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Belvin BR, Musayev FN, Escalante CR, Lewis JP. Full-length structure and heme binding in the transcriptional regulator HcpR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.06.611725. [PMID: 39282349 PMCID: PMC11398531 DOI: 10.1101/2024.09.06.611725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2024]
Abstract
HcpR is a CRP-family transcriptional regulator found in many Gram-negative anaerobic bacteria. In the perio-pathogen Porphyromonas gingivalis, HcpR is crucial for the response to reactive nitrogen species such as nitric oxide (NO). Binding of NO to the heme group of HcpR leads to transcription of the redox enzyme Hcp. However, the molecular mechanisms of heme binding to HcpR remain unknown. In this study we present the 2.3 Å structure of the P. gingivalis HcpR. Interdomain interactions present in the structure help to form a hydrophobic pocket in the N-terminal sensing domain. A comparison analysis with other CRP-family members reveals that the molecular mechanisms of HcpR-mediated regulation may be distinct from other family members. Using docking studies, we identify a putative heme binding site in the sensing domain. In vitro complementation and mutagenesis studies verify Met68 as an important residue in activation of HcpR. Finally, heme binding studies with purified forms of recombinant HcpR support Met68 and His149 residues as important for proper heme coordination in HcpR.
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Morales-Olavarría M, Nuñez-Belmar J, González D, Vicencio E, Rivas-Pardo JA, Cortez C, Cárdenas JP. Phylogenomic analysis of the Porphyromonas gingivalis - Porphyromonas gulae duo: approaches to the origin of periodontitis. Front Microbiol 2023; 14:1226166. [PMID: 37538845 PMCID: PMC10394638 DOI: 10.3389/fmicb.2023.1226166] [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: 05/20/2023] [Accepted: 07/04/2023] [Indexed: 08/05/2023] Open
Abstract
Porphyromonas gingivalis is an oral human pathogen associated with the onset and progression of periodontitis, a chronic immune-inflammatory disease characterized by the destruction of the teeth-supporting tissue. P. gingivalis belongs to the genus Porphyromonas, which is characterized by being composed of Gram-negative, asaccharolytic, non-spore-forming, non-motile, obligatory anaerobic species, inhabiting niches such as the oral cavity, urogenital tract, gastrointestinal tract and infected wound from different mammals including humans. Among the Porphyromonas genus, P. gingivalis stands out for its specificity in colonizing the human oral cavity and its keystone pathogen role in periodontitis pathogenesis. To understand the evolutionary process behind P. gingivalis in the context of the Pophyoromonas genus, in this study, we performed a comparative genomics study with publicly available Porphyromonas genomes, focused on four main objectives: (A) to confirm the phylogenetic position of P. gingivalis in the Porphyromonas genus by phylogenomic analysis; (B) the definition and comparison of the pangenomes of P. gingivalis and its relative P. gulae; and (C) the evaluation of the gene family gain/loss events during the divergence of P. gingivalis and P. gulae; (D) the evaluation of the evolutionary pressure (represented by the calculation of Tajima-D values and dN/dS ratios) comparing gene families of P. gingivalis and P. gulae. Our analysis found 84 high-quality assemblies representing P. gingivalis and 14 P. gulae strains (from a total of 233 Porphyromonas genomes). Phylogenomic analysis confirmed that P. gingivalis and P. gulae are highly related lineages, close to P. loveana. Both organisms harbored open pangenomes, with a strong core-to-accessory ratio for housekeeping genes and a negative ratio for unknown function genes. Our analyses also characterized the gene set differentiating P. gulae from P. gingivalis, mainly associated with unknown functions. Relevant virulence factors, such as the FimA, Mfa1, and the hemagglutinins, are conserved in P. gulae, P. gingivalis, and P. loveana, suggesting that the origin of those factors occurred previous to the P. gulae - P. gingivalis divergence. These results suggest an unexpected evolutionary relationship between the P. gulae - P. gingivalis duo and P. loveana, showing more clues about the origin of the role of those organisms in periodontitis.
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Affiliation(s)
- Mauricio Morales-Olavarría
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
| | - Josefa Nuñez-Belmar
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
| | - Dámariz González
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
| | - Emiliano Vicencio
- Escuela de Tecnología Médica, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Jaime Andres Rivas-Pardo
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
- Escuela de Biotecnología, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
| | - Cristian Cortez
- Escuela de Tecnología Médica, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Juan P. Cárdenas
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
- Escuela de Biotecnología, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile
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Huffines JT, Stoner SN, Baty JJ, Scoffield JA. Nitrite Triggers Reprogramming of the Oral Polymicrobial Metabolome by a Commensal Streptococcus. Front Cell Infect Microbiol 2022; 12:833339. [PMID: 35300375 PMCID: PMC8923425 DOI: 10.3389/fcimb.2022.833339] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 02/08/2022] [Indexed: 12/21/2022] Open
Abstract
Commensal streptococci regulate health and homeostasis within oral polymicrobial communities. Remarkably, high salivary nitrite concentrations have also been associated with improved health in the oral cavity. We previously demonstrated that nitrite assists hydrogen peroxide-producing oral commensal streptococci in regulating homeostasis via the generation of reactive nitrogen species (RNS), which have antimicrobial activity on oral pathogens. However, it is unknown how nitrite and commensal streptococci work in concert to influence the metabolome of oral polymicrobial communities. In this study, we report that nitrite aids commensal streptococci in the inhibition of multi-kingdom pathogens that reside in distinct oral niches, which supports commensal dominance. More importantly, we show that commensal streptococci utilize nitrite to drive the metabolic signature of multispecies biofilms in a manner that supports commensal metabolism and resistance to RNS, and restricts metabolic processes that are required for pathogen virulence. Taken together, our study provides insight into how commensal streptococci use nitrite to trigger shifts in the oral polymicrobial metabolome to support health and homeostasis.
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Affiliation(s)
| | | | | | - Jessica A. Scoffield
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States
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Yao K, Cai JY, Zhao L, Wu YF, Zhao ZH, Shen DN. Research progress on two-component signal transduction systems in Porphyromonas gingivalis. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2021; 39:88-93. [PMID: 33723942 DOI: 10.7518/hxkq.2021.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Porphyromonas gingivalis (P. gingivalis), a Gram-negative oral anaerobe, is considered to be a major pathogenic agent involved in the onset and progression of chronic periodontitis. P. gingivalis must be able to perceive and respond to the complicated changes in host to survive the environmental challenges, in which the two-component signal transduction systems (TCSs) play critical roles by connecting input signals to cellular physiological output. Canonical TCS consists of a sensor histidine kinase and a cognate response regulator that functions via a phosphorylation cascade. In this review, the roles of TCSs in P. gingivalis were demonstrated by illustrating the target genes and modulation modes, which may help elucidate the underlying mechanisms in future studies.
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Affiliation(s)
- Ke Yao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jing-Yi Cai
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Lei Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Ya-Fei Wu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Zhi-He Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Dao-Nan Shen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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Jones KR, Belvin BR, Macrina FL, Lewis JP. Sequence and characterization of shuttle vectors for molecular cloning in Porphyromonas, Bacteroides and related bacteria. Mol Oral Microbiol 2020; 35:181-191. [PMID: 32592236 DOI: 10.1111/omi.12304] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/19/2020] [Accepted: 06/19/2020] [Indexed: 11/28/2022]
Abstract
There is a lack of shuttle vectors to be needed for investigations into the genetics of Porphyromonas gingivalis and related species. To better understand the prevalence of candidates for such tools, we have examined multiple strains of black-pigmented anaerobes (clinical and laboratory isolates) for plasmids. As no plasmids were found in P. gingivalis strains, we have used the pYH420 plasmid, derived from P. asaccharolytica, as backbone to construct a shuttle vector in combination with pUC19 from Escherichia coli. Nucleotide sequence determination of the pYH420 plasmid revealed that it contained a gene with similarity to rep from plasmid pTS1 (isolated from Treponema denticola) as well as a homolog of mobA, a member of a gene family found on mobilizable genetic elements found in the genus Bacteroides. We constructed the pG106 and pG108 shuttle vectors using parts of the pUC19 and pYH420 vectors. This resulted in a vector with a multiple cloning site (MCS) in the lacZ gene enabling us to perform blue-white colony selection. The pG106 and pG108 shuttle vectors are electro-transformable into E. coli, P. gingivalis and B. thetaiotaomicron, where they are stable. We demonstrated that these vectors were suitable in these species for applications of molecular cloning including complementation and gene expression studies. Using the pG108 vector, we complement the hcpR mutant strain of P. gingivalis and rescued its NO 2 - -sensitive phenotype. We also performed a gene expression study using the P-glow BS2 fluorescent reporter gene and the ahpC promoter in B. thetaiotaomicron.
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Affiliation(s)
- Kevin R Jones
- The Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, USA
| | - Benjamin Ross Belvin
- The Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, USA
| | - Francis L Macrina
- The Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA
| | - Janina P Lewis
- The Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA.,Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, USA
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Śmiga M, Olczak T. PgRsp Is a Novel Redox-Sensing Transcription Regulator Essential for Porphyromonas gingivalis Virulence. Microorganisms 2019; 7:microorganisms7120623. [PMID: 31795139 PMCID: PMC6955866 DOI: 10.3390/microorganisms7120623] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/20/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022] Open
Abstract
Porphyromonas gingivalis is one of the etiological agents of chronic periodontitis. Both heme and oxidative stress impact expression of genes responsible for its survival and virulence. Previously we showed that P. gingivalis ferric uptake regulator homolog affects expression of a gene encoding a putative Crp/Fnr superfamily member, termed P. gingivalis redox-sensing protein (PgRsp). Although PgRsp binds heme and shows the highest similarity to proteins assigned to the CooA family, it could be a member of a novel, separate family of proteins with unknown function. Expression of the pgrsp gene is autoregulated and iron/heme dependent. Genes encoding proteins engaged in the oxidative stress response were upregulated in the pgrsp mutant (TO11) strain compared with the wild-type strain. The TO11 strain showed higher biomass production, biofilm formation, and coaggregation ability with Tannerella forsythia and Prevotella intermedia. We suggest that PgRsp may regulate production of virulence factors, proteases, Hmu heme acquisition system, and FimA protein. Moreover, we observed growth retardation of the TO11 strain under oxidative conditions and decreased survival ability of the mutant cells inside macrophages. We conclude that PgRsp protein may play a role in the oxidative stress response using heme as a ligand for sensing changes in redox status, thus regulating the alternative pathway of the oxidative stress response alongside OxyR.
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Belvin BR, Musayev FN, Burgner J, Scarsdale JN, Escalante CR, Lewis JP. Nitrosative stress sensing in Porphyromonas gingivalis: structure of and heme binding by the transcriptional regulator HcpR. Acta Crystallogr D Struct Biol 2019; 75:437-450. [PMID: 30988260 PMCID: PMC6465984 DOI: 10.1107/s205979831900264x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 02/21/2019] [Indexed: 11/10/2022] Open
Abstract
Although the HcpR regulator plays a vital step in initiation of the nitrosative stress response in many Gram-negative anaerobic bacteria, the molecular mechanisms that it uses to mediate gas sensing are not well understood. Here, a 2.6 Å resolution crystal structure of the N-terminal sensing domain of the anaerobic periodontopathogen Porphyromonas gingivalis HcpR is presented. The protein has classical features of the regulators belonging to the FNR-CRP family and contains a hydrophobic pocket in its N-terminal sensing domain. It is shown that heme bound to HcpR exhibits heme iron as a hexacoordinate system in the absence of nitric oxide (NO) and that upon nitrosylation it transitions to a pentacoordinate system. Finally, small-angle X-ray scattering experiments on full-length HcpR reveal that the C-terminal DNA-binding domain of HcpR has a high degree of interdomain flexibility.
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Affiliation(s)
- B. Ross Belvin
- Department of Biochemistry and Molecular Biology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
- The Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Faik N. Musayev
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, USA
- The Institute for Structural Biology, Drug Discovery, and Development, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - John Burgner
- The Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - J. Neel Scarsdale
- Department of Biochemistry and Molecular Biology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
- The Institute for Structural Biology, Drug Discovery, and Development, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Carlos R. Escalante
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Janina P. Lewis
- Department of Biochemistry and Molecular Biology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
- The Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, VA 23298, USA
- Department of Microbiology and Immunology, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
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The Porphyromonas gingivalis Hybrid Cluster Protein Hcp Is Required for Growth with Nitrite and Survival with Host Cells. Infect Immun 2019; 87:IAI.00572-18. [PMID: 30670550 DOI: 10.1128/iai.00572-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 01/11/2019] [Indexed: 12/13/2022] Open
Abstract
Although the periodontal pathogen Porphyromonas gingivalis must withstand high levels of nitrosative stress while in the oral cavity, the mechanisms of nitrosative stress defense are not well understood in this organism. Previously we showed that the transcriptional regulator HcpR plays a significant role in defense, and here we further defined its regulon. Our study shows that hcp (PG0893), a putative nitric oxide (NO) reductase, is the only gene significantly upregulated in response to nitrite (NO2) and that this regulation is dependent on HcpR. An isogenic mutant deficient in hcp is not able to grow with 200 μM nitrite, demonstrating that the sensitivity of the HcpR mutant is mediated through Hcp. We further define the molecular mechanisms of HcpR interaction with the hcp promoter through mutational analysis of the inverted repeat present within the promoter. Although other putative nitrosative stress protection mechanisms present on the nrfAH operon are also found in the P. gingivalis genome, we show that their gene products play no role in growth of the bacterium with nitrite. As growth of the hcp-deficient strain was also significantly diminished in the presence of a nitric oxide-producing compound, S-nitrosoglutathione (GSNO), Hcp appears to be the primary means by which P. gingivalis responds to NO2 --based stress. Finally, we show that Hcp is required for survival with host cells but that loss of Hcp has no effect on association and entry of P. gingivalis into human oral keratinocytes.
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Chang D, Yu Z, Ul Islam Z, French WT, Zhang Y, Zhang H. Proteomic and metabolomic analysis of the cellular biomarkers related to inhibitors tolerance in Zymomonas mobilis ZM4. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:283. [PMID: 30356850 PMCID: PMC6190654 DOI: 10.1186/s13068-018-1287-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/09/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Toxic compounds present in both the hydrolysate and pyrolysate of lignocellulosic biomass severely hinder the further conversion of lignocellulose-derived fermentable sugars into useful chemicals by common biocatalysts like Zymomonas mobilis, which has remarkable advantages over yeast. Although the extra detoxification treatment prior to fermentation process can help biocatalysts to eliminate the inhibitory environment, it is not environment friendly and cost effective for industrial application. As also reported by previous studies, an ideal and holistic approach to solve this issue is to develop microbial strains with inhibitor tolerance. However, previously engineered strains had the limitation that they could not cope well with the synergistic effect of multiple inhibitors as they are resistant only to a single inhibitor. Hence, understanding the universal cellular responses of Z. mobilis to various inhibitors may guide the designing of rational strategies to obtain more robust engineered strains for biofuel production from lignocellulosic biomass. RESULTS Quantitative proteomics and metabolomics approaches were used to determine the cellular responses of Z. mobilis ZM4 to representative biomass-derived inhibitors like formic acid, acetic acid, furfural, 5-hydroxymethylfurfural, and phenol. The differentially expressed proteins identified under the challenge of single and combined inhibitors were involved in cell wall/membrane biogenesis, energy production, DNA replication, DNA recombination, DNA repair, DNA transcription, RNA translation, posttranslational modification, biosynthesis of amino acids, central carbon metabolism, etc. Metabolomics analysis showed that the up- or down-regulation pattern of metabolites was changed consistently with that of relevant proteins. CONCLUSION Fifteen up-regulated proteins (e.g., Isopropylmalate isomerase LeuC, transcription-repair-coupling factor Mfd, and phosphoglucose isomerase PGI) and thirteen down-regulated proteins (e.g., TonB-dependent transporter ZMO1522, transcription termination factor Rho, and S1/P1 nuclease ZMO0127) were identified as candidate proteins related to all the stress conditions, implying that these proteins are potential biomarkers for the improvement of Z. mobilis ZM4 to resist complex biomass-derived inhibitors. These data can be used to generate a database of inhibitor-tolerance biomarkers, which could provide a basis for engineering Z. mobilis that would be able to grow in the presence of multiple inhibitors and directly ferment the biomass-derived sugars into biofuels.
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Affiliation(s)
- Dongdong Chang
- College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing, 100049 People’s Republic of China
| | - Zhisheng Yu
- College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing, 100049 People’s Republic of China
| | - Zia Ul Islam
- College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing, 100049 People’s Republic of China
- Department of Sustainable Bioproducts, Mississippi State University, Mississippi State, MS 39762 USA
| | - W. Todd French
- Dave C. Swalm School of Chemical Engineering, Mississippi State University, P.O. Box 9595, Mississippi State, MS 39762 USA
| | - Yiming Zhang
- Environmental Protection Bureau, Shunyi District, Beijing, 101300 People’s Republic of China
| | - Hongxun Zhang
- College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing, 100049 People’s Republic of China
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Miller DP, Hutcherson JA, Wang Y, Nowakowska ZM, Potempa J, Yoder-Himes DR, Scott DA, Whiteley M, Lamont RJ. Genes Contributing to Porphyromonas gingivalis Fitness in Abscess and Epithelial Cell Colonization Environments. Front Cell Infect Microbiol 2017; 7:378. [PMID: 28900609 PMCID: PMC5581868 DOI: 10.3389/fcimb.2017.00378] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/09/2017] [Indexed: 12/11/2022] Open
Abstract
Porphyromonas gingivalis is an important cause of serious periodontal diseases, and is emerging as a pathogen in several systemic conditions including some forms of cancer. Initial colonization by P. gingivalis involves interaction with gingival epithelial cells, and the organism can also access host tissues and spread haematogenously. To better understand the mechanisms underlying these properties, we utilized a highly saturated transposon insertion library of P. gingivalis, and assessed the fitness of mutants during epithelial cell colonization and survival in a murine abscess model by high-throughput sequencing (Tn-Seq). Transposon insertions in many genes previously suspected as contributing to virulence showed significant fitness defects in both screening assays. In addition, a number of genes not previously associated with P. gingivalis virulence were identified as important for fitness. We further examined fitness defects of four such genes by generating defined mutations. Genes encoding a carbamoyl phosphate synthetase, a replication-associated recombination protein, a nitrosative stress responsive HcpR transcription regulator, and RNase Z, a zinc phosphodiesterase, showed a fitness phenotype in epithelial cell colonization and in a competitive abscess infection. This study verifies the importance of several well-characterized putative virulence factors of P. gingivalis and identifies novel fitness determinants of the organism.
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Affiliation(s)
- Daniel P Miller
- Department of Oral Immunology and Infectious Diseases, University of LouisvilleLouisville, KY, United States
| | - Justin A Hutcherson
- Department of Oral Immunology and Infectious Diseases, University of LouisvilleLouisville, KY, United States
| | - Yan Wang
- Department of Oral Immunology and Infectious Diseases, University of LouisvilleLouisville, KY, United States
| | - Zuzanna M Nowakowska
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian UniversityKrakow, Poland
| | - Jan Potempa
- Department of Oral Immunology and Infectious Diseases, University of LouisvilleLouisville, KY, United States.,Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian UniversityKrakow, Poland.,Malopolska Centre of Biotechnology, Jagiellonian UniversityKrakow, Poland
| | | | - David A Scott
- Department of Oral Immunology and Infectious Diseases, University of LouisvilleLouisville, KY, United States
| | - Marvin Whiteley
- Department of Molecular Biosciences, University of Texas at AustinAustin, TX, United States
| | - Richard J Lamont
- Department of Oral Immunology and Infectious Diseases, University of LouisvilleLouisville, KY, United States
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Nies F, Wörner S, Wunsch N, Armant O, Sharma V, Hesselschwerdt A, Falk F, Weber N, Weiß J, Trautmann A, Posten C, Prakash T, Lamparter T. Characterization of Phormidium lacuna strains from the North Sea and the Mediterranean Sea for biotechnological applications. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.05.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Cadby IT, Ibrahim SA, Faulkner M, Lee DJ, Browning D, Busby SJ, Lovering AL, Stapleton MR, Green J, Cole JA. Regulation, sensory domains and roles of twoDesulfovibrio desulfuricansATCC27774 Crp family transcription factors, HcpR1 and HcpR2, in response to nitrosative stress. Mol Microbiol 2016; 102:1120-1137. [DOI: 10.1111/mmi.13540] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Ian T. Cadby
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
| | - Susan A. Ibrahim
- Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | - Matthew Faulkner
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
| | - David J. Lee
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
| | - Douglas Browning
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
| | - Stephen J. Busby
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
| | - Andrew L. Lovering
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
| | - Melanie R. Stapleton
- Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | - Jeffrey Green
- Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | - Jeffrey A. Cole
- Institute of Microbiology & Infection, School of Biosciences; University of Birmingham; Birmingham B15 2TT UK
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14
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Wang J, Vine CE, Balasiny BK, Rizk J, Bradley CL, Tinajero-Trejo M, Poole RK, Bergaust LL, Bakken LR, Cole JA. The roles of the hybrid cluster protein, Hcp and its reductase, Hcr, in high affinity nitric oxide reduction that protects anaerobic cultures ofEscherichia coliagainst nitrosative stress. Mol Microbiol 2016; 100:877-92. [DOI: 10.1111/mmi.13356] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Jing Wang
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Claire E. Vine
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Basema K. Balasiny
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - John Rizk
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Charlene L. Bradley
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Mariana Tinajero-Trejo
- Department of Molecular Biology & Biotechnology; University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | - Robert K. Poole
- Department of Molecular Biology & Biotechnology; University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | | | - Lars R. Bakken
- Norwegian University of Life Science; PO box 5003 N-1432 Ås Norway
| | - Jeffrey A. Cole
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
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15
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Scoffield JA, Wu H. Nitrite reductase is critical for Pseudomonas aeruginosa survival during co-infection with the oral commensal Streptococcus parasanguinis. MICROBIOLOGY-SGM 2015; 162:376-383. [PMID: 26673783 DOI: 10.1099/mic.0.000226] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pseudomonas aeruginosa is the major aetiological agent of chronic pulmonary infections in cystic fibrosis (CF) patients. However, recent evidence suggests that the polymicrobial community of the CF lung may also harbour oral streptococci, and colonization by these micro-organisms may have a negative impact on P. aeruginosa within the CF lung. Our previous studies demonstrated that nitrite abundance plays an important role in P. aeruginosa survival during co-infection with oral streptococci. Nitrite reductase is a key enzyme involved in nitrite metabolism. Therefore, the objective of this study was to examine the role nitrite reductase (gene nirS) plays in P. aeruginosa survival during co-infection with an oral streptococcus, Streptococcus parasanguinis. Inactivation of nirS in both the chronic CF isolate FRD1 and acute wound isolate PAO1 reduced the survival rate of P. aeruginosa when co-cultured with S. parasanguinis. Growth of both mutants was restored when co-cultured with S. parasanguinis that was defective for H2O2 production. Furthermore, the nitrite reductase mutant was unable to kill Drosophila melanogaster during co-infection with S. parasanguinis. Taken together, these results suggest that nitrite reductase plays an important role for survival of P. aeruginosa during co-infection with S. parasanguinis.
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Affiliation(s)
- Jessica A Scoffield
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hui Wu
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA
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16
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Boutrin MC, Yu Y, Wang C, Aruni W, Dou Y, Shi L, Fletcher HM. A putative TetR regulator is involved in nitric oxide stress resistance in Porphyromonas gingivalis. Mol Oral Microbiol 2015; 31:340-53. [PMID: 26332057 DOI: 10.1111/omi.12128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2015] [Indexed: 02/02/2023]
Abstract
To survive in the periodontal pocket, Porphyromonas gingivalis, the main causative agent of periodontal disease, must overcome oxidative and nitric oxide (NO) stress. Previously, we reported that, in the presence of NO comparable to stress conditions, the transcriptome of P. gingivalis was differentially expressed, and genes belonging to the PG1178-81 cluster were significantly upregulated. To further evaluate their role(s) in NO stress resistance, these genes were inactivated by allelic exchange mutagenesis. Isogenic mutants P. gingivalis FLL460 (ΔPG1181::ermF) and FLL461 (ΔPG1178-81::ermF) were black-pigmented, with gingipain and hemolytic activities comparable to that of the wild-type strain. Whereas the recovery of these isogenic mutants from NO stress was comparable to the wild-type, there was increased sensitivity to hydrogen peroxide-induced stress. RNA-Seq analysis under conditions of NO stress showed that approximately 5 and 8% of the genome was modulated in P. gingivalis FLL460 and FLL461, respectively. The PG1178-81 gene cluster was shown to be part of the same transcriptional unit and is inducible in response to NO stress. In the presence of NO, PG1181, a putative transcriptional regulator, was shown to bind to its own promoter region and that of several other NO responsive genes including PG0214 an extracytoplasmic function σ factor, PG0893 and PG1236. Taken together, the data suggest that PG1181 is a NO responsive transcriptional regulator that may play an important role in the NO stress resistance regulatory network in P. gingivalis.
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Affiliation(s)
- M-C Boutrin
- Division of Microbiology and Molecular Genetics, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Y Yu
- School of Pharmacy, Fudan University, Shanghai, China
| | - C Wang
- Division of Microbiology and Molecular Genetics, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - W Aruni
- Division of Microbiology and Molecular Genetics, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Y Dou
- Division of Microbiology and Molecular Genetics, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - L Shi
- School of Pharmacy, Fudan University, Shanghai, China
| | - H M Fletcher
- Division of Microbiology and Molecular Genetics, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA, USA.,Institute of Oral Biology, Kyung Hee University, Seoul, Korea
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17
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da Silva SM, Amaral C, Neves SS, Santos C, Pimentel C, Rodrigues-Pousada C. An HcpR paralog of Desulfovibrio gigas provides protection against nitrosative stress. FEBS Open Bio 2015; 5:594-604. [PMID: 26273559 PMCID: PMC4534486 DOI: 10.1016/j.fob.2015.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/01/2015] [Indexed: 01/12/2023] Open
Abstract
Desulfovibrio gigas genome encodes two HcpR paralogs, HcpR1 and HcpR2. Cells lacking HcpR1 are less tolerant to NO. HcpR1 regulates the expression of several genes related to nitrogen metabolism. Phylogenetic analyses indicate that the presence of HcpR paralogs is a common finding among Desulfovibrio species.
Desulfovibrio gigas belongs to the group of sulfate reducing bacteria (SRB). These ubiquitous and metabolically versatile microorganisms are often exposed to reactive nitrogen species (RNS). Nonetheless, the mechanisms and regulatory elements involved in nitrosative stress protection are still poorly understood. The transcription factor HcpR has emerged as a putative regulator of nitrosative stress response among anaerobic bacteria. HcpR is known to orchestrate the expression of the hybrid cluster protein gene, hcp, proposed to be involved in cellular defense against RNS. According to phylogenetic analyses, the occurrence of hcpR paralog genes is a common feature among several Desulfovibrio species. Within the D. gigas genome we have identified two HcpR-related sequences. One of these sequences, hcpR1, was found in the close vicinity of the hcp gene and this finding prompted us to proceed with its functional characterization. We observed that the growth of a D. gigas strain lacking hcpR1 is severely impaired under nitrosative stress. An in silico search revealed several putative targets of HcpR1 that were experimentally validated. The fact that HcpR1 regulates several genes encoding proteins involved in nitrite and nitrate metabolism, together with the sensitive growth phenotype to NO displayed by an hcpR1 mutant strain, strongly supports a relevant role of this factor under nitrosative stress. Moreover, the finding that several Desulfovibrio species possess HcpR paralogs, which have been transmitted vertically in the evolution and diversification of the genus, suggests that these sequences may confer adaptive or survival advantage to these organisms, possibly by increasing their tolerance to nitrosative stress.
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Key Words
- BI, Bayesian inference
- BS, bootstrap
- CRP/FNR, cAMP receptor protein/fumarate and nitrate reductase regulatory protein
- Desulfovibrio
- Frdx, ferredoxin
- GSNO, S-nitrosoglutathione
- HGT, horizontal gene transfer
- Hcp, hybrid cluster protein
- HcpR
- ML, maximum likelihood
- MP, maximum parsimony
- Molecular phylogeny
- NO, nitric oxide
- Nitrosative stress
- PP, posterior probability
- RNS, reactive nitrogen species
- ROO, rubredoxin oxygen reductase
- SRB, sulfate reducing bacteria
- Sulfate reducing bacteria
- Transcription regulation
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Affiliation(s)
- Sofia M da Silva
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Catarina Amaral
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Susana S Neves
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Cátia Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Catarina Pimentel
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Claudina Rodrigues-Pousada
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
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18
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Frederick RE, Caranto JD, Masitas CA, Gebhardt LL, MacGowan CE, Limberger RJ, Kurtz DM. Dioxygen and nitric oxide scavenging by Treponema denticola flavodiiron protein: a mechanistic paradigm for catalysis. J Biol Inorg Chem 2015; 20:603-13. [PMID: 25700637 PMCID: PMC4768905 DOI: 10.1007/s00775-015-1248-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 02/13/2015] [Indexed: 10/24/2022]
Abstract
Flavodiiron proteins (FDPs) contain a unique active site consisting of a non-heme diiron carboxylate site proximal to a flavin mononucleotide (FMN). FDPs serve as the terminal components for reductive scavenging of dioxygen (to water) or nitric oxide (to nitrous oxide), which combats oxidative or nitrosative stress in many bacteria. Characterizations of FDPs from spirochetes or from any oral microbes have not been previously reported. Here, we report characterization of an FDP from the anaerobic spirochete, Treponema (T.) denticola, which is associated with chronic periodontitis. The isolated T. denticola FDP exhibited efficient four-electron dioxygen reductase activity and lower but significant anaerobic nitric oxide reductase activity. A mutant T. denticola strain containing the inactivated FDP-encoding gene was significantly more air-sensitive than the wild-type strain. Single turnover reactions of the four-electron-reduced FDP (FMNH2-Fe(II)Fe(II)) (FDPred) with O2 monitored on the milliseconds to seconds time scale indicated initial rapid formation of a spectral feature consistent with a cis-μ-1,2-peroxo-diferric intermediate, which triggered two-electron oxidation of FMNH2. Reaction of FDPred with NO showed apparent cooperativity between binding of the first and second NO to the diferrous site. The resulting diferrous dinitrosyl complex triggered two-electron oxidation of the FMNH2. Our cumulative results on this and other FDPs indicate that smooth two-electron FMNH2 oxidation triggered by the FDPred/substrate complex and overall four-electron oxidation of FDPred to FDPox constitutes a mechanistic paradigm for both dioxygen and nitric oxide reductase activities of FDPs. Four-electron reductive O2 scavenging by FDPs could contribute to oxidative stress protection in many other oral bacteria.
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Affiliation(s)
- Rosanne E. Frederick
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Jonathan D. Caranto
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Cesar A. Masitas
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Linda L. Gebhardt
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Charles E. MacGowan
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Ronald J. Limberger
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Donald M. Kurtz
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, USA
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19
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Skeff MA, Brito GAC, de Oliveira MG, Braga CM, Cavalcante MM, Baldim V, Holanda-Afonso RC, Silva-Boghossian CM, Colombo AP, Ribeiro RA, Moura-Neto V, Leitão RFC. S-nitrosoglutathione accelerates recovery from 5-fluorouracil-induced oral mucositis. PLoS One 2014; 9:e113378. [PMID: 25478918 PMCID: PMC4257535 DOI: 10.1371/journal.pone.0113378] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 10/16/2014] [Indexed: 11/19/2022] Open
Abstract
Introduction Mucositis induced by anti-neoplastic drugs is an important, dose-limiting and costly side-effect of cancer therapy. Aim To evaluate the effect of the topical application of S-nitrosoglutathione (GSNO), a nitric oxide donor, on 5-fluorouracil (5-FU)-induced oral mucositis in hamsters. Materials and Methods Oral mucositis was induced in male hamsters by two intraperitoneal administrations of 5-FU on the first and second days of the experiment (60 and 40 mg/kg, respectively) followed by mechanical trauma on the fourth day. Animals received saline, HPMC or HPMC/GSNO (0.1, 0.5 or 2.0 mM) 1 h prior to the 5-FU injection and twice a day for 10 or 14 days. Samples of cheek pouches were harvested for: histopathological analysis, TNF-α and IL-1β levels, immunohistochemical staining for iNOS, TNF-α, IL-1β, Ki67 and TGF-β RII and a TUNEL assay. The presence and levels of 39 bacterial taxa were analyzed using the Checkerboard DNA-DNA hybridization method. The profiles of NO released from the HPMC/GSNO formulations were characterized using chemiluminescence. Results The HPMC/GSNO formulations were found to provide sustained release of NO for more than 4 h at concentration-dependent rates of 14 to 80 nmol/mL/h. Treatment with HPMC/GSNO (0.5 mM) significantly reduced mucosal damage, inflammatory alterations and cell death associated with 5-FU-induced oral mucositis on day 14 but not on day 10. HPMC/GSNO administration also reversed the inhibitory effect of 5-FU on cell proliferation on day 14. In addition, we observed that the chemotherapy significantly increased the levels and/or prevalence of several bacterial species. Conclusion Topical HPMC/GSNO accelerates mucosal recovery, reduces inflammatory parameters, speeds up re-epithelization and decreases levels of periodontopathic species in mucosal ulcers.
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Affiliation(s)
- Maria Adriana Skeff
- Laboratory of Cell Morphogenesis, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Gerly A. C. Brito
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | | | - Cintia M. Braga
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Matheus M. Cavalcante
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Victor Baldim
- Institute of Chemistry, University of Campinas, UNICAMP, Campinas, SP, Brazil
| | - Rosenilde C. Holanda-Afonso
- Laboratory of Cell Morphogenesis, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Carina M. Silva-Boghossian
- Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Faculty of Dentistry, University of Grande Rio, Duque de Caxias, RJ, Brazil
| | - Ana Paula Colombo
- Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Ronaldo A. Ribeiro
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Vivaldo Moura-Neto
- Laboratory of Cell Morphogenesis, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Instituto Estadual do Cérebro Paulo Niemeyer, Rio de Janeiro, RJ, Brazil
| | - Renata F. C. Leitão
- Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
- * E-mail:
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20
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Henry LG, Boutrin MC, Aruni W, Robles A, Ximinies A, Fletcher HM. Life in a Diverse Oral Community - Strategies for Oxidative Stress Survival. J Oral Biosci 2014; 56:63-71. [PMID: 26744578 DOI: 10.1016/j.job.2014.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND While the oral cavity harbors more than 680 bacterial species, the interaction and association of selected bacterial species play a role in periodontal diseases. Bacterial species including Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia, a consortium previously designated as the "red complex" is now being expanded to include other new emerging pathogens that are significantly associated with periodontal disease. HIGHLIGHT In addition to novel mechanisms for oxidative resistance of individual species, community dynamics may lead to an overall strategy for survival in the inflammatory environment of the periodontal pocket. Complex systems controlled by response regulators protect against oxidative and nitrosative stress. CONCLUSION The combination of these multifaceted strategies would provide a comprehensive defense and support system against the repetitive host immune response to promote microbial persistence and disease.
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Affiliation(s)
- Leroy G Henry
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
| | - Marie-Claire Boutrin
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
| | - Wilson Aruni
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
| | - Antonette Robles
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
| | - Alexia Ximinies
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
| | - Hansel M Fletcher
- Division of Microbiology and Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California 92350
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21
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Stern AM, Zhu J. An introduction to nitric oxide sensing and response in bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2014; 87:187-220. [PMID: 24581392 DOI: 10.1016/b978-0-12-800261-2.00005-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nitric oxide (NO) is a radical gas that has been intensively studied for its role as a bacteriostatic agent. NO reacts in complex ways with biological molecules, especially metal centers and other radicals, to generate other bioactive compounds that inhibit enzymes, oxidize macromolecules, and arrest bacterial growth. Bacteria encounter not only NO derived from the host during infection but also NO derived from other bacteria and inorganic sources. The transcriptional responses used by bacteria to respond to NO are diverse but usually involve an iron-containing transcription factor that binds NO and alters its affinity for either DNA or factors involved in transcription, leading to the production of enzymatic tolerance systems. Some of these systems, such as flavohemoglobin and flavorubredoxin, directly remove NO. Some do not but are still important for NO tolerance through other mechanisms. The targets of NO that are protected by these systems include many metabolic pathways such as the tricarboxylic acid cycle and branched chain amino acid synthesis. This chapter discusses these topics and others and serves as a general introduction to microbial NO biology.
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22
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Krishnan K, Duncan MJ. Role of sodium in the RprY-dependent stress response in Porphyromonas gingivalis. PLoS One 2013; 8:e63180. [PMID: 23671672 PMCID: PMC3646045 DOI: 10.1371/journal.pone.0063180] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 03/31/2013] [Indexed: 01/09/2023] Open
Abstract
Porphyromonas gingivalis is a Gram-negative oral anaerobe which is strongly associated with periodontal disease. Environmental changes in the gingival sulcus trigger the growth of P. gingivalis and a concurrent shift from periodontal health to disease. Bacteria adjust their physiology in response to environmental changes and gene regulation by two-component phospho-relay systems is one mechanism by which such adjustments are effected. In P. gingivalis RprY is an orphan response regulator and previously we showed that the RprY regulon included genes associated with oxidative stress and sodium metabolism. The goals of the present study were to identify environmental signals that induce rprY and clarify the role of the regulator in the stress response. In Escherichia coli an RprY-LacZ fusion protein was induced in sodium- depleted medium and a P. gingivalis rprY mutant was unable to grow in similar medium. By several approaches we established that sodium depletion induced up-regulation of genes involved in oxidative stress. In addition, we demonstrated that RprY interacted directly with the promoters of several molecular chaperones. Further, both genetic and transcription data suggest that the regulator acts as a repressor. We conclude that RprY is one of the regulators that controls stress responses in P. gingivalis, possibly by acting as a repressor since an rprY mutant showed a superstress reponse in sodium-depleted medium which we propose inhibited growth.
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Affiliation(s)
- Karthik Krishnan
- Department of Microbiology, The Forsyth Institute, Cambridge, Massachusetts, United States of America
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