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Gurung V, Biswas S, Biswas I. Diverse nature of ClpX degradation motifs in Streptococcus mutans. Microbiol Spectr 2024; 12:e0345723. [PMID: 38051052 PMCID: PMC10782952 DOI: 10.1128/spectrum.03457-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 11/07/2023] [Indexed: 12/07/2023] Open
Abstract
IMPORTANCE Cytoplasmic Clp-related proteases play a major role in maintaining cellular proteome in bacteria. ClpX/P is one such proteolytic complex that is important for conserving protein homeostasis. In this study, we investigated the role of ClpX/P in Streptococcus mutans, an important oral pathogen. We identified several putative substrates whose cellular levels are regulated by ClpX/P in S. mutans and subsequently discovered several recognition motifs that are critical for degradation. Our study is the first comprehensive analysis of determining ClpX/P motifs in streptococci. We believe that identifying the substrates that are regulated by ClpX/P will enhance our understanding about virulence regulation in this important group of pathogens.
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Affiliation(s)
- Vivek Gurung
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Saswati Biswas
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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2
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张 梦, 程 兴, 徐 欣. [Latest Findings on Polyketides/Non-ribosomal Peptides That Are Secondary Metabolites of Streptococcus mutans]. SICHUAN DA XUE XUE BAO. YI XUE BAN = JOURNAL OF SICHUAN UNIVERSITY. MEDICAL SCIENCE EDITION 2023; 54:685-691. [PMID: 37248606 PMCID: PMC10475436 DOI: 10.12182/20230560302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Indexed: 05/31/2023]
Abstract
Dental caries is a chronic infectious disease that occurs in the hard tissue of teeth under the influence of multiple factors, among which bacteria being a key factor. Streptococcus mutans ( S. mutans) is considered a major pathogen that causes caries. Secondary metabolites, including bacteriocins and polyketides/non-ribosomal peptides, are a class of small-molecule compounds synthesized by S. mutans. To date, polyketides/non-ribosomal peptides identified in S. mutans include mutanobactin, mutanocyclin, and mutanofactin, which are synthesized by the mub, muc, and muf biosynthetic gene clusters, respectively. These polyketides/non-ribosomal peptides play important roles in bacterial inter-species competition, oxidative stress, and biofilm formation. In this review, we provided an overview of the synthesis, function and regulation of three polyketides/non-ribosomal peptides of S. mutans, including mutanobactin, mutanocyclin, and mutanofactin, aiming to provide new insights into the cariogenic mechanism of S. mutans and to promote the better management of dental caries.
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Affiliation(s)
- 梦碟 张
- 口腔疾病研究国家重点实验室,国家口腔疾病临床医学研究中心,四川大学华西口腔医院 牙体牙髓病科 (成都 610041)The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Department of Cariology and Endodontics, Sichuan University, Chengdu 610041, China
| | - 兴群 程
- 口腔疾病研究国家重点实验室,国家口腔疾病临床医学研究中心,四川大学华西口腔医院 牙体牙髓病科 (成都 610041)The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Department of Cariology and Endodontics, Sichuan University, Chengdu 610041, China
| | - 欣 徐
- 口腔疾病研究国家重点实验室,国家口腔疾病临床医学研究中心,四川大学华西口腔医院 牙体牙髓病科 (成都 610041)The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Department of Cariology and Endodontics, Sichuan University, Chengdu 610041, China
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3
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King S, Quick A, King K, Walker AR, Shields RC. Activation of TnSmu1, an integrative and conjugative element, by an ImmR-like transcriptional regulator in Streptococcus mutans. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36201342 DOI: 10.1099/mic.0.001254] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Integrative and conjugative elements (ICEs) are chromosomally encoded mobile genetic elements that can transfer DNA between bacterial strains. Recently, as part of efforts to determine hypothetical gene functions, we have discovered an important regulatory module encoded on an ICE known as TnSmu1 on the Streptococcus mutans chromosome. The regulatory module consists of a cI-like repressor with a helix-turn-helix DNA binding domain immR Smu (immunity repressor) and a metalloprotease immA Smu (anti-repressor). It is not possible to create an in-frame deletion mutant of immR Smu and repression of immR Smu with CRISPRi (CRISPR interference) causes substantial cell defects. We used a bypass of essentiality (BoE) screen to discover genes that allow deletion of the regulatory module. This revealed that conjugation genes, located within TnSmu1, can restore the viability of an immR Smu mutant. Deletion of immR Smu also leads to production of a circular intermediate form of TnSmu1, which is also inducible by the genotoxic agent mitomycin C. To gain further insights into potential regulation of TnSmu1 by ImmRSmu and broader effects on S. mutans UA159 physiology, we used CRISPRi and RNA-seq. Strongly induced genes included all the TnSmu1 mobile element, genes involved in amino acid metabolism, transport systems and a type I-C CRISPR-Cas system. Lastly, bioinformatic analysis shows that the TnSmu1 mobile element and its associated genes are well distributed across S. mutans isolates. Taken together, our results show that activation of TnSmu1 is controlled by the immRA Smu module, and that activation is deleterious to S. mutans, highlighting the complex interplay between mobile elements and their host.
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Affiliation(s)
- Shawn King
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, USA
| | - Allison Quick
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, USA
| | - Kalee King
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, USA
| | | | - Robert C Shields
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR, USA
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Zhang Y, Wang Y, Wei W, Wang M, Jia S, Yang M, Ge F. Proteomic analysis of the regulatory networks of ClpX in a model cyanobacterium Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2022; 13:994056. [PMID: 36247581 PMCID: PMC9560874 DOI: 10.3389/fpls.2022.994056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Protein homeostasis is tightly regulated by protein quality control systems such as chaperones and proteases. In cyanobacteria, the ClpXP proteolytic complex is regarded as a representative proteolytic system and consists of a hexameric ATPase ClpX and a tetradecameric peptidase ClpP. However, the functions and molecular mechanisms of ClpX in cyanobacteria remain unclear. This study aimed to decipher the unique contributions and regulatory networks of ClpX in the model cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis). We showed that the interruption of clpX led to slower growth, decreased high light tolerance, and impaired photosynthetic cyclic electron transfer. A quantitative proteomic strategy was employed to globally identify ClpX-regulated proteins in Synechocystis cells. In total, we identified 172 differentially expressed proteins (DEPs) upon the interruption of clpX. Functional analysis revealed that these DEPs are involved in diverse biological processes, including glycolysis, nitrogen assimilation, photosynthetic electron transport, ATP-binding cassette (ABC) transporters, and two-component signal transduction. The expression of 24 DEPs was confirmed by parallel reaction monitoring (PRM) analysis. In particular, many hypothetical or unknown proteins were found to be regulated by ClpX, providing new candidates for future functional studies on ClpX. Together, our study provides a comprehensive ClpX-regulated protein network, and the results serve as an important resource for understanding protein quality control systems in cyanobacteria.
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Affiliation(s)
- Yumeng Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yaqi Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wei Wei
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- The Analysis and Testing Center, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Shuzhao Jia
- The Analysis and Testing Center, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Mingkun Yang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Feng Ge
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
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Pandey SD, Biswas I. Clp ATPases differentially affect natural competence development in Streptococcus mutans. Microbiologyopen 2022; 11:e1288. [PMID: 35765180 PMCID: PMC9108599 DOI: 10.1002/mbo3.1288] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/27/2022] [Indexed: 11/25/2022] Open
Abstract
In naturally competent bacteria, DNA transformation through horizontal gene transfer is an evolutionary mechanism to receive extracellular DNA. Bacteria need to maintain a state of competence to accept foreign DNA, and this is an energy-driven phenomenon that is tightly controlled. In Streptococcus, competence development is a complex process that is not fully understood. In this study, we used Streptococcus mutans, an oral bacterium, to determine how cell density affects competence development. We found that in S. mutans the transformation efficiency is maximum when the transforming DNA was added at low cell density and incubated for 2.5 h before selecting for transformants. We also found that S. mutans cells remain competent until the mid-logarithmic phase, after which the competence decreases drastically. Surprisingly, we observed that individual components of Clp proteolytic complexes differentially regulate competence. If the transformation is carried out at the early growth phase, both ClpP protease and ClpX ATPase are needed for competence. In contrast, we found that both ClpC and ClpE negatively affect competence. We also found that if the transformation is carried out at the mid-logarithmic growth phase ClpX is still required for competence, but ClpP negatively affects competence. While the exact reason for this differential effect of ClpP and ClpX on transformation is currently unknown, we found that both ClpC and ClpE have a negative effect on transformation, which was not reported before.
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Affiliation(s)
- Satya D. Pandey
- Department of MicrobiologyUniversity of Kansas Medical CenterKansas CityKansasUSA
| | - Indranil Biswas
- Department of MicrobiologyUniversity of Kansas Medical CenterKansas CityKansasUSA
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Ge Z, Yuan P, Chen L, Chen J, Shen D, She Z, Lu Y. New Global Insights on the Regulation of the Biphasic Life Cycle and Virulence Via ClpP-Dependent Proteolysis in Legionella pneumophila. Mol Cell Proteomics 2022; 21:100233. [PMID: 35427813 PMCID: PMC9112007 DOI: 10.1016/j.mcpro.2022.100233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 02/17/2022] [Accepted: 04/07/2022] [Indexed: 01/11/2023] Open
Abstract
Legionella pneumophila, an environmental bacterium that parasitizes protozoa, causes Legionnaires’ disease in humans that is characterized by severe pneumonia. This bacterium adopts a distinct biphasic life cycle consisting of a nonvirulent replicative phase and a virulent transmissive phase in response to different environmental conditions. Hence, the timely and fine-tuned expression of growth and virulence factors in a life cycle–dependent manner is crucial for survival and replication. Here, we report that the completion of the biphasic life cycle and bacterial pathogenesis is greatly dependent on the protein homeostasis regulated by caseinolytic protease P (ClpP)-dependent proteolysis. We characterized the ClpP-dependent dynamic profiles of the regulatory and substrate proteins during the biphasic life cycle of L. pneumophila using proteomic approaches and discovered that ClpP-dependent proteolysis specifically and conditionally degraded the substrate proteins, thereby directly playing a regulatory role or indirectly controlling cellular events via the regulatory proteins. We further observed that ClpP-dependent proteolysis is required to monitor the abundance of fatty acid biosynthesis–related protein Lpg0102/Lpg0361/Lpg0362 and SpoT for the normal regulation of L. pneumophila differentiation. We also found that the control of the biphasic life cycle and bacterial virulence is independent. Furthermore, the ClpP-dependent proteolysis of Dot/Icm (defect in organelle trafficking/intracellular multiplication) type IVB secretion system and effector proteins at a specific phase of the life cycle is essential for bacterial pathogenesis. Therefore, our findings provide novel insights on ClpP-dependent proteolysis, which spans a broad physiological spectrum involving key metabolic pathways that regulate the transition of the biphasic life cycle and bacterial virulence of L. pneumophila, facilitating adaptation to aquatic and intracellular niches. ClpP is the major determinant of biphasic life cycle–dependent protein turnover. ClpP-dependent proteolysis monitors SpoT abundance for cellular differentiation. ClpP-dependent regulation of life cycle and bacterial virulence is independent. ClpP-dependent proteolysis of T4BSS and effector proteins is vital for virulence.
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Affiliation(s)
- Zhenhuang Ge
- School of Chemistry, Sun Yat-sen University, Guangzhou, China; School of Life Sciences, Sun Yat-sen University, Guangzhou, China; Run Ze Laboratory for Gastrointestinal Microbiome Study, Sun Yat-sen University, Guangzhou, China
| | - Peibo Yuan
- Microbiome Medicine Center, Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Lingming Chen
- Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Junyi Chen
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China; Run Ze Laboratory for Gastrointestinal Microbiome Study, Sun Yat-sen University, Guangzhou, China
| | - Dong Shen
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhigang She
- School of Chemistry, Sun Yat-sen University, Guangzhou, China
| | - Yongjun Lu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China; Run Ze Laboratory for Gastrointestinal Microbiome Study, Sun Yat-sen University, Guangzhou, China.
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7
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Santos HSDB, Do T, Parolo CCF, Poloni JDF, Maltz M, Arthur RA, Damé-Teixeira N. Streptococcus mutans gene expression and functional profile in root caries: an RNA-seq study. Caries Res 2022; 56:116-128. [DOI: 10.1159/000524196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/20/2022] [Indexed: 11/19/2022] Open
Abstract
The literature is still scarce on studies describing S. mutans global gene expression under clinical conditions such as those found on complex biofilms from sound root surfaces (SRS) and carious root surfaces (RC). This study aimed to investigate the S. mutans gene expression and functional profile within the metatranscriptome of biofilms from SRS and from RC in an attempt to identify enriched functional signatures potentially associated with healthy to disease transitioning process. Total RNA was extracted, and prepared libraries (SRS=10 and RC=9) were paired-end sequenced using the Illumina HiSeq2500. Read count assigned to each gene of the S. mutans UA159 strain were obtained. Differentially expressed genes (DEG) between SRS and RC were identified using the DESeq2 R package and weighted gene co-expression network analysis (WGCNA) was performed to explore and identify functional modules related to SRS and RC. We found seventeen DEG between SRS and RC samples, with three overexpressed in RC and related to membrane protein, alanyl-tRNA synthetase and GTP-binding protein with the remaining ones overexpressed in SRS samples and related to hypothetical protein, transposon integrase, histidine kinase, putative transporter, bacteriocin immunity protein, response regulator, 6-phospho-beta-galactosidase, purine metabolism and to transcriptional regulator. Key-functional modules were identified for SRS and RC conditions based on WCGNA, being 139 hub genes found on SRS key-module and 17 genes on RC key-module. Functional analysis of S. mutans within the metatranscriptome of biofilms from sound root and from carious root revealed a similar pattern of gene expression, and only a few genes have been differentially expressed between biofilms from sound root surfaces and from root carious lesions. However, S. mutans presented a greater functional abundance in the lesion samples. Some functional patterns related to sugar (starch, sucrose, fructose, mannose and lactose) and heterofermentative metabolisms, to cell-wall biosynthesis and to acid tolerance stress seem to be enriched on carious root surfaces conferring ecological advantages to S. mutans. Altogether, the present data suggest that a functional signature may be associated with carious root lesions.
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Abstract
Regulated proteolysis is where AAA+ ATPases (ClpX, ClpC, and ClpE) are coupled to a protease subunit (ClpP) to facilitate degradation of misfolded and native regulatory proteins in the cell. The process is intricately linked to protein quality control and homeostasis and modulates several biological processes. In streptococci, regulated proteolysis is vital to various functions, including virulence expression, competence development, bacteriocin production, biofilm formation, and stress responses. Among the various Clp ATPases, ClpX is the major one that recognizes specific amino acid residues in its substrates and delivers them to the ClpP proteolytic chamber for degradation. While multiple ClpX substrates have been identified in Escherichia coli and other bacteria, little is known about the identity of these substrates in streptococci. Here, we used a preliminary proteomic analysis to identify putative ClpX substrates using Streptococcus mutans as a model organism. SMU.961 is one such putative substrate where we identified the Glu-Lue-Gln (ELQ) motif at the C terminus that is recognized by ClpX/P. We identified several other proteins, including MecA, which also harbor ELQ and are degraded by ClpX/P. This is surprising since MecA is known to be degraded by ClpC/P in Bacillus subtilis; however, ClpX/P-mediated MecA degradation is unknown. We also identified Glu and Gln as the crucial residues for ClpX recognition. Our data indicate a species and perhaps strain-specific recognition of ELQ by streptococcal ClpX/P. At present, we do not know whether this species-dependent degradation by ClpX/P is unique to S. mutans, and we are currently examining the phenomenon in other pathogenic streptococci. IMPORTANCE ClpX/P is a major intracellular proteolytic complex that is responsible for protein quality control in the cell. ClpX, an AAA+ ATPase, distinguishes the potential substrates by recognizing short motifs at the C-terminal end of proteins and delivers the substrates for degradation by ClpP protease. The identity of these ClpX substrates, which varies greatly among bacteria, is known only for a few well-studied species. Here, we used Streptococcus mutans as a model organism to identify ClpX substrates. We found that a short motif of three residues is successfully recognized by ClpX/P. Interestingly, the motif is not present at the ultimate C-terminal end; rather it is present close to the end. This result suggests that streptococcal ClpX ATPase can recognize internal motifs.
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Biswas S, Dhaked HPS, Keightley A, Biswas I. Involvement of ClpE ATPase in Physiology of Streptococcus mutans. Microbiol Spectr 2021; 9:e0163021. [PMID: 34851151 PMCID: PMC8635124 DOI: 10.1128/spectrum.01630-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/01/2021] [Indexed: 11/25/2022] Open
Abstract
Streptococcus mutans, a dental pathogen, harbors at least three Clp ATPases (ClpC, ClpE, and ClpX) that form complexes with ClpP protease and participate in regulated proteolysis. Among these, the function of ClpE ATPase is poorly understood. We have utilized an isogenic clpE-deficient strain derived from S. mutans UA159 and evaluated the role of ClpE in cellular physiology. We found that loss of ClpE leads to increased susceptibility against thiol stress but not to oxidative and thermal stress. Furthermore, we found that the mutant displays altered tolerance against some antibiotics and altered biofilm formation. We performed a label-free proteomic analysis by comparing the mutant with the wild-type UA159 strain under nonstressed conditions and found that ClpE modulates a relatively limited proteome in the cell compared to the proteomes modulated by ClpX and ClpP. Nevertheless, we found that ClpE deficiency leads to an overabundance of some cell wall synthesis enzymes, ribosomal proteins, and an unknown protease encoded by SMU.2153. Our proteomic data strongly support some of the stress-related phenotypes that we observed. Our study emphasizes the significance of ClpE in the physiology of S. mutans. IMPORTANCE When bacteria encounter environmental stresses, the expression of various proteins collectively known as heat shock proteins is induced. These heat shock proteins are necessary for cell survival specifically under conditions that induce protein denaturation. A subset of heat shock proteins known as the Clp proteolytic complex is required for the degradation of the misfolded proteins in the cell. The Clp proteolytic complex contains an ATPase and a protease. A specific Clp ATPase, ClpE, is uniquely present in Gram-positive bacteria, including streptococci. Here, we have studied the functional role of the ClpE protein in Streptococcus mutans, a dental pathogen. Our results suggest that ClpE is required for survival under certain antibiotic exposure and stress conditions but not others. Our results demonstrate that loss of ClpE leads to a significantly altered cellular proteome, and the analysis of those changes suggests that ClpE's functions in S. mutans are different from its functions in other Gram-positive bacteria.
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Affiliation(s)
- Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Hemendra Pal Singh Dhaked
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Andrew Keightley
- Department of Ophthalmology, University of Missouri School of Medicine, Kansas City, Missouri, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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Wang Y, Cao W, Merritt J, Xie Z, Liu H. Characterization of FtsH Essentiality in Streptococcus mutans via Genetic Suppression. Front Genet 2021; 12:659220. [PMID: 33986772 PMCID: PMC8112672 DOI: 10.3389/fgene.2021.659220] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/07/2021] [Indexed: 12/15/2022] Open
Abstract
FtsH belongs to the AAA+ ATP-dependent family of proteases, which participate in diverse cellular processes and are ubiquitous among bacteria, chloroplasts, and mitochondria. FtsH is poorly characterized in most organisms, especially compared to other major housekeeping proteases. In the current study, we examined the source of FtsH essentiality in the human oral microbiome species Streptococcus mutans, one of the primary etiological agents of dental caries. By creating a conditionally lethal ftsH mutant, we were able to identify a secondary suppressor missense mutation in the vicR gene, encoding the response regulator of the essential VicRK two-component system (TCS). Transcriptomic analysis of the vicR (G195R) mutant revealed significantly reduced expression of 46 genes, many of which were located within the genomic island Tnsmu2, which harbors the mutanobactin biosynthetic gene cluster. In agreement with the transcriptomic data, deletion of the mutanobactin biosynthetic gene cluster suppressed ftsH essentiality in S. mutans. We also explored the role of FtsH in S. mutans physiology and demonstrated its critical role in stress tolerance, especially acid stress. The presented results reveal the first insights within S. mutans for the pleiotropic regulatory function of this poorly understood global regulator.
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Affiliation(s)
- Yaqi Wang
- MOE Key Laboratory of Industrial Fermentation Microbiology, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, China
| | - Wei Cao
- MOE Key Laboratory of Industrial Fermentation Microbiology, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, China
| | - Justin Merritt
- Department of Restorative Dentistry, Oregon Health & Science University, Portland, OR, United States.,Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR, United States
| | - Zhoujie Xie
- MOE Key Laboratory of Industrial Fermentation Microbiology, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, China
| | - Hao Liu
- MOE Key Laboratory of Industrial Fermentation Microbiology, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, China
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Chen J, Zhang A, Xiang Z, Lu M, Huang P, Gong T, Pan Y, Lin Y, Zhou X, Li Y. EpsR Negatively Regulates Streptococcus mutans Exopolysaccharide Synthesis. J Dent Res 2021; 100:968-976. [PMID: 33749354 DOI: 10.1177/00220345211000668] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Streptococcus mutans is considered the primary etiological agent of human dental caries. Glucosyltransferases (Gtfs) from S. mutans play important roles in the formation of biofilm matrix and the development of cariogenic oral biofilm. Therefore, Gtfs are considered an important target to prevent the development of dental caries. However, the role of transcription factors in regulating gtf expression is not yet clear. Here, we identify a MarR (multiple antibiotic resistance regulator) family transcription factor named EpsR (exopolysaccharide synthesis regulator), which negatively regulates gtfB expression and exopolysaccharide (EPS) production in S. mutans. The epsR in-frame deletion strain grew slowly, aggregated more easily in the presence of dextran, and displayed different colony morphology and biofilm structure. Notably, epsR deletion resulted in altered 3-dimensional biofilm architecture, increased water-insoluble EPS production, and upregulated GtfB protein content and activity. In addition, global gene expression profiling revealed differences in the expression levels of 69 genes in which gtfB was markedly upregulated. The conserved DNA motif for EpsR binding was determined by electrophoretic mobility shift assay and DNase I footprinting assays. Moreover, analysis of β-galactosidase activity suggested that EpsR acted as a repressor and inhibited gtfB expression. Taken together, our findings indicate that EpsR is an important transcription factor that regulates gtfB expression and EPS production in S. mutans. These results add new aspects to the complexity of regulating the expression of genes involved in the cariogenicity of S. mutans, which might lead to novel strategies to prevent the formation of cariogenic biofilm that may favor diseases.
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Affiliation(s)
- J Chen
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - A Zhang
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Z Xiang
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - M Lu
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - P Huang
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - T Gong
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Y Pan
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Y Lin
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - X Zhou
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Y Li
- Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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12
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Khara P, Biswas S, Biswas I. Induction of clpP expression by cell-wall targeting antibiotics in Streptococcus mutans. MICROBIOLOGY-SGM 2020; 166:641-653. [PMID: 32416745 DOI: 10.1099/mic.0.000920] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Streptococcus mutans is one of the major bacteria of the human oral cavity that is associated with dental caries. The pathogenicity of this bacterium is attributed to its ability to rapidly respond and adapt to the ever-changing conditions of the oral cavity. The major player in this adaptive response is ClpP, an intracellular protease involved in degradation of misfolded proteins during stress responses. S. mutans encodes a single clpP gene with an upstream region uniquely containing multiple tandem repeat sequences (RSs). Here, we explored expression of clpP with respect to various stresses and report some new findings. First, we found that at sub-inhibitory concentration, certain cell-wall damaging antibiotics were able to induce clpP expression. Specifically, third- and fourth-generation cephalosporins that target penicillin-binding protein 3 (PBP3) strongly enhanced the clpP expression. However, induction of clpP was weak when the first-generation cephalosporins with lower affinity to PBP3 were used. Surprisingly, carbapenems, which primarily target PBP2, induced expression of clpP the least. Second, we found that a single RS element was capable of inducing clpP expression as efficiently as with the wild-type seven RS elements. Third, we found that the RS-element-mediated modulation of clpP expression was strain dependent, suggesting that specific host factors might be involved in the transcription. And finally, we observed that ClpP regulates its own expression, as the expression of clpP-gusA was higher in a clpP-deficient mutant. This suggests that ClpP is involved in the degradation of activator(s) involved in its own transcription.
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Affiliation(s)
- Pratick Khara
- Present address: Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, Texas, USA.,Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
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13
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Kajfasz JK, Katrak C, Ganguly T, Vargas J, Wright L, Peters ZT, Spatafora GA, Abranches J, Lemos JA. Manganese Uptake, Mediated by SloABC and MntH, Is Essential for the Fitness of Streptococcus mutans. mSphere 2020; 5:e00764-19. [PMID: 31915219 PMCID: PMC6952196 DOI: 10.1128/msphere.00764-19] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 12/06/2019] [Indexed: 01/02/2023] Open
Abstract
Early epidemiological studies implicated manganese (Mn) as a possible caries-promoting agent, while laboratory studies have indicated that manganese stimulates the expression of virulence-related factors in the dental pathogen Streptococcus mutans To better understand the importance of manganese homeostasis to S. mutans pathophysiology, we first used RNA sequencing to obtain the global transcriptional profile of S. mutans UA159 grown under Mn-restricted conditions. Among the most highly expressed genes were those of the entire sloABC operon, encoding a dual iron/manganese transporter, and an uncharacterized gene, here mntH, that codes for a protein bearing strong similarity to Nramp-type transporters. While inactivation of sloC, which encodes the lipoprotein receptor of the SloABC system, or of mntH alone had no major consequence for the overall fitness of S. mutans, simultaneous inactivation of sloC and mntH (ΔsloC ΔmntH) impaired growth and survival under Mn-restricted conditions, including in human saliva or in the presence of calprotectin. Further, disruption of Mn transport resulted in diminished stress tolerance and reduced biofilm formation in the presence of sucrose. These phenotypes were markedly improved when cells were provided with excess Mn. Metal quantifications revealed that the single mutant strains contained intracellular levels of Mn similar to those seen with the parent strain, whereas Mn was nearly undetectable in the ΔsloC ΔmntH strain. Collectively, these results reveal that SloABC and MntH work independently and cooperatively to promote cell growth under Mn-restricted conditions and that maintenance of Mn homeostasis is essential for the expression of major virulence attributes in S. mutansIMPORTANCE As transition biometals such as manganese (Mn) are essential for all forms of life, the ability to scavenge biometals in the metal-restricted host environment is an important trait of successful cariogenic pathobionts. Here, we showed that the caries pathogen Streptococcus mutans utilizes two Mn transport systems, namely, SloABC and MntH, to acquire Mn from the environment and that the ability to maintain the cellular levels of Mn is important for the manifestation of characteristics that associate S. mutans with dental caries. Our results indicate that the development of strategies to deprive S. mutans of Mn hold promise in the combat against this important bacterial pathogen.
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Affiliation(s)
- Jessica K Kajfasz
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Callahan Katrak
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Tridib Ganguly
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Jonathan Vargas
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Logan Wright
- Department of Biology, Middlebury College, Middlebury, Vermont, USA
| | - Zachary T Peters
- Department of Biology, Middlebury College, Middlebury, Vermont, USA
| | | | - Jacqueline Abranches
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - José A Lemos
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
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14
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Tian XL, Li M, Scinocca Z, Rutherford H, Li YH. ClpP is required for proteolytic regulation of type II toxin-antitoxin systems and persister cell formation in Streptococcus mutans. Access Microbiol 2019; 1:e000054. [PMID: 32974554 PMCID: PMC7470404 DOI: 10.1099/acmi.0.000054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 11/18/2022] Open
Abstract
The type II toxin-antitoxin (TA) modules, mazEF and relBE, in Streptococcus mutans have been implicated in stress response, antibiotic tolerance and persister cell formation. However, how S. mutans regulates these systems to prevent unwanted toxin activation and persister cell formation is unclear. In this study, we provide evidence that ClpP is required for the proteolytic regulation of these TA systems and persister cell formation in S. mutans following antibiotic challenge. A persister viability assay showed that S. mutans UA159 (WT) formed a larger quantity of persister cells than its isogenic mutant ΔclpP following antibiotic challenge. However, the lux reporter assay revealed that clpP deletion did not affect the transcriptional levels of mazEF and relBE, since no significant differences (P>0.05) in the reporter activities were detected between the wild-type and ΔclpP background. Instead, all antibiotics tested at a sub-minimum inhibitory concentration (sub-MIC) induced transcriptional levels of mazEF and relBE operons. We then examined the protein profiles of His-tagged MazE and RelB proteins in the UA159 and ΔclpP backgrounds by Western blotting analysis. The results showed that S. mutans strains grown under non-stress conditions expressed very low but detectable levels of MazE and RelB antitoxin proteins. Antibiotics at sub-MICs induced the levels of the MazE and RelB proteins, but the protein levels decreased rapidly in the wild-type background. In contrast, a stable level of MazE and RelB proteins could be detected in the ΔclpP mutant background, suggesting that both proteins accumulated in the ΔclpP mutant. We conclude that ClpP is required for the proteolytic regulation of cellular levels of the MazE and RelB antitoxins in S. mutans , which may play a critical role in modulating the TA activities and persister cell formation of this organism following antibiotic challenge.
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Affiliation(s)
- Xiao-Lin Tian
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada
| | - Miao Li
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada.,Lanzhou University, Gansu, PR China
| | - Zachariah Scinocca
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada
| | - Heather Rutherford
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada
| | - Yung-Hua Li
- Department of Applied Oral Sciences, Dalhousie Universit, Halifax, NS, Canada.,Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada
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15
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He L, Wang H, Zhang R, Li H. The regulation of Porphyromonas gingivalis biofilm formation by ClpP. Biochem Biophys Res Commun 2018; 509:335-340. [PMID: 30579592 DOI: 10.1016/j.bbrc.2018.12.071] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 12/11/2018] [Indexed: 12/16/2022]
Abstract
Porphyromonas gingivalis is one of the most commonly detected pathogens in periodontal disease and root canal infections. Its viability and pathogenicity are greatly increased in plaque biofilms. Some caseinolytic proteases (Clp) reportedly regulate biofilm formation by various pathogenic bacteria, including P. gingivalis. However, the specific influence of ClpP and its mechanism of regulating biofilm formation by P. gingivalis remains unclear. Hence, in this study, a clpP deletion strain and complemented strain were constructed by homologous recombination, and an in vitro biofilm model was established. Biofilm architecture was observed by scanning electron microscopy. Bacterial cells within the biofilms were examined using confocal scanning laser microscopy. Crystal violet staining was used to determine the amount of formed biofilm. mRNA levels of related regulatory genes were assessed using real-time PCR. The clpP deletion and complemented strains of P. gingivalis were successfully constructed. The biofilm formation ability of the deletion strain was significantly reduced compared with that of the wild-type strain, while that of the complemented strain did not differ from that of the wild-type strain. The expression of fimA, mfa1, and luxS in the deletion strain was lower than in the wild-type and complemented strains at each timepoint. It can be concluded that ClpP increases the biofilm formation of P. gingivalis by regulating the expression levels of fimA, mfa1, and luxS.
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Affiliation(s)
- Lu He
- Department of Endodontics, Beijing Stomatological Hospital, School of Stomatology, Capital Medical University, Beijing, 100050, China
| | - Hongyuan Wang
- Department of Endodontics, Beijing Stomatological Hospital, School of Stomatology, Capital Medical University, Beijing, 100050, China
| | - Ru Zhang
- Department of Endodontics, Beijing Stomatological Hospital, School of Stomatology, Capital Medical University, Beijing, 100050, China
| | - Hong Li
- Department of Endodontics, Beijing Stomatological Hospital, School of Stomatology, Capital Medical University, Beijing, 100050, China.
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16
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Edlund A, Yang Y, Yooseph S, He X, Shi W, McLean JS. Uncovering complex microbiome activities via metatranscriptomics during 24 hours of oral biofilm assembly and maturation. MICROBIOME 2018; 6:217. [PMID: 30522530 PMCID: PMC6284299 DOI: 10.1186/s40168-018-0591-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 11/06/2018] [Indexed: 05/11/2023]
Abstract
BACKGROUND Dental plaque is composed of hundreds of bacterial taxonomic units and represents one of the most diverse and stable microbial ecosystems associated with the human body. Taxonomic composition and functional capacity of mature plaque is gradually shaped during several stages of community assembly via processes such as co-aggregation, competition for space and resources, and by bacterially produced reactive agents. Knowledge on the dynamics of assembly within complex communities is very limited and derives mainly from studies composed of a limited number of bacterial species. To fill current knowledge gaps, we applied parallel metagenomic and metatranscriptomic analyses during assembly and maturation of an in vitro oral biofilm. This model system has previously demonstrated remarkable reproducibility in taxonomic composition across replicate samples during maturation. RESULTS Time course analysis of the biofilm maturation was performed by parallel sampling every 2-3 h for 24 h for both DNA and RNA. Metagenomic analyses revealed that community taxonomy changed most dramatically between three and six hours of growth when pH dropped from 6.5 to 5.5. By applying comparative metatranscriptome analysis we could identify major shifts in overall community activities between six and nine hours of growth when pH dropped below 5.5, as 29,015 genes were significantly up- or down- expressed. Several of the differentially expressed genes showed unique activities for individual bacterial genomes and were associated with pyruvate and lactate metabolism, two-component signaling pathways, production of antibacterial molecules, iron sequestration, pH neutralization, protein hydrolysis, and surface attachment. Our analysis also revealed several mechanisms responsible for the niche expansion of the cariogenic pathogen Lactobacillus fermentum. CONCLUSION It is highly regarded that acidic conditions in dental plaque cause a net loss of enamel from teeth. Here, as pH drops below 5.5 pH to 4.7, we observe blooms of cariogenic lactobacilli, and a transition point of many bacterial gene expression activities within the community. To our knowledge, this represents the first study of the assembly and maturation of a complex oral bacterial biofilm community that addresses gene level functional responses over time.
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Affiliation(s)
- Anna Edlund
- Genomic Medicine Group, J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92137, USA.
| | - Youngik Yang
- National Marine Biodiversity Institute of Korea, 75, Jansang-ro 101beon-gil, Janghang-eup, Seocheon-gun, Chungcheongnam-do, 33662, Korea
| | - Shibu Yooseph
- Department of Computer Science, University of Central Florida, 4328 Scorpius Street, Orlando, FL, 32816, USA
| | - Xuesong He
- The Forsyth Institute, Cambridge, MA, 02142, USA
| | - Wenyuan Shi
- The Forsyth Institute, Cambridge, MA, 02142, USA
| | - Jeffrey S McLean
- Department of Periodontics, University of Washington, Seattle, WA, 98195, USA.
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17
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De A, Jorgensen AN, Beatty WL, Lemos J, Wen ZT. Deficiency of MecA in Streptococcus mutans Causes Major Defects in Cell Envelope Biogenesis, Cell Division, and Biofilm Formation. Front Microbiol 2018; 9:2130. [PMID: 30254619 PMCID: PMC6141683 DOI: 10.3389/fmicb.2018.02130] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/20/2018] [Indexed: 12/28/2022] Open
Abstract
MecA is an adaptor protein that guides the ClpC/P-mediated proteolysis. A S. mutans MecA-deficient mutant was constructed by double-crossover allelic exchange and analyzed for the effects of such a deficiency on cell biology and biofilm formation. Unlike the wild-type, UA159, the mecA mutant, TW416, formed mucoid and smooth colonies, severely clumped in broth and had a reduced growth rate. Transmission electron microscopy analysis revealed that TW416 grows primarily in chains of giant “swollen” cells with multiple asymmetric septa, unlike the coccoid form of UA159. As compared to UA159, biofilm formation by TW416 was significantly reduced regardless of the carbohydrate sources used for growth (P < 0.001). Western blot analysis of TW416 whole cell lysates showed a reduced expression of the glucosyltransferase GtfC and GtfB, as well as the P1 and WapA adhesins providing an explanation for the defective biofilm formation of TW416. When analyzed by a colorimetric assay, the cell wall phosphate of the mutant murein sacculi was almost 20-fold lower than the parent strain (P < 0.001). Interestingly, however, when analyzed using immunoblotting of the murein sacculi preps with UA159 whole cell antiserum as a probe, TW416 was shown to possess significantly higher signal intensity as compared to the wild-type. There is also evidence that MecA in S. mutans is more than an adaptor protein, although how it modulates the bacterial pathophysiology, including cell envelope biogenesis, cell division, and biofilm formation awaits further investigation.
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Affiliation(s)
- Arpan De
- Department of Comprehensive Dentistry and Biomaterials, University of Florida, Gainesville, FL, United States
| | - Ashton N Jorgensen
- Department of Comprehensive Dentistry and Biomaterials, University of Florida, Gainesville, FL, United States
| | - Wandy L Beatty
- Center of Oral and Craniofacial Biology, University of Florida, Gainesville, FL, United States
| | - Jose Lemos
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Zezhang T Wen
- Department of Comprehensive Dentistry and Biomaterials, University of Florida, Gainesville, FL, United States.,Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO, United States.,Department of Oral Biology, University of Florida, Gainesville, FL, United States
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18
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Kaspar J, Shields RC, Burne RA. Competence inhibition by the XrpA peptide encoded within the comX gene of Streptococcus mutans. Mol Microbiol 2018; 109:345-364. [PMID: 29802741 DOI: 10.1111/mmi.13989] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2018] [Indexed: 01/06/2023]
Abstract
Streptococcus mutans displays complex regulation of natural genetic competence. Competence development in S. mutans is controlled by a peptide derived from ComS (XIP); which along with the cytosolic regulator ComR controls the expression of the alternative sigma factor comX, the master regulator of competence development. Recently, a gene embedded within the coding region of comX was discovered and designated xrpA (comX regulatory peptide A). XrpA was found to be an antagonist of ComX, but the mechanism was not established. In this study, we reveal through both genomic and proteomic techniques that XrpA is the first described negative regulator of ComRS systems in streptococci. Transcriptomic and promoter activity assays in the ΔxrpA strain revealed an up-regulation of genes controlled by both the ComR- and ComX-regulons. An in vivo protein crosslinking and in vitro fluorescent polarization assays confirmed that the N-terminal region of XrpA were found to be sufficient in inhibiting ComR-XIP complex binding to ECom-box located within the comX promoter. This inhibitory activity was sufficient for decreases in PcomX activity, transformability and ComX accumulation. XrpA serving as a modulator of ComRS activity ultimately results in changes to subpopulation behaviors and cell fate during competence activation.
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Affiliation(s)
- Justin Kaspar
- Department of Oral Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Robert C Shields
- Department of Oral Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Robert A Burne
- Department of Oral Biology, University of Florida, Gainesville, FL, 32610, USA
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19
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Pleiotropic Regulation of Virulence Genes in Streptococcus mutans by the Conserved Small Protein SprV. J Bacteriol 2017; 199:JB.00847-16. [PMID: 28167518 DOI: 10.1128/jb.00847-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 01/30/2017] [Indexed: 12/27/2022] Open
Abstract
Streptococcus mutans, an oral pathogen associated with dental caries, colonizes tooth surfaces as polymicrobial biofilms known as dental plaque. S. mutans expresses several virulence factors that allow the organism to tolerate environmental fluctuations and compete with other microorganisms. We recently identified a small hypothetical protein (90 amino acids) essential for the normal growth of the bacterium. Inactivation of the gene, SMU.2137, encoding this protein caused a significant growth defect and loss of various virulence-associated functions. An S. mutans strain lacking this gene was more sensitive to acid, temperature, osmotic, oxidative, and DNA damage-inducing stresses. In addition, we observed an altered protein profile and defects in biofilm formation, bacteriocin production, and natural competence development, possibly due to the fitness defect associated with SMU.2137 deletion. Transcriptome sequencing revealed that nearly 20% of the S. mutans genes were differentially expressed upon SMU.2137 deletion, thereby suggesting a pleiotropic effect. Therefore, we have renamed this hitherto uncharacterized gene as sprV (streptococcal pleiotropic regulator of virulence). The transcript levels of several relevant genes in the sprV mutant corroborated the phenotypes observed upon sprV deletion. Owing to its highly conserved nature, inactivation of the sprV ortholog in Streptococcus gordonii also resulted in poor growth and defective UV tolerance and competence development as in the case of S. mutans Our experiments suggest that SprV is functionally distinct from its homologs identified by structure and sequence homology. Nonetheless, our current work is aimed at understanding the importance of SprV in the S. mutans biology.IMPORTANCEStreptococcus mutans employs several virulence factors and stress resistance mechanisms to colonize tooth surfaces and cause dental caries. Bacterial pathogenesis is generally controlled by regulators of fitness that are critical for successful disease establishment. Sometimes these regulators, which are potential targets for antimicrobials, are lost in the genomic context due to the lack of annotated homologs. This work outlines the regulatory impact of a small, highly conserved hypothetical protein, SprV, encoded by S. mutans We show that SprV affects the transcript levels of various virulence factors required for normal growth, biofilm formation, stress tolerance, genetic competence, and bacteriocin production.
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20
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Rice KC, Turner ME, Carney OV, Gu T, Ahn SJ. Modification of the Streptococcus mutans transcriptome by LrgAB and environmental stressors. Microb Genom 2017; 3:e000104. [PMID: 28348880 PMCID: PMC5361627 DOI: 10.1099/mgen.0.000104] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/20/2016] [Indexed: 12/14/2022] Open
Abstract
The Streptococcus mutans Cid/Lrg system is central to the physiology of this cariogenic organism, affecting oxidative stress resistance, biofilm formation and competence. Previous transcriptome analyses of lytS (responsible for the regulation of lrgAB expression) and cidB mutants have revealed pleiotropic effects on carbohydrate metabolism and stress resistance genes. In this study, it was found that an lrgAB mutant, previously shown to have diminished aerobic and oxidative stress growth, was also much more growth impaired in the presence of heat and vancomycin stresses, relative to wild-type, lrgA and lrgB mutants. To obtain a more holistic picture of LrgAB and its involvement in stress resistance, RNA sequencing and bioinformatics analyses were used to assess the transcriptional response of wild-type and isogenic lrgAB mutants under anaerobic (control) and stress-inducing culture conditions (aerobic, heat and vancomycin). Hierarchical clustering and principal components analyses of all differentially expressed genes revealed that the most distinct gene expression profiles between S. mutans UA159 and lrgAB mutant occurred during aerobic and high-temperature growth. Similar to previous studies of a cidB mutant, lrgAB stress transcriptomes were characterized by a variety of gene expression changes related to genomic islands, CRISPR-C as systems, ABC transporters, competence, bacteriocins, glucosyltransferases, protein translation, tricarboxylic acid cycle, carbohydrate metabolism/storage and transport. Notably, expression of lrgAB was upregulated in the wild-type strain under all three stress conditions. Collectively, these results demonstrate that mutation of lrgAB alters the transcriptional response to stress, and further support the idea that the Cid/Lrg system acts to promote cell homeostasis in the face of environmental stress.
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Affiliation(s)
- Kelly C Rice
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Matthew E Turner
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - O'neshia V Carney
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.,†Present address: Department of Health Outcomes and Policy, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Tongjun Gu
- 2Bioinformatics, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610, USA
| | - Sang-Joon Ahn
- 3Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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21
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Strain-Dependent Recognition of a Unique Degradation Motif by ClpXP in Streptococcus mutans. mSphere 2016; 1:mSphere00287-16. [PMID: 27981232 PMCID: PMC5143411 DOI: 10.1128/msphere.00287-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 11/09/2016] [Indexed: 01/02/2023] Open
Abstract
Regulated proteolysis in bacteria is an important biological process that maintains protein homeostasis. ClpXP, an intracellular proteolytic complex, is the primary protease that is responsible for protein turnover. While the substrates for ClpXP were identified in Escherichia coli, the substrates for vast majority of bacteria are currently unknown. In this study, we identified a unique substrate for ClpXP-mediated degradation in Streptococcus mutans, a dental pathogen. We also found that a small motif composed of 3 amino acids is sufficient for ClpXP-mediated degradation. Identification of this motif will clearly help us to understand the pathogenesis of this organism and other related pathogens. Streptococcus mutans, a dental pathogen, has a remarkable ability to cope with environmental stresses. Under stress conditions, cytoplasmic proteases play a major role in controlling the stability of regulatory proteins and preventing accumulation of damaged and misfolded proteins. ClpXP, a well-conserved cytoplasmic proteolytic system, is crucial in maintaining cellular homeostasis in bacteria. ClpX is primarily responsible for recognition of substrates and subsequent translocation of unfolded substrates into the ClpP proteolytic compartment for degradation. In Escherichia coli, ClpX recognizes distinct motifs present at the C-terminal end of target proteins. However, recognition sequences for ClpXP in other bacteria, including S. mutans, are not known. In this study, using two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE) analysis, we have identified several putative substrates for S. mutans ClpXP. SsbA, which encodes a small DNA binding protein, is one such substrate that is degraded by ClpXP. By sequential deletions, we found that the last 3 C-terminal amino acids, LPF, are sufficient for ClpXP-mediated degradation. Addition of LPF at the C-terminal end of green fluorescent protein (GFP) rendered the protein completely degradable by ClpXP. Alterations of this tripeptide motif impeded ClpXP-mediated degradation. However, recognition of LPF by ClpXP is highly specific to some S. mutans strains (UA159, UA130, and N3209) since not all S. mutans strains recognize the motif. We speculate that an adaptor protein is involved in either substrate recognition or substrate degradation by ClpXP. Nevertheless, this is the first report of a unique recognition sequence for ClpXP in streptococci. IMPORTANCE Regulated proteolysis in bacteria is an important biological process that maintains protein homeostasis. ClpXP, an intracellular proteolytic complex, is the primary protease that is responsible for protein turnover. While the substrates for ClpXP were identified in Escherichia coli, the substrates for vast majority of bacteria are currently unknown. In this study, we identified a unique substrate for ClpXP-mediated degradation in Streptococcus mutans, a dental pathogen. We also found that a small motif composed of 3 amino acids is sufficient for ClpXP-mediated degradation. Identification of this motif will clearly help us to understand the pathogenesis of this organism and other related pathogens.
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22
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Sadeghinejad L, Cvitkovitch DG, Siqueira WL, Santerre JP, Finer Y. Triethylene Glycol Up-Regulates Virulence-Associated Genes and Proteins in Streptococcus mutans. PLoS One 2016; 11:e0165760. [PMID: 27820867 PMCID: PMC5098727 DOI: 10.1371/journal.pone.0165760] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/17/2016] [Indexed: 01/30/2023] Open
Abstract
Triethylene glycol dimethacrylate (TEGDMA) is a diluent monomer used pervasively in dental composite resins. Through hydrolytic degradation of the composites in the oral cavity it yields a hydrophilic biodegradation product, triethylene glycol (TEG), which has been shown to promote the growth of Streptococcus mutans, a dominant cariogenic bacterium. Previously it was shown that TEG up-regulated gtfB, an important gene contributing to polysaccharide synthesis function in biofilms. However, molecular mechanisms related to TEG’s effect on bacterial function remained poorly understood. In the present study, S. mutans UA159 was incubated with clinically relevant concentrations of TEG at pH 5.5 and 7.0. Quantitative real-time PCR, proteomics analysis, and glucosyltransferase enzyme (GTF) activity measurements were employed to identify the bacterial phenotypic response to TEG. A S. mutans vicK isogenic mutant (SMΔvicK1) and its associated complemented strain (SMΔvicK1C), an important regulatory gene for biofilm-associated genes, were used to determine if this signaling pathway was involved in modulation of the S. mutans virulence-associated genes. Extracted proteins from S. mutans biofilms grown in the presence and absence of TEG were subjected to mass spectrometry for protein identification, characterization and quantification. TEG up-regulated gtfB/C, gbpB, comC, comD and comE more significantly in biofilms at cariogenic pH (5.5) and defined concentrations. Differential response of the vicK knock-out (SMΔvicK1) and complemented strains (SMΔvicK1C) implicated this signalling pathway in TEG-modulated cellular responses. TEG resulted in increased GTF enzyme activity, responsible for synthesizing insoluble glucans involved in the formation of cariogenic biofilms. As well, TEG increased protein abundance related to biofilm formation, carbohydrate transport, acid tolerance, and stress-response. Proteomics data was consistent with gene expression findings for the selected genes. These findings demonstrate a mechanistic pathway by which TEG derived from commercial resin materials in the oral cavity promote S. mutans pathogenicity, which is typically associated with secondary caries.
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Affiliation(s)
- Lida Sadeghinejad
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Dennis G. Cvitkovitch
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Walter L. Siqueira
- Schulich Dentistry and Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
| | - J. Paul Santerre
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Yoav Finer
- Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Xie F, Li G, Zhang Y, Zhou L, Liu S, Liu S, Wang C. The Lon protease homologue LonA, not LonC, contributes to the stress tolerance and biofilm formation of Actinobacillus pleuropneumoniae. Microb Pathog 2016; 93:38-43. [PMID: 26796296 DOI: 10.1016/j.micpath.2016.01.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/10/2015] [Accepted: 01/11/2016] [Indexed: 01/09/2023]
Abstract
Lon proteases are a family of ATP-dependent proteases that are involved in the degradation of abnormal proteins in bacteria exposed to adverse environmental stress. An analysis of the genome sequence of Actinobacillus pleuropneumoniae revealed the unusual presence of two putative ATP-dependent Lon homologues, LonA and LonC. Sequence comparisons indicated that LonA has the classical domain organization of the LonA subfamily, which includes the N-terminal domain, central ATPase (AAA) domain, and C-terminal proteolytic (P) domain. LonC belongs to the recently classified LonC subfamily, which includes Lon proteases that contain neither the N-terminal domain of LonA nor the transmembrane region that is present only in LonB subfamily members. To investigate the roles of LonA and LonC in A. pleuropneumoniae, mutants with deletions in the lonA and lonC genes were constructed. The impaired growth of the △lonA mutant exposed to low and high temperatures and osmotic and oxidative stress conditions indicates that the LonA protease is required for the stress tolerance of A. pleuropneumoniae. Furthermore, the △lonA mutant exhibited significantly reduced biofilm formation compared to the wild-type strain. However, no significant differences in stress responses or biofilm formation were observed between the △lonC mutant and the wild-type strain. The △lonA mutant exhibited reduced colonization ability and attenuated virulence of A. pleuropneumoniae in the BALB/c mouse model compared to the wild-type strain. Disruption of lonC gene did not significantly influence the colonization and virulence of A. pleuropneumoniae. The data presented in this study illustrate that the LonA protease, but not the LonC protease, is required for the stress tolerance, biofilm formation and pathogenicity of A. pleuropneumoniae.
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Affiliation(s)
- Fang Xie
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China
| | - Gang Li
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China
| | - Yanhe Zhang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China
| | - Long Zhou
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China
| | - Shuanghong Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China
| | - Chunlai Wang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 15001, People's Republic of China.
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de Brito DM, Maracaja-Coutinho V, de Farias ST, Batista LV, do Rêgo TG. A Novel Method to Predict Genomic Islands Based on Mean Shift Clustering Algorithm. PLoS One 2016; 11:e0146352. [PMID: 26731657 PMCID: PMC4711805 DOI: 10.1371/journal.pone.0146352] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 12/16/2015] [Indexed: 01/04/2023] Open
Abstract
Genomic Islands (GIs) are regions of bacterial genomes that are acquired from other organisms by the phenomenon of horizontal transfer. These regions are often responsible for many important acquired adaptations of the bacteria, with great impact on their evolution and behavior. Nevertheless, these adaptations are usually associated with pathogenicity, antibiotic resistance, degradation and metabolism. Identification of such regions is of medical and industrial interest. For this reason, different approaches for genomic islands prediction have been proposed. However, none of them are capable of predicting precisely the complete repertory of GIs in a genome. The difficulties arise due to the changes in performance of different algorithms in the face of the variety of nucleotide distribution in different species. In this paper, we present a novel method to predict GIs that is built upon mean shift clustering algorithm. It does not require any information regarding the number of clusters, and the bandwidth parameter is automatically calculated based on a heuristic approach. The method was implemented in a new user-friendly tool named MSGIP—Mean Shift Genomic Island Predictor. Genomes of bacteria with GIs discussed in other papers were used to evaluate the proposed method. The application of this tool revealed the same GIs predicted by other methods and also different novel unpredicted islands. A detailed investigation of the different features related to typical GI elements inserted in these new regions confirmed its effectiveness. Stand-alone and user-friendly versions for this new methodology are available at http://msgip.integrativebioinformatics.me.
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Affiliation(s)
- Daniel M. de Brito
- Departamento de Informática, Centro de Informática, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Vinicius Maracaja-Coutinho
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
- Departamento de Biologia Molecular, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, João Pessoa, Brazil
- Instituto Vandique, João Pessoa, Brazil
- Beagle Bioinformatics, Santiago, Chile
| | - Savio T. de Farias
- Departamento de Biologia Molecular, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Leonardo V. Batista
- Departamento de Informática, Centro de Informática, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Thaís G. do Rêgo
- Departamento de Informática, Centro de Informática, Universidade Federal da Paraíba, João Pessoa, Brazil
- * E-mail:
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Cheng X, Zheng X, Zhou X, Zeng J, Ren Z, Xu X, Cheng L, Li M, Li J, Li Y. Regulation of oxidative response and extracellular polysaccharide synthesis by a diadenylate cyclase in Streptococcus mutans. Environ Microbiol 2015; 18:904-22. [PMID: 26548332 DOI: 10.1111/1462-2920.13123] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/29/2015] [Accepted: 11/01/2015] [Indexed: 02/05/2023]
Abstract
Cyclic diadenosine monophosphate (c-di-AMP) has been implicated in the control of many important bacterial activities. However, the function of this molecule in Streptococcus mutans, the primary aetiological agent of human dental caries, is unknown. In this study, we identified and characterized a diadenylate cyclase, named CdaA, in S. mutans. Furthermore, we showed that in-frame deletion of the cdaA gene in S. mutans causes decreased c-di-AMP levels, increased sensitivity to hydrogen peroxide and increased production of extracellular polysaccharides. Global gene expression profiling revealed that more than 200 genes were significantly upregulated or downregulated (> 2.0-fold) in the cdaA mutant. Interestingly, genes with increased or decreased expression were clustered in cellular polysaccharide biosynthetic processes and oxidoreductase activity respectively. Notably, the expression of several genomic islands, such as GTF-B/C, TnSmu, CRISPR1-Cas and CRISPR2-Cas, was found to be altered in the cdaA mutant, indicating a possible link between these genomic islands and c-di-AMP signalling. Collectively, the results reported here show that CdaA is an important global modulator in S. mutans and is required for optimal growth and environmental adaption. This report also paves the way to unveil further the roles of c-di-AMP signalling networks in the biology and pathogenicity of S. mutans.
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Affiliation(s)
- Xingqun Cheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Zheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jumei Zeng
- Department of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Zhi Ren
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lei Cheng
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Mingyun Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiyao Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yuqing Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Nguyen CT, Park SS, Rhee DK. Stress responses in Streptococcus species and their effects on the host. J Microbiol 2015; 53:741-9. [PMID: 26502957 DOI: 10.1007/s12275-015-5432-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 09/30/2015] [Accepted: 09/30/2015] [Indexed: 12/15/2022]
Abstract
Streptococci cause a variety of diseases, such as dental caries, pharyngitis, meningitis, pneumonia, bacteremia, endocarditis, erysipelas, and necrotizing fasciitis. The natural niche of this genus of bacteria ranges from the mouth and nasopharynx to the skin, indicating that the bacteria will inevitably be subjected to environmental changes during invasion into the host, where it is exposed to the host immune system. Thus, the Streptococcus-host interaction determines whether bacteria are cleared by the host's defenses or whether they survive after invasion to cause serious diseases. If this interaction was to be deciphered, it could aid in the development of novel preventive and therapeutic agents. Streptococcus species possess many virulent factors, such as peroxidases and heat-shock proteins (HSPs), which play key roles in protecting the bacteria from hostile host environments. This review will discuss insights into the mechanism(s) by which streptococci adapt to host environments. Additionally, we will address how streptococcal infections trigger host stress responses; however, the mechanism by which bacterial components modulate host stress responses remains largely unknown.
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Affiliation(s)
- Cuong Thach Nguyen
- School of Pharmacy, Sungkyunkwan University, Su-Won, 16419, Republic of Korea
| | - Sang-Sang Park
- School of Pharmacy, Sungkyunkwan University, Su-Won, 16419, Republic of Korea
| | - Dong-Kwon Rhee
- School of Pharmacy, Sungkyunkwan University, Su-Won, 16419, Republic of Korea.
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Zhang JQ, Hou XH, Song XY, Ma XB, Zhao YX, Zhang SY. ClpP Affects Biofilm Formation of Streptococcus mutans Differently in the Presence of Cariogenic Carbohydrates Through Regulating gtfBC and ftf. Curr Microbiol 2015; 70:716-23. [DOI: 10.1007/s00284-015-0779-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 12/19/2014] [Indexed: 12/24/2022]
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Role of the Streptococcus mutans CRISPR-Cas systems in immunity and cell physiology. J Bacteriol 2014; 197:749-61. [PMID: 25488301 DOI: 10.1128/jb.02333-14] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas systems provide adaptive microbial immunity against invading viruses and plasmids. The cariogenic bacterium Streptococcus mutans UA159 has two CRISPR-Cas systems: CRISPR1 (type II-A) and CRISPR2 (type I-C) with several spacers from both CRISPR cassettes matching sequences of phage M102 or genomic sequences of other S. mutans. The deletion of the cas genes of CRISPR1 (ΔC1S), CRISPR2 (ΔC2E), or both CRISPR1+2 (ΔC1SC2E) or the removal of spacers 2 and 3 (ΔCR1SP13E) in S. mutans UA159 did not affect phage sensitivity when challenged with virulent phage M102. Using plasmid transformation experiments, we demonstrated that the CRISPR1-Cas system inhibits transformation of S. mutans by the plasmids matching the spacers 2 and 3. Functional analysis of the cas deletion mutants revealed that in addition to a role in plasmid targeting, both CRISPR systems also contribute to the regulation of bacterial physiology in S. mutans. Compared to wild-type cells, the ΔC1S strain displayed diminished growth under cell membrane and oxidative stress, enhanced growth under low pH, and had reduced survival under heat shock and DNA-damaging conditions, whereas the ΔC2E strain exhibited increased sensitivity to heat shock. Transcriptional analysis revealed that the two-component signal transduction system VicR/K differentially modulates expression of cas genes within CRISPR-Cas systems, suggesting that VicR/K might coordinate the expression of two CRISPR-Cas systems. Collectively, we provide in vivo evidence that the type II-A CRISPR-Cas system of S. mutans may be targeted to manipulate its stress response and to influence the host to control the uptake and dissemination of antibiotic resistance genes.
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Salomäki T, Karonen T, Siljamäki P, Savijoki K, Nyman TA, Varmanen P, Iivanainen A. A Streptococcus uberis transposon mutant screen reveals a negative role for LiaR homologue in biofilm formation. J Appl Microbiol 2014; 118:1-10. [PMID: 25308550 DOI: 10.1111/jam.12664] [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: 07/02/2014] [Revised: 09/03/2014] [Accepted: 10/07/2014] [Indexed: 11/30/2022]
Abstract
AIMS The environmental pathogen Streptococcus uberis causes intramammary infections in dairy cows. Because biofilm growth might contribute to Strep. uberis mastitis, we conducted a biological screen to identify genes potentially involved in the regulation of biofilm growth. METHODS AND RESULTS By screening a transposon mutant library of Strep. uberis, we determined that the disruption of 13 genes (including hasA, coaC, clpP, miaA, nox and uidA) led to increased biofilm formation. One of the genes (SUB1382) encoded a homologue of the LiaR response regulator (RR) of the Bacillus subtilis two-component signalling system (TCS). Electrophoretic mobility shift assays revealed that DNA binding by LiaR was greatly enhanced by phosphorylation. Two-dimensional differential in-gel electrophoresis analyses of the liaR mutant and the parental Strep. uberis strain revealed five differentially produced proteins with at least a 1·5-fold change in relative abundance (P < 0·05). CONCLUSIONS The DNA-binding protein LiaR is a potential regulator of biofilm formation by Strep. uberis. SIGNIFICANCE AND IMPACT OF THE STUDY Several molecular primary and downstream targets involved in biofilm formation by Strep. uberis were identified. This provides a solid foundation for further studies on the regulation of biofilm formation in this important pathogen.
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Affiliation(s)
- T Salomäki
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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Abstract
Oral colonising bacteria are highly adapted to the various environmental niches harboured within the mouth, whether that means while contributing to one of the major oral diseases of caries, pulp infections, or gingival/periodontal disease or as part of a commensal lifestyle. Key to these infections is the ability to adhere to surfaces via a range of specialised adhesins targeted at both salivary and epithelial proteins, their glycans and to form biofilm. They must also resist the various physical stressors they are subjected to, including pH and oxidative stress. Possibly most strikingly, they have developed the ability to harvest both nutrient sources provided by the diet and those derived from the host, such as protein and surface glycans. We have attempted to review recent developments that have revealed much about the molecular mechanisms at work in shaping the physiology of oral bacteria and how we might use this information to design and implement new treatment strategies.
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Hou XH, Zhang JQ, Song XY, Ma XB, Zhang SY. Contribution of ClpP to stress tolerance and virulence properties of Streptococcus mutans. J Basic Microbiol 2014; 54:1222-32. [PMID: 24979467 DOI: 10.1002/jobm.201300747] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 03/18/2014] [Indexed: 11/06/2022]
Abstract
Abilities to tolerate environmental stresses and to form biofilms on teeth surface are key virulence attributes of Streptococcus mutans, the primary causative agent of human dental caries. ClpP, the chief intracellular protease of S. mutans, along with ATPases degrades altered proteins that might be toxic for bacteria, and thus plays important roles in stress response. To further understand the roles of ClpP in stress response of S. mutans, a ClpP deficient strain was constructed and used for general stress tolerance, autolysis, mutacins production, and virulence assays. Here, we demonstrated that inactivation of ClpP in S. mutans resulted in a sensitive phenotype to several environmental stresses, including acid, cold, thermal, and oxidative stresses. The ClpP deficient strain displayed slow growth rates, poor growth yields, formation of long chains, increased clumping in broth, and reduced capacity to form biofilms in presence of glucose. Mutacins production and autolysis of S. mutans were also impaired by mutation of clpP. Animals study showed that clpP mutation increased virulence of S. mutans but not significant. However, enhanced abilities to survive lethal acid and to form biofilm in sucrose were observed in ClpP deficient strain. Our findings revealed a broad impact of ClpP on several virulence properties of S. mutans and highlighted the relevance of ClpP proteolysis with progression of diseases caused by S. mutans.
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Affiliation(s)
- Xiang-Hua Hou
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, Xiamen, China
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Barbour A, Philip K. Variable characteristics of bacteriocin-producing Streptococcus salivarius strains isolated from Malaysian subjects. PLoS One 2014; 9:e100541. [PMID: 24941127 PMCID: PMC4062538 DOI: 10.1371/journal.pone.0100541] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/28/2014] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Salivaricins are bacteriocins produced by Streptococcus salivarius, some strains of which can have significant probiotic effects. S. salivarius strains were isolated from Malaysian subjects showing variable antimicrobial activity, metabolic profile, antibiotic susceptibility and lantibiotic production. METHODOLOGY/PRINCIPAL FINDINGS In this study we report new S. salivarius strains isolated from Malaysian subjects with potential as probiotics. Safety assessment of these strains included their antibiotic susceptibility and metabolic profiles. Genome sequencing using Illumina's MiSeq system was performed for both strains NU10 and YU10 and demonstrating the absence of any known streptococcal virulence determinants indicating that these strains are safe for subsequent use as probiotics. Strain NU10 was found to harbour genes encoding salivaricins A and 9 while strain YU10 was shown to harbour genes encoding salivaricins A3, G32, streptin and slnA1 lantibiotic-like protein. Strain GT2 was shown to harbour genes encoding a large non-lantibiotic bacteriocin (salivaricin-MPS). A new medium for maximum biomass production buffered with 2-(N-morpholino)ethanesulfonic acid (MES) was developed and showed better biomass accumulation compared with other commercial media. Furthermore, we extracted and purified salivaricin 9 (by strain NU10) and salivaricin G32 (by strain YU10) from S. salivarius cells grown aerobically in this medium. In addition to bacteriocin production, S. salivarius strains produced levan-sucrase which was detected by a specific ESI-LC-MS/MS method which indicates additional health benefits from the developed strains. CONCLUSION The current study established the bacteriocin, levan-sucrase production and basic safety features of S. salivarius strains isolated from healthy Malaysian subjects demonstrating their potential for use as probiotics. A new bacteriocin-production medium was developed with potential scale up application for pharmaceuticals and probiotics from S. salivarius generating different lantibiotics. This is relevant for the clinical management of oral cavity and upper respiratory tract in the human population.
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Affiliation(s)
- Abdelahhad Barbour
- Institute of Biological Sciences, Microbiology Division, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Koshy Philip
- Institute of Biological Sciences, Microbiology Division, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
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Abstract
Bacterial genomes are remarkably stable from one generation to the next but are plastic on an evolutionary time scale, substantially shaped by horizontal gene transfer, genome rearrangement, and the activities of mobile DNA elements. This implies the existence of a delicate balance between the maintenance of genome stability and the tolerance of genome instability. In this review, we describe the specialized genetic elements and the endogenous processes that contribute to genome instability. We then discuss the consequences of genome instability at the physiological level, where cells have harnessed instability to mediate phase and antigenic variation, and at the evolutionary level, where horizontal gene transfer has played an important role. Indeed, this ability to share DNA sequences has played a major part in the evolution of life on Earth. The evolutionary plasticity of bacterial genomes, coupled with the vast numbers of bacteria on the planet, substantially limits our ability to control disease.
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Kuboniwa M, Tribble GD, Hendrickson EL, Amano A, Lamont RJ, Hackett M. Insights into the virulence of oral biofilms: discoveries from proteomics. Expert Rev Proteomics 2013; 9:311-23. [PMID: 22809209 DOI: 10.1586/epr.12.16] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This review covers developments in the study of polymicrobial communities, biofilms and selected areas of host response relevant to dental plaque and related areas of oral biology. The emphasis is on recent studies in which proteomic methods, particularly those using mass spectrometry as a readout, have played a major role in the investigation. The last 5-10 years have seen a transition of such methods from the periphery of oral biology to the mainstream, as in other areas of biomedical science. For reasons of focus and space, the authors do not discuss biomarker studies relevant to improved diagnostics for oral health, as this literature is rather substantial in its own right and deserves a separate treatment. Here, global gene regulation studies of plaque-component organisms, biofilm formation, multispecies interactions and host-microbe interactions are discussed. Several aspects of proteomics methodology that are relevant to the studies of multispecies systems are commented upon.
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Affiliation(s)
- Masae Kuboniwa
- Department of Preventive Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Allam AB, Brown MB, Reyes L. Disruption of the S41 peptidase gene in mycoplasma mycoides capri impacts proteome profile, H(2)O(2) production, and sensitivity to heat shock. PLoS One 2012; 7:e51345. [PMID: 23300541 PMCID: PMC3534093 DOI: 10.1371/journal.pone.0051345] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 11/07/2012] [Indexed: 12/30/2022] Open
Abstract
Members of the Mycoplasma mycoides cluster are among the most virulent of the mycoplasmas, causing worldwide economically significant diseases of cattle and goats. A distinguishing phenotype among the members of the cluster is the ability to degrade casein. The MMCAP2_0241 gene, an S41 peptidase, confers the proteolytic phenotype in Mycoplasma mycoides subsp. capri GM12. In order to determine the impact of disruption of the gene, we used differential proteome profiling to compare the M. mycoides subsp. capri wild type with a mutant lacking the proteolytic phenotype. Disruption of MMCAP2_0241 resulted in altered phenotypes reminiscent of M. mycoides subsp. mycoides SC and had significant impacts on the proteome profile of the microbe. The mutant exhibited increased production of hydrogen peroxide, decreased lactate dehydrogenase activity, and increased sensitivity to heat shock.
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Affiliation(s)
- Ayman B. Allam
- Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Mary B. Brown
- Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | - Leticia Reyes
- Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
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Klein MI, Xiao J, Lu B, Delahunty CM, Yates JR, Koo H. Streptococcus mutans protein synthesis during mixed-species biofilm development by high-throughput quantitative proteomics. PLoS One 2012; 7:e45795. [PMID: 23049864 PMCID: PMC3458072 DOI: 10.1371/journal.pone.0045795] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 08/24/2012] [Indexed: 01/15/2023] Open
Abstract
Biofilms formed on tooth surfaces are comprised of mixed microbiota enmeshed in an extracellular matrix. Oral biofilms are constantly exposed to environmental changes, which influence the microbial composition, matrix formation and expression of virulence. Streptococcus mutans and sucrose are key modulators associated with the evolution of virulent-cariogenic biofilms. In this study, we used a high-throughput quantitative proteomics approach to examine how S. mutans produces relevant proteins that facilitate its establishment and optimal survival during mixed-species biofilms development induced by sucrose. Biofilms of S. mutans, alone or mixed with Actinomyces naeslundii and Streptococcus oralis, were initially formed onto saliva-coated hydroxyapatite surface under carbohydrate-limiting condition. Sucrose (1%, w/v) was then introduced to cause environmental changes, and to induce biofilm accumulation. Multidimensional protein identification technology (MudPIT) approach detected up to 60% of proteins encoded by S. mutans within biofilms. Specific proteins associated with exopolysaccharide matrix assembly, metabolic and stress adaptation processes were highly abundant as the biofilm transit from earlier to later developmental stages following sucrose introduction. Our results indicate that S. mutans within a mixed-species biofilm community increases the expression of specific genes associated with glucan synthesis and remodeling (gtfBC, dexA) and glucan-binding (gbpB) during this transition (P<0.05). Furthermore, S. mutans up-regulates specific adaptation mechanisms to cope with acidic environments (F1F0-ATPase system, fatty acid biosynthesis, branched chain amino acids metabolism), and molecular chaperones (GroEL). Interestingly, the protein levels and gene expression are in general augmented when S. mutans form mixed-species biofilms (vs. single-species biofilms) demonstrating fundamental differences in the matrix assembly, survival and biofilm maintenance in the presence of other organisms. Our data provide insights about how S. mutans optimizes its metabolism and adapts/survives within the mixed-species community in response to a dynamically changing environment. This reflects the intricate physiological processes linked to expression of virulence by this bacterium within complex biofilms.
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Affiliation(s)
- Marlise I. Klein
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail: (MIK); (HK)
| | - Jin Xiao
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, United States of America
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, People’s Republic of China
| | - Bingwen Lu
- The Scripps Research Institute, La Jolla, California, United States of America
| | - Claire M. Delahunty
- The Scripps Research Institute, La Jolla, California, United States of America
| | - John R. Yates
- The Scripps Research Institute, La Jolla, California, United States of America
| | - Hyun Koo
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail: (MIK); (HK)
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Van Oudenhove L, De Vriendt K, Van Beeumen J, Mercuri PS, Devreese B. Differential proteomic analysis of the response of Stenotrophomonas maltophilia to imipenem. Appl Microbiol Biotechnol 2012; 95:717-33. [DOI: 10.1007/s00253-012-4167-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/09/2012] [Accepted: 05/10/2012] [Indexed: 11/28/2022]
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CovR alleviates transcriptional silencing by a nucleoid-associated histone-like protein in Streptococcus mutans. J Bacteriol 2012; 194:2050-61. [PMID: 22343292 DOI: 10.1128/jb.06812-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Streptococcus mutans, the global response regulator CovR plays an important role in biofilm formation, stress tolerance response, and caries production. We have previously demonstrated that CovR activates a large gene cluster, which is a part of a genomic island, TnSmu2. In this article, we have further characterized CovR at the molecular level to understand the gene activation mechanism. Toward this end, we mapped the transcription start site of the operon that lies upstream of the SMU.1348 gene (P(SMU.1348)), the first gene of the cluster. We constructed a transcriptional reporter fusion and showed that CovR induces expression from P(SMU.1348). We also demonstrated that purified CovR protects the sequence surrounding the -10 region of P(SMU.1348). In an in vitro transcription assay, we showed that histone-like protein (HLP), a homologue of Escherichia coli HU protein, represses transcription from P(SMU.1348). In vivo overexpression of HLP in trans also represses transcription from P(SMU.1348). Addition of CovR to the HLP-repressed P(SMU.1348) resulted in increased transcription from the promoter, suggesting a role for CovR in countering HLP silencing. Moreover, addition of SMU.1349, a transcriptional activator of the operon, to the in vitro assay further stimulated the transcription. Based on our in vivo and in vitro results, we propose a model for transcriptional activation of the operon.
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Pharmacological inhibition of the ClpXP protease increases bacterial susceptibility to host cathelicidin antimicrobial peptides and cell envelope-active antibiotics. Antimicrob Agents Chemother 2012; 56:1854-61. [PMID: 22252821 DOI: 10.1128/aac.05131-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The ClpXP protease is a critical bacterial intracellular protease that regulates protein turnover in many bacterial species. Here we identified a pharmacological inhibitor of the ClpXP protease, F2, and evaluated its action in Bacillus anthracis and Staphylococcus aureus. We found that F2 exhibited synergistic antimicrobial activity with cathelicidin antimicrobial peptides and antibiotics that target the cell well and/or cell membrane, such as penicillin and daptomycin, in B. anthracis and drug-resistant strains of S. aureus. ClpXP inhibition represents a novel therapeutic strategy to simultaneously sensitize pathogenic bacteria to host defenses and pharmaceutical antibiotics.
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Abstract
Acquisition of foreign DNA can be of advantage or disadvantage to the host cell. New DNAs can increase the fitness of an organism to certain environmental conditions; however, replication and maintenance of incorporated nucleotide sequences can be a burden for the host cell. These circumstances have resulted in the development of certain cellular mechanisms limiting horizontal gene transfer, including the immune system of vertebrates or RNA interference mechanisms in eukaryotes. Also, in prokaryotes, specific systems have been characterized, which are aimed especially at limiting the invasion of bacteriophage DNA, for example, adsorption inhibition, injection blocking, restriction/modification, or abortive infection. Quite recently, another distinct mechanism limiting horizontal transfer of genetic elements has been identified in procaryotes and shown to protect microbial cells against exogenous nucleic acids of phage or plasmid origin. This system has been termed CRISPR/cas and consists of two main components: (i) the CRISPR (clustered, regularly interspaced short palindromic regions) locus and (ii) cas genes, encoding CRISPR-associated (Cas) proteins. In simplest words, the mechanism of CRISPR/cas activity is based on the active integration of small fragments (proto-spacers) of the invading DNAs (phage or plasmids) into microbial genomes, which are subsequently transcribed into short RNAs that direct the degradation of foreign invading DNA elements. In this way, the host organism acquires immunity toward mobile elements carrying matching sequences. The CRISPR/cas system is regarded as one of the earliest defense system that has evolved in prokaryotic organisms. It is inheritable, but at the same time is unstable when regarding the evolutionary scale. Comparative sequence analyses indicate that CRISPR/cas systems play an important role in the evolution of microbial genomes and their predators, bacteriophages.
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Regulation of transcription by SMU.1349, a TetR family regulator, in Streptococcus mutans. J Bacteriol 2011; 193:6605-13. [PMID: 21965566 DOI: 10.1128/jb.06122-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The TetR family of transcriptional regulators is ubiquitous in bacteria, where it plays an important role in bacterial gene expression. Streptococcus mutans, a gram-positive pathogen considered to be the primary etiological agent in the formation of dental caries, encodes at least 18 TetR regulators. Here we characterized one such TetR regulator, SMU.1349, encoded by the TnSmu2 operon, which appeared to be acquired by the organism via horizontal gene transfer. SMU.1349 is transcribed divergently from the rest of the genes encoded by the operon. By the use of a transcriptional reporter system and semiquantitative reverse transcription-PCR (RT-PCR), we demonstrated that SMU.1349 activates the transcription of several genes that are encoded within the TnSmu2 operon. Gel mobility shift and DNase I footprinting assays with purified SMU.1349 protein demonstrated binding to the intergenic region between SMU.1349 and the TnSmu2 operon; therefore, SMU.1349 is directly involved in gene transcription. Using purified S. mutans RpoD and Escherichia coli RNA polymerase, we also demonstrated in an in vitro transcription assay that SMU.1349 could activate transcription from the TnSmu2 operon promoter. Furthermore, we showed that SMU.1349 could also repress transcription from its own promoter by binding to the intergenic region, suggesting that SMU.1349 acts as both an activator and a repressor. Thus, unlike most of the TetR family proteins, which generally function as transcriptional repressors, SMU.1349 is unique in that it can function as both.
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Kajfasz JK, Abranches J, Lemos JA. Transcriptome analysis reveals that ClpXP proteolysis controls key virulence properties of Streptococcus mutans. MICROBIOLOGY-SGM 2011; 157:2880-2890. [PMID: 21816882 DOI: 10.1099/mic.0.052407-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ClpXP proteolytic complex is critical for maintaining cellular homeostasis, as well as expression of virulence properties. However, with the exception of the Spx global regulator, the molecular mechanisms by which the ClpXP complex exerts its influence in Streptococcus mutans are not well understood. Here, microarray analysis was used to provide novel insights into the scope of ClpXP proteolysis in S. mutans. In a ΔclpP strain, 288 genes showed significant changes in relative transcript amounts (P≤0.001, twofold cut-off) as compared with the parent. Similarly, 242 genes were differentially expressed by a ΔclpX strain, 113 (47 %) of which also appeared in the ΔclpP microarrays. Several genes associated with cell growth were downregulated in both mutants, consistent with the slow-growth phenotype of the Δclp strains. Among the upregulated genes were those encoding enzymes required for the biosynthesis of intracellular polysaccharides (glg genes) and malolactic fermentation (mle genes). Enhanced expression of glg and mle genes in ΔclpP and ΔclpX strains correlated with increased storage of intracellular polysaccharide and enhanced malolactic fermentation activity, respectively. Expression of several genes known or predicted to be involved in competence and mutacin production was downregulated in the Δclp strains. Follow-up transformation efficiency and deferred antagonism assays validated the microarray data by showing that competence and mutacin production were dramatically impaired in the Δclp strains. Collectively, our results reveal the broad scope of ClpXP regulation in S. mutans homeostasis and identify several virulence-related traits that are influenced by ClpXP proteolysis.
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Affiliation(s)
- Jessica K Kajfasz
- Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Jacqueline Abranches
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - José A Lemos
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Dmitriev A, Mohapatra SS, Chong P, Neely M, Biswas S, Biswas I. CovR-controlled global regulation of gene expression in Streptococcus mutans. PLoS One 2011; 6:e20127. [PMID: 21655290 PMCID: PMC3105014 DOI: 10.1371/journal.pone.0020127] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 04/13/2011] [Indexed: 12/15/2022] Open
Abstract
CovR/S is a two-component signal transduction system (TCS) that controls the expression of various virulence related genes in many streptococci. However, in the dental pathogen Streptococcus mutans, the response regulator CovR appears to be an orphan since the cognate sensor kinase CovS is absent. In this study, we explored the global transcriptional regulation by CovR in S. mutans. Comparison of the transcriptome profiles of the wild-type strain UA159 with its isogenic covR deleted strain IBS10 indicated that at least 128 genes (∼6.5% of the genome) were differentially regulated. Among these genes, 69 were down regulated, while 59 were up regulated in the IBS10 strain. The S. mutans CovR regulon included competence genes, virulence related genes, and genes encoded within two genomic islands (GI). Genes encoded by the GI TnSmu2 were found to be dramatically reduced in IBS10, while genes encoded by the GI TnSmu1 were up regulated in the mutant. The microarray data were further confirmed by real-time RT-PCR analyses. Furthermore, direct regulation of some of the differentially expressed genes was demonstrated by electrophoretic mobility shift assays using purified CovR protein. A proteomic study was also carried out that showed a general perturbation of protein expression in the mutant strain. Our results indicate that CovR truly plays a significant role in the regulation of several virulence related traits in this pathogenic streptococcus.
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Affiliation(s)
- Alexander Dmitriev
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- Department of Molecular Microbiology, Institute of Experimental Medicine, Saint-Petersburg, Russia
| | - Saswat S. Mohapatra
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Patrick Chong
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Melody Neely
- Department of Microbiology and Immunology, Wayne State School of Medicine, Detroit, Michigan, United States of America
| | - Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- * E-mail:
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Abstract
Sequence-directed genetic interference pathways control gene expression and preserve genome integrity in all kingdoms of life. The importance of such pathways is highlighted by the extensive study of RNA interference (RNAi) and related processes in eukaryotes. In many bacteria and most archaea, clustered, regularly interspaced short palindromic repeats (CRISPRs) are involved in a more recently discovered interference pathway that protects cells from bacteriophages and conjugative plasmids. CRISPR sequences provide an adaptive, heritable record of past infections and express CRISPR RNAs - small RNAs that target invasive nucleic acids. Here, we review the mechanisms of CRISPR interference and its roles in microbial physiology and evolution. We also discuss potential applications of this novel interference pathway.
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Mutacins from Streptococcus mutans UA159 are active against multiple streptococcal species. Appl Environ Microbiol 2011; 77:2428-34. [PMID: 21296932 DOI: 10.1128/aem.02320-10] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Streptococcus mutans UA159, whose genome is completely sequenced, produces two nonlantibiotic mutacins, mutacin IV (encoded by nlmAB) and mutacin V (encoded by nlmC). In this study, we investigated the contribution of nlmA and nlmB to mutacin IV activity and demonstrated by performing genetic studies as well as by using semipurified molecules that, in contrast to a previous report, both of these genes are required for optimum mutacin IV activity. We also showed that mutacin IV is active against multiple Streptococcus species. In contrast, mutacin V displayed a narrower inhibitory range than mutacin IV. Our results suggest that mutacin IV and mutacin V may act synergistically to inhibit various organisms.
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Role of VltAB, an ABC transporter complex, in viologen tolerance in Streptococcus mutans. Antimicrob Agents Chemother 2011; 55:1460-9. [PMID: 21282456 DOI: 10.1128/aac.01094-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans, a Gram-positive organism, is the primary causative agent in the formation of dental caries in humans. To persist in the oral cavity, S. mutans must be able to tolerate rapid environmental fluctuations and exposure to various toxic chemicals. However, the mechanisms underlying the ability of this cariogenic pathogen to survive and proliferate under harsh environmental conditions remain largely unknown. Here, we wanted to understand the mechanisms by which S. mutans withstands exposure to methyl viologen (MV), a quaternary ammonium compound (QAC) that generates superoxide radicals in the cell. To elucidate the essential genes for MV tolerance, screening of ∼3,500 mutants generated by ISS1 mutagenesis, revealed 15 MV-sensitive mutants. Among them, five and four independent insertions had occurred in SMU.905 and SMU.906 genes, respectively. These two genes are appeared to be organized in an operon and encode a putative ABC transporter complex; we designated the genes as vltA and vltB, for viologen transporter. To verify our results, vltA was deleted by using an antibiotic resistance marker; the mutant was just as sensitive to MV as the ISS1 insertion mutants. Furthermore, vltA and vltB mutants were also sensitive to other viologen compounds such as benzyl and ethyl viologens. Complementation assays were also carried out to confirm the role of VltA and VltB in viologen tolerance. Sensitivity to various drugs, including a wide range of QACs, was evaluated. It appears that a functional VltA is also required for full resistance toward acriflavin, ethidium bromide, and safranin; all are well-known QACs. These results indicate that VltA/B constitute a heterodimeric multidrug efflux pump of the ABC family. BLAST-P analysis suggests that homologs of VltA/B are widely present in streptococci, enterococci, and other important Gram-positive pathogens.
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Vinckx T, Wei Q, Matthijs S, Noben JP, Daniels R, Cornelis P. A proteome analysis of the response of a Pseudomonas aeruginosa oxyR mutant to iron limitation. Biometals 2011; 24:523-32. [PMID: 21207115 DOI: 10.1007/s10534-010-9403-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 12/22/2010] [Indexed: 11/30/2022]
Abstract
In Pseudomonas aeruginosa the response to oxidative stress is orchestrated by the LysR regulator OxyR by activation of the transcription of two catalase genes (katA and katB), of the alkyl-hydroxyperoxidases ahpCF and ahpB. Next to the expected high sensitivity to oxidative stress generated by reactive oxygen species (ROS: H(2)O(2), O(2)(-)), the oxyR mutant shows a defective growth under conditions of iron limitation (Vinckx et al. 2008). Although production and uptake of the siderophore pyoverdine is not affected by the absence of oxyR, the mutant is unable to satisfy its need for iron when grown under iron limiting conditions. In order to get a better insight into the effects caused by iron limitation on the physiological response of the oxyR mutant we decided to compare the proteomes of the wild type and the mutant grown in the iron-poor casamino acids medium (CAA), in CAA plus H(2)O(2), and in CAA plus the strong iron chelator ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (EDDHA). Especially in the presence of hydrogen peroxide the oxyR cells increase the production of stress proteins (Dps and IbpA). The superoxide dismutase SodM is produced in higher amounts in the oxyR mutant grown in CAA plus H(2)O(2). The PchB protein, a isochorismate-pyruvate lyase involved in the siderophore pyochelin biosynthesis is not detectable in the extracts from the oxyR mutant grown in the presence of hydrogen peroxide. When cells were grown in the presence of EDDHA, we observed a reduction of the ferric uptake regulator (Fur), and an increase in the two subunits of the succinyl-CoA synthetase and the fumarase FumC1.
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Affiliation(s)
- Tiffany Vinckx
- Laboratory of Microbial Interactions, Department of Molecular and Cellular Interactions, VIB, Vrije Universiteit Brussel, Brussels, Belgium
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Deveau H, Garneau JE, Moineau S. CRISPR/Cas system and its role in phage-bacteria interactions. Annu Rev Microbiol 2010; 64:475-93. [PMID: 20528693 DOI: 10.1146/annurev.micro.112408.134123] [Citation(s) in RCA: 404] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPRs) along with Cas proteins is a widespread system across bacteria and archaea that causes interference against foreign nucleic acids. The CRISPR/Cas system acts in at least two general stages: the adaptation stage, where the cell acquires new spacer sequences derived from foreign DNA, and the interference stage, which uses the recently acquired spacers to target and cleave invasive nucleic acid. The CRISPR/Cas system participates in a constant evolutionary battle between phages and bacteria through addition or deletion of spacers in host cells and mutations or deletion in phage genomes. This review describes the recent progress made in this fast-expanding field.
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Affiliation(s)
- Hélène Deveau
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Quebec City, Quebec, G1V 0A6, Canada.
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Two Spx proteins modulate stress tolerance, survival, and virulence in Streptococcus mutans. J Bacteriol 2010; 192:2546-56. [PMID: 20233935 DOI: 10.1128/jb.00028-10] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Previous work suggested that the underlying mechanisms by which the Streptococcus mutans ClpXP protease affects virulence traits are associated with accumulation of two orthologues of the Spx regulator, named SpxA and SpxB. Here, a thorough characterization of strains lacking the spx genes (Delta spxA, Delta spxB, and Delta spxA Delta spxB) revealed that Spx, indeed, participates in the regulation of processes associated with S. mutans pathogenesis. The Delta spxA strain displayed impaired ability to grow under acidic and oxidative stress conditions and had diminished long-term viability at low pH. Although the Delta spxB strain did not show any inherent stress-sensitive phenotype, the phenotypes observed in Delta spxA were more pronounced in the Delta spxA Delta spxB double mutant. By using two in vivo models, we demonstrate for the first time that Spx is required for virulence in a gram-positive pathogen. Microarrays confirmed the global regulatory role of SpxA and SpxB. In particular, SpxA was shown to positively regulate genes associated with oxidative stress, a finding supported by enzymatic assays. SpxB had a secondary role in regulation of oxidative stress genes but appeared to play a larger role in controlling processes associated with cell wall homeostasis. Given the high degree of conservation between Spx proteins of low-GC gram-positive bacteria, these results are likely to have broad implications.
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