sculpting of the proteomes of all living organisms. ClpXP is a central AAA+ chaperone-protease complex present in both prokaryotes and eukaryotes that facilitates the unfolding and subsequent degradation of target substrates. ClpX is a hexameric unfoldase ATPase, while ClpP is a tetradecameric serine protease. Substrates of ClpXP belong to many cellular pathways such as DNA damage response, metabolism, and transcriptional regulation. Crucially, disruption of this proteolytic complex in microbes has been shown to impact the virulence and infectivity of various human pathogenic bacteria. Loss of ClpXP impacts stress responses, biofilm formation, and virulence effector protein production, leading to decreased pathogenicity in cell and animal infection models. Here, we provide an overview of the multiple critical functions of ClpXP and its substrates that modulate bacterial virulence with examples from several important human pathogens.
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Affiliation(s)
- Mazen E. Aljghami
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Marim M. Barghash
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Emily Majaesic
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
| | - Vaibhav Bhandari
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Walid A. Houry
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
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6
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ESKAPE Pathogens: Looking at Clp ATPases as Potential Drug Targets. Antibiotics (Basel) 2022; 11:antibiotics11091218. [PMID: 36139999 PMCID: PMC9495089 DOI: 10.3390/antibiotics11091218] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 11/29/2022] Open
Abstract
Bacterial antibiotic resistance is rapidly growing globally and poses a severe health threat as the number of multidrug resistant (MDR) and extensively drug-resistant (XDR) bacteria increases. The observed resistance is partially due to natural evolution and to a large extent is attributed to antibiotic misuse and overuse. As the rate of antibiotic resistance increases, it is crucial to develop new drugs to address the emergence of MDR and XDR pathogens. A variety of strategies are employed to address issues pertaining to bacterial antibiotic resistance and these strategies include: (1) the anti-virulence approach, which ultimately targets virulence factors instead of killing the bacterium, (2) employing antimicrobial peptides that target key proteins for bacterial survival and, (3) phage therapy, which uses bacteriophages to treat infectious diseases. In this review, we take a renewed look at a group of ESKAPE pathogens which are known to cause nosocomial infections and are able to escape the bactericidal actions of antibiotics by reducing the efficacy of several known antibiotics. We discuss previously observed escape mechanisms and new possible therapeutic measures to combat these pathogens and further suggest caseinolytic proteins (Clp) as possible therapeutic targets to combat ESKAPE pathogens. These proteins have displayed unmatched significance in bacterial growth, viability and virulence upon chronic infection and under stressful conditions. Furthermore, several studies have showed promising results with targeting Clp proteins in bacterial species, such as Mycobacterium tuberculosis, Staphylococcus aureus and Bacillus subtilis.
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Genome-Wide Identification of Pseudomonas aeruginosa Genes Important for Desiccation Tolerance on Inanimate Surfaces. mSystems 2022; 7:e0011422. [PMID: 35469420 PMCID: PMC9239045 DOI: 10.1128/msystems.00114-22] [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] [Indexed: 11/24/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen prevalent in the environment and in health care settings. Transmission in the health care setting occurs through human-human interactions and/or contact with contaminated surfaces. Moist surfaces such as respirators, sink and tub drains, and even disinfectants can serve as reservoirs. Dry surfaces such as plastic and stainless steel could also serve as a reservoir but would necessitate some degree of tolerance to desiccation. Using an assay to measure P. aeruginosa tolerance to desiccation on plastic and stainless-steel surfaces, we found that only 0.05 to 0.1% of the desiccated cells could be recovered 24 h postdesiccation. We took advantage of the strong selection imposed by desiccation to identify genes important for tolerance using Tn-seq. A highly saturated Tn-seq library was desiccated on plastic and stainless-steel surfaces. NexGen sequencing of the recovered cells identified 97 genes important for survival. Comparing cells desiccated under low- and high-nutrient conditions allowed for differentiation of genes important for desiccation tolerance. The 53 genes identified in the latter analysis are involved in maintenance of cell envelope integrity, purine and pyrimidine biosynthesis, tricarboxylic acid (TCA) cycle, and the hydrolysis of misfolded proteins. The Tn-seq findings were validated by competition experiments with wild-type (WT) cells and select Tn insertion mutants. Mutants lacking carB and surA demonstrated the largest fitness defects, indicating that pyrimidine biosynthesis and outer membrane integrity are essential for desiccation tolerance. Increased understanding of desiccation tolerance could provide insight into approaches to control environmental reservoirs of P. aeruginosa. IMPORTANCE Health care-associated infections (HAIs) caused by Pseudomonas aeruginosa result in significant morbidity and mortality and are a significant economic burden. Moist environments that promote biofilm formation are an important reservoir for P. aeruginosa. Dry environments may also serve as a reservoir but would require some degree of desiccation tolerance. Here, we took a genome-wide approach to identify genes important for desiccation tolerance on plastic and stainless-steel surfaces. Genes involved in assembly of outer membrane proteins and pyrimidine biosynthesis were particularly important. Strains lacking these functions were unable to tolerate surface desiccation. These findings suggest that inhibitors of these pathways could be used to prevent P. aeruginosa survival on dry surfaces.
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8
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Dong S, Chen H, Zhou Q, Liao N. Protein degradation control and regulation of bacterial survival and pathogenicity: the role of protein degradation systems in bacteria. Mol Biol Rep 2021; 48:7575-7585. [PMID: 34655017 DOI: 10.1007/s11033-021-06744-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Protein degradation systems play crucial roles in all the kingdoms of life. Their natural function is to eliminate proteins that are improperly synthesized, damaged, aggregated, or short-lived, ensuring the timely and accurate regulation of the response to abrupt environmental changes. Thus, proteolysis plays an important role in protein homeostasis, quality control, and the control of regulatory processes, such as adaptation and cell development. Except for the lysosome, ATPases Associated with various cellular Activities (AAA+) ATPase-protease complex is another major protein degradation system in the cell. METHODS AND RESULTS The AAA+ ATPase-protease complex is a giant energy-dependent protease complex found in almost all kinds of cells, including bacteria, archaea and eukarya. Based on sequence analysis of ClpQ (HslV) and 20S proteasome beta subunits, it was found that bacterial ClpQ possess multiple same highly conserved motifs with 20S proteasome beta subunits of archaea and eukaryote. In this review, we also discussed the structure and functional mechanism, protein degradation signals and pathogenic role of proteasome / Clp protease complex in prokaryotes. CONCLUSION Bacterial protein degradation systems play important roles in stress tolerance, protein quality control, DNA protection, transcription and pathogenicity of bacteria. But our current knowledge of the bacterial protease system is incomplete, and further research into the Clp protease complex and associated protein degradation signals will extend our understanding of the metabolism, physiology, reproduction, and pathogenicity of bacteria.
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Affiliation(s)
- Shilei Dong
- Department of Clinical Laboratory, Zhejiang Hospital, Hangzhou, 310013, China
| | - Honghu Chen
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China
| | - Qingxue Zhou
- Department of Clinical Laboratory, Hangzhou Women's Hospital (Hangzhou Maternity and Child Health Care Hospital), Hangzhou, 310008, China
| | - Ningbo Liao
- College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, 330045, China.
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9
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Powell M, Blaskovich MAT, Hansford KA. Targeted Protein Degradation: The New Frontier of Antimicrobial Discovery? ACS Infect Dis 2021; 7:2050-2067. [PMID: 34259518 DOI: 10.1021/acsinfecdis.1c00203] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Targeted protein degradation aims to hijack endogenous protein quality control systems to achieve direct knockdown of protein targets. This exciting technology utilizes event-based pharmacology to produce therapeutic outcomes, a feature that distinguishes it from classical occupancy-based inhibitor agents. Early degrader candidates display resilience to mutations while possessing potent nanomolar activity and high target specificity. Paired with the rapid advancement of our knowledge in the factors driving targeted degradation, the expansion of this style of therapeutic agent to a range of disease indications is eagerly awaited. In particular, the area of antibiotic discovery is sorely lacking in novel approaches, with the Antimicrobial Resistance (AMR) crisis looming as the next potential global health calamity. Here, the current advances in targeted protein degradation are highlighted, and potential approaches for designing novel antimicrobial protein degraders are proposed, ranging from adaptations of current strategies to completely novel approaches to targeted protein degradation.
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Affiliation(s)
- Matthew Powell
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Mark A. T. Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Karl A. Hansford
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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10
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Mawla GD, Hall BM, Cárcamo-Oyarce G, Grant RA, Zhang JJ, Kardon JR, Ribbeck K, Sauer RT, Baker TA. ClpP1P2 peptidase activity promotes biofilm formation in Pseudomonas aeruginosa. Mol Microbiol 2021; 115:1094-1109. [PMID: 33231899 PMCID: PMC8141546 DOI: 10.1111/mmi.14649] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 01/07/2023]
Abstract
Caseinolytic proteases (Clp) are central to bacterial proteolysis and control cellular physiology and stress responses. They are composed of a double-ring compartmentalized peptidase (ClpP) and a AAA+ unfoldase (ClpX or ClpA/ClpC). Unlike many bacteria, the opportunistic pathogen Pseudomonas aeruginosa contains two ClpP homologs: ClpP1 and ClpP2. The specific functions of these homologs, however, are largely elusive. Here, we report that the active form of PaClpP2 is a part of a heteromeric PaClpP17 P27 tetradecamer that is required for proper biofilm development. PaClpP114 and PaClpP17 P27 complexes exhibit distinct peptide cleavage specificities and interact differentially with P. aeruginosa ClpX and ClpA. Crystal structures reveal that PaClpP2 has non-canonical features in its N- and C-terminal regions that explain its poor interaction with unfoldases. However, experiments in vivo indicate that the PaClpP2 peptidase active site uniquely contributes to biofilm development. These data strongly suggest that the specificity of different classes of ClpP peptidase subunits contributes to the biological outcome of proteolysis. This specialized role of PaClpP2 highlights it as an attractive target for developing antimicrobial agents that interfere specifically with late-stage P. aeruginosa development.
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Affiliation(s)
- Gina D. Mawla
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Branwen M. Hall
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Gerardo Cárcamo-Oyarce
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Robert A. Grant
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Jia Jia Zhang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Julia R. Kardon
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Katharina Ribbeck
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Robert T. Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Tania A. Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
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11
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Craig K, Johnson BR, Grunden A. Leveraging Pseudomonas Stress Response Mechanisms for Industrial Applications. Front Microbiol 2021; 12:660134. [PMID: 34040596 PMCID: PMC8141521 DOI: 10.3389/fmicb.2021.660134] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/12/2021] [Indexed: 12/25/2022] Open
Abstract
Members of the genus Pseudomonas are metabolically versatile and capable of adapting to a wide variety of environments. Stress physiology of Pseudomonas strains has been extensively studied because of their biotechnological potential in agriculture as well as their medical importance with regards to pathogenicity and antibiotic resistance. This versatility and scientific relevance led to a substantial amount of information regarding the stress response of a diverse set of species such as Pseudomonas chlororaphis, P. fluorescens, P. putida, P. aeruginosa, and P. syringae. In this review, environmental and industrial stressors including desiccation, heat, and cold stress, are cataloged along with their corresponding mechanisms of survival in Pseudomonas. Mechanisms of survival are grouped by the type of inducing stress with a focus on adaptations such as synthesis of protective substances, biofilm formation, entering a non-culturable state, enlisting chaperones, transcription and translation regulation, and altering membrane composition. The strategies Pseudomonas strains utilize for survival can be leveraged during the development of beneficial strains to increase viability and product efficacy.
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Affiliation(s)
- Kelly Craig
- AgBiome Inc., Research Triangle Park, NC, United States
| | | | - Amy Grunden
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, United States
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12
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Schofield MC, Rodriguez DQ, Kidman AA, Cassin EK, Michaels LA, Campbell EA, Jorth PA, Tseng BS. The anti-sigma factor MucA is required for viability in Pseudomonas aeruginosa. Mol Microbiol 2021; 116:550-563. [PMID: 33905139 PMCID: PMC10069406 DOI: 10.1111/mmi.14732] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 12/16/2022]
Abstract
During decades-long infections in the cystic fibrosis (CF) airway, Pseudomonas aeruginosa undergoes selection. One bacterial genetic adaptation often observed in CF isolates is mucA mutations. MucA inhibits the sigma factor AlgU. Mutations in mucA lead to AlgU misregulation, resulting in a mucoid phenotype that is associated with poor CF disease outcomes. Due to its ability to be mutated, mucA is assumed to be dispensable for bacterial viability. Here we show that, paradoxically, a portion of mucA is essential in P. aeruginosa. We demonstrate that mucA is no longer required in a strain lacking algU, that mucA alleles encoding for proteins that do not bind to AlgU are insufficient for viability, and that mucA is no longer essential in mutant strains containing AlgU variants with reduced sigma factor activity. Furthermore, we found that overexpression of algU prevents cell growth in the absence of MucA, and that this phenotype can be rescued by the overproduction of RpoD, the housekeeping sigma factor. Together, these results suggest that in the absence of MucA, the inability to regulate AlgU activity results in the loss of bacterial viability. Finally, we speculate that the essentiality of anti-sigma factors that regulate envelope function may be a widespread phenomenon in bacteria.
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Affiliation(s)
| | | | - Amanda A Kidman
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Erin K Cassin
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Lia A Michaels
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Elizabeth A Campbell
- Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, USA
| | - Peter A Jorth
- Departments of Pathology and Laboratory Medicine, Medicine, and Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Boo Shan Tseng
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
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13
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Acyldepsipeptide activated ClpP1P2 macromolecule of Leptospira, an ideal Achilles' heel to hamper the cell survival and deregulate ClpP proteolytic activity. Res Microbiol 2021; 172:103797. [PMID: 33460738 DOI: 10.1016/j.resmic.2021.103797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/30/2020] [Accepted: 01/07/2021] [Indexed: 11/22/2022]
Abstract
Antibiotic acyldepsipeptide (ADEP) targets the bacterial ClpP serine protease and can inhibit the growth of numerous bacterial species by activating/dysregulating the protease activity within the cell. The spirochete Leptospira interrogans harbors two ClpP isoforms (LepClpP1 and LepClpP2). Supplementation of ADEP in the Leptospira growth medium resulted in the inhibition of bacterial growth. The ADEP mediated activation of the LepClpP mixture was dependent on the time allowed for the self-assembly of LepClpP1 and LepClpP2. The dynamic light scattering of the LepClpP mixture in the presence of the ADEP indicated a conformational transformation of the LepClpP machinery. Serine 98, a catalytic triad residue of the LepClpP1 in the LepClpP1P2 heterocomplex, was critical for the ADEP mediated activation. The computational prototype of the LepClpP1P2 structure suggested that the hydrophobic pockets wherein the ADEPs or the physiological chaperone ClpX predominantly dock are exclusively present in the LepClpP2 heptamer. Using the ADEP as a tool, this investigation provides an insight into the molecular function of the LepClpP1P2 in a coalition with its ATPase chaperone LepClpX. The shreds of the evidence illustrated in this investigation verify that ADEP1 possesses the ability to control the LepClpP system in an unconventional approach than the other organisms.
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14
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Wettstadt S, Llamas MA. Role of Regulated Proteolysis in the Communication of Bacteria With the Environment. Front Mol Biosci 2020; 7:586497. [PMID: 33195433 PMCID: PMC7593790 DOI: 10.3389/fmolb.2020.586497] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/22/2020] [Indexed: 12/29/2022] Open
Abstract
For bacteria to flourish in different niches, they need to sense signals from the environment and translate these into appropriate responses. Most bacterial signal transduction systems involve proteins that trigger the required response through the modification of gene transcription. These proteins are often produced in an inactive state that prevents their interaction with the RNA polymerase and/or the DNA in the absence of the inducing signal. Among other mechanisms, regulated proteolysis is becoming increasingly recognized as a key process in the modulation of the activity of these signal response proteins. Regulated proteolysis can either produce complete degradation or specific cleavage of the target protein, thus modifying its function. Because proteolysis is a fast process, the modulation of signaling proteins activity by this process allows for an immediate response to a given signal, which facilitates adaptation to the surrounding environment and bacterial survival. Moreover, regulated proteolysis is a fundamental process for the transmission of extracellular signals to the cytosol through the bacterial membranes. By a proteolytic mechanism known as regulated intramembrane proteolysis (RIP) transmembrane proteins are cleaved within the plane of the membrane to liberate a cytosolic domain or protein able to modify gene transcription. This allows the transmission of a signal present on one side of a membrane to the other side where the response is elicited. In this work, we review the role of regulated proteolysis in the bacterial communication with the environment through the modulation of the main bacterial signal transduction systems, namely one- and two-component systems, and alternative σ factors.
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Affiliation(s)
- Sarah Wettstadt
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
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15
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Yu Z, Zhang J, Ding M, Wu S, Shuangjia Li, Zhang M, Yin J, Meng Q. SspA positively controls exopolysaccharides production and biofilm formation by up-regulating the algU expression in Pseudoalteromonas sp. R3. Biochem Biophys Res Commun 2020; 533:988-994. [PMID: 33010891 DOI: 10.1016/j.bbrc.2020.09.118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 09/25/2020] [Indexed: 10/23/2022]
Abstract
Biofilm formation enhances the survival and persistence of microorganisms in response to environmental stresses. It has been revealed that stringent starvation protein A (SspA) can function as an important regulator dealing with environmental stresses for bacterial survival. However, the connection between SspA and biofilm formation is essentially unclear yet. In this study, we presented evidence showing SspA positively controls biofilm formation by up-regulating exopolysaccharides (EPS) production in marine bacterium Pseudoalteromonas sp. R3. Both qPCR and lacZ reporter system congruously revealed that SspA positively controls the expression of EPS biosynthesis gene cluster. Unlike generally accepted thought that SspA regulates bacterial physiology by inhibiting the expression of histone-like nucleotide structuring protein (H-NS) gene, the function of SspA on EPS production and biofilm formation in Pseudoalteromonas sp. R3 is H-NS-independent. Instead, SspA positively regulates the expression of sigma factor AlgU-encoding gene, thus affecting EPS biosynthesis and biofilm formation. In view of the important role of SspA in biofilm formation, we believe that the improvement of tolerance to marine environmental stresses could be related to tuning of SspA-involved biofilm formation.
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Affiliation(s)
- Zhiliang Yu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China.
| | - Jiadi Zhang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China
| | - Mengdan Ding
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China
| | - Shijun Wu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China
| | - Shuangjia Li
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China
| | - Mengting Zhang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China
| | - Jianhua Yin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China
| | - Qiu Meng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang Province, China.
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16
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Ju Y, He L, Zhou Y, Yang T, Sun K, Song R, Yang Y, Li C, Sang Z, Bao R, Luo Y. Discovery of Novel Peptidomimetic Boronate ClpP Inhibitors with Noncanonical Enzyme Mechanism as Potent Virulence Blockers in Vitro and in Vivo. J Med Chem 2020; 63:3104-3119. [PMID: 32031798 DOI: 10.1021/acs.jmedchem.9b01746] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Caseinolytic protease P (ClpP) is considered as a promising target for the treatment of Staphylococcus aureus infections. In an unbiased screen of 2632 molecules, a peptidomimetic boronate, MLN9708, was found to be a potent suppressor of SaClpP function. A time-saving and cost-efficient strategy integrating in silico position scanning, multistep miniaturized synthesis, and bioactivity testing was deployed for optimization of this hit compound and led to fast exploration of structure-activity relationships. Five of 150 compounds from the miniaturized synthesis exhibited improved inhibitory activity. Compound 43Hf was the most active inhibitor and showed reversible covalent binding to SaClpP while did not destabilize the tetradecameric structure of SaClpP. The crystal structure of 43Hf-SaClpP complex provided mechanistic insight into the covalent binding mode of peptidomimetic boronate and SaClpP. Furthermore, 43Hf could bind endogenous ClpP in S. aureus cells and exhibited significant efficacy in attenuating S. aureus virulence in vitro and in vivo.
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Affiliation(s)
- Yuan Ju
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Lihui He
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yuanzheng Zhou
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Tao Yang
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.,Laboratory of Human Disease and Immunotherapies, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Ke Sun
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Rao Song
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yang Yang
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Chengwei Li
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.,Suzhou Zelgen Biopharmaceuticals Co., Ltd., Kunshan, Jiangsu 215301, China
| | - Zitai Sang
- Institute of Life Science, Luoyang Normal University, Luoyang, Henan 471934, China
| | - Rui Bao
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Youfu Luo
- State Key Laboratory of Biotherapy and Cancer Center/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
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17
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Hews CL, Cho T, Rowley G, Raivio TL. Maintaining Integrity Under Stress: Envelope Stress Response Regulation of Pathogenesis in Gram-Negative Bacteria. Front Cell Infect Microbiol 2019; 9:313. [PMID: 31552196 PMCID: PMC6737893 DOI: 10.3389/fcimb.2019.00313] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/19/2019] [Indexed: 12/20/2022] Open
Abstract
The Gram-negative bacterial envelope is an essential interface between the intracellular and harsh extracellular environment. Envelope stress responses (ESRs) are crucial to the maintenance of this barrier and function to detect and respond to perturbations in the envelope, caused by environmental stresses. Pathogenic bacteria are exposed to an array of challenging and stressful conditions during their lifecycle and, in particular, during infection of a host. As such, maintenance of envelope homeostasis is essential to their ability to successfully cause infection. This review will discuss our current understanding of the σE- and Cpx-regulated ESRs, with a specific focus on their role in the virulence of a number of model pathogens.
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Affiliation(s)
- Claire L Hews
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Timothy Cho
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Tracy L Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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18
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Otero-Asman JR, Wettstadt S, Bernal P, Llamas MA. Diversity of extracytoplasmic function sigma (σ ECF ) factor-dependent signaling in Pseudomonas. Mol Microbiol 2019; 112:356-373. [PMID: 31206859 DOI: 10.1111/mmi.14331] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2019] [Indexed: 12/23/2022]
Abstract
Pseudomonas bacteria are widespread and are found in soil and water, as well as pathogens of both plants and animals. The ability of Pseudomonas to colonize many different environments is facilitated by the multiple signaling systems these bacteria contain that allow Pseudomonas to adapt to changing circumstances by generating specific responses. Among others, signaling through extracytoplasmic function σ (σECF ) factors is extensively present in Pseudomonas. σECF factors trigger expression of functions required under particular conditions in response to specific signals. This manuscript reviews the phylogeny and biological roles of σECF factors in Pseudomonas, and highlights the diversity of σECF -signaling pathways of this genus in terms of function and activation. We show that Pseudomonas σECF factors belong to 16 different phylogenetic groups. Most of them are included within the iron starvation group and are mainly involved in iron acquisition. The second most abundant group is formed by RpoE-like σECF factors, which regulate the responses to cell envelope stress. Other groups controlling solvent tolerance, biofilm formation and the response to oxidative stress, among other functions, are present in lower frequency. The role of σECF factors in the virulence of Pseudomonas pathogenic species is described.
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Affiliation(s)
- Joaquín R Otero-Asman
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Sarah Wettstadt
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Patricia Bernal
- Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | - María A Llamas
- Department of Environmental Protection, Estación Experimental del Zaidín-Consejo Superior de Investigaciones Científicas, Granada, Spain
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19
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Ethanol Stimulates Trehalose Production through a SpoT-DksA-AlgU-Dependent Pathway in Pseudomonas aeruginosa. J Bacteriol 2019; 201:JB.00794-18. [PMID: 30936375 DOI: 10.1128/jb.00794-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/26/2019] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa frequently resides among ethanol-producing microbes, making its response to the microbially produced concentrations of ethanol relevant to understanding its biology. Our transcriptome analysis found that genes involved in trehalose metabolism were induced by low concentrations of ethanol, and biochemical assays showed that levels of intracellular trehalose increased significantly upon growth with ethanol. The increase in trehalose was dependent on the TreYZ pathway but not other trehalose-metabolic enzymes (TreS or TreA). The sigma factor AlgU (AlgT), a homolog of RpoE in other species, was required for increased expression of the treZ gene and trehalose levels, but induction was not controlled by the well-characterized proteolysis of its anti-sigma factor, MucA. Growth with ethanol led to increased SpoT-dependent (p)ppGpp accumulation, which stimulates AlgU-dependent transcription of treZ and other AlgU-regulated genes through DksA, a (p)ppGpp and RNA polymerase binding protein. Ethanol stimulation of trehalose also required acylhomoserine lactone (AHL)-mediated quorum sensing (QS), as induction was not observed in a ΔlasR ΔrhlR strain. A network analysis using a model, eADAGE, built from publicly available P. aeruginosa transcriptome data sets (J. Tan, G. Doing, K. A. Lewis, C. E. Price, et al., Cell Syst 5:63-71, 2017, https://doi.org/10.1016/j.cels.2017.06.003) provided strong support for our model in which treZ and coregulated genes are controlled by both AlgU- and AHL-mediated QS. Consistent with (p)ppGpp- and AHL-mediated quorum-sensing regulation, ethanol, even when added at the time of culture inoculation, stimulated treZ transcript levels and trehalose production in cells from post-exponential-phase cultures but not in cells from exponential-phase cultures. These data highlight the integration of growth and cell density cues in the P. aeruginosa transcriptional response to ethanol.IMPORTANCE Pseudomonas aeruginosa is often found with bacteria and fungi that produce fermentation products, including ethanol. At concentrations similar to those produced by environmental microbes, we found that ethanol stimulated expression of trehalose-biosynthetic genes and cellular levels of trehalose, a disaccharide that protects against environmental stresses. The induction of trehalose by ethanol required the alternative sigma factor AlgU through DksA- and SpoT-dependent (p)ppGpp. Trehalose accumulation also required AHL quorum sensing and occurred only in post-exponential-phase cultures. This work highlights how cells integrate cell density and growth cues in their responses to products made by other microbes and reveals a new role for (p)ppGpp in the regulation of AlgU activity.
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20
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Moreno-Cinos C, Goossens K, Salado IG, Van Der Veken P, De Winter H, Augustyns K. ClpP Protease, a Promising Antimicrobial Target. Int J Mol Sci 2019; 20:ijms20092232. [PMID: 31067645 PMCID: PMC6540193 DOI: 10.3390/ijms20092232] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/18/2019] [Accepted: 04/29/2019] [Indexed: 01/25/2023] Open
Abstract
The caseinolytic protease proteolytic subunit (ClpP) is a serine protease playing an important role in proteostasis of eukaryotic organelles and prokaryotic cells. Alteration of ClpP function has been proved to affect the virulence and infectivity of a number of pathogens. Increased bacterial resistance to antibiotics has become a global problem and new classes of antibiotics with novel mechanisms of action are needed. In this regard, ClpP has emerged as an attractive and potentially viable option to tackle pathogen fitness without suffering cross-resistance to established antibiotic classes and, when not an essential target, without causing an evolutionary selection pressure. This opens a greater window of opportunity for the host immune system to clear the infection by itself or by co-administration with commonly prescribed antibiotics. A comprehensive overview of the function, regulation and structure of ClpP across the different organisms is given. Discussion about mechanism of action of this protease in bacterial pathogenesis and human diseases are outlined, focusing on the compounds developed in order to target the activation or inhibition of ClpP.
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Affiliation(s)
- Carlos Moreno-Cinos
- Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Kenneth Goossens
- Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Irene G Salado
- Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Pieter Van Der Veken
- Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Hans De Winter
- Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
| | - Koen Augustyns
- Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
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21
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Moreno-Cinos C, Sassetti E, Salado IG, Witt G, Benramdane S, Reinhardt L, Cruz CD, Joossens J, Van der Veken P, Brötz-Oesterhelt H, Tammela P, Winterhalter M, Gribbon P, Windshügel B, Augustyns K. α-Amino Diphenyl Phosphonates as Novel Inhibitors of Escherichia coli ClpP Protease. J Med Chem 2019; 62:774-797. [PMID: 30571121 DOI: 10.1021/acs.jmedchem.8b01466] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Increased Gram-negative bacteria resistance to antibiotics is becoming a global problem, and new classes of antibiotics with novel mechanisms of action are required. The caseinolytic protease subunit P (ClpP) is a serine protease conserved among bacteria that is considered as an interesting drug target. ClpP function is involved in protein turnover and homeostasis, stress response, and virulence among other processes. The focus of this study was to identify new inhibitors of Escherichia coli ClpP and to understand their mode of action. A focused library of serine protease inhibitors based on diaryl phosphonate warheads was tested for ClpP inhibition, and a chemical exploration around the hit compounds was conducted. Altogether, 14 new potent inhibitors of E. coli ClpP were identified. Compounds 85 and 92 emerged as most interesting compounds from this study due to their potency and, respectively, to its moderate but consistent antibacterial properties as well as the favorable cytotoxicity profile.
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Affiliation(s)
- Carlos Moreno-Cinos
- Laboratory of Medicinal Chemistry , University of Antwerp , Universiteitsplein 1 , B-2610 Antwerp , Belgium
| | - Elisa Sassetti
- Fraunhofer Institute for Molecular Biology and Applied Ecology, ScreeningPort , Schnackenburgallee 114 , 22525 Hamburg , Germany.,Department of Life Sciences and Chemistry , Jacobs University Bremen gGmbH , Campus Ring 1 , 28759 Bremen , Germany
| | - Irene G Salado
- Laboratory of Medicinal Chemistry , University of Antwerp , Universiteitsplein 1 , B-2610 Antwerp , Belgium
| | - Gesa Witt
- Fraunhofer Institute for Molecular Biology and Applied Ecology, ScreeningPort , Schnackenburgallee 114 , 22525 Hamburg , Germany
| | - Siham Benramdane
- Laboratory of Medicinal Chemistry , University of Antwerp , Universiteitsplein 1 , B-2610 Antwerp , Belgium
| | - Laura Reinhardt
- Interfaculty Institute for Microbiology and Infection Medicine , University of Tübingen , Auf der Morgenstelle 28 , 72076 Tübingen , Germany
| | - Cristina D Cruz
- Drug Research Program, Division of Pharmaceutical Biosciences , University of Helsinki , Viikinkaari 5E , FI-00014 Helsinki , Finland
| | - Jurgen Joossens
- Laboratory of Medicinal Chemistry , University of Antwerp , Universiteitsplein 1 , B-2610 Antwerp , Belgium
| | - Pieter Van der Veken
- Laboratory of Medicinal Chemistry , University of Antwerp , Universiteitsplein 1 , B-2610 Antwerp , Belgium
| | - Heike Brötz-Oesterhelt
- Interfaculty Institute for Microbiology and Infection Medicine , University of Tübingen , Auf der Morgenstelle 28 , 72076 Tübingen , Germany
| | - Päivi Tammela
- Drug Research Program, Division of Pharmaceutical Biosciences , University of Helsinki , Viikinkaari 5E , FI-00014 Helsinki , Finland
| | - Mathias Winterhalter
- Department of Life Sciences and Chemistry , Jacobs University Bremen gGmbH , Campus Ring 1 , 28759 Bremen , Germany
| | - Philip Gribbon
- Fraunhofer Institute for Molecular Biology and Applied Ecology, ScreeningPort , Schnackenburgallee 114 , 22525 Hamburg , Germany
| | - Björn Windshügel
- Fraunhofer Institute for Molecular Biology and Applied Ecology, ScreeningPort , Schnackenburgallee 114 , 22525 Hamburg , Germany
| | - Koen Augustyns
- Laboratory of Medicinal Chemistry , University of Antwerp , Universiteitsplein 1 , B-2610 Antwerp , Belgium
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22
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Pyrimidine Biosynthesis Regulates the Small-Colony Variant and Mucoidy in Pseudomonas aeruginosa through Sigma Factor Competition. J Bacteriol 2018; 201:JB.00575-18. [PMID: 30322853 DOI: 10.1128/jb.00575-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 10/05/2018] [Indexed: 01/21/2023] Open
Abstract
Mucoidy due to alginate overproduction by the Gram-negative bacterium Pseudomonas aeruginosa facilitates chronic lung infections in patients with cystic fibrosis (CF). We previously reported that disruption in de novo synthesis of pyrimidines resulted in conversion to a nonmucoid small-colony variant (SCV) in the mucoid P. aeruginosa strain (PAO581), which has a truncated anti-sigma factor, MucA25, that cannot sequester sigma factor AlgU (AlgT). Here, we showed that supplementation with the nitrogenous bases uracil or cytosine in growth medium complemented the SCV to normal growth, and nonmucoidy to mucoidy, in these mucA25 mutants. This conversion was associated with an increase in intracellular levels of UMP and UTP suggesting that nucleotide restoration occurred via a salvage pathway. In addition, supplemented pyrimidines caused an increase in activity of the alginate biosynthesis promoter (P algD ), but had no effect on P algU , which controls transcription of algU Cytosolic levels of AlgU were not influenced by uracil supplementation, yet levels of RpoN, a sigma factor that regulates nitrogen metabolism, increased with disruption of pyrimidine synthesis and decreased after supplementation of uracil. This suggested that an elevated level of RpoN in SCV may block alginate biosynthesis. To support this, we observed that overexpressing rpoN resulted in a phenotypic switch to nonmucoidy in PAO581 and in mucoid clinical isolates. Furthermore, transcription of an RpoN-regulated promoter increased in the mutants and decreased after uracil supplementation. These results suggest that the balance of RpoN and AlgU levels may regulate growth from SCV to mucoidy through sigma factor competition for P algD IMPORTANCE Chronic lung infections with P. aeruginosa are the main cause of morbidity and mortality in patients with cystic fibrosis. This bacterium overproduces a capsular polysaccharide called alginate (also known as mucoidy), which aids in bacterial persistence in the lungs and in resistance to therapeutic regimens and host immune responses. The current study explores a previously unknown link between pyrimidine biosynthesis and mucoidy at the level of transcriptional regulation. Identifying/characterizing this link could provide novel targets for the control of bacterial growth and mucoidy. Inhibiting mucoidy may improve antimicrobial efficacy and facilitate host defenses to clear the noncapsulated P. aeruginosa bacteria, leading to improved prognosis for patients with cystic fibrosis.
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23
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Pseudomonas aeruginosa Regulated Intramembrane Proteolysis: Protease MucP Can Overcome Mutations in the AlgO Periplasmic Protease To Restore Alginate Production in Nonmucoid Revertants. J Bacteriol 2018; 200:JB.00215-18. [PMID: 29784885 DOI: 10.1128/jb.00215-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/15/2018] [Indexed: 01/07/2023] Open
Abstract
The progression of cystic fibrosis (CF) from an acute to a chronic disease is often associated with the conversion of the opportunistic pathogen Pseudomonas aeruginosa from a nonmucoid form to a mucoid form in the lung. This conversion involves the constitutive synthesis of the exopolysaccharide alginate, whose production is under the control of the AlgT/U sigma factor. This factor is regulated posttranslationally by an extremely unstable process and has been commonly attributed to mutations in the algT (algU) gene. By exploiting this unstable phenotype, we isolated 34 spontaneous nonmucoid variants arising from the mucoid strain PDO300, a PAO1 derivative containing the mucA22 allele commonly found in mucoid CF isolates. Complementation analysis using a minimal tiling path cosmid library revealed that most of these mutants mapped to two protease-encoding genes, algO, also known as prc or PA3257, and mucP Interestingly, our algO mutations were complemented by both mucP and algO, leading us to delete, clone, and overexpress mucP, algO, mucE, and mucD in both wild-type PAO1 and PDO300 backgrounds to better understand the regulation of this complex regulatory mechanism. Our findings suggest that the regulatory proteases follow two pathways for regulated intramembrane proteolysis (RIP), where both the AlgO/MucP pathway and MucE/AlgW pathway are required in the wild-type strain but where the AlgO/MucP pathway can bypass the MucE/AlgW pathway in mucoid strains with membrane-associated forms of MucA with shortened C termini, such as the MucA22 variant. This work gives us a better understanding of how alginate production is regulated in the clinically important mucoid variants of Pseudomonas aeruginosaIMPORTANCE Infection by the opportunistic pathogen Pseudomonas aeruginosa is the leading cause of morbidity and mortality seen in CF patients. Poor patient prognosis correlates with the genotypic and phenotypic change of the bacteria from a typical nonmucoid to a mucoid form in the CF lung, characterized by the overproduction of alginate. The expression of this exopolysaccharide is under the control an alternate sigma factor, AlgT/U, that is regulated posttranslationally by a series of proteases. A better understanding of this regulatory phenomenon will help in the development of therapies targeting alginate production, ultimately leading to an increase in the length and quality of life for those suffering from CF.
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24
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Pandey S, Delgado C, Kumari H, Florez L, Mathee K. Outer-membrane protein LptD (PA0595) plays a role in the regulation of alginate synthesis in Pseudomonas aeruginosa. J Med Microbiol 2018; 67:1139-1156. [PMID: 29923820 DOI: 10.1099/jmm.0.000752] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE The presence of alginate-overproducing (Alg+) strains of Pseudomonas aeruginosa in cystic fibrosis patients is indicative of chronic infection. The Alg+ phenotype is generally due to a mutation in the mucA gene, encoding an innermembrane protein that sequesters AlgT/U, the alginate-specific sigma factor. AlgT/U release from the anti-sigma factor MucA is orchestrated via a complex cascade called regulated intramembrane proteolysis. The goal of this study is to identify new players involved in the regulation of alginate production. METHODOLOGY Previously, a mutant with a second-site suppressor of alginate production (sap), sap27, was isolated from the constitutively Alg+ PDO300 that harbours the mucA22 allele. A cosmid from a P. aeruginosa minimum tiling path library was identified via en masse complementation of sap27. The cosmid was transposon mutagenized to map the contributing gene involved in the alginate production. The identified gene was sequenced in sap27 along with algT/U, mucA, algO and mucP. The role of the novel gene was explored using precise in-frame algO and algW deletion mutants of PAO1 and PDO300.Results/Key findings. The gene responsible for restoring the mucoid phenotype was mapped to lptD encoding an outer-membrane protein. However, the sequencing of sap27 revealed a mutation in algO, but not in lptD. In addition, we demonstrate that lipopolysaccharide transport protein D (LptD)-dependent alginate production requires AlgW in PAO1 and AlgO in PDO300. CONCLUSION LptD plays a specific role in alginate production. Our findings suggest that there are two pathways for the production of alginate in P. aeruginosa, one involving AlgW in the wild-type, and one involving AlgO in the mucA22 mutant.
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Affiliation(s)
- Sundar Pandey
- 1Department of Biological Sciences, College of Arts Sciences and Education, Florida International University, Miami, FL, USA
| | - Camila Delgado
- 2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,†Present address: Langone Medical Center, New York University School of Medicine, New York, USA
| | - Hansi Kumari
- 2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,3Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Laura Florez
- 2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Kalai Mathee
- 4Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.,2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,3Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
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Bhandari V, Wong KS, Zhou JL, Mabanglo MF, Batey RA, Houry WA. The Role of ClpP Protease in Bacterial Pathogenesis and Human Diseases. ACS Chem Biol 2018; 13:1413-1425. [PMID: 29775273 DOI: 10.1021/acschembio.8b00124] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In prokaryotic cells and eukaryotic organelles, the ClpP protease plays an important role in proteostasis. The disruption of the ClpP function has been shown to influence the infectivity and virulence of a number of bacterial pathogens. More recently, ClpP has been found to be involved in various forms of carcinomas and in Perrault syndrome, which is an inherited condition characterized by hearing loss in males and females and by ovarian abnormalities in females. Hence, targeting ClpP is a potentially viable, attractive option for the treatment of different ailments. Herein, the biochemical and cellular activities of ClpP are discussed along with the mechanisms by which ClpP affects bacterial pathogenesis and various human diseases. In addition, a comprehensive overview is given of the new classes of compounds in development that target ClpP. Many of these compounds are currently primarily aimed at treating bacterial infections. Some of these compounds inhibit ClpP activity, while others activate the protease and lead to its dysregulation. The ClpP activators are remarkable examples of small molecules that inhibit protein-protein interactions but also result in a gain of function.
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Affiliation(s)
- Vaibhav Bhandari
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Keith S. Wong
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Jin Lin Zhou
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Mark F. Mabanglo
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Robert A. Batey
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Walid A. Houry
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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Chevalier S, Bouffartigues E, Bazire A, Tahrioui A, Duchesne R, Tortuel D, Maillot O, Clamens T, Orange N, Feuilloley MGJ, Lesouhaitier O, Dufour A, Cornelis P. Extracytoplasmic function sigma factors in Pseudomonas aeruginosa. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:706-721. [PMID: 29729420 DOI: 10.1016/j.bbagrm.2018.04.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/06/2018] [Accepted: 04/30/2018] [Indexed: 01/26/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa, like all members of the genus Pseudomonas, has the capacity to thrive in very different environments, ranging from water, plant roots, to animals, including humans to whom it can cause severe infections. This remarkable adaptability is reflected in the number of transcriptional regulators, including sigma factors in this bacterium. Among those, the 19 to 21 extracytoplasmic sigma factors (ECFσ) are endowed with different regulons and functions, including the iron starvation σ (PvdS, FpvI, HasI, FecI, FecI2 and others), the cell wall stress ECFσ AlgU, SigX and SbrI, and the unorthodox σVreI involved in the expression of virulence. Recently published data show that these ECFσ have separate regulons although presenting some cross-talk. We will present evidence that these different ECFσ are involved in the expression of different phenotypes, ranging from cell-wall stress response, production of extracellular polysaccharides, formation of biofilms, to iron acquisition.
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Affiliation(s)
- Sylvie Chevalier
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France.
| | - Emeline Bouffartigues
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Alexis Bazire
- IUEM, Université de Bretagne-Sud (UBL), Laboratoire de Biotechnologie et Chimie Marines EA 3884, Lorient, France
| | - Ali Tahrioui
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Rachel Duchesne
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Damien Tortuel
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Olivier Maillot
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Thomas Clamens
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Nicole Orange
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Marc G J Feuilloley
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
| | - Alain Dufour
- IUEM, Université de Bretagne-Sud (UBL), Laboratoire de Biotechnologie et Chimie Marines EA 3884, Lorient, France
| | - Pierre Cornelis
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, Normandy University, University of Rouen, 27000 Evreux, France
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RpoN (σ 54) Is Required for Floc Formation but Not for Extracellular Polysaccharide Biosynthesis in a Floc-Forming Aquincola tertiaricarbonis Strain. Appl Environ Microbiol 2017; 83:AEM.00709-17. [PMID: 28500044 DOI: 10.1128/aem.00709-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 05/08/2017] [Indexed: 11/20/2022] Open
Abstract
Some bacteria are capable of forming flocs, in which bacterial cells become self-flocculated by secreted extracellular polysaccharides and other biopolymers. The floc-forming bacteria play a central role in activated sludge, which has been widely utilized for the treatment of municipal sewage and industrial wastewater. Here, we use a floc-forming bacterium, Aquincolatertiaricarbonis RN12, as a model to explore the biosynthesis of extracellular polysaccharides and the regulation of floc formation. A large gene cluster for exopolysaccharide biosynthesis and a gene encoding the alternative sigma factor RpoN1, one of the four paralogues, have been identified in floc formation-deficient mutants generated by transposon mutagenesis, and the gene functions have been further confirmed by genetic complementation analyses. Interestingly, the biosynthesis of exopolysaccharides remained in the rpoN1-disrupted flocculation-defective mutants, but most of the exopolysaccharides were secreted and released rather than bound to the cells. Furthermore, the expression of exopolysaccharide biosynthesis genes seemed not to be regulated by RpoN1. Taken together, our results indicate that RpoN1 may play a role in regulating the expression of a certain gene(s) involved in the self-flocculation of bacterial cells but not in the biosynthesis and secretion of exopolysaccharides required for floc formation.IMPORTANCE Floc formation confers bacterial resistance to predation of protozoa and plays a central role in the widely used activated sludge process. In this study, we not only identified a large gene cluster for biosynthesis of extracellular polysaccharides but also identified four rpoN paralogues, one of which (rpoN1) is required for floc formation in A. tertiaricarbonis RN12. In addition, this RpoN sigma factor regulates the transcription of genes involved in biofilm formation and swarming motility, as previously shown in other bacteria. However, this RpoN paralogue is not required for the biosynthesis of exopolysaccharides, which are released and dissolved into culture broth by the rpoN1 mutant rather than remaining tightly bound to cells, as observed during the flocculation of the wild-type strain. These results indicate that floc formation is a regulated complex process, and other yet-to-be identified RpoN1-dependent factors are involved in self-flocculation of bacterial cells via exopolysaccharides and/or other biopolymers.
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Bai S, Chen H, Zhu L, Liu W, Yu HD, Wang X, Yin Y. Comparative study on the in vitro effects of Pseudomonas aeruginosa and seaweed alginates on human gut microbiota. PLoS One 2017; 12:e0171576. [PMID: 28170428 PMCID: PMC5295698 DOI: 10.1371/journal.pone.0171576] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 01/22/2017] [Indexed: 02/06/2023] Open
Abstract
Alginates pertain to organic polysaccharides that have been extensively used in food- and medicine-related industries. The present study obtained alginates from an alginate overproducing Pseudomonas aeruginosa PAO1 mutant by screening transposon mutagenesis libraries. The interaction between bacterial and seaweed alginates and gut microbiota were further studied by using an in vitro batch fermentation system. Thin-layer chromatography (TLC) analysis indicated that both bacterial and seaweed alginates can be completely degraded by fecal bacteria isolated from study volunteers, indicating that a minor structural difference between bacterial and seaweed alginates (O-acetylation and lack of G-G blocks) didn’t affect the digestion of alginates by human microbiota. Although, the digestion of bacterial and seaweed alginates was attributed to different Bacteroides xylanisolvens strains, they harbored similar alginate lyase genes. Genus Bacteroides with alginate-degrading capability were enriched in growth medium containing bacterial or seaweed alginates after in vitro fermentation. Short-chain fatty acid (SCFA) production in both bacterial and seaweed alginates was also comparable, but was significantly higher than the same medium using starch. In summary, the present study has isolated an alginate-overproducing P. aeruginosa mutant strain. Both seaweed and bacterial alginates were degraded by human gut microbiota, and their regulatory function on gut microbiota was similar.
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Affiliation(s)
- Shaofeng Bai
- State Key Laboratory of Breeding Base for Zhejiang Sustainable Pest, and Key laboratory for Food Microbial Technology of Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, P. R. China
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Huahai Chen
- State Key Laboratory of Breeding Base for Zhejiang Sustainable Pest, and Key laboratory for Food Microbial Technology of Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, P. R. China
| | - Liying Zhu
- State Key Laboratory of Breeding Base for Zhejiang Sustainable Pest, and Key laboratory for Food Microbial Technology of Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, P. R. China
| | - Wei Liu
- State Key Laboratory of Breeding Base for Zhejiang Sustainable Pest, and Key laboratory for Food Microbial Technology of Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, P. R. China
| | - Hongwei D. Yu
- Departments of Biomedical Sciences, Pediatrics, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia, United States of America
- Progenesis Technologies, LLC, One John Marshall Drive, Robert C. Byrd Biotechnology Science Center, Huntington, West Virginia, United States of America
| | - Xin Wang
- State Key Laboratory of Breeding Base for Zhejiang Sustainable Pest, and Key laboratory for Food Microbial Technology of Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, P. R. China
| | - Yeshi Yin
- State Key Laboratory of Breeding Base for Zhejiang Sustainable Pest, and Key laboratory for Food Microbial Technology of Zhejiang Province, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, P. R. China
- * E-mail:
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Two Isoforms of Clp Peptidase in Pseudomonas aeruginosa Control Distinct Aspects of Cellular Physiology. J Bacteriol 2017; 199:JB.00568-16. [PMID: 27849175 DOI: 10.1128/jb.00568-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/20/2016] [Indexed: 02/07/2023] Open
Abstract
Caseinolytic peptidases (ClpPs) regulate diverse aspects of cellular physiology in bacteria. Some species have multiple ClpPs, including the opportunistic pathogen Pseudomonas aeruginosa, in which there is an archetypical isoform, ClpP1, and a second isoform, ClpP2, about which little is known. Here, we use phenotypic assays to investigate the biological roles of ClpP1 and ClpP2 and biochemical assays to characterize purified ClpP1, ClpP2, ClpX, and ClpA. Interestingly, ClpP1 and ClpP2 have distinct intracellular roles for motility, pigment production, iron scavenging, and biofilm formation. Of particular interest, ClpP2, but not ClpP1, is required for microcolony organization, where multicellular organized structures first form on the pathway to biofilm production. We found that purified ClpP1 with ClpX or ClpA was enzymatically active, yet to our surprise, ClpP2 was inactive and not fully assembled in vitro; attempts to assist ClpP2 assembly and activation by mixing with the other Clp components failed to turn on ClpP2, as did solution conditions that have helped activate other ClpPs in vitro We postulate that the active form of ClpP2 has yet to be discovered, and we present several potential models to explain its activation as well as the unique role ClpP2 plays in the development of the clinically important biofilms in P. aeruginosaIMPORTANCEPseudomonas aeruginosa is responsible for severe infections of immunocompromised patients. Our work demonstrates that two different isoforms of the Clp peptidase, ClpP1 and ClpP2, control distinct aspects of cellular physiology for this organism. In particular, we identify ClpP2 as being necessary for microcolony organization. Pure active forms of ClpP1 and either ClpX or ClpA were characterized as assembled and active, and ClpP2 was incompletely assembled and inactive. By establishing both the unique biological roles of ClpP1 and ClpP2 and their initial biochemical assemblies, we have set the stage for important future work on the structure, function, and biological targets of Clp proteolytic enzymes in this important opportunistic pathogen.
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30
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Li R, Withers RT, Dai J, Ruan J, Li W, Dai Y, An W, Yu D, Wei H, Xia M, Tian C, Yu HD, Qiu D. Truncated type IV pilin PilA(108) activates the intramembrane protease AlgW to cleave MucA and PilA(108) itself in vitro. Arch Microbiol 2016; 198:885-92. [PMID: 27270273 DOI: 10.1007/s00203-016-1248-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/10/2016] [Accepted: 05/23/2016] [Indexed: 11/29/2022]
Abstract
For alginate production in Pseudomonas aeruginosa, the intramembrane protease AlgW must be activated to cleave the periplasmic domain of anti-sigma factor MucA for release of the sequestered ECF sigma factor AlgU. Previously, we reported that three tandem point mutations in the pilA gene, resulting in a truncated type IV pilin termed PilA(108) with a C-terminal motif of phenylalanine-threonine-phenylalanine (FTF), induced mucoidy in strain PAO579. In this study, we purified PilA(108) protein and synthesized a peptide 'SGAGDITFTF' corresponding to C-terminus of PilA(108) and found they both caused the degradation of MucA by AlgW. Interestingly, AlgW could also cleave PilA(108) between alanine(62) and glycine(63) residues. Overexpression of the recombinant FTF motif-bearing MucE protein, originally a small periplasmic polypeptide with the C-terminal motif WVF, could induce mucoid conversion in the PAO1 strain. In all, our results provided a model of activation of AlgW by another protein ending with proper motifs. Our data suggest that in addition to MucA cleavage, AlgW may cleave other substrates.
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Affiliation(s)
- Ronghui Li
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China.,Guizhou Provincial People's Hospital, Guiyang, 550002, Guizhou, China
| | - Ryan T Withers
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV, USA
| | - Jingcheng Dai
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jing Ruan
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China
| | - Wei Li
- Guizhou Provincial People's Hospital, Guiyang, 550002, Guizhou, China
| | - Yujun Dai
- School of Life Sciences and Technology, Hubei Engineering University, Xiaogan, 432000, China
| | - Weixing An
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dianzhen Yu
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hehong Wei
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ming Xia
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chunyuan Tian
- School of Life Sciences and Technology, Hubei Engineering University, Xiaogan, 432000, China
| | - Hongwei D Yu
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV, USA
| | - Dongru Qiu
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China. .,School of Life Sciences and Technology, Hubei Engineering University, Xiaogan, 432000, China.
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31
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Veselova MA, Romanova YM, Lipasova VA, Koksharova OA, Zaitseva YV, Chernukha MU, Gintsburg AL, Khmel IA. The effect of mutation in the clpX gene on the synthesis of N-acyl-homoserine lactones and other properties of Burkholderia cenocepacia 370. Microbiol Res 2016; 186-187:90-8. [PMID: 27242147 DOI: 10.1016/j.micres.2016.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 03/24/2016] [Accepted: 03/31/2016] [Indexed: 10/22/2022]
Abstract
In order to study the regulation of N-acyl-homoserine lactones synthesis (AHLs, the signal molecules of Quorum Sensing regulation) in Burkholderia cenocepacia strain 370 we obtained mutants with increased AHL production. One of the mutants, named BC-B6, was obtained by TnMod-RKm(r) plasposon mutagenesis. The plasposon insertion was located within the clpX gene encoding the ATPase subunit ClpX of the ClpXP protease. The mutation reduced bacterial virulence in mice intranasal infection. The results of proteomic analysis demonstrated that the expression of at least 19 proteins differed not less than 2-fold between the parental and mutant strains. 18 of the proteins were upregulated in the mutant, and one protein was downregulated. The proteins included those that involved in protein synthesis and modification, in energy production, in general metabolism, in transport and regulation. To check the effect of the clpX mutation on the AHL synthesis, a mutant with inactivated clpX gene (BC-clpX:Km(r)) was constructed by gene replacement method. This mutant also exhibited increased AHLs production. A swarming motility of both mutants was reduced compared to the original strain. Thus, the obtained results show that the clpX gene was involved in the regulation of AHL production and a number of cellular processes in B. cenocepacia 370.
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Affiliation(s)
- M A Veselova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square 2, Moscow 123182, Russia
| | - Yu M Romanova
- The Gamaleya Scientific Research Centre of Epidemiology and Microbiology, Gamaleya Str. 18, Moscow 123098, Russia
| | - V A Lipasova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square 2, Moscow 123182, Russia
| | - O A Koksharova
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square 2, Moscow 123182, Russia; M.V. Lomonosov Moscow State University, A.N. Belozersky Institute of Physico-Chemical Biology, Leninskie Gory 1-40, Moscow 119991, Russia
| | - Yu V Zaitseva
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square 2, Moscow 123182, Russia
| | - M U Chernukha
- The Gamaleya Scientific Research Centre of Epidemiology and Microbiology, Gamaleya Str. 18, Moscow 123098, Russia
| | - A L Gintsburg
- The Gamaleya Scientific Research Centre of Epidemiology and Microbiology, Gamaleya Str. 18, Moscow 123098, Russia
| | - I A Khmel
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Square 2, Moscow 123182, Russia.
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Anionic fluoroquinolones as antibacterials against biofilm-producing Pseudomonas aeruginosa. Bioorg Med Chem Lett 2016; 26:1305-9. [PMID: 26826023 DOI: 10.1016/j.bmcl.2016.01.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 01/05/2016] [Accepted: 01/06/2016] [Indexed: 01/30/2023]
Abstract
Pseudomonas aeruginosa is a common biofilm-forming bacterial pathogen implicated in diseases of the lungs. The extracellular polymeric substances (EPS) of respiratory Pseudomonas biofilms are largely comprised of anionic molecules such as rhamnolipids and alginate that promote a mucoid phenotype. In this Letter, we examine the ability of negatively-charged fluoroquinolones to transverse the EPS and inhibit the growth of mucoid P. aeruginosa. Anionic fluoroquinolones were further compared with standard antibiotics via a novel microdiffusion assay to evaluate drug penetration through pseudomonal alginate and respiratory mucus from a patient with cystic fibrosis.
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Kong W, Zhao J, Kang H, Zhu M, Zhou T, Deng X, Liang H. ChIP-seq reveals the global regulator AlgR mediating cyclic di-GMP synthesis in Pseudomonas aeruginosa. Nucleic Acids Res 2015. [PMID: 26206672 PMCID: PMC4787818 DOI: 10.1093/nar/gkv747] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
AlgR is a key transcriptional regulator required for the expression of multiple virulence factors, including type IV pili and alginate in Pseudomonas aeruginosa. However, the regulon and molecular regulatory mechanism of AlgR have yet to be fully elucidated. Here, among 157 loci that were identified by a ChIP-seq assay, we characterized a gene, mucR, which encodes an enzyme that synthesizes the intracellular second messenger cyclic diguanylate (c-di-GMP). A ΔalgR strain produced lesser biofilm than did the wild-type strain, which is consistent with a phenotype controlled by c-di-GMP. AlgR positively regulates mucR via direct binding to its promoter. A ΔalgRΔmucR double mutant produced lesser biofilm than did the single ΔalgR mutant, demonstrating that c-di-GMP is a positive regulator of biofilm formation. AlgR controls the levels of c-di-GMP synthesis via direct regulation of mucR. In addition, the cognate sensor of AlgR, FimS/AlgZ, also plays an important role in P. aeruginosa virulence. Taken together, this study provides new insights into the AlgR regulon and reveals the involvement of c-di-GMP in the mechanism underlying AlgR regulation.
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Affiliation(s)
- Weina Kong
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Jingru Zhao
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Huaping Kang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Miao Zhu
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
| | - Tianhong Zhou
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Xin Deng
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Haihua Liang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi'an, ShaanXi 710069, China
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Rahmani-Badi A, Sepehr S, Fallahi H, Heidari-Keshel S. Dissection of the cis-2-decenoic acid signaling network in Pseudomonas aeruginosa using microarray technique. Front Microbiol 2015; 7:383. [PMID: 25972860 PMCID: PMC4412052 DOI: 10.3389/fmicb.2015.00383] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 03/10/2016] [Indexed: 11/29/2022] Open
Abstract
Many bacterial pathogens use quorum-sensing (QS) signaling to regulate the expression of factors contributing to virulence and persistence. Bacteria produce signals of different chemical classes. The signal molecule, known as diffusible signal factor (DSF), is a cis-unsaturated fatty acid that was first described in the plant pathogen Xanthomonas campestris. Previous works have shown that human pathogen, Pseudomonas aeruginosa, also synthesizes a structurally related molecule, characterized as cis-2-decenoic acid (C10: Δ2, CDA) that induces biofilm dispersal by multiple types of bacteria. Furthermore, CDA has been shown to be involved in inter-kingdom signaling that modulates fungal behavior. Therefore, an understanding of its signaling mechanism could suggest strategies for interference, with consequences for disease control. To identify the components of CDA signaling pathway in this pathogen, a comparative transcritpome analysis was conducted, in the presence and absence of CDA. A protein-protein interaction (PPI) network for differentially expressed (DE) genes with known function was then constructed by STRING and Cytoscape. In addition, the effects of CDA in combination with antimicrobial agents on the biofilm surface area and bacteria viability were evaluated using fluorescence microscopy and digital image analysis. Microarray analysis identified 666 differentially expressed genes in the presence of CDA and gene ontology (GO) analysis revealed that in P. aeruginosa, CDA mediates dispersion of biofilms through signaling pathways, including enhanced motility, metabolic activity, virulence as well as persistence at different temperatures. PPI data suggested that a cluster of five genes (PA4978, PA4979, PA4980, PA4982, PA4983) is involved in the CDA synthesis and perception. Combined treatments using both CDA and antimicrobial agents showed that following exposure of the biofilms to CDA, remaining cells on the surface were easily removed and killed by antimicrobials.
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Affiliation(s)
| | - Shayesteh Sepehr
- Department of Biology, School of Science, Alzahra University Tehran, Iran
| | - Hossein Fallahi
- Department of Biology, School of Science, Razi University Kermanshah, Iran
| | - Saeed Heidari-Keshel
- Stem Cell Preparation Unit, Eye Research Center, Farabi Eye Hospital Tehran, Iran
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Yang N, Ding S, Chen F, Zhang X, Xia Y, Di H, Cao Q, Deng X, Wu M, Wong CCL, Tian XX, Yang CG, Zhao J, Lan L. The Crc protein participates in down-regulation of the Lon gene to promote rhamnolipid production and rhl quorum sensing in Pseudomonas aeruginosa. Mol Microbiol 2015; 96:526-47. [PMID: 25641250 DOI: 10.1111/mmi.12954] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/28/2015] [Indexed: 12/20/2022]
Abstract
Rhamnolipid acts as a virulence factor during Pseudomonas aeruginosa infection. Here, we show that deletion of the catabolite repression control (crc) gene in P. aeruginosa leads to a rhamnolipid-negative phenotype. This effect is mediated by the down-regulation of rhl quorum sensing (QS). We discover that a disruption of the gene encoding the Lon protease entirely offsets the effect of crc deletion on the production of both rhamnolipid and rhl QS signal C4-HSL. Crc is unable to bind lon mRNA in vitro in the absence of the RNA chaperon Hfq, while Crc contributes to Hfq-mediated repression of the lon gene expression at a posttranscriptional level. Deletion of crc, which results in up-regulation of lon, significantly reduces the in vivo stability and abundance of the RhlI protein that synthesizes C4-HSL, causing the attenuation of rhl QS. Lon is also capable of degrading the RhlI protein in vitro. In addition, constitutive expression of rhlI suppresses the defects of the crc deletion mutant in rhamnolipid, C4-HSL and virulence on lettuce leaves. This study therefore uncovers a novel posttranscriptional regulatory cascade, Crc-Hfq/Lon/RhlI, for the regulation of rhamnolipid production and rhl QS in P. aeruginosa.
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Affiliation(s)
- Nana Yang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Pudong Zhangjiang Hi-Tech Park, Shanghai, 201203, China
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Dai J, Wei H, Tian C, Damron FH, Zhou J, Qiu D. An extracytoplasmic function sigma factor-dependent periplasmic glutathione peroxidase is involved in oxidative stress response of Shewanella oneidensis. BMC Microbiol 2015; 15:34. [PMID: 25887418 PMCID: PMC4336711 DOI: 10.1186/s12866-015-0357-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 01/20/2015] [Indexed: 11/30/2022] Open
Abstract
Background Bacteria use alternative sigma factors (σs) to regulate condition-specific gene expression for survival and Shewanella harbors multiple ECF (extracytoplasmic function) σ genes and cognate anti-sigma factor genes. Here we comparatively analyzed two of the rpoE-like operons in the strain MR-1: rpoE-rseA-rseB-rseC and rpoE2-chrR. Results RpoE was important for bacterial growth at low and high temperatures, in the minimal medium, and high salinity. The degP/htrA orthologue, required for growth of Escherichia coli and Pseudomonas aeruginosa at high temperature, is absent in Shewanella, while the degQ gene is RpoE-regulated and is required for bacterial growth at high temperature. RpoE2 was essential for the optimal growth in oxidative stress conditions because the rpoE2 mutant was sensitive to hydrogen peroxide and paraquat. The operon encoding a ferrochelatase paralogue (HemH2) and a periplasmic glutathione peroxidase (PgpD) was identified as RpoE2-dependent. PgpD exhibited higher activities and played a more important role in the oxidative stress responses than the cytoplasmic glutathione peroxidase CgpD under tested conditions. The rpoE2-chrR operon and the identified regulon genes, including pgpD and hemH2, are coincidently absent in several psychrophilic and/or deep-sea Shewanella strains. Conclusion In S. oneidensis MR-1, the RpoE-dependent degQ gene is required for optimal growth under high temperature. The rpoE2 and RpoE2-dependent pgpD gene encoding a periplasmic glutathione peroxidase are involved in oxidative stress responses. But rpoE2 is not required for bacterial growth at low temperature and it even affected bacterial growth under salt stress, indicating that there is a tradeoff between the salt resistance and RpoE2-mediated oxidative stress responses. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0357-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jingcheng Dai
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Hehong Wei
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Chunyuan Tian
- School of Life Sciences and Technology, Hubei University of Engineering, 272 Jiaotong Avenue, Xiaogan, 432000, China.
| | - Fredrick Heath Damron
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA.
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Botany and Microbiology, The University of Oklahoma, Stephenson Research and Technology Center, 101 David L. Boren Blvd, Norman, OK 73019, USA.
| | - Dongru Qiu
- Institute of Hydrobiology, Chinese Academy of Sciences, 7 South Donghu Road, Wuchang District, Wuhan, 430072, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
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Wood LF, Ohman DE. Cell wall stress activates expression of a novel stress response facilitator (SrfA) under σ22 (AlgT/U) control in Pseudomonas aeruginosa. MICROBIOLOGY-SGM 2014; 161:30-40. [PMID: 25336469 DOI: 10.1099/mic.0.081182-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ECF (extracytoplasmic function) alternative sigma factor, σ(22) (AlgT/U), is required for expression of the algD promoter of the operon for alginate biosynthesis in Pseudomonas aeruginosa. Alginate production promotes chronic pulmonary infections by this opportunistic pathogen in patients with cystic fibrosis and chronic obstructive pulmonary disease. σ(22) is normally sequestered, but its deregulation and activation occur either by mutation in mucA (encoding an anti-sigma factor) or in response to envelope stress, such as inhibition of peptidoglycan synthesis. The σ(22) stress response system includes many genes in addition to those for alginate. In the present study, we characterized an intergenic region between ORFs PA2559 and PA2560 in PAO1 for a σ(22)-dependent, stress-responsive transcript, described here as PA2559.1. Northern analysis and transcript end-mapping indicated the PA2559.1 transcript was ~310 nt in length. Examination of the DNA sequence upstream of +1 revealed a σ(22) core promoter motif, GAATTT-N16-TCTGT, and site-directed mutagenesis confirmed this to be a σ(22)-dependent promoter that was highly activated during cell wall stress. PA2559.1 also contained an ORF that demonstrated increased translational activity upon cell wall stress. As determined by mutant analysis, the protein encoded by PA2559.1 was shown to play a positive role in the σ(22)-dependent activation of the algD promoter under stress in both sessile (i.e. biofilm) and planktonic conditions. Thus, it appeared to act as a stress response facilitator and so was named SrfA. The sequence of SrfA was found to be novel in nature and extremely well conserved only in P. aeruginosa, suggesting that it is of high evolutionary importance in this species.
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Affiliation(s)
- Lynn F Wood
- McGuire Veterans Affairs Medical Center, Richmond, VA 23249, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
| | - Dennis E Ohman
- McGuire Veterans Affairs Medical Center, Richmond, VA 23249, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
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de Regt AK, Yin Y, Withers TR, Wang X, Baker TA, Sauer RT, Yu HD. Overexpression of CupB5 activates alginate overproduction in Pseudomonas aeruginosa by a novel AlgW-dependent mechanism. Mol Microbiol 2014; 93:415-25. [PMID: 24913916 DOI: 10.1111/mmi.12665] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2014] [Indexed: 11/29/2022]
Abstract
In Pseudomonas aeruginosa, alginate overproduction, also known as mucoidy, is negatively regulated by the transmembrane protein MucA, which sequesters the alternative sigma factor AlgU. MucA is degraded via a proteolysis pathway that frees AlgU from sequestration, activating alginate biosynthesis. Initiation of this pathway normally requires two signals: peptide sequences in unassembled outer-membrane proteins (OMPs) activate the AlgW protease, and unassembled lipopolysaccharides bind periplasmic MucB, releasing MucA and facilitating its proteolysis by activated AlgW. To search for novel alginate regulators, we screened a transposon library in the non-mucoid reference strain PAO1, and identified a mutant that confers mucoidy through overexpression of a protein encoded by the chaperone-usher pathway gene cupB5. CupB5-dependent mucoidy occurs through the AlgU pathway and can be reversed by overexpression of MucA or MucB. In the presence of activating OMP peptides, peptides corresponding to a region of CupB5 needed for mucoidy further stimulated AlgW cleavage of MucA in vitro. Moreover, the CupB5 peptide allowed OMP-activated AlgW cleavage of MucA in the presence of the MucB inhibitor. These results support a novel mechanism for conversion to mucoidy in which the proteolytic activity of AlgW and its ability to compete with MucB for MucA is mediated by independent peptide signals.
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Affiliation(s)
- Anna K de Regt
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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Llamas MA, Imperi F, Visca P, Lamont IL. Cell-surface signaling inPseudomonas: stress responses, iron transport, and pathogenicity. FEMS Microbiol Rev 2014; 38:569-97. [DOI: 10.1111/1574-6976.12078] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 05/20/2014] [Accepted: 05/27/2014] [Indexed: 01/06/2023] Open
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40
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Dwyer M, Shan Q, D'Ortona S, Maurer R, Mitchell R, Olesen H, Thiel S, Huebner J, Gadjeva M. Cystic fibrosis sputum DNA has NETosis characteristics and neutrophil extracellular trap release is regulated by macrophage migration-inhibitory factor. J Innate Immun 2014; 6:765-79. [PMID: 24862346 DOI: 10.1159/000363242] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 04/28/2014] [Indexed: 12/14/2022] Open
Abstract
Neutrophils are the main proinflammatory cell type in chronically infected lungs of cystic fibrosis (CF) patients; however, they fail to effectively clear the colonizing pathogens. Here, we investigated the molecular composition of non-mucoid and mucoid Pseudomonas aeruginosa-induced neutrophil extracellular traps (NETs) in vitro and compared them to the DNA-protein complexes present in the CF sputum. The protein composition of P. aeruginosa-induced NET fragments revealed that irrespective of the inducing stimuli, NET fragments were decorated with a conserved set of proteins. The DNA-protein complexes derived from CF sputum were consistent with NETosis and shared a similar protein signature, suggesting that the majority of the extracellular DNA was NET derived. The ability of polymorphonuclear leukocytes to produce NETs in response to P. aeruginosa was driven by macrophage migration-inhibitory factor (MIF) by promoting mitogen-activated protein kinase. Analysis of 132 CF patient samples revealed that elevated MIF protein levels correlated with poorer lung function. We suggest that targeting MIF by small molecular inhibitors might reduce the presence of extracellular DNA and serve as an adjunct to the use of antimicrobial drugs that could ultimately reduce bacterial fitness in the lungs during the later stages of CF disease.
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Affiliation(s)
- Markryan Dwyer
- Department of Medicine, Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass., USA
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Strain-specific parallel evolution drives short-term diversification during Pseudomonas aeruginosa biofilm formation. Proc Natl Acad Sci U S A 2014; 111:E1419-27. [PMID: 24706926 DOI: 10.1073/pnas.1314340111] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Generation of genetic diversity is a prerequisite for bacterial evolution and adaptation. Short-term diversification and selection within populations is, however, largely uncharacterised, as existing studies typically focus on fixed substitutions. Here, we use whole-genome deep-sequencing to capture the spectrum of mutations arising during biofilm development for two Pseudomonas aeruginosa strains. This approach identified single nucleotide variants with frequencies from 0.5% to 98.0% and showed that the clinical strain 18A exhibits greater genetic diversification than the type strain PA01, despite its lower per base mutation rate. Mutations were found to be strain specific: the mucoid strain 18A experienced mutations in alginate production genes and a c-di-GMP regulator gene; while PA01 acquired mutations in PilT and PilY1, possibly in response to a rapid expansion of a lytic Pf4 bacteriophage, which may use type IV pili for infection. The Pf4 population diversified with an evolutionary rate of 2.43 × 10(-3) substitutions per site per day, which is comparable to single-stranded RNA viruses. Extensive within-strain parallel evolution, often involving identical nucleotides, was also observed indicating that mutation supply is not limiting, which was contrasted by an almost complete lack of noncoding and synonymous mutations. Taken together, these results suggest that the majority of the P. aeruginosa genome is constrained by negative selection, with strong positive selection acting on an accessory subset of genes that facilitate adaptation to the biofilm lifecycle. Long-term bacterial evolution is known to proceed via few, nonsynonymous, positively selected mutations, and here we show that similar dynamics govern short-term, within-population bacterial diversification.
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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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Pseudomonas aeruginosa ceftolozane-tazobactam resistance development requires multiple mutations leading to overexpression and structural modification of AmpC. Antimicrob Agents Chemother 2014; 58:3091-9. [PMID: 24637685 DOI: 10.1128/aac.02462-13] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We compared the dynamics and mechanisms of resistance development to ceftazidime, meropenem, ciprofloxacin, and ceftolozane-tazobactam in wild-type (PAO1) and mutator (PAOMS, ΔmutS) P. aeruginosa. The strains were incubated for 24 h with 0.5 to 64× MICs of each antibiotic in triplicate experiments. The tubes from the highest antibiotic concentration showing growth were reinoculated in fresh medium containing concentrations up to 64× MIC for 7 consecutive days. The susceptibility profiles and resistance mechanisms were assessed in two isolated colonies from each step, antibiotic, and strain. Ceftolozane-tazobactam-resistant mutants were further characterized by whole-genome analysis through RNA sequencing (RNA-seq). The development of high-level resistance was fastest for ceftazidime, followed by meropenem and ciprofloxacin. None of the mutants selected with these antibiotics showed cross-resistance to ceftolozane-tazobactam. On the other hand, ceftolozane-tazobactam resistance development was much slower, and high-level resistance was observed for the mutator strain only. PAO1 derivatives that were moderately resistant (MICs, 4 to 8 μg/ml) to ceftolozane-tazobactam showed only 2 to 4 mutations, which determined global pleiotropic effects associated with a severe fitness cost. High-level-resistant (MICs, 32 to 128 μg/ml) PAOMS derivatives showed 45 to 53 mutations. Major changes in the global gene expression profiles were detected in all mutants, but only PAOMS mutants showed ampC overexpression, which was caused by dacB or ampR mutations. Moreover, all PAOMS mutants contained 1 to 4 mutations in the conserved residues of AmpC (F147L, Q157R, G183D, E247K, or V356I). Complementation studies revealed that these mutations greatly increased ceftolozane-tazobactam and ceftazidime MICs but reduced those of piperacillin-tazobactam and imipenem, compared to those in wild-type ampC. Therefore, the development of high-level resistance to ceftolozane-tazobactam appears to occur efficiently only in a P. aeruginosa mutator background, in which multiple mutations lead to overexpression and structural modifications of AmpC.
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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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Withers TR, Yin Y, Yu HD. Identification and characterization of a novel inhibitor of alginate overproduction in Pseudomonas aeruginosa. Pathog Dis 2013; 70:185-8. [PMID: 24115673 DOI: 10.1111/2049-632x.12102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/30/2013] [Accepted: 09/17/2013] [Indexed: 11/28/2022] Open
Abstract
In this study, we performed whole-genome complementation using a PAO1-derived cosmid library, coupled with in vitro transposon mutagenesis, to identify gene locus PA1494 as a novel inhibitor of alginate overproduction in P. aeruginosa strains possessing a wild-type mucA.
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Affiliation(s)
- T Ryan Withers
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV, USA
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Yin Y, Damron FH, Withers TR, Pritchett CL, Wang X, Schurr MJ, Yu HD. Expression of mucoid induction factor MucE is dependent upon the alternate sigma factor AlgU in Pseudomonas aeruginosa. BMC Microbiol 2013; 13:232. [PMID: 24138584 PMCID: PMC3819740 DOI: 10.1186/1471-2180-13-232] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 10/09/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Alginate overproduction in P. aeruginosa, also referred to as mucoidy, is a poor prognostic marker for patients with cystic fibrosis (CF). We previously reported the construction of a unique mucoid strain which overexpresses a small envelope protein MucE leading to activation of the protease AlgW. AlgW then degrades the anti-sigma factor MucA thus releasing the alternative sigma factor AlgU/T (σ(22)) to initiate transcription of the alginate biosynthetic operon. RESULTS In the current study, we mapped the mucE transcriptional start site, and determined that P(mucE) activity was dependent on AlgU. Additionally, the presence of triclosan and sodium dodecyl sulfate was shown to cause an increase in P(mucE) activity. It was observed that mucE-mediated mucoidy in CF isolates was dependent on both the size of MucA and the genotype of algU. We also performed shotgun proteomic analysis with cell lysates from the strains PAO1, VE2 (PAO1 with constitutive expression of mucE) and VE2ΔalgU (VE2 with in-frame deletion of algU). As a result, we identified nine algU-dependent and two algU-independent proteins that were affected by overexpression of MucE. CONCLUSIONS Our data indicates there is a positive feedback regulation between MucE and AlgU. Furthermore, it seems likely that MucE may be part of the signal transduction system that senses certain types of cell wall stress to P. aeruginosa.
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Affiliation(s)
| | | | | | | | | | | | - Hongwei D Yu
- Department of Biochemistry and Microbiology, Joan C, Edwards School of Medicine at Marshall University, Huntington, WV 25755, USA.
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Draft Genome Sequence of a Mucoid Isolate of Pseudomonas aeruginosa Strain C7447m from a Patient with Cystic Fibrosis. GENOME ANNOUNCEMENTS 2013; 1:1/5/e00837-13. [PMID: 24115552 PMCID: PMC3795222 DOI: 10.1128/genomea.00837-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alginate overproduction by Pseudomonas aeruginosa, or mucoidy, plays an important role in the pathogenesis of chronic lung infections in cystic fibrosis (CF) patients. Here we report the draft genome sequence of a clinical isolate of mucoid P. aeruginosa strain C7447m from a CF patient with chronic lung infection.
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Draft Genome Sequence of a Stable Mucoid Strain of Pseudomonas aeruginosa PAO581 with a mucA25 Mutation. GENOME ANNOUNCEMENTS 2013; 1:1/5/e00834-13. [PMID: 24115549 PMCID: PMC3795219 DOI: 10.1128/genomea.00834-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A mutation in the mucA gene, which encodes a negative regulator of alginate production in Pseudomonas aeruginosa, is the main mechanism underlying the conversion to mucoidy in clinical isolates from patients with cystic fibrosis (CF). Here, we announce the draft genome sequence of the stable alginate-overproducing mucoid strain P. aeruginosa PAO581 with a mucA25 mutation, a derivative from the nonmucoid strains P. aeruginosa PAO381 and PAO1.
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Costaglioli P, Barthe C, Fayon M, Christoflour N, Bui S, Derlich L, Domblides P, Crouzet M, Vilain S, Garbay B. Selection of Pseudomonas aeruginosa reference genes for RT-qPCR analysis from sputum of cystic fibrosis patients. Mol Cell Probes 2013; 28:10-2. [PMID: 24075879 DOI: 10.1016/j.mcp.2013.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/12/2013] [Accepted: 09/15/2013] [Indexed: 11/17/2022]
Abstract
The prerequisite to monitor gene expression is the selection of reference genes for normalization of RT-qPCR results. Using 13 sputum samples collected from 9 CF patients, we demonstrated that PA2875 and PA3340 are better reference genes than the previously used clpX and oprL genes.
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Affiliation(s)
- Patricia Costaglioli
- Univ. Bordeaux, Biotechnologie des Protéines Recombinantes à Visée Santé, EA 4135, F-33000 Bordeaux, France.
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Westritschnig K, Hochreiter R, Wallner G, Firbas C, Schwameis M, Jilma B. A randomized, placebo-controlled phase I study assessing the safety and immunogenicity of a Pseudomonas aeruginosa hybrid outer membrane protein OprF/I vaccine (IC43) in healthy volunteers. Hum Vaccin Immunother 2013; 10:170-83. [PMID: 24064511 DOI: 10.4161/hv.26565] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION IC43 is a recombinant outer membrane protein-based vaccine against Pseudomonas aeruginosa (P. aeruginosa) consisting of OprF- and OprI- epitopes (Opr, outer membrane protein; OprF/I, OprF/OprI hybrid vaccine) with an N-terminal His 6 tag (Met-Ala-(His)6-OprF190-342-OprI21-83). OBJECTIVES The study aimed to confirm the optimal dose of IC43 in adults with regard to immunogenicity, safety, and tolerability after vaccination with three different dosages of IC43, compared with placebo, and to investigate a potential immune-enhancing effect of the adjuvant, aluminum hydroxide. Subjects were randomly allocated in a 1:1:1:1:1 ratio to one of five treatment groups: 50, 100, or 200 µg IC43 with adjuvant, 100 µg IC43 without adjuvant, or placebo (0.9% sodium chloride) and two intramuscular injections were given in the deltoid region 7 d apart. RESULTS The primary immunogenicity analysis of OprF/I-specific IgG antibody titers on day 14 demonstrated statistically significant differences among treatment groups (P<0.0001), with a significantly higher immune response detected in each IC43 treatment group compared with placebo. From day 0 to day 14, a ≥4-fold increase in OprF/I-specific immunoglobulin G (IgG) antibody titers were observed in>90% of subjects in all IC43 treatment groups in the per-protocol (PP) and intention-to-treat (ITT) populations; a ≥50-fold titer increase was observed in 42.6% subjects including all IC43 treatment groups. On day 90, OprF/I-specific IgGs started to decline in all IC43 treatment groups but remained significantly higher until 6 mo compared with placebo. Assessment of functional antibody induction by opsonophagocytic assay (OPA) followed a similar pattern compared with OprF/I-specific IgG kinetics. At day 14, a ≥2-fold increase in OPA titer was observed in 54.5% subjects within all IC43 treatment groups. An increase in antibody avidity index was observed after the second vaccination. At day 14, >96% of subjects in each IC43 treatment group had detectable OprF/I-specific IgG antibodies. Anti-histidine IgG antibody titers peaked on day 14 and were reduced on day 90 in all IC43 treatment groups. OprF/I-specific IgG secreted by antibody-secreting cell (ASC) was detected in all IC43 groups by B-cell ELIspot after the second vaccination and up to 6 mo. All vaccinations were safe and well tolerated up to the maximum cumulative dosage of 400 µg IC43. CONCLUSION IC43 doses equal to or greater than 50 µg were sufficient to induce a plateau of IgG antibody responses in healthy volunteers. Higher doses, whether adjuvanted or non-adjuvanted, were not more effective. METHODS In this phase I, randomized, placebo-controlled, observer-blinded, multicenter clinical trial, 163 healthy volunteers (18-65 y) were randomly assigned to five treatment groups (1:1:1:1:1). Three groups received IC43 with adjuvant: 50 µg (n=32), 100 µg (n=33), or 200 µg (n=33). One group received IC43 100 µg without adjuvant (n=32), and one group received placebo (0.9% sodium chloride) (n=33). Each subject received two intramuscular vaccinations, separated by a 7-d interval (days 0 and 7) (Fig. 1). Humoral immune response was assessed by measurement of outer membrane protein F/I (OprF/I)-specific antibodies determined by enzyme-linked immunosorbent assay (ELISA), anti-histidine antibodies determined by ELISA, and functional antibody activity determined by opsonophagocytic assay (OPA), up to 6 mo post-vaccination. Antibody avidity was measured on days 7 and 14 from samples that had detectable vaccine antibody-specific immunoglobulin G (IgG) antibody titers. At the Austrian site only, the B-cell ELIspot assay was used to determine specific ASC responses. Safety was assessed using adverse event monitoring and clinical laboratory tests. Local and systemic tolerability was recorded in a subject diary for 7 d after each vaccination and by investigators up to 6 mo post-vaccination.
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Affiliation(s)
| | | | | | - Christa Firbas
- Department of Clinical Pharmacology Medical University of Vienna; Währinger Gürtel; Vienna, Austria
| | - Michael Schwameis
- Department of Clinical Pharmacology Medical University of Vienna; Währinger Gürtel; Vienna, Austria
| | - Bernd Jilma
- Department of Clinical Pharmacology Medical University of Vienna; Währinger Gürtel; Vienna, Austria
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