1
|
Mao C, Wang Y, Yang Y, Li L, Yuan K, Cao H, Qiu Z, Guo G, Wu J, Peng J. Cec4-Derived Peptide Inhibits Planktonic and Biofilm-Associated Methicillin Resistant Staphylococcus epidermidis. Microbiol Spectr 2022; 10:e0240922. [PMID: 36453944 PMCID: PMC9769716 DOI: 10.1128/spectrum.02409-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/08/2022] [Indexed: 12/05/2022] Open
Abstract
Staphylococcus epidermidis is part of the normal microbiota that colonizes the skin and mucosal surfaces of human beings. Previous studies suggested that S. epidermidis possessed low virulence, but recent studies confirmed that it can acquire high virulence from Staphylococcus aureus and with the increasing detection of methicillin-resistant S. epidermidis. It has become a major pathogen of graft-associated and hospital-acquired infections. In previous studies, we modified the antimicrobial peptide Cec4 (41 amino acids) and obtained the derived peptide C9 (16 amino acids) showing better antimicrobial activity against S. epidermidis with an MIC value of 8 μg/mL. The peptide has rapid bactericidal activity without detectable high-level resistance, showing certain inhibition and eradication ability on S. epidermidis biofilms. The damage of cell membrane structures by C9 was observed by scanning emission microscopy (SEM) and transmission electron microscopy (TEM). In addition, C9 altered the S. epidermidis cell membrane permeability, depolarization levels, fluidity, and reactive oxygen species (ROS) accumulation and possessed the ability to bind genomic DNA. Analysis of the transcriptional profiles of C9-treated cells revealed changes in genes involved in cell wall and ribosome biosynthesis, membrane protein transport, oxidative stress, and DNA transcription regulation. At the same time, the median lethal dose of C9 in mice was more than 128 mg/kg, and the intraperitoneal administration of 64 mg/kg was less toxic to the liver and kidneys of mice. Furthermore, C9 also showed a certain therapeutic effect on the mouse bacteremia model. In conclusion, C9 may be a candidate drug against S. epidermidis, which has the potential to be further developed as an antibacterial therapeutic agent. IMPORTANCE S. epidermidis is one of the most important pathogens of graft-related infection and hospital-acquired infection. The growing problem of antibiotic resistance, as well as the emergence of bacterial pathogenicity, highlights the need for antimicrobials with new modes of action. Antimicrobial peptides have been extensively studied over the past 30 years as ideal alternatives to antibiotics, and we report here that the derived peptide C9 is characterized by rapid bactericidal and antibiofilm activity, avoiding the development of resistance by acting on multiple nonspecific targets of the cell membrane or cell components. In addition, it has therapeutic potential against S. epidermidis infection in vivo. This study provides a rationale for the further development and application of C9 as an effective candidate antibiotic.
Collapse
Affiliation(s)
- Chengju Mao
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Yue Wang
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Yifan Yang
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Lu Li
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- Center for Clinical Laboratories, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Kexin Yuan
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- Center for Clinical Laboratories, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Huijun Cao
- Center for Clinical Laboratories, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Zhilang Qiu
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Guo Guo
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Jianwei Wu
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Jian Peng
- Key Laboratory of Infectious Immune and Antibody Engineering of Guizhou Province, Cellular Immunotherapy Engineering Research Center of Guizhou Province, School of Biology and Engineering/School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| |
Collapse
|
2
|
Dey S, Shahrear S, Afroj Zinnia M, Tajwar A, Islam ABMMK. Functional Annotation of Hypothetical Proteins From the Enterobacter cloacae B13 Strain and Its Association With Pathogenicity. Bioinform Biol Insights 2022; 16:11779322221115535. [PMID: 35958299 PMCID: PMC9358594 DOI: 10.1177/11779322221115535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/11/2022] [Indexed: 11/25/2022] Open
Abstract
Enterobacter cloacae B13 strain is a rod-shaped gram-negative bacterium that belongs to the Enterobacteriaceae family. It can cause respiratory and urinary tract infections, and is responsible for several outbreaks in hospitals. E. cloacae has become an important pathogen and an emerging global threat because of its opportunistic and multidrug resistant ability. However, little knowledge is present about a large portion of its proteins and functions. Therefore, functional annotation of the hypothetical proteins (HPs) can provide an improved understanding of this organism and its virulence activity. The workflow in the study included several bioinformatic tools which were utilized to characterize functions, family and domains, subcellular localization, physiochemical properties, and protein-protein interactions. The E. cloacae B13 strain has overall 604 HPs, among which 78 were functionally annotated with high confidence. Several proteins were identified as enzymes, regulatory, binding, and transmembrane proteins with essential functions. Furthermore, 23 HPs were predicted to be virulent factors. These virulent proteins are linked to pathogenesis with their contribution to biofilm formation, quorum sensing, 2-component signal transduction or secretion. Better knowledge about the HPs’ characteristics and functions will provide a greater overview of the proteome. Moreover, it will help against E. cloacae in neonatal intensive care unit (NICU) outbreaks and nosocomial infections.
Collapse
Affiliation(s)
- Supantha Dey
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Sazzad Shahrear
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | | | - Ahnaf Tajwar
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | | |
Collapse
|
3
|
Liu Y, Wu Z, Zeng X, Weng P, Zhang X, Wang C. A novel cold-adapted phospho-beta-galactosidase from Bacillus velezensis and its potential application for lactose hydrolysis in milk. Int J Biol Macromol 2020; 166:760-770. [PMID: 33144261 DOI: 10.1016/j.ijbiomac.2020.10.233] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/10/2020] [Accepted: 10/29/2020] [Indexed: 12/25/2022]
Abstract
A phospho-β-galactosidase gene (BsGal1332) was cloned from Bacillus velezensis and successfully expressed in Escherichia coli BL21(DE3). The active BsGal1332 was identified to be a homodimer with a combined molecular mass of approximately 113 kDa, and it belonged to the glycoside hydrolase family 1. The BsGal1332 displayed relative strict substrate specificity for galactosyl compounds compared with the other phospho-β-galactosidases. The purified BsGal1332 showed the maximum activity at pH 8.0 and 50 °C for 2-nitrophenyl-β-d-galactopyranoside (oNPGal) and at 40 °C for lactose. BsGal1332 was slightly activated by K+ and Na+, but not strongly affected by Ca2+, and was stable at pH 6.0-7.0 and 40 °C or below it. The activity of BsGal1332 decreased quickly after incubation at 50 °C or higher temperature, suggesting it was a cold-adapted enzyme. Moreover, BsGal1332 could hydrolyze lactose and oNPGal with Km values of 23.68 and 2.36 mM and kcat values of 117.55 and 155.61 s-1 at 4 °C, respectively. Additionally, 1 U of the BsGal1332 could thus be capable of hydrolyzing about 38% of the lactose in 1 mL of milk after incubating at 4 °C for 4 h. Taken together, these properties of BsGal1332 made it a new promising industrial biocatalyst for efficient lactose hydrolysis in milk.
Collapse
Affiliation(s)
- Yang Liu
- Department of Food Science and Engineering, Ningbo University, Ningbo 315211, PR China; Institute of Quality Standards and Testing Technology for Agro-Products, Fujian Academy of Agricultural Sciences, Fuzhou 350003, PR China
| | - Zufang Wu
- Department of Food Science and Engineering, Ningbo University, Ningbo 315211, PR China.
| | - Xiaoxiong Zeng
- Department of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China.
| | - Peifang Weng
- Department of Food Science and Engineering, Ningbo University, Ningbo 315211, PR China
| | - Xin Zhang
- Department of Food Science and Engineering, Ningbo University, Ningbo 315211, PR China
| | - Changyu Wang
- Department of Food Science and Engineering, Ningbo University, Ningbo 315211, PR China
| |
Collapse
|
4
|
Zeng L, Burne RA. Subpopulation behaviors in lactose metabolism by Streptococcus mutans. Mol Microbiol 2020; 115:58-69. [PMID: 32881164 DOI: 10.1111/mmi.14596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/17/2020] [Accepted: 08/24/2020] [Indexed: 01/08/2023]
Abstract
When Streptococcus mutans is transferred from a preferred carbohydrate (glucose or fructose) to lactose, initiation of growth can take several hours, and substantial amounts of glucose are released during growth. Here, S. mutans strains UA159 and GS-5 were examined for stochastic behaviors in transcription of the lac operon. Using a gfp reporter fusion, we demonstrated that induction of the lac operon occurs in only a fraction of the population, with prior exposure to carbohydrate source and strain influencing the magniture of the sub-population response. Lower glucokinase activity in GS-5 was associated with release of substantially more glucose than UA159 and significantly lower lac expression. Mutants unable to use lactose grew on lactose as the sole carbohydrate when strains with an intact lac operon were also present in the cultures, indicative of the potential for population cheating. Utilizing a set of engineered obligate cheating and non-cheating strains, we confirmed that cheating can sustain a heterogeneous population. Futher, obligate cheaters of GS-5 competed well with the non-cheaters and showed a high degree of competitive fitness in a human-derived consortium biofilm model. The results show that bet-hedging behaviors in carbohydrate metabolism may substantially influence the composition and pathogenic potential of oral biofilms.
Collapse
Affiliation(s)
- Lin Zeng
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| |
Collapse
|
5
|
Zeng L, Burne RA. Molecular mechanisms controlling fructose-specific memory and catabolite repression in lactose metabolism by Streptococcus mutans. Mol Microbiol 2020; 115:70-83. [PMID: 32881130 DOI: 10.1111/mmi.14597] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/17/2020] [Accepted: 08/24/2020] [Indexed: 01/26/2023]
Abstract
Lactose is an abundant dietary carbohydrate metabolized by the dental pathogen Streptococcus mutans. Lactose metabolism presents both classic diauxic behaviors and long-term memory, where the bacteria can pause for >11 h before initiating growth on lactose. Here, we explored mechanisms contributing to unusual aspects of regulation of the lac operon. The fructose-phosphate metabolites, F-1-P and F-6-P, could modulate the DNA-binding activities of the lactose repressor. Recombinant LacR proteins bound upstream of lacA and Gal-6-P induced the formation of different LacR-DNA complexes. Deletion of lacR resulted in strain-specific growth phenotypes on lactose, but also on a number of mono- and di-saccharides that involve the glucose-PTS or glucokinase in their catabolism. The phenotypes were consistent with the novel findings that loss of LacR altered glucose-PTS activity and expression of the gene for glucokinase. CcpA was also shown to affect lactose metabolism in vivo and to bind to the lacA promoter region in vitro. Collectively, our study reveals complex molecular circuits controlling lactose metabolism in S. mutans, where LacR and CcpA integrate cellular and environmental cues to regulate metabolism of a variety of carbohydrates that are critical to persistence and pathogenicity of S. mutans.
Collapse
Affiliation(s)
- Lin Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| |
Collapse
|
6
|
Lei L, Zhang B, Mao M, Chen H, Wu S, Deng Y, Yang Y, Zhou H, Hu T. Carbohydrate Metabolism Regulated by Antisense vicR RNA in Cariogenicity. J Dent Res 2019; 99:204-213. [PMID: 31821772 DOI: 10.1177/0022034519890570] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Streptococcus mutans is a major cariogenic pathogen that resides in multispecies oral microbial biofilms. The VicRK 2-component system is crucial for bacterial adaptation, virulence, and biofilm organization and contains a global and vital response regulator, VicR. Notably, we identified an antisense vicR RNA (AS vicR) associated with an adjacent RNase III–encoding ( rnc) gene that was relevant to microRNA-size small RNAs (msRNAs). Here, we report that ASvicR overexpression significantly impeded bacterial growth, biofilm exopolysaccharide synthesis, and cariogenicity in vivo. Transcriptome analysis revealed that the AS vicR RNA mainly regulated carbohydrate metabolism. In particular, overproducing AS vicR demonstrated a reduction in galactose and glucose metabolism by monosaccharide composition analysis. The results of high-performance gel permeation chromatography revealed that the water-insoluble glucans isolated from AS vicR presented much lower molecular weights. Furthermore, direct evidence showed that total RNAs were disrupted by rnc-encoded RNase III. With the coexpression of T4 RNA ligase, putative msRNA1657, which is an rnc-related messenger RNA, was verified to bind to the 5′-UTR regions of the vicR gene. Furthermore, AS vicR regulation revealed a sponge regulatory-mediated network for msRNA associated with adjacent RNase III–encoding genes. There was an increase in AS vicR transcript levels in clinical S. mutans strains from caries-free children, while the expression of AS vicR was decreased in early childhood caries patients; this outcome may be explored as a potential strategy contributing to the management of dental caries. Taken together, our findings suggest an important role of AS vicR-mediated sponge regulation in S. mutans, indicating the characterization of lactose metabolism by a vital response regulator in cariogenicity. These findings have a number of implications and have reshaped our understanding of bacterial gene regulation from its transcriptional conception to the key roles of regulatory RNAs.
Collapse
Affiliation(s)
- L. Lei
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - B. Zhang
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - M. Mao
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Endodontics, College of Stomatology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - H. Chen
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - S. Wu
- West China School of Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Y. Deng
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - Y. Yang
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| | - H. Zhou
- Department of Oral Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - T. Hu
- State Key Laboratory of Oral Diseases, Department of Preventive Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
| |
Collapse
|
7
|
Schoenenberger B, Kind S, Meier R, Eggert T, Obkircher M, Wohlgemuth R. Efficient biocatalytic synthesis of D-tagatose 1,6-diphosphate by LacC-catalysed phosphorylation of D-tagatose 6-phosphate. BIOCATAL BIOTRANSFOR 2019. [DOI: 10.1080/10242422.2019.1634694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
| | | | | | | | | | - Roland Wohlgemuth
- Sigma-Aldrich/Merck KGaA, Buchs, Switzerland
- Institute of Technical Biochemistry, Technical University Lodz, Lodz, Poland
| |
Collapse
|
8
|
Iskandar CF, Cailliez-Grimal C, Borges F, Revol-Junelles AM. Review of lactose and galactose metabolism in Lactic Acid Bacteria dedicated to expert genomic annotation. Trends Food Sci Technol 2019. [DOI: 10.1016/j.tifs.2019.03.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
9
|
Li Z, Xiang Z, Zeng J, Li Y, Li J. A GntR Family Transcription Factor in Streptococcus mutans Regulates Biofilm Formation and Expression of Multiple Sugar Transporter Genes. Front Microbiol 2019; 9:3224. [PMID: 30692967 PMCID: PMC6340165 DOI: 10.3389/fmicb.2018.03224] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 12/11/2018] [Indexed: 02/05/2023] Open
Abstract
GntR family transcription factors have been implicated in the regulation of carbohydrate transport and metabolism in many bacteria. However, the function of this transcription factor family is poorly studied in Streptococcus mutans, which is a commensal bacterium in the human oral cavity and a well-known cariogenic pathogen. One of the most important virulence traits of S. mutans is its ability to transport and metabolize carbohydrates. In this study, we identified a GntR transcription factor in S. mutans named StsR (Sugar Transporter Systems Regulator). The deletion of the stsR gene in S. mutans caused a decrease in both the formation of biofilm and the production of extracellular polysaccharides (EPS) at early stage. Global gene expression profiling revealed that the expression levels of 188 genes were changed in the stsR mutant, which could be clustered with the sugar PTS and ABC transporters. Furthermore, StsR protein was purified and its conserved DNA binding motif was determined using electrophoretic mobility shift assays (EMSA) and DNase I footprinting assays. Collectively, the results of this research indicate that StsR is an important transcription factor in S. mutans that regulates the expression of sugar transporter genes, production of EPS and formation of biofilm.
Collapse
Affiliation(s)
- Zongbo Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Zhenting Xiang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jumei Zeng
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
| | - Yuqing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiyao Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| |
Collapse
|
10
|
Lansky S, Zehavi A, Belrhali H, Shoham Y, Shoham G. Structural basis for enzyme bifunctionality – the case of Gan1D fromGeobacillus stearothermophilus. FEBS J 2017; 284:3931-3953. [DOI: 10.1111/febs.14283] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/31/2017] [Accepted: 09/28/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Shifra Lansky
- Institute of Chemistry The Laboratory for Structural Chemistry and Biology The Hebrew University of Jerusalem Israel
| | - Arie Zehavi
- Department of Biotechnology and Food Engineering Technion ‐ Israel Institute of Technology Haifa Israel
| | | | - Yuval Shoham
- Department of Biotechnology and Food Engineering Technion ‐ Israel Institute of Technology Haifa Israel
| | - Gil Shoham
- Institute of Chemistry The Laboratory for Structural Chemistry and Biology The Hebrew University of Jerusalem Israel
| |
Collapse
|
11
|
Wu X, Hou J, Chen X, Chen X, Zhao W. Identification and functional analysis of the L-ascorbate-specific enzyme II complex of the phosphotransferase system in Streptococcus mutans. BMC Microbiol 2016; 16:51. [PMID: 27001419 PMCID: PMC4802650 DOI: 10.1186/s12866-016-0668-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/07/2016] [Indexed: 12/27/2022] Open
Abstract
Background Streptococcus mutans is the primary etiological agent of human dental caries. It can metabolize a wide variety of carbohydrates and produce large amounts of organic acids that cause enamel demineralization. Phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) plays an important role in carbohydrates uptake of S. mutans. The ptxA and ptxB genes in S. mutans encode putative enzyme IIA and enzyme IIB of the L-ascorbate-specific PTS. The aim of this study was to analyze the function of these proteins and understand the transcriptional regulatory mechanism. Results ptxA−, ptxB−, as well as ptxA−, ptxB− double-deletion mutants all had more extended lag phase and lower growth yield than wild-type strain UA159 when grown in the medium using L-ascorbate as the sole carbon source. Acid production and acid killing assays showed that the absence of the ptxA and ptxB genes resulted in a reduction in the capacity for acidogenesis, and all three mutant strains did not survive an acid shock. According to biofilm and extracellular polysaccharides (EPS) formation analysis, all the mutant strains formed much less prolific biofilms with small amounts of EPS than wild-type UA159 when using L-ascorbate as the sole carbon source. Moreover, PCR analysis and quantitative real-time PCR revealed that sgaT, ptxA, ptxB, SMU.273, SMU.274 and SMU.275 appear to be parts of the same operon. The transcription levels of these genes were all elevated in the presence of L-ascorbate, and the expression of ptxA gene decreased significantly once ptxB gene was knockout. Conclusions The ptxA and ptxB genes are involved in the growth, aciduricity, acidogenesis, and formation of biofilms and EPS of S. mutans when L-ascorbate is the sole carbon source. In addition, the expression of ptxA is regulated by ptxB. ptxA, ptxB, and the upstream gene sgaT, the downstream genes SMU.273, SMU.274 and SMU.275 appear to be parts of the same operon, and L-ascorbate is a potential inducer of the operon. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0668-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Xinyu Wu
- Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, Guangdong, China
| | - Jin Hou
- Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, Guangdong, China
| | - Xiaodan Chen
- Department of Stomatology, the Second Affiliated Hospital of Shantou University, Shantou, Guangdong, China
| | - Xuan Chen
- Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, Guangdong, China
| | - Wanghong Zhao
- Department of Stomatology, Nanfang Hospital and College of Stomatology, Southern Medical University, Guangzhou, Guangdong, China.
| |
Collapse
|
12
|
Van der Heiden E, Delmarcelle M, Simon P, Counson M, Galleni M, Freedberg DI, Thompson J, Joris B, Battistel MD. Synthesis and Physicochemical Characterization of D-Tagatose-1-Phosphate: The Substrate of the Tagatose-1-Phosphate Kinase in the Phosphotransferase System-Mediated D-Tagatose Catabolic Pathway of Bacillus licheniformis. J Mol Microbiol Biotechnol 2015; 25:106-19. [PMID: 26159072 DOI: 10.1159/000370115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We report the first enzymatic synthesis of D-tagatose-1-phosphate (Tag-1P) by the multicomponent phosphoenolpyruvate:sugar phosphotransferase system (PEP-PTS) present in tagatose-grown cells of Klebsiella pneumoniae. Physicochemical characterization by (31)P and (1)H nuclear magnetic resonance spectroscopy reveals that, in solution, this derivative is primarily in the pyranose form. Tag-1P was used to characterize the putative tagatose-1-phosphate kinase (TagK) of the Bacillus licheniformis PTS-mediated D-tagatose catabolic pathway (Bli-TagP). For this purpose, a soluble protein fusion was obtained with the 6 His-tagged trigger factor (TF(His6)) of Escherichia coli. The active fusion enzyme was named TagK-TF(His6). Tag-1P and D-fructose-1-phosphate are substrates for the TagK-TF(His6) enzyme, whereas the isomeric derivatives D-tagatose-6-phosphate and D-fructose-6-phosphate are inhibitors. Studies of catalytic efficiency (kcat/Km) reveal that the enzyme specificity is markedly in favor of Tag-1P as the substrate. Importantly, we show in vivo that the transfer of the phosphate moiety from PEP to the B. licheniformis tagatose-specific Enzyme II in E. coli is inefficient. The capability of the PTS general cytoplasmic components of B. subtilis, HPr and Enzyme I to restore the phosphate transfer is demonstrated.
Collapse
Affiliation(s)
- Edwige Van der Heiden
- Center for Protein Engineering, University of Liège, Institut de Chimie, Sart-Tilman, Belgium
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Moye ZD, Zeng L, Burne RA. Fueling the caries process: carbohydrate metabolism and gene regulation by Streptococcus mutans. J Oral Microbiol 2014; 6:24878. [PMID: 25317251 PMCID: PMC4157138 DOI: 10.3402/jom.v6.24878] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 11/17/2022] Open
Abstract
The nature of the oral cavity and host behaviors has mandated that the oral microbiota evolve mechanisms for coping with environmental fluctuations, especially changes in the type and availability of carbohydrates. In the case of human dental caries, the presence of excess carbohydrates is often responsible for altering the local environment to be more favorable for species associated with the initiation and progression of disease, including Streptococcus mutans. Some of the earliest endeavors to understand how cariogenic species respond to environmental perturbations were carried out using chemostat cultivation, which provides fine control over culture conditions and bacterial behaviors. The development of genome-scale methodologies has allowed for the combination of sophisticated cultivation technologies with genome-level analysis to more thoroughly probe how bacterial pathogens respond to environmental stimuli. Recent investigations in S. mutans and other closely related streptococci have begun to reveal that carbohydrate metabolism can drastically impact pathogenic potential and highlight the important influence that nutrient acquisition has on the success of pathogens; inside and outside of the oral cavity. Collectively, research into pathogenic streptococci, which have evolved in close association with the human host, has begun to unveil the essential nature of careful orchestration of carbohydrate acquisition and catabolism to allow the organisms to persist and, when conditions allow, initiate or worsen disease.
Collapse
Affiliation(s)
- Zachary D Moye
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Lin Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| |
Collapse
|
14
|
LacR is a repressor of lacABCD and LacT is an activator of lacTFEG, constituting the lac gene cluster in Streptococcus pneumoniae. Appl Environ Microbiol 2014; 80:5349-58. [PMID: 24951784 DOI: 10.1128/aem.01370-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Comparison of the transcriptome of Streptococcus pneumoniae strain D39 grown in the presence of either lactose or galactose with that of the strain grown in the presence of glucose revealed the elevated expression of various genes and operons, including the lac gene cluster, which is organized into two operons, i.e., lac operon I (lacABCD) and lac operon II (lacTFEG). Deletion of the DeoR family transcriptional regulator lacR that is present downstream of the lac gene cluster revealed elevated expression of lac operon I even in the absence of lactose. This suggests a function of LacR as a transcriptional repressor of lac operon I, which encodes enzymes involved in the phosphorylated tagatose pathway in the absence of lactose or galactose. Deletion of lacR did not affect the expression of lac operon II, which encodes a lactose-specific phosphotransferase. This finding was further confirmed by β-galactosidase assays with PlacA-lacZ and PlacT-lacZ in the presence of either lactose or glucose as the sole carbon source in the medium. This suggests the involvement of another transcriptional regulator in the regulation of lac operon II, which is the BglG-family transcriptional antiterminator LacT. We demonstrate the role of LacT as a transcriptional activator of lac operon II in the presence of lactose and CcpA-independent regulation of the lac gene cluster in S. pneumoniae.
Collapse
|
15
|
Lansky S, Zehavi A, Dann R, Dvir H, Belrhali H, Shoham Y, Shoham G. Purification, crystallization and preliminary crystallographic analysis of Gan1D, a GH1 6-phospho-β-galactosidase from Geobacillus stearothermophilus T1. Acta Crystallogr F Struct Biol Commun 2014; 70:225-31. [PMID: 24637762 PMCID: PMC3936444 DOI: 10.1107/s2053230x13034778] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/28/2013] [Indexed: 11/10/2022] Open
Abstract
Geobacillus stearothermophilus T1 is a Gram-positive thermophilic soil bacterium that contains an extensive system for the utilization of plant cell-wall polysaccharides, including xylan, arabinan and galactan. The bacterium uses a number of extracellular enzymes that break down the high-molecular-weight polysaccharides into short oligosaccharides, which enter the cell and are further hydrolyzed into sugar monomers by dedicated intracellular glycoside hydrolases. The interest in the biochemical characterization and structural analysis of these proteins originates mainly from the wide range of their potential biotechnological applications. Studying the different hemicellulolytic utilization systems in G. stearothermophilus T1, a new galactan-utilization gene cluster was recently identified, which encodes a number of proteins, one of which is a GH1 putative 6-phospho-β-galactosidase (Gan1D). Gan1D has recently been cloned, overexpressed, purified and crystallized as part of its comprehensive structure-function study. The best crystals obtained for this enzyme belonged to the triclinic space group P1, with average crystallographic unit-cell parameters of a = 67.0, b = 78.1, c = 92.1 Å, α = 102.4, β = 93.5, γ = 91.7°. A full diffraction data set to 1.33 Å resolution has been collected for the wild-type enzyme, as measured from flash-cooled crystals at 100 K, using synchrotron radiation. These data are currently being used for the detailed three-dimensional crystal structure analysis of Gan1D.
Collapse
Affiliation(s)
- Shifra Lansky
- Institute of Chemistry and the Laboratory for Structural Chemistry and Biology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Arie Zehavi
- Department of Biotechnology and Food Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Roie Dann
- Institute of Chemistry and the Laboratory for Structural Chemistry and Biology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Hay Dvir
- Technion Center for Structural Biology, The Lorry I. Lokey Interdisciplinary Center for Life Science and Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Hassan Belrhali
- European Molecular Biology Laboratory, Grenoble Outstation, and Unit for Virus–Host Cell Interactions, European Synchrotron Radiation Facility, Université Grenoble Alpes–EMBL–CNRS, 6 Rue Jules Horowitz, 38042 Grenoble, France
| | - Yuval Shoham
- Department of Biotechnology and Food Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Gil Shoham
- Institute of Chemistry and the Laboratory for Structural Chemistry and Biology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| |
Collapse
|
16
|
Jung WS, Singh RK, Lee JK, Pan CH. Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates. PLoS One 2013; 8:e72902. [PMID: 24015281 PMCID: PMC3755991 DOI: 10.1371/journal.pone.0072902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/14/2013] [Indexed: 11/29/2022] Open
Abstract
D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays.
Collapse
Affiliation(s)
- Woo-Suk Jung
- Functional Food Center, Korea Institute of Science and Technology Gangneung Institute, Gangneung, Korea
| | - Raushan Kumar Singh
- Department of Chemical Engineering, Konkuk University, Gwangjin-Gu, Seoul, Korea
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, Gwangjin-Gu, Seoul, Korea
| | - Cheol-Ho Pan
- Functional Food Center, Korea Institute of Science and Technology Gangneung Institute, Gangneung, Korea
| |
Collapse
|
17
|
Zeng L, Xue P, Stanhope MJ, Burne RA. A galactose-specific sugar: phosphotransferase permease is prevalent in the non-core genome of Streptococcus mutans. Mol Oral Microbiol 2013; 28:292-301. [PMID: 23421335 DOI: 10.1111/omi.12025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2013] [Indexed: 12/01/2022]
Abstract
Three genes predicted to encode the A, B and C domains of a sugar : phosphotransferase system (PTS) permease specific for galactose\(EII(Gal) ) were identified in the genomes of 35 of 57 recently sequenced isolates of Streptococcus mutans, the primary etiological agent of human dental caries. Mutants defective in the EII(Gal) complex were constructed in six of the isolates and showed markedly reduced growth rates on galactose-based medium relative to the parental strains. An EII(Gal) -deficient strain constructed using the invasive serotype f strain OMZ175 (OMZ/IIGal) expressed significantly lower PTS activity when galactose was present as the substrate. Galactose was shown to be an effective inducer of catabolite repression in OMZ175, but not in the EII(Gal) -deficient strain. In a mixed-species competition assay with galactose as the sole carbohydrate source, OMZ/IIGal was less effective than the parental strain at competing with the oral commensal bacterium Streptococcus gordonii, which has a high-affinity galactose transporter. Hence, a significant proportion of S. mutans strains encode a galactose PTS permease that could enhance the ability of these isolates to compete more effectively with commensal streptococci for galactose in salivary constituents and the diet.
Collapse
Affiliation(s)
- L Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | | | | | | |
Collapse
|
18
|
Two gene clusters coordinate galactose and lactose metabolism in Streptococcus gordonii. Appl Environ Microbiol 2012; 78:5597-605. [PMID: 22660715 DOI: 10.1128/aem.01393-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus gordonii is an early colonizer of the human oral cavity and an abundant constituent of oral biofilms. Two tandemly arranged gene clusters, designated lac and gal, were identified in the S. gordonii DL1 genome, which encode genes of the tagatose pathway (lacABCD) and sugar phosphotransferase system (PTS) enzyme II permeases. Genes encoding a predicted phospho-β-galactosidase (LacG), a DeoR family transcriptional regulator (LacR), and a transcriptional antiterminator (LacT) were also present in the clusters. Growth and PTS assays supported that the permease designated EII(Lac) transports lactose and galactose, whereas EII(Gal) transports galactose. The expression of the gene for EII(Gal) was markedly upregulated in cells growing on galactose. Using promoter-cat fusions, a role for LacR in the regulation of the expressions of both gene clusters was demonstrated, and the gal cluster was also shown to be sensitive to repression by CcpA. The deletion of lacT caused an inability to grow on lactose, apparently because of its role in the regulation of the expression of the genes for EII(Lac), but had little effect on galactose utilization. S. gordonii maintained a selective advantage over Streptococcus mutans in a mixed-species competition assay, associated with its possession of a high-affinity galactose PTS, although S. mutans could persist better at low pHs. Collectively, these results support the concept that the galactose and lactose systems of S. gordonii are subject to complex regulation and that a high-affinity galactose PTS may be advantageous when S. gordonii is competing against the caries pathogen S. mutans in oral biofilms.
Collapse
|
19
|
Effects of the ERES pathogenicity region regulator Ralp3 on Streptococcus pyogenes serotype M49 virulence factor expression. J Bacteriol 2012; 194:3618-26. [PMID: 22544273 DOI: 10.1128/jb.00227-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Streptococcus pyogenes (group A streptococcus [GAS]) is a highly virulent Gram-positive bacterium. For successful infection, GAS expresses many virulence factors, which are clustered together with transcriptional regulators in distinct genomic regions. Ralp3 is a central regulator of the ERES region. In this study, we investigated the role of Ralp3 in GAS M49 pathogenesis. The inactivation of Ralp3 resulted in reduced attachment to and internalization into human keratinocytes. The Δralp3 mutant failed to survive in human blood and serum, and the hyaluronic acid capsule was slightly decreased. In addition, the mutant showed a lower binding capacity to human plasminogen, and the SpeB activity was significantly decreased. Complementation of the Δralp3 mutant restored the wild-type phenotype. The transcriptome and quantitative reverse transcription-PCR analysis of the serotype M49 GAS strain and its isogenic Δralp3 mutant identified 16 genes as upregulated, and 43 genes were found to be downregulated. Among the downregulated genes, there were open reading frames encoding proteins involved in metabolism (e.g., both lac operons and the fru operon), genes encoding lantibiotics (e.g., the putative salivaricin operon), and ORFs encoding virulence factors (such as the whole Mga core regulon and further genes under Mga control). In summary, the ERES region regulator Ralp3 is an important serotype-specific transcriptional regulator for virulence and metabolic control.
Collapse
|
20
|
Bidossi A, Mulas L, Decorosi F, Colomba L, Ricci S, Pozzi G, Deutscher J, Viti C, Oggioni MR. A functional genomics approach to establish the complement of carbohydrate transporters in Streptococcus pneumoniae. PLoS One 2012; 7:e33320. [PMID: 22428019 PMCID: PMC3302838 DOI: 10.1371/journal.pone.0033320] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 02/10/2012] [Indexed: 01/02/2023] Open
Abstract
The aerotolerant anaerobe Streptococcus pneumoniae is part of the normal nasopharyngeal microbiota of humans and one of the most important invasive pathogens. A genomic survey allowed establishing the occurrence of twenty-one phosphotransferase systems, seven carbohydrate uptake ABC transporters, one sodium:solute symporter and a permease, underlining an exceptionally high capacity for uptake of carbohydrate substrates. Despite high genomic variability, combined phenotypic and genomic analysis of twenty sequenced strains did assign the substrate specificity only to two uptake systems. Systematic analysis of mutants for most carbohydrate transporters enabled us to assign a phenotype and substrate specificity to twenty-three transport systems. For five putative transporters for galactose, pentoses, ribonucleosides and sulphated glycans activity was inferred, but not experimentally confirmed and only one transport system remains with an unknown substrate and lack of any functional annotation. Using a metabolic approach, 80% of the thirty-two fermentable carbon substrates were assigned to the corresponding transporter. The complexity and robustness of sugar uptake is underlined by the finding that many transporters have multiple substrates, and many sugars are transported by more than one system. The present work permits to draw a functional map of the complete arsenal of carbohydrate utilisation proteins of pneumococci, allows re-annotation of genomic data and might serve as a reference for related species. These data provide tools for specific investigation of the roles of the different carbon substrates on pneumococcal physiology in the host during carriage and invasive infection.
Collapse
Affiliation(s)
- Alessandro Bidossi
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Laura Mulas
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Francesca Decorosi
- Sezione Microbiologia, Dip. Biotecnologie Agrarie, Università degli Studi di Firenze, Firenze, Italy
| | - Leonarda Colomba
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Susanna Ricci
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
| | - Gianni Pozzi
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
- UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Carlo Viti
- Sezione Microbiologia, Dip. Biotecnologie Agrarie, Università degli Studi di Firenze, Firenze, Italy
| | - Marco Rinaldo Oggioni
- Lab. Microbiologia Molecolare e Biotecnologia, Dip. Biologia Molecolare, Università di Siena, Siena, Italy
- UOC Batteriologia, Azienda Ospedaliera Universitaria Senese, Siena, Italy
- * E-mail:
| |
Collapse
|
21
|
Zeng L, Das S, Burne RA. Genetic analysis of the functions and interactions of components of the LevQRST signal transduction complex of Streptococcus mutans. PLoS One 2011; 6:e17335. [PMID: 21364902 PMCID: PMC3043104 DOI: 10.1371/journal.pone.0017335] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 01/31/2011] [Indexed: 12/04/2022] Open
Abstract
Transcription of the genes for a fructan hydrolase (fruA) and a
fructose/mannose sugar:phosphotransferase permease (levDEFG) in
Streptococcus mutans is activated by a four-component
regulatory system consisting of a histidine kinase (LevS), a response regulator
(LevR) and two carbohydrate-binding proteins (LevQT). The expression of the
fruA and levD operons was at baseline in a
levQ mutant and substantially decreased in a
levT null mutant, with lower expression with the cognate
inducers fructose or mannose, but slightly higher expression in glucose or
galactose. A strain expressing levQ with two point mutations
(E170A/F292S) did not require inducers to activate gene expression and displayed
altered levD expression when growing on various carbohydrates,
including cellobiose. Linker-scanning (LS) mutagenesis was used to generate
three libraries of mutants of levQ, levS and
levT that displayed various levels of altered substrate
specificity and of fruA/levD gene expression. The data support
that LevQ and LevT are intimately involved in the sensing of carbohydrate
signals, and that LevQ appears to be required for the integrity of the signal
transduction complex, apparently by interacting with the sensor kinase LevS.
Collapse
Affiliation(s)
- Lin Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida, United States of America.
| | | | | |
Collapse
|
22
|
Zeng L, Burne RA. Seryl-phosphorylated HPr regulates CcpA-independent carbon catabolite repression in conjunction with PTS permeases in Streptococcus mutans. Mol Microbiol 2010; 75:1145-58. [PMID: 20487301 DOI: 10.1111/j.1365-2958.2009.07029.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Carbohydrate catabolite repression (CCR) in Streptococcus mutans can be independent of catabolite control protein A (CcpA) and requires specific components of phosphoenolpyruvate-dependent sugar:phosphotransferase system (PTS) permeases. Here, the effects of various ptsH (HPr) and hprK (HPr kinase/phosphatase) mutations on growth and CCR were evaluated. An hprKV265F mutation, which enhanced Ser46 phosphorylation of HPr, inhibited growth on multiple PTS sugars. A ptsHS46A mutation reversed the effects of hprKV265F in most cases. A strain carrying a ptsHS46D mutation, which mimics HPr(Ser-P), presented with more severe growth defects than the hprKV265F mutant. The hprKV265F mutant enhanced CCR of the fruA and levD operons, a phenotype reversible by the ptsHS46A mutation. The effects of the hprKV265F mutation on fruA and levD expression were independent of CcpA, but dependent on ManL (IIAB(Man)) and, to a lesser extent, on FruI (IIABC(Fru)), in a carbohydrate-specific fashion. Expression of the Bacillus subtilis ptsG gene in the manL mutant did not restore CCR of the lev or fru operons. The hprKV265F mutation inhibited growth on cellobiose and lactose, but only the transcription of the cel operon was decreased. Thus, in S. mutans, serine-phosphorylated HPr functions in concert with particular PTS permeases to prioritize carbohydrate utilization by modulating sugar transport and transcription of catabolic operons.
Collapse
Affiliation(s)
- Lin Zeng
- Department of Oral Biology, University of Florida, Gainesville, FL 32610, USA
| | | |
Collapse
|
23
|
Utilization of lactose and galactose by Streptococcus mutans: transport, toxicity, and carbon catabolite repression. J Bacteriol 2010. [PMID: 20190045 DOI: 10.1128/jb.01624–09] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abundant in milk and other dairy products, lactose is considered to have an important role in oral microbial ecology and can contribute to caries development in both adults and young children. To better understand the metabolism of lactose and galactose by Streptococcus mutans, the major etiological agent of human tooth decay, a genetic analysis of the tagatose-6-phosphate (lac) and Leloir (gal) pathways was performed in strain UA159. Deletion of each gene in the lac operon caused various alterations in expression of a P(lacA)-cat promoter fusion and defects in growth on either lactose (lacA, lacB, lacF, lacE, and lacG), galactose (lacA, lacB, lacD, and lacG) or both sugars (lacA, lacB, and lacG). Failure to grow in the presence of galactose or lactose by certain lac mutants appeared to arise from the accumulation of intermediates of galactose metabolism, particularly galatose-6-phosphate. The glucose- and lactose-PTS permeases, EII(Man) and EII(Lac), respectively, were shown to be the only effective transporters of galactose in S. mutans. Furthermore, disruption of manL, encoding EIIAB(Man), led to increased resistance to glucose-mediated CCR when lactose was used to induce the lac operon, but resulted in reduced lac gene expression in cells growing on galactose. Collectively, the results reveal a remarkably high degree of complexity in the regulation of lactose/galactose catabolism.
Collapse
|
24
|
Utilization of lactose and galactose by Streptococcus mutans: transport, toxicity, and carbon catabolite repression. J Bacteriol 2010; 192:2434-44. [PMID: 20190045 DOI: 10.1128/jb.01624-09] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abundant in milk and other dairy products, lactose is considered to have an important role in oral microbial ecology and can contribute to caries development in both adults and young children. To better understand the metabolism of lactose and galactose by Streptococcus mutans, the major etiological agent of human tooth decay, a genetic analysis of the tagatose-6-phosphate (lac) and Leloir (gal) pathways was performed in strain UA159. Deletion of each gene in the lac operon caused various alterations in expression of a P(lacA)-cat promoter fusion and defects in growth on either lactose (lacA, lacB, lacF, lacE, and lacG), galactose (lacA, lacB, lacD, and lacG) or both sugars (lacA, lacB, and lacG). Failure to grow in the presence of galactose or lactose by certain lac mutants appeared to arise from the accumulation of intermediates of galactose metabolism, particularly galatose-6-phosphate. The glucose- and lactose-PTS permeases, EII(Man) and EII(Lac), respectively, were shown to be the only effective transporters of galactose in S. mutans. Furthermore, disruption of manL, encoding EIIAB(Man), led to increased resistance to glucose-mediated CCR when lactose was used to induce the lac operon, but resulted in reduced lac gene expression in cells growing on galactose. Collectively, the results reveal a remarkably high degree of complexity in the regulation of lactose/galactose catabolism.
Collapse
|
25
|
Nobbs AH, Lamont RJ, Jenkinson HF. Streptococcus adherence and colonization. Microbiol Mol Biol Rev 2009; 73:407-50, Table of Contents. [PMID: 19721085 PMCID: PMC2738137 DOI: 10.1128/mmbr.00014-09] [Citation(s) in RCA: 431] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Streptococci readily colonize mucosal tissues in the nasopharynx; the respiratory, gastrointestinal, and genitourinary tracts; and the skin. Each ecological niche presents a series of challenges to successful colonization with which streptococci have to contend. Some species exist in equilibrium with their host, neither stimulating nor submitting to immune defenses mounted against them. Most are either opportunistic or true pathogens responsible for diseases such as pharyngitis, tooth decay, necrotizing fasciitis, infective endocarditis, and meningitis. Part of the success of streptococci as colonizers is attributable to the spectrum of proteins expressed on their surfaces. Adhesins enable interactions with salivary, serum, and extracellular matrix components; host cells; and other microbes. This is the essential first step to colonization, the development of complex communities, and possible invasion of host tissues. The majority of streptococcal adhesins are anchored to the cell wall via a C-terminal LPxTz motif. Other proteins may be surface anchored through N-terminal lipid modifications, while the mechanism of cell wall associations for others remains unclear. Collectively, these surface-bound proteins provide Streptococcus species with a "coat of many colors," enabling multiple intimate contacts and interplays between the bacterial cell and the host. In vitro and in vivo studies have demonstrated direct roles for many streptococcal adhesins as colonization or virulence factors, making them attractive targets for therapeutic and preventive strategies against streptococcal infections. There is, therefore, much focus on applying increasingly advanced molecular techniques to determine the precise structures and functions of these proteins, and their regulatory pathways, so that more targeted approaches can be developed.
Collapse
Affiliation(s)
- Angela H Nobbs
- Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Bristol BS1 2LY, United Kingdom
| | | | | |
Collapse
|
26
|
Gryllos I, Grifantini R, Colaprico A, Cary ME, Hakansson A, Carey DW, Suarez-Chavez M, Kalish LA, Mitchell PD, White GL, Wessels MR. PerR confers phagocytic killing resistance and allows pharyngeal colonization by group A Streptococcus. PLoS Pathog 2008; 4:e1000145. [PMID: 18773116 PMCID: PMC2518855 DOI: 10.1371/journal.ppat.1000145] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Accepted: 08/07/2008] [Indexed: 01/24/2023] Open
Abstract
The peroxide response transcriptional regulator, PerR, is thought to contribute to virulence of group A Streptococcus (GAS); however, the specific mechanism through which it enhances adaptation for survival in the human host remains unknown. Here, we identify a critical role of PerR-regulated gene expression in GAS phagocytosis resistance and in virulence during pharyngeal infection. Deletion of perR in M-type 3 strain 003Sm was associated with reduced resistance to phagocytic killing in human blood and by murine macrophages in vitro. The increased phagocytic killing of the perR mutant was abrogated in the presence of the general oxidative burst inhibitor diphenyleneiodonium chloride (DPI), a result that suggests PerR-dependent gene expression counteracts the phagocyte oxidative burst. Moreover, an isogenic perR mutant was severely attenuated in a baboon model of GAS pharyngitis. In competitive infection experiments, the perR mutant was cleared from two animals at 24 h and from four of five animals by day 14, in sharp contrast to wild-type bacteria that persisted in the same five animals for 28 to 42 d. GAS genomic microarrays were used to compare wild-type and perR mutant transcriptomes in order to characterize the PerR regulon of GAS. These studies identified 42 PerR-dependent loci, the majority of which had not been previously recognized. Surprisingly, a large proportion of these loci are involved in sugar utilization and transport, in addition to oxidative stress adaptive responses and virulence. This finding suggests a novel role for PerR in mediating sugar uptake and utilization that, together with phagocytic killing resistance, may contribute to GAS fitness in the infected host. We conclude that PerR controls expression of a diverse regulon that enhances GAS resistance to phagocytic killing and allows adaptation for survival in the pharynx.
Collapse
Affiliation(s)
- Ioannis Gryllos
- Division of Infectious Diseases, Children's Hospital Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| | | | | | - Max E. Cary
- Department of Pathology and Comparative Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Anders Hakansson
- Division of Infectious Diseases, Children's Hospital Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - David W. Carey
- Department of Pathology and Comparative Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Maria Suarez-Chavez
- Department of Pathology and Comparative Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Leslie A. Kalish
- Division of Infectious Diseases, Children's Hospital Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
- Clinical Research Program, Children's Hospital Boston, Boston, Massachusetts, United States of America
| | - Paul D. Mitchell
- Division of Infectious Diseases, Children's Hospital Boston, Massachusetts, United States of America
- Clinical Research Program, Children's Hospital Boston, Boston, Massachusetts, United States of America
| | - Gary L. White
- Department of Pathology and Comparative Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Michael R. Wessels
- Division of Infectious Diseases, Children's Hospital Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| |
Collapse
|
27
|
Ajdić D, Pham VTT. Global transcriptional analysis of Streptococcus mutans sugar transporters using microarrays. J Bacteriol 2007; 189:5049-59. [PMID: 17496079 PMCID: PMC1951856 DOI: 10.1128/jb.00338-07] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transport of carbohydrates by Streptococcus mutans is accomplished by the phosphoenolpyruvate-phosphotransferase system (PTS) and ATP-binding cassette (ABC) transporters. To undertake a global transcriptional analysis of all S. mutans sugar transporters simultaneously, we used a whole-genome expression microarray. Global transcription profiles of S. mutans UA159 were determined for several monosaccharides (glucose, fructose, galactose, and mannose), disaccharides (sucrose, lactose, maltose, and trehalose), a beta-glucoside (cellobiose), oligosaccharides (raffinose, stachyose, and maltotriose), and a sugar alcohol (mannitol). The results revealed that PTSs were responsible for transport of monosaccharides, disaccharides, beta-glucosides, and sugar alcohol. Six PTSs were transcribed only if a specific sugar was present in the growth medium; thus, they were regulated at the transcriptional level. These included transporters for fructose, lactose, cellobiose, and trehalose and two transporters for mannitol. Three PTSs were repressed under all conditions tested. Interestingly, five PTSs were always highly expressed regardless of the sugar source used, presumably suggesting their availability for immediate uptake of most common dietary sugars (glucose, fructose, maltose, and sucrose). The ABC transporters were found to be specific for oligosaccharides, raffinose, stachyose, and isomaltosaccharides. Compared to the PTSs, the ABC transporters showed higher transcription under several tested conditions, suggesting that they might be transporting multiple substrates.
Collapse
Affiliation(s)
- Dragana Ajdić
- University of Oklahoma Health Sciences Center, Department of Microbiology and Immunology, 940 S. L. Young Blvd., Oklahoma City, OK 73104, USA.
| | | |
Collapse
|
28
|
Abstract
Having no known environmental reservoir, Streptococcus pyogenes, a bacterium responsible for a wider variety of human diseases than any other bacterial species, must rely on its host for metabolic substrates. Although a streptococcal aldolase, LacD.1, has been adapted to virulence gene regulation, both LacD.1 and a paralogous protein, LacD.2, are predicted to function in the tagatose 6-phosphate pathway for lactose and galactose utilization. In order to gain insight into the mechanism of the LacD.1 regulatory pathway and the role of genome context in the emergence of LacD.1's novel regulatory functions, we compared the function and regulation of the Lac.1 and Lac.2 loci. The Lac.1 operon is not inducible, and regulation by LacD.1 is independent of a functional tagatose 6-phosphate pathway and enhanced by the conserved truncation of upstream Lac.1 genes. In contrast, Lac.2 expression is sensitive to environmental carbohydrates, and LacD.2, not LacD.1, contributes to growth on galactose. Thus, we conclude that the Lac.1 locus has been specialized to participate in regulation, leaving efficient utilization of carbohydrate sources to the Lac.2 locus. The adaptation of LacD for transcription regulation may be an underappreciated strategy among prokaryotes, as homologues of this multifaceted enzyme are present in a broad range of species.
Collapse
Affiliation(s)
- Jennifer A Loughman
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110-1093, USA.
| | | |
Collapse
|
29
|
Yu Y, Tangney M, Aass HC, Mitchell WJ. Analysis of the mechanism and regulation of lactose transport and metabolism in Clostridium acetobutylicum ATCC 824. Appl Environ Microbiol 2007; 73:1842-50. [PMID: 17209069 PMCID: PMC1828815 DOI: 10.1128/aem.02082-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although the acetone-butanol-ethanol fermentation of Clostridium acetobutylicum is currently uneconomic, the ability of the bacterium to metabolize a wide range of carbohydrates offers the potential for revival based on the use of cheap, low-grade substrates. We have investigated the uptake and metabolism of lactose, the major sugar in industrial whey waste, by C. acetobutylicum ATCC 824. Lactose is taken up via a phosphoenolpyruvate-dependent phosphotransferase system (PTS) comprising both soluble and membrane-associated components, and the resulting phosphorylated derivative is hydrolyzed by a phospho-beta-galactosidase. These activities are induced during growth on lactose but are absent in glucose-grown cells. Analysis of the C. acetobutylicum genome sequence identified a gene system, lacRFEG, encoding a transcriptional regulator of the DeoR family, IIA and IICB components of a lactose PTS, and phospho-beta-galactosidase. During growth in medium containing both glucose and lactose, C. acetobutylicum exhibited a classical diauxic growth, and the lac operon was not expressed until glucose was exhausted from the medium. The presence upstream of lacR of a potential catabolite responsive element (cre) encompassing the transcriptional start site is indicative of the mechanism of carbon catabolite repression characteristic of low-GC gram-positive bacteria. A pathway for the uptake and metabolism of lactose by this industrially important organism is proposed.
Collapse
Affiliation(s)
- Yang Yu
- School of Life Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom
| | | | | | | |
Collapse
|
30
|
Loughman JA, Caparon MG. A novel adaptation of aldolase regulates virulence in Streptococcus pyogenes. EMBO J 2006; 25:5414-22. [PMID: 17066081 PMCID: PMC1636624 DOI: 10.1038/sj.emboj.7601393] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Accepted: 09/26/2006] [Indexed: 11/09/2022] Open
Abstract
Regulation of virulence factor expression is critical for pathogenic microorganisms that must sense and adapt to a dynamic host environment; yet, the signal transduction pathways that enable this process are generally poorly understood. Here, we identify LacD.1 as a global regulator of virulence factor expression in the versatile human pathogen, Streptococcus pyogenes. LacD.1 is derived from a class I tagatose-1,6-bisphosphate aldolase homologous to those involved in lactose and galactose metabolism in related prokaryotes. However, regulation of transcription by LacD.1 is not dependent on this enzymatic activity or the canonical catabolite repression pathway, but likely does require substrate recognition. Our results suggest that LacD.1 has been adapted as a metabolic sensor, and raise the possibility that regulation of gene expression by metabolic enzymes may be a novel mechanism by which Gram-positive bacteria, including S. pyogenes, coordinate multiple environmental cues, allowing essential transcription programs to be coupled with perceived nutritional status.
Collapse
Affiliation(s)
- Jennifer A Loughman
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA
| | - Michael G Caparon
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA
- Department of Molecular Microbiology, Washington University School of Medicine, Campus Box 8230, 660 S. Euclid Ave., St Louis, MO 63110-1093, USA. Tel.: +1 314 362 1485; Fax: +1 314 362 3203; E-mail:
| |
Collapse
|
31
|
Tsai YK, Lin TH. Sequence, organization, transcription and regulation of lactose and galactose operons in Lactobacillus rhamnosus TCELL-1. J Appl Microbiol 2006; 100:446-59. [PMID: 16478484 DOI: 10.1111/j.1365-2672.2005.02790.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Understanding the metabolism of lactose and galactose and their regulation in Lactobacillus rhamnosus. METHODS AND RESULTS A gene cluster containing nine open reading frames (ORFs) involved in the metabolism of lactose and galactose in Lact. rhamnosus TCELL-1 was sequenced and characterized. The order of the ORFs was lacTEGF and galKETRM. Northern blotting experiments revealed that the gene cluster could be transcribed as one lacTEGF-galKETRM mRNA though three major transcripts (lacTEGF, galKETRM and galETRM) were detected for the gene cluster. The transcription of the lac or gal operon was independently induced in the presence of lactose or galactose. Northern blotting and primer extension experiments found the presence of four putative promoters upstream from the ORFs lacT (lacTp), galK (galKp1 and galKp2) and galE (galEp). The measurements of enzymatic activities of GalK, GalE and GalT suggested that the expression of the gal operon was subjected to a galactose activation and glucose repression mechanism. CONCLUSIONS In Lact. rhamnosus TCELL-1, the galactose moiety of lactose could be metabolized by two alternative pathways (the Leloir and the tagatose 6-phosphate pathways) whereas galactose metabolism could be mediated by the Leloir pathway. SIGNIFICANCE AND IMPACT OF THE STUDY This work provides important information about sugar metabolism in Lact. rhamnosus.
Collapse
Affiliation(s)
- Y-K Tsai
- Institute of Molecular Medicine and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | | |
Collapse
|
32
|
Old LA, Lowes S, Russell RRB. Genomic variation in Streptococcus mutans: deletions affecting the multiple pathways of β-glucoside metabolism. ACTA ACUST UNITED AC 2006; 21:21-7. [PMID: 16390337 DOI: 10.1111/j.1399-302x.2005.00246.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The genome of Streptococcus mutans UA159 contains two phospho-beta-glucosidase genes, bglA and celA, which occur in operon-like arrangements along with genes for components of phosphotransferase transport systems and a third phospho-beta-glucosidase encoded by the arb gene, which does not have its own associated transport system but relies on uptake by the bgl or cel systems. Targeted inactivation of each of the phospho-beta-glucosidase genes revealed that bglA is involved in aesculin hydrolysis, celA is essential for utilisation of cellobiose, amygdalin, gentobiose and salicin, and arb is required for utilisation of arbutin. Inactivation of genes for the phosphotransferase systems revealed an overlap of specificity for transport of beta-glucosides and also indicated that further, unidentified transport systems exist. The cel and arb genes are subject to catabolite repression by glucose, but the regM gene is not essential for catabolite repression. Screening a collection of isolates of S. mutans revealed strains with deletions affecting the msm, bgl and/or cel operons. The phenotypes of these strains could largely be explained on the basis of the results obtained from the knockout mutants of S. mutans UA159 but also indicated the existence of other pathways apparently absent from UA159. The extensive genetic and phenotypic variation found in beta-glucoside metabolism indicates that there may be extensive heterogeneity in the species.
Collapse
Affiliation(s)
- L A Old
- Oral Biology, School of Dental Sciences, University of Newcastle, Newcastle upon Tyne, UK
| | | | | |
Collapse
|
33
|
Aleksandrzak-Piekarczyk T, Kok J, Renault P, Bardowski J. Alternative lactose catabolic pathway in Lactococcus lactis IL1403. Appl Environ Microbiol 2005; 71:6060-9. [PMID: 16204522 PMCID: PMC1265982 DOI: 10.1128/aem.71.10.6060-6069.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, we present a glimpse of the diversity of Lactococcus lactis subsp. lactis IL1403 beta-galactosidase phenotype-negative mutants isolated by negative selection on solid media containing cellobiose or lactose and X-Gal (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside), and we identify several genes essential for lactose assimilation. Among these are ccpA (encoding catabolite control protein A), bglS (encoding phospho-beta-glucosidase), and several genes from the Leloir pathway gene cluster encoding proteins presumably essential for lactose metabolism. The functions of these genes were demonstrated by their disruption and testing of the growth of resultant mutants in lactose-containing media. By examining the ccpA and bglS mutants for phospho-beta-galactosidase activity, we showed that expression of bglS is not under strong control of CcpA. Moreover, this analysis revealed that although BglS is homologous to a putative phospho-beta-glucosidase, it also exhibits phospho-beta-galactosidase activity and is the major enzyme in L. lactis IL1403 involved in lactose hydrolysis.
Collapse
|
34
|
Abstract
The galK gene, encoding galactokinase of the Leloir pathway, was insertionally inactivated in Streptococcus mutans UA159. The galK knockout strain displayed only marginal growth on galactose, but growth on glucose or lactose was not affected. In strain UA159, the sugar phosphotransferase system (PTS) for lactose and the PTS for galactose were induced by growth in lactose and galactose, although galactose PTS activity was very low, suggesting that S. mutans does not have a galactose-specific PTS and that the lactose PTS may transport galactose, albeit poorly. To determine if the galactose growth defect of the galK mutant could be overcome by enhancing lactose PTS activity, the gene encoding a putative repressor of the operon for lactose PTS and phospho-beta-galactosidase, lacR, was insertionally inactivated. A galK and lacR mutant still could not grow on galactose, although the strain had constitutively elevated lactose PTS activity. The glucose PTS activity of lacR mutants grown in glucose was lower than in the wild-type strain, revealing an influence of LacR or the lactose PTS on the regulation of the glucose PTS. Mutation of the lacA gene of the tagatose pathway caused impaired growth in lactose and galactose, suggesting that galactose can only be efficiently utilized when both the Leloir and tagatose pathways are functional. A mutation of the permease in the multiple sugar metabolism operon did not affect growth on galactose. Thus, the galactose permease of S. mutans is not present in the gal, lac, or msm operons.
Collapse
Affiliation(s)
- Jacqueline Abranches
- Department of Oral Biology, University of Florida College of Dentistry, P.O. Box 100424, Gainesville, FL 32610, USA
| | | | | |
Collapse
|
35
|
Wang T, Shen G, Balasubramanian R, McIntosh L, Bryant DA, Golbeck JH. The sufR gene (sll0088 in Synechocystis sp. strain PCC 6803) functions as a repressor of the sufBCDS operon in iron-sulfur cluster biogenesis in cyanobacteria. J Bacteriol 2004; 186:956-67. [PMID: 14761990 PMCID: PMC344230 DOI: 10.1128/jb.186.4.956-967.2004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Accepted: 11/11/2003] [Indexed: 11/20/2022] Open
Abstract
The suf operon is composed of four genes (sufB, sufC, sufD, and sufS) and is highly conserved in the genomes of cyanobacteria. Open reading frame sll0088 in Synechocystis sp. strain PCC 6803 is located near the 5' end of the suf operon but is transcribed in the direction opposite that of the suf operon. We previously reported the isolation of two independent suppressor strains of C14S(PsaC) that mapped to sll0088 and restored photoautotrophic growth. The protein encoded by sll0088 has two significant features: (i) a DNA-binding domain near the N terminus and (ii) four highly conserved cysteine residues near the C terminus. The protein has high sequence similarity to transcription regulatory proteins with a conserved DNA-binding domain and can be classified in the DeoR family of helix-loop-helix proteins. The protein falls into a further subclass that contains a C-X(12)-C-X(13)-C-X(14)-C motif near the C terminus, which may represent a metal-binding site. The expressed Sll0088 protein harbored an iron-sulfur cluster as shown by optical and electron paramagnetic resonance spectroscopy. Compared to the wild type, expression levels of the sufBCDS genes were elevated when cells were grown under conditions of oxidative and iron stress and were even higher in a null mutant of Synechococcus sp. strain PCC 7002 in which the sll0088 homolog was insertionally inactivated. In agreement with the proposed role of the sufBCDS genes in iron metabolism, the growth rate of the null mutant was significantly higher than that of the wild type under iron-limiting conditions. We propose that the protein encoded by sll0088 is a transcriptional repressor of the suf operon, and we name the gene sufR.
Collapse
Affiliation(s)
- Tao Wang
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | | | | | | | | |
Collapse
|
36
|
Yu J, Shen G, Wang T, Bryant DA, Golbeck JH, McIntosh L. Suppressor mutations in the study of photosystem I biogenesis: sll0088 is a previously unidentified gene involved in reaction center accumulation in Synechocystis sp. strain PCC 6803. J Bacteriol 2003; 185:3878-87. [PMID: 12813082 PMCID: PMC161560 DOI: 10.1128/jb.185.13.3878-3887.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2003] [Accepted: 04/16/2003] [Indexed: 11/20/2022] Open
Abstract
In previous work, some members of our group isolated mutant strains of Synechocystis sp. strain PCC 6803 in which point mutations had been inserted into the psaC gene to alter the cysteine residues to the F(A) and F(B) iron-sulfur clusters in the PsaC subunit of photosystem I (J. P. Yu, I. R. Vassiliev, Y. S. Jung, J. H. Golbeck, and L. McIntosh, J. Biol. Chem. 272:8032-8039, 1997). These mutant strains did not grow photoautotrophically due to suppressed levels of chlorophyll a and photosystem I. In the results described here, we show that suppressor mutations produced strains that are capable of photoautotrophic growth at moderate light intensity (20 micromol m(-2) s(-1)). Two separate suppressor strains of C14S(PsaC), termed C14S(PsaC)-R62 and C14S(PsaC)-R18, were studied and found to have mutations in a previously uncharacterized open reading frame of the Synechocystis sp. strain PCC 6803 genome named sll0088. C14S(PsaC)-R62 was found to substitute Pro for Arg at residue 161 as the result of a G482-->C change in sll0088, and C14S(PsaC)-R18 was found to have a three-amino-acid insertion of Gly-Tyr-Phe following Cys231 as the result of a TGGTTATTT duplication at T690 in sll0088. These suppressor strains showed near-wild-type levels of chlorophyll a and photosystem I, yet the serine oxygen ligand to F(B) was retained as shown by the retention of the S > or = 3/2 spin state of the [4Fe-4S] cluster. The inactivation of sll0088 by insertion of a kanamycin resistance cartridge in the primary C14S(PsaC) mutant produced an engineered suppressor strain capable of photoautotrophic growth. There was no difference in psaC gene expression or in the amount of PsaC protein assembled in thylakoids between the wild type and an sll0088 deletion mutant. The sll0088 gene encodes a protein predicted to be a transcriptional regulator with sequence similarities to transcription factors in other prokaryotic and eukaryotic organisms, including Arabidopsis thaliana. The protein contains a typical helix-turn-helix DNA-binding motif and can be classified as a negative regulator by phylogenetic analysis. This suggests that the product of sll0088 has a role in regulating the biogenesis of photosystem I.
Collapse
Affiliation(s)
- Jianping Yu
- MSU-DOE Plant Research Laboratory and Biochemistry and Molecular Biology Department, Michigan State University, East Lansing, Michigan 48824, USA
| | | | | | | | | | | |
Collapse
|
37
|
Chan PF, O'Dwyer KM, Palmer LM, Ambrad JD, Ingraham KA, So C, Lonetto MA, Biswas S, Rosenberg M, Holmes DJ, Zalacain M. Characterization of a novel fucose-regulated promoter (PfcsK) suitable for gene essentiality and antibacterial mode-of-action studies in Streptococcus pneumoniae. J Bacteriol 2003; 185:2051-8. [PMID: 12618474 PMCID: PMC150135 DOI: 10.1128/jb.185.6.2051-2058.2003] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The promoter of the Streptococcus pneumoniae putative fuculose kinase gene (fcsK), the first gene of a novel fucose utilization operon, is induced by fucose and repressed by glucose or sucrose. When the streptococcal polypeptide deformylase (PDF) gene (def1, encoding PDF) was placed under the control of P(fcsK), fucose-dependent growth of the S. pneumoniae (P(fcsK)::def1) strain was observed, confirming the essential nature of PDF in this organism. The mode of antibacterial action of actinonin, a known PDF inhibitor, was also confirmed with this strain. The endogenous fuculose kinase promoter is a tightly regulated, titratable promoter which will be useful for target validation and for confirmation of the mode of action of novel antibacterial drugs in S. pneumoniae.
Collapse
Affiliation(s)
- Pan F Chan
- Microbial, Musculoskeletal and Proliferative Diseases Center of Excellence for Drug Discovery, GlaxoSmithKline Pharmaceuticals, Collegeville, Pennsylvania 19426, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Songy WB, Ruoff KL, Facklam RR, Ferraro MJ, Falkow S. Identification of Streptococcus bovis biotype I strains among S. bovis clinical isolates by PCR. J Clin Microbiol 2002; 40:2913-8. [PMID: 12149351 PMCID: PMC120625 DOI: 10.1128/jcm.40.8.2913-2918.2002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2002] [Accepted: 04/24/2002] [Indexed: 11/20/2022] Open
Abstract
Streptococcus bovis causes 24% of all streptococcal infective endocarditis cases. There are many reports linking both S. bovis bacteremia and endocarditis with various forms of gastrointestinal disease (primarily colonic cancers). S. bovis is divided into two biotypes: I and II. The biotype I strain is much more frequently isolated from patients with endocarditis, gastrointestinal disease, or both. We describe here the isolation of biotype I-specific DNA sequences and the development of a PCR test which can identify S. bovis biotype I strains among S. bovis clinical isolates.
Collapse
Affiliation(s)
- Wanda B Songy
- Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305, USA
| | | | | | | | | |
Collapse
|
39
|
Benchabane H, Lortie LA, Buckley ND, Trahan L, Frenette M. Inactivation of the Streptococcus mutans fxpC gene confers resistance to xylitol, a caries-preventive natural carbohydrate sweetener. J Dent Res 2002; 81:380-6. [PMID: 12097428 DOI: 10.1177/0810380] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Xylitol is transported by Streptococcus mutans via a constitutive phosphoenolpyruvate:fructose phosphotransferase system (PTS) composed of a IIABC protein. Spontaneous xylitol-resistant strains are depleted in constitutive fructose-PTS activity, exhibit additional phenotypes, and are associated with the caries-preventive properties of xylitol. Polymerase chain-reactions and chromosome walking were used to clone the fxp operon that codes for the constitutive fructose/xylitol-PTS. The operon contained three open reading frames: fxpA, which coded for a putative regulatory protein of the deoxyribose repressor (DeoR) family, fxpB, which coded for a 1-phosphofructokinase, and fxpC, which coded for a IIABC protein of the fructose-PTS family. Northern blot analysis revealed that these genes were co-transcribed into a 4.4-kb mRNA even in the absence of fructose. Inactivation of the fxpC gene conferred resistance to xylitol, confirming its function. The fxp operon is also present in the genomes of other xylitol-sensitive streptococci, which could explain their sensitivity to xylitol.
Collapse
Affiliation(s)
- H Benchabane
- Groupe de Recherche en Ecologie Buccale, Département de Biochimie et Microbiologie (Sciences) and Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada, G1K 7P4
| | | | | | | | | |
Collapse
|
40
|
Honeyman AL, Cote CK, Curtiss R. Construction of transcriptional and translational lacZ gene reporter plasmids for use in Streptococcus mutans. J Microbiol Methods 2002; 49:163-71. [PMID: 11830302 DOI: 10.1016/s0167-7012(01)00368-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Reporter genes have become standard genetic tools used to evaluate either the transcriptional or the translational activity associated with genes of interest, whose products cannot be easily assayed. The lacZ gene from Escherichia coli has been used very effectively to quantify such regulated activities in many different organisms. This report describes the construction of a pair of plasmids that may be used for either transcriptional or translational lacZ gene fusions in Streptococcus mutans. The translational E. coli beta-galactosidase gene (lacZ) fusion plasmid, pALH109, as well as the transcriptional lacZ gene fusion plasmid, pALH122, have been used successfully in S. mutans to measure the activity of various PTS genes. Both plasmids employ fusions with the E. coli lacZ gene that can be easily quantified using standard O-nitrophenyl-beta-D-galactopyranoside (ONPG) based enzyme assays or the more sensitive fluorometric assays using 4-methyl-umbelliferyl beta-D-galactopyranoside (MUG) as the enzyme substrate. Currently, there has been only one other report of the use of lacZ as a gene reporter in S. mutans. The plasmids described in this paper will provide new tools and techniques for the analysis of S. mutans gene regulation. In addition, we have compiled the complete nucleotide sequences of these gene reporter plasmids.
Collapse
Affiliation(s)
- Allen L Honeyman
- Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, 12901 Bruce B. Downs Boulevard, Tampa, FL 33612, USA.
| | | | | |
Collapse
|
41
|
Chen YYM, Betzenhauser MJ, Snyder JA, Burne RA. Pathways for lactose/galactose catabolism by Streptococcus salivarius. FEMS Microbiol Lett 2002; 209:75-9. [PMID: 12007657 DOI: 10.1111/j.1574-6968.2002.tb11112.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Galactokinase and beta-galactosidase-deficient strains of Streptococcus salivarius were constructed to define the pathways for lactose and galactose catabolism. It was found that S. salivarius does not possess a lactose-specific phosphoenolpyruvate phosphotransferase system (PTS), that intracellular lactose was hydrolyzed by beta-galactosidase, and that galactose is catabolized exclusively through the Leloir pathway. The lack of a high-affinity PTS for lactose may reflect the higher availability of the substrates to soft tissue organisms, such as S. salivarius, compared to dental plaque bacteria.
Collapse
Affiliation(s)
- Yi-Ywan M Chen
- Department of Oral Biology, University of Florida College of Dentistry, 1600 SW Archer Road, P.O. Box 100424, Gainesville 32610, USA
| | | | | | | |
Collapse
|
42
|
Cote CK, Honeyman AL. The transcriptional regulation of the Streptococcus mutans bgl regulon. ORAL MICROBIOLOGY AND IMMUNOLOGY 2002; 17:1-8. [PMID: 11860549 DOI: 10.1046/j.0902-0055.2001.00087.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A beta-glucoside utilization regulon recently isolated from Streptococcus mutans has been shown to contain genes involved in beta-glucoside hydrolysis and a putative regulator. The bglP gene encodes a beta-glucoside-specific enzyme II (EII) component of the phosphoenolpyruvate-dependent phosphotransferase system, the bglC gene encodes a putative transcriptional regulator, and the bglA gene encodes a putative phospho-beta-glucosidase. To investigate the transcriptional activity of these genes, the putative promoter regions of the bglP, bglC and bglA genes were fused with the E. coli lacZ reporter gene. The resultant reporter plasmids were used to monitor the transcriptional activity of these loci in S. mutans. The results illustrate that these genes are not repressed by glucose in the presence of an inducing beta-glucoside, esculin, to the levels of expression observed in the absence of esculin. Therefore, these loci are not subject to catabolite repression by glucose to noninduced levels of expression. The bglC gene product was determined to be a positive transcriptional regulator of the bglA gene but does not regulate the expression of the bglP gene. Thus, regulation of these loci requires different and multiple control mechanisms.
Collapse
Affiliation(s)
- C K Cote
- Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, 12901 Bruce B. Downs Boulevard, Tampa, FL 33612, USA
| | | |
Collapse
|
43
|
Honeyman AL, Curtiss R. The mannitol-specific enzyme II (mtlA) gene and the mtlR gene of the PTS of Streptococcus mutans. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 7):1565-1572. [PMID: 10878121 DOI: 10.1099/00221287-146-7-1565] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The phosphoenolpyruvate-dependent phosphotransferase system (PTS) is widely found among Gram-positive bacteria. It is the major source of carbohydrate transport in the dental pathogen Streptococcus mutans. The transported carbohydrates are fermented to produce large amounts of lactic acid which initiates dental caries. The authors have isolated the S. mutans gene for the mannitol-specific Enzyme II (EII) component of the PTS, mtlA, and the adjacent mtlR gene, which is located in the same operon. The mtlR gene is located between mtlA and the genes mtlF and mtlD. The nucleotide sequence of the mtlA and mtlR loci has been determined. The deduced mtlA gene product of S. mutans consists of 589 amino acids with a molecular mass of 62.0 kDa. It exhibits similarity with the mtlA gene products from other organisms. However, the similarity between these proteins is generally restricted to the 470 amino-terminal residues of the S. mutans protein. This region would correspond to the EIICB domains of the PTS. The authors have previously shown that the S. mutans mtlF gene product exhibits 76.6% similarity to the carboxyl-terminal 143 amino acids of the Escherichia coli mtlA product and that the mtlF gene encodes the EIIA domain of the PTS. Thus, the genes that encode the EIICB and the EIIA domains are separated by approximately 2250 bp. In many organisms, all of the EII domains may be fused together to form one molecule. The fact that these domains are separated by this distance in S. mutans supports the hypothesis that various functional domains of the PTS have been rearranged during evolution. The sequence of the 119 carboxyl-terminal amino acids of the S. mutans mtlA gene product also displays homology to the carboxyl-terminal end of the EIIB domain of various mannitol PTSs. Thus, this domain may have been duplicated in S. mutans during evolution of the operon. The mtlR gene is located in the same operon structure as mtlA but these loci are separated by an intragenic space. The precise 5' end of the mtlR locus cannot be determined either by in vitro transcription-translation assays or based upon nucleotide sequence analysis because of the apparent lack of a ribosome-binding site preceding the gene. The deduced mtlR gene product, which consists of approximately 650 amino acids with a molecular mass of 75.3 kDa, exhibits limited similarity to several potential transcriptional regulators. However, the exact function of this locus is currently unknown.
Collapse
Affiliation(s)
- Allen L Honeyman
- Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, 12901 Bruce B. Downs Boulevard, Tampa, FL 33612, USA2
- Department of Biology, Washington University, St Louis, MO 63130, USA1
| | - Roy Curtiss
- Department of Biology, Washington University, St Louis, MO 63130, USA1
| |
Collapse
|
44
|
Pérez-Rueda E, Collado-Vides J. The repertoire of DNA-binding transcriptional regulators in Escherichia coli K-12. Nucleic Acids Res 2000; 28:1838-47. [PMID: 10734204 PMCID: PMC102813 DOI: 10.1093/nar/28.8.1838] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Using a combination of several approaches we estimated and characterized a total of 314 regulatory DNA-binding proteins in Escherichia coli, which might represent its minimal set of transcription factors. The collection is comprised of 35% activators, 43% repressors and 22% dual regulators. Within many regulatory protein families, the members are homogeneous in their regulatory roles, physiology of regulated genes, regulatory function, length and genome position, showing that these families have evolved homogeneously in prokaryotes, particularly in E.coli. This work describes a full characterization of the repertoire of regulatory interactions in a whole living cell. This repertoire should contribute to the interpretation of global gene expression profiles in both prokaryotes and eukaryotes.
Collapse
Affiliation(s)
- E Pérez-Rueda
- Programa de Biología Molecular Computacional, Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, AP 565-A 62110, Mexico
| | | |
Collapse
|
45
|
Coombs JM, Brenchley JE. Biochemical and phylogenetic analyses of a cold-active beta-galactosidase from the lactic acid bacterium Carnobacterium piscicola BA. Appl Environ Microbiol 1999; 65:5443-50. [PMID: 10584002 PMCID: PMC91742 DOI: 10.1128/aem.65.12.5443-5450.1999] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We are investigating glycosyl hydrolases from new psychrophilic isolates to examine the adaptations of enzymes to low temperatures. A beta-galactosidase from isolate BA, which we have classified as a strain of the lactic acid bacterium Carnobacterium piscicola, was capable of hydrolyzing the chromogen 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside (X-Gal) at 4 degrees C and possessed higher activity in crude cell lysates at 25 than at 37 degrees C. Sequence analysis of a cloned DNA fragment encoding this activity revealed a gene cluster containing three glycosyl hydrolases with homology to an alpha-galactosidase and two beta-galactosidases. The larger of the two beta-galactosidase genes, bgaB, encoded the 76.8-kDa cold-active enzyme. This gene was homologous to family 42 glycosyl hydrolases, a group which contains several thermophilic enzymes but none from lactic acid bacteria. The bgaB gene from isolate BA was subcloned in Escherichia coli, and its enzyme, BgaB, was purified. The purified enzyme was highly unstable and required 10% glycerol to maintain activity. Its optimal temperature for activity was 30 degrees C, and it was inactivated at 40 degrees C in 10 min. The K(m) of freshly purified enzyme at 30 degrees C was 1.7 mM, and the V(max) was 450 micromol. min(-1). mg(-1) with o-nitrophenyl beta-D-galactopyranoside. This cold-active enzyme is interesting because it is homologous to a thermophilic enzyme from Bacillus stearothermophilus, and comparisons could provide information about structural features important for activity at low temperatures.
Collapse
Affiliation(s)
- J M Coombs
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | |
Collapse
|
46
|
Cappiello MG, Hantman MJ, Zuccon FM, Peruzzi F, Amjad M, Piggot PJ, Daneo-Moore L. Physical and genetic map of Streptococcus mutans GS-5 and localization of five rRNA operons. ORAL MICROBIOLOGY AND IMMUNOLOGY 1999; 14:225-32. [PMID: 10551166 DOI: 10.1034/j.1399-302x.1999.140405.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The physical map of the 2.1 megabase chromosome of Streptococcus mutans GS-5 has been refined by including all ApaI and SmaI fragments of 5 kbp or greater, and by positioning the fragments generated by the endonuclease I-CeuI. Sixty-three new genetic loci have been added to the map, so that it now contains 90 loci. The new loci include those for 35 cloned streptococcal genes of established function and for 23 S. mutans genes of putative function. In addition, five rrn operons were identified and placed on the map of the chromosome. The presence of a SmaI site in each of the rrn operons allowed the direction of transcription of each operon to be deduced. The orientation of the rrn loci indicates that their transcription is directed away from a small region of the chromosome, identifying a possible region for the initiation of chromosome replication.
Collapse
Affiliation(s)
- M G Cappiello
- Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
| | | | | | | | | | | | | |
Collapse
|
47
|
Henstra SA, Tuinhof M, Duurkens RH, Robillard GT. The Bacillus stearothermophilus mannitol regulator, MtlR, of the phosphotransferase system. A DNA-binding protein, regulated by HPr and iicbmtl-dependent phosphorylation. J Biol Chem 1999; 274:4754-63. [PMID: 9988713 DOI: 10.1074/jbc.274.8.4754] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
D-Mannitol is taken up by Bacillus stearothermophilus and phosphorylated via a phosphoenolpyruvate-dependent phosphotransferase system (PTS). The genes involved in the mannitol uptake were recently cloned and sequenced. One of the genes codes for a putative transcriptional regulator, MtlR. The presence of a DNA binding helix-turn-helix motif and two antiterminator-like PTS regulation domains, suggest that MtlR is a DNA-binding protein, the activity of which can be regulated by phosphorylation by components of the PTS. To demonstrate DNA binding of MtlR to a region upstream of the mannitol promoter, by DNA footprinting, MtlR was overproduced and purified. EI, HPr, IIAmtl, and IICBmtl of B. stearothermophilus were purified and used to demonstrate that MtlR can be phosphorylated and regulated by HPr and IICBmtl, in vitro. Phosphorylation of MtlR by HPr increases the affinity of MtlR for its binding site, whereas phosphorylation by IICBmtl results in a reduction of this affinity. The differential effect of phosphorylation, by two different proteins, on the DNA binding properties of a bacterial transcriptional regulator has not, to our knowledge, been described before. Regulation of MtlR by two components of the PTS is an example of an elegant control system sensing both the presence of mannitol and the need to utilize this substrate.
Collapse
Affiliation(s)
- S A Henstra
- Departments of Biochemistry, the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | | | | | | |
Collapse
|
48
|
Bettenbrock K, Siebers U, Ehrenreich P, Alpert CA. Lactobacillus casei 64H contains a phosphoenolpyruvate-dependent phosphotransferase system for uptake of galactose, as confirmed by analysis of ptsH and different gal mutants. J Bacteriol 1999; 181:225-30. [PMID: 9864334 PMCID: PMC103553 DOI: 10.1128/jb.181.1.225-230.1999] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/1998] [Accepted: 10/26/1998] [Indexed: 11/20/2022] Open
Abstract
Galactose metabolism in Lactobacillus casei 64H was analyzed by genetic and biochemical methods. Mutants with defects in ptsH, galK, or the tagatose 6-phosphate pathway were isolated either by positive selection using 2-deoxyglucose or 2-deoxygalactose or by an enrichment procedure with streptozotocin. ptsH mutations abolish growth on lactose, cellobiose, N-acetylglucosamine, mannose, fructose, mannitol, glucitol, and ribitol, while growth on galactose continues at a reduced rate. Growth on galactose is also reduced, but not abolished, in galK mutants. A mutation in galK in combination with a mutation in the tagatose 6-phosphate pathway results in sensitivity to galactose and lactose, while a galK mutation in combination with a mutation in ptsH completely abolishes galactose metabolism. Transport assays, in vitro phosphorylation assays, and thin-layer chromatography of intermediates of galactose metabolism also indicate the functioning of a permease/Leloir pathway and a phosphoenolpyruvate-dependent phosphotransferase system (PTS)/tagatose 6-phosphate pathway. The galactose-PTS is induced by growth on either galactose or lactose, but the induction kinetics for the two substrates are different.
Collapse
Affiliation(s)
- K Bettenbrock
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, 49076 Osnabrück, Germany
| | | | | | | |
Collapse
|
49
|
Abstract
The lactose utilization genes of Staphylococcus xylosus have been isolated and characterized. The system is comprised of two structural genes, lacP and lacH, encoding the lactose permease and the beta-galactosidase proteins, respectively, and a regulatory gene, lacR, coding for an activator of the AraC/XylS family. The lactose utilization genes are divergently arranged, the lacPH genes being opposite to lacR. The lacPH genes are cotranscribed from one promoter in front of lacP, whereas lacR is transcribed from two promoters of different strengths. Lactose transport as well as beta-galactosidase activity are inducible by the addition of lactose to the growth medium. Primer extension experiments demonstrated that regulation is achieved at the level of lacPH transcription initiation. Inducibility and efficient lacPH transcription are dependent on a functional lacR gene. Inactivation of lacR resulted in low and constitutive lacPH expression. Expression of lacR itself is practically constitutive, since transcription initiated at the major lacR promoter does not respond to the availability of lactose. Only the minor lacR promoter is lactose inducible. Apart from lactose-specific, LacR-dependent control, the lacPH promoter is also subject to carbon catabolite repression mediated by the catabolite control protein CcpA. When glucose is present in the growth medium, lacPH transcription initiation is reduced. Upon ccpA inactivation, repression at the lacPH promoter is relieved. Despite this loss of transcriptional regulation in the ccpA mutant strain, beta-galactosidase activity is still reduced by glucose, suggesting another level of control.
Collapse
Affiliation(s)
- J Bassias
- Mikrobielle Genetik, Universität Tübingen, Germany
| | | |
Collapse
|
50
|
Simpson CL, Russell RR. Identification of a homolog of CcpA catabolite repressor protein in Streptococcus mutans. Infect Immun 1998; 66:2085-92. [PMID: 9573093 PMCID: PMC108167 DOI: 10.1128/iai.66.5.2085-2092.1998] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A locus containing a gene with homology to ccpA of other bacteria has been cloned from Streptococcus mutans LT11, sequenced, and named regM. Upstream of the regM gene, on the opposite strand, is a gene encoding an X-Pro dipeptidase, pepQ. A 14-bp palindromic sequence with homology to the consensus catabolite-responsive element sequence lay in the promoter region between the two genes. To study the function of regM, the gene was inactivated by insertion of an antibiotic resistance marker. Diauxic growth of S. mutans on a number of sugars in the presence of glucose was not affected by disruption of regM. The loss of RegM increased glucose repression of alpha-galactosidase, mannitol-1-P dehydrogenase, and P-beta-galactosidase activities. These results suggest that while RegM can affect catabolite repression in S. mutans, it does not conform to the model proposed for CcpA in Bacillus subtilis.
Collapse
Affiliation(s)
- C L Simpson
- Department of Oral Biology, The Dental School, University of Newcastle upon Tyne, United Kingdom
| | | |
Collapse
|