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Matsumoto T, Hashimoto M, Huang WC, Teng CH, Niwa T, Yamada M, Negishi T. Molecular characterization of a carbon dioxide-dependent Proteus mirabilis small-colony variant isolated from a clinical specimen. J Infect Chemother 2024; 30:881-886. [PMID: 38442770 DOI: 10.1016/j.jiac.2024.02.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 02/23/2024] [Accepted: 02/28/2024] [Indexed: 03/07/2024]
Abstract
INTRODUCTION Carbon dioxide-dependent Proteus mirabilis has been isolated from clinical specimens. It is not clear whether mutations in carbonic anhydrase are responsible for the carbon dioxide dependence of P. mirabilis. The pathogenicity of carbon dioxide-dependent P. mirabilis also remains unclear. The purpose of this study was to determine the cause carbon dioxide dependence of P. mirabilis and its pathogenicity. METHODS The DNA sequence of can encoding carbonic anhydrase of a carbon dioxide-dependent P. mirabilis small colony variant (SCV) isolate was analyzed. To confirm that impaired carbonic anhydrase activity is responsible for the formation of the carbon dioxide-dependent SCV phenotype of P. mirabilis, we performed complementation experiments using plasmids with intact can. Additionally, mouse infection experiments were performed to confirm the change in virulence due to the mutation of carbonic anhydrase. RESULTS We found that the can gene of the carbon dioxide-dependent P. mirabilis SCV isolate showed had a frameshift mutation with a deletion of 1 bp (c. 173delC). The can of P. mirabilis encodes carbonic anhydrase was also found to function in Escherichia coli. The cause of the carbon dioxide-dependent SCV phenotype of P. mirabilis was an abnormality in carbonic anhydrase. Nevertheless, no changes were observed in virulence due to the mutation of carbonic anhydrase in mouse infection experiments. CONCLUSIONS The can gene is essential for the growth of P. mirabilis in ambient air. The mechanisms underlying this fitness advantage in terms of infection warrant further investigation.
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Affiliation(s)
- Takehisa Matsumoto
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Japan; Department of Biomedical Laboratory Sciences, Shinshu University School of Medicine, School of Health Sciences, Shinshu University, Matsumoto, Japan.
| | - Masayuki Hashimoto
- Institute of Molecular Medicine, College of Medicine, National Cheng-Kung University, Tainan City, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wen-Chun Huang
- Institute of Molecular Medicine, College of Medicine, National Cheng-Kung University, Tainan City, Taiwan
| | - Ching-Hao Teng
- Institute of Molecular Medicine, College of Medicine, National Cheng-Kung University, Tainan City, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Takahiko Niwa
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Japan; Department of Clinical Laboratory, Gunma University Hospital, Maebashi, Japan
| | - Mariko Yamada
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Japan
| | - Tatsuya Negishi
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
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Molecular characterization of a carbon dioxide-dependent Escherichia coli small-colony variant isolated from blood cultures. Int J Med Microbiol 2020; 310:151431. [PMID: 32654769 DOI: 10.1016/j.ijmm.2020.151431] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 04/22/2020] [Accepted: 05/23/2020] [Indexed: 11/23/2022] Open
Abstract
A carbon dioxide-dependent small-colony variant of Escherichia coli SH4888 was isolated from blood cultures of a patient with cholangitis. To date, little is known regarding the molecular mechanisms leading to formation of carbon dioxide-dependent phenotypes in clinical isolates, but abnormalities in the carbonic anhydrase are thought to cause carbon dioxide autotrophy. In this study DNA sequence analysis of the carbonic anhydrase-encoding can locus in the carbon dioxide-dependent E. coli SH4888 revealed that the isolate had a 325-bp deletion spanning from the 3'-terminal region of can to the 3'-terminal region of hpt, which encodes a hypoxanthine phosphoribosyltransferase. To confirm that the carbon dioxide-dependent SCV phenotype of E. coli SH4888 was due to the can mutation, we performed a complementation test with a plasmid carrying an intact can that restored the normal phenotype. However, E. coli SH4888 had increased virulence compared to the can-complemented E. coli SH4888 in a murine infection model. In conclusion, these data confirm that impaired carbonic anhydrase function can cause a carbon dioxide-dependent SCV phenotype in E. coli SH4888 and provides a fitness advantage in terms of infection.
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Tao L, Kang Y, Zhang L, Shi Q, Li Y, Wu T, Qian A, Sun W, Shan X. Cadaverine reverse transporter (CadB protein) contributes to the virulence of Aeromonas veronii TH0426. Int Microbiol 2020; 23:489-499. [PMID: 31950405 DOI: 10.1007/s10123-020-00120-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 01/06/2020] [Accepted: 01/09/2020] [Indexed: 11/25/2022]
Abstract
Aeromonas veronii is one of the main pathogens causing sepsis and ulcer syndrome in freshwater fish. Analysis of the results of epidemiological investigations in recent years has revealed that the virulence of A. veronii and its tolerance to drugs have been increasing year by year. Currently, most of the research on A. veronii focuses on its isolation, identification, and drug susceptibility, whereas research on its virulence factors and pathogenesis mechanisms is relatively rare. In this study, we identified and obtained the highly expressed TH0426 cadaverine reverse transporter (CadB) of A. veronii. We used efficient suicide plasmid-mediated homologous recombination to delete the cadB gene in TH0426 and constructed a cadB deletion strain. The LD50 of ΔcadB was 93.2 times higher than that of TH0426 in zebrafish, the toxicity of ΔcadB was 9.5 times less than that of TH0426 in EPC cells, and the biofilm formation ability of ΔcadB was 5.6-fold greater than that of TH0426. In addition, motility detection results indicated that ΔcadB had lost its swimming ability. The results of flagellar staining and TEM demonstrated that ΔcadB shed the flagella. In summary, the virulence and adhesion of A. veronii TH0426 were significantly decreased by the deletion of cadB, which might provide a theoretical basis for research into A. veronii virulence factors.
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Affiliation(s)
- LuoTao Tao
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China
| | - YuanHuan Kang
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China
| | - Lei Zhang
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China
| | - Qiumei Shi
- Key Laboratory of Hebei Province Preventive Veterinary Medicine, Hebei Normal University of Science & Technology, Qinhuangdao, 066004, China
| | - Ying Li
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China
| | - Tonglei Wu
- Key Laboratory of Hebei Province Preventive Veterinary Medicine, Hebei Normal University of Science & Technology, Qinhuangdao, 066004, China
| | - Aidong Qian
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China
| | - WuWen Sun
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China.
| | - Xiaofeng Shan
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, Jilin, China.
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4
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Bañares AB, Valdehuesa KNG, Ramos KRM, Nisola GM, Lee WK, Chung WJ. A pH-responsive genetic sensor for the dynamic regulation of D-xylonic acid accumulation in Escherichia coli. Appl Microbiol Biotechnol 2020; 104:2097-2108. [PMID: 31900554 DOI: 10.1007/s00253-019-10297-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/28/2019] [Accepted: 12/03/2019] [Indexed: 11/25/2022]
Abstract
The xylose oxidative pathway (XOP) is continuously gaining prominence as an alternative for the traditional pentose assimilative pathways in prokaryotes. It begins with the oxidation of D-xylose to D-xylonic acid, which is further converted to α-ketoglutarate or pyruvate + glycolaldehyde through a series of enzyme reactions. The persistent drawback of XOP is the accumulation of D-xylonic acid intermediate that causes culture media acidification. This study addresses this issue through the development of a novel pH-responsive synthetic genetic controller that uses a modified transmembrane transcription factor called CadCΔ. This genetic circuit was tested for its ability to detect extracellular pH and to control the buildup of D-xylonic acid in the culture media. Results showed that the pH-responsive genetic sensor confers dynamic regulation of D-xylonic acid accumulation, which adjusts with the perturbation of culture media pH. This is the first report demonstrating the use of a pH-responsive transmembrane transcription factor as a transducer in a synthetic genetic circuit that was designed for XOP. This may serve as a benchmark for the development of other genetic controllers for similar pathways that involve acidic intermediates.
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Affiliation(s)
- Angelo B Bañares
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, 17058, Gyeonggi-do, Republic of Korea
| | - Kris Niño G Valdehuesa
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, 17058, Gyeonggi-do, Republic of Korea
| | - Kristine Rose M Ramos
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, 17058, Gyeonggi-do, Republic of Korea
| | - Grace M Nisola
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, 17058, Gyeonggi-do, Republic of Korea
| | - Won-Keun Lee
- Division of Bioscience and Bioinformatics, Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, 17058, Gyeonggi-do, Republic of Korea.
| | - Wook-Jin Chung
- Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, 17058, Gyeonggi-do, Republic of Korea.
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Soga E, Akiyama M, Ohsaki Y, Hayashi W, Matsumoto T, Oana K, Nagano N, Kawakami Y. Isolation of a Capnophilic and Extended-Spectrum β-Lactamase-Producing Proteus mirabilis Strain from the Urine of an Octogenarian Male Patient with Acute Pyelonephritis. Jpn J Infect Dis 2019; 72:193-195. [PMID: 30504644 DOI: 10.7883/yoken.jjid.2018.201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A capnophilic Gram-negative rod-shaped bacterium was recovered from the urine of an octogenarian male patient with acute pyelonephritis. The isolate was found to produce CTX-M-2-type extended-spectrum β-lactamase. Interestingly, the isolate failed to grow on modified Drigalski (BTB) and MacConkey agar media, even under CO2-enriched atmosphere. Our analysis revealed that the pH-indicator dyes, bromothymol blue, and/or crystal violet that were incorporated into the agar media inhibited the growth of the isolate. Although routine identification methods using Vitek® 2 Compact systems were unsuccessful, the isolate was identified as Proteus mirabilis by 16S rRNA sequencing and MALDI-TOF MS analysis. The carbonic anhydrase (CA) region spanning approximately 2,000 bp upstream to 2,000 bp downstream, which is responsible for the CO2 requirement, was not amplified, which could be attributed to the large-scale deletion or mutation of the DNA sequences containing the CA gene region. In fact, revertants with the ability to grow without CO2 were not detected. However, a revertant that was capable of growing in both BTB and MacConkey agar was detected at frequencies less than 10-9. Therefore, the genes responsible for the highly sensitive reactions of the isolate to pH indicator dyes is not likely to be linked to the CA genes.
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Affiliation(s)
- Eiji Soga
- Department of Laboratory Medicine, Nakatsugawa Municipal General Hospital
| | - Miki Akiyama
- Department of Laboratory Medicine, Nakatsugawa Municipal General Hospital
| | - Yusuke Ohsaki
- Department of Health and Medical Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine
| | - Wataru Hayashi
- Department of Health and Medical Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine
| | - Takehisa Matsumoto
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences
| | - Kozue Oana
- Department of Health and Medical Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine.,Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine
| | - Noriyuki Nagano
- Department of Health and Medical Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine.,Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine
| | - Yoshiyuki Kawakami
- Department of Health and Medical Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine.,Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University Graduate School of Medicine
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Jung K, Fabiani F, Hoyer E, Lassak J. Bacterial transmembrane signalling systems and their engineering for biosensing. Open Biol 2019; 8:rsob.180023. [PMID: 29695618 PMCID: PMC5936718 DOI: 10.1098/rsob.180023] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/03/2018] [Indexed: 12/27/2022] Open
Abstract
Every living cell possesses numerous transmembrane signalling systems that receive chemical and physical stimuli from the environment and transduce this information into an intracellular signal that triggers some form of cellular response. As unicellular organisms, bacteria require these systems for survival in rapidly changing environments. The receptors themselves act as ‘sensory organs’, while subsequent signalling circuits can be regarded as forming a ‘neural network’ that is involved in decision making, adaptation and ultimately in ensuring survival. Bacteria serve as useful biosensors in industry and clinical diagnostics, in addition to producing drugs for therapeutic purposes. Therefore, there is a great demand for engineered bacterial strains that contain transmembrane signalling systems with high molecular specificity, sensitivity and dose dependency. In this review, we address the complexity of transmembrane signalling systems and discuss principles to rewire receptors and their signalling outputs.
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Affiliation(s)
- Kirsten Jung
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Florian Fabiani
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Elisabeth Hoyer
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Jürgen Lassak
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
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7
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Abstract
This review considers the pathways for the degradation of amino acids and a few related compounds (agmatine, putrescine, ornithine, and aminobutyrate), along with their functions and regulation. Nitrogen limitation and an acidic environment are two physiological cues that regulate expression of several amino acid catabolic genes. The review considers Escherichia coli, Salmonella enterica serovar Typhimurium, and Klebsiella species. The latter is included because the pathways in Klebsiella species have often been thoroughly characterized and also because of interesting differences in pathway regulation. These organisms can essentially degrade all the protein amino acids, except for the three branched-chain amino acids. E. coli, Salmonella enterica serovar Typhimurium, and Klebsiella aerogenes can assimilate nitrogen from D- and L-alanine, arginine, asparagine, aspartate, glutamate, glutamine, glycine, proline, and D- and L-serine. There are species differences in the utilization of agmatine, citrulline, cysteine, histidine, the aromatic amino acids, and polyamines (putrescine and spermidine). Regardless of the pathway of glutamate synthesis, nitrogen source catabolism must generate ammonia for glutamine synthesis. Loss of glutamate synthase (glutamineoxoglutarate amidotransferase, or GOGAT) prevents utilization of many organic nitrogen sources. Mutations that create or increase a requirement for ammonia also prevent utilization of most organic nitrogen sources.
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8
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New Insights into the Interplay Between the Lysine Transporter LysP and the pH Sensor CadC in Escherichia Coli. J Mol Biol 2014; 426:215-29. [DOI: 10.1016/j.jmb.2013.09.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 09/12/2013] [Accepted: 09/15/2013] [Indexed: 11/20/2022]
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9
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Properties of putrescine uptake by PotFGHI and PuuP and their physiological significance in Escherichia coli. Amino Acids 2013; 46:661-70. [PMID: 23719730 DOI: 10.1007/s00726-013-1517-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 05/15/2013] [Indexed: 01/27/2023]
Abstract
Properties of putrescine uptake by PotFGHI and PuuP and their physiological significance were studied using a polyamine biosynthesis and uptake deficient Escherichia coli KK3131 transformed with pACYC184 containing potFGHI or puuP. Putrescine uptake activity of E. coli KK3131 transformed with pACYC184-PotFGHI was higher than that of E. coli 3131 transformed with pACYC-PuuP when cells were cultured in the absence of putrescine. Putrescine uptake by PotFGHI was both ATP and membrane potential dependent, while that by PuuP was membrane potential dependent. Feedback inhibition by polyamines occurred at the PotFGHI uptake system but not at the PuuP uptake system. Expression of PuuP was reduced in the presence of PuuR, a negative regulator for PuuP, and expression of PuuR was positively regulated by glucose, which reduces the level of cAMP. The complex of cAMP and CRP (cAMP receptor protein) inhibited the expression of PuuR in the absence of glucose. Thus, the growth rate of E. coli KK3131 in the presence of both 0.4% (22.2 mM) glucose and 10 mM putrescine was in the order of cells transformed with pACYC-PotFGHI > pACYC-PuuP > pACYC-PuuP + PuuR, which was parallel with the polyamine content in cells. The results indicate that PotFGHI is necessary for rapid cell growth in the presence of glucose as an energy source. When glucose in medium was depleted, however, PuuP was absolutely necessary for cell growth in the presence of putrescine, because accumulation of putrescine to a high level by PuuP was necessary for utilization of putrescine as an energy source.
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Tomitori H, Kashiwagi K, Igarashi K. Structure and function of polyamine-amino acid antiporters CadB and PotE in Escherichia coli. Amino Acids 2011; 42:733-40. [DOI: 10.1007/s00726-011-0989-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Accepted: 03/26/2011] [Indexed: 10/17/2022]
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Bringel F, Hammann P, Kugler V, Arsène-Ploetze F. Lactobacillus plantarum response to inorganic carbon concentrations: PyrR2-dependent and -independent transcription regulation of genes involved in arginine and nucleotide metabolism. MICROBIOLOGY-SGM 2008; 154:2629-2640. [PMID: 18757797 DOI: 10.1099/mic.0.2008/018184-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Lactobacillus plantarum susbp. plantarum is a capnophilic Gram-positive heterotroph with optimal growth in 4 % CO(2)-enriched air. At low inorganic carbon (C(i)) concentrations, the pyr genes encoding the enzymes of the pyrimidine biosynthetic pathway were overexpressed, in agreement with a previous study showing that these genes are regulated at the transcription level in response to C(i) via a PyrR(2)-mediated mechanism. A previous study of high-CO(2)-requiring (HCR) mutants revealed an unknown genetic link between arginine regulation and C(i)-dependent nutritional needs. To better understand L. plantarum's adaptation to C(i) availability, additional C(i)-responsive genes were sought in the arginine biosynthetic pathway (arg and car genes) using slot-blot hybridization and a proteomic differential 2D gel electrophoresis (DIGE) global approach. Besides the nine pyr-encoded proteins, 16 new Icr (inorganic-carbon-regulated) proteins accumulated differentially in response to C(i) availability, suggesting that the C(i) response involves several metabolic pathways and adaptation processes. Among these Icr proteins only argininosuccinate lyase, encoded by argH, was involved in arginine biosynthesis. Three proteins involved in the purine biosynthetic pathway and nucleotide conversion, adenylate kinase (Adk), GMP synthase (GuaA), and IMP dehydrogenase (GuaB), accumulated differentially in response to changes in C(i) levels. Expression of the Icr protein-encoding genes argH and guaB was regulated at the transcription level or by RNA stability in response to C(i) availability, as previously demonstrated for the pyr genes. However, PyrR(2) was not essential for the C(i)-regulated transcription of argH and guaB, demonstrating that PyrR(2) modulates only a subset of C(i)-regulated genes. These results suggest that the C(i) response may involve at least two regulatory mechanisms in L. plantarum.
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Affiliation(s)
- Françoise Bringel
- Université Louis-Pasteur Strasbourg-I, Strasbourg, France.,CNRS, UMR7156, Génétique Moléculaire, Génomique Microbiologie, Département Microorganismes, Génomes, Environnement, 28 Rue Goethe, 67083 Strasbourg, France
| | - Philippe Hammann
- CNRS, FRC 1589, Plateforme Protéomique Esplanade, 15 Rue René Descartes, 67084 Strasbourg, France
| | - Valérie Kugler
- Université Louis-Pasteur Strasbourg-I, Strasbourg, France.,CNRS, UMR7156, Génétique Moléculaire, Génomique Microbiologie, Département Microorganismes, Génomes, Environnement, 28 Rue Goethe, 67083 Strasbourg, France
| | - Florence Arsène-Ploetze
- Université Louis-Pasteur Strasbourg-I, Strasbourg, France.,CNRS, UMR7156, Génétique Moléculaire, Génomique Microbiologie, Département Microorganismes, Génomes, Environnement, 28 Rue Goethe, 67083 Strasbourg, France
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Tetsch L, Koller C, Haneburger I, Jung K. The membrane-integrated transcriptional activator CadC ofEscherichia colisenses lysine indirectly via the interaction with the lysine permease LysP. Mol Microbiol 2008; 67:570-83. [DOI: 10.1111/j.1365-2958.2007.06070.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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13
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Higashi K, Ishigure H, Demizu R, Uemura T, Nishino K, Yamaguchi A, Kashiwagi K, Igarashi K. Identification of a spermidine excretion protein complex (MdtJI) in Escherichia coli. J Bacteriol 2008; 190:872-8. [PMID: 18039771 PMCID: PMC2223573 DOI: 10.1128/jb.01505-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Accepted: 11/02/2007] [Indexed: 11/20/2022] Open
Abstract
A spermidine excretion protein in Escherichia coli was looked for among 33 putative drug exporters thus far identified. Cell toxicity and inhibition of growth due to overaccumulation of spermidine were examined in an E. coli strain deficient in spermidine acetyltransferase, an enzyme that metabolizes spermidine. Toxicity and inhibition of cell growth by spermidine were recovered in cells transformed with pUCmdtJI or pMWmdtJI, encoding MdtJ and MdtI, which belong to the small multidrug resistance family of drug exporters. Both mdtJ and mdtI are necessary for recovery from the toxicity of overaccumulated spermidine. It was also found that the level of mdtJI mRNA was increased by spermidine. The spermidine content in cells cultured in the presence of 2 mM spermidine was decreased, and excretion of spermidine from cells was enhanced by MdtJI, indicating that the MdtJI complex can catalyze excretion of spermidine from cells. It was found that Tyr4, Trp5, Glu15, Tyr45, Tyr61, and Glu82 in MdtJ and Glu5, Glu19, Asp60, Trp68, and Trp81 in MdtI are involved in the excretion activity of MdtJI.
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Affiliation(s)
- Kyohei Higashi
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
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Bury-Moné S, Mendz GL, Ball GE, Thibonnier M, Stingl K, Ecobichon C, Avé P, Huerre M, Labigne A, Thiberge JM, De Reuse H. Roles of alpha and beta carbonic anhydrases of Helicobacter pylori in the urease-dependent response to acidity and in colonization of the murine gastric mucosa. Infect Immun 2008; 76:497-509. [PMID: 18025096 PMCID: PMC2223474 DOI: 10.1128/iai.00993-07] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/06/2007] [Accepted: 11/05/2007] [Indexed: 01/03/2023] Open
Abstract
Carbon dioxide occupies a central position in the physiology of Helicobacter pylori owing to its capnophilic nature, the large amounts of carbon dioxide produced by urease-mediated urea hydrolysis, and the constant bicarbonate supply in the stomach. Carbonic anhydrases (CA) catalyze the interconversion of carbon dioxide and bicarbonate and are involved in functions such as CO(2) transport or trapping and pH homeostasis. H. pylori encodes a periplasmic alpha-CA (alpha-CA-HP) and a cytoplasmic beta-CA (beta-CA-HP). Single CA inactivation and double CA inactivation were obtained for five genetic backgrounds, indicating that H. pylori CA are not essential for growth in vitro. Bicarbonate-carbon dioxide exchange rates were measured by nuclear magnetic resonance spectroscopy using lysates of parental strains and CA mutants. Only the mutants defective in the alpha-CA-HP enzyme showed strongly reduced exchange rates. In H. pylori, urease activity is essential for acid resistance in the gastric environment. Urease activity measured using crude cell extracts was not modified by the absence of CA. With intact CA mutant cells incubated in acidic conditions (pH 2.2) in the presence of urea there was a delay in the increase in the pH of the incubation medium, a phenotype most pronounced in the absence of H. pylori alpha-CA. This correlated with a delay in acid activation of the urease as measured by slower ammonia production in whole cells. The role of CA in vivo was examined using the mouse model of infection with two mouse-adapted H. pylori strains, SS1 and X47-2AL. Compared to colonization by the wild-type strain, colonization by X47-2AL single and double CA mutants was strongly reduced. Colonization by SS1 CA mutants was not significantly different from colonization by wild-type strain SS1. However, when mice were infected by SS1 Delta(beta-CA-HP) or by a SS1 double CA mutant, the inflammation scores of the mouse gastric mucosa were strongly reduced. In conclusion, CA contribute to the urease-dependent response to acidity of H. pylori and are required for high-grade inflammation and efficient colonization by some strains.
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Affiliation(s)
- Stéphanie Bury-Moné
- Unité de Pathogénie Bactérienne des Muqueuses, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
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Prosseda G, Carmela Latella M, Barbagallo M, Nicoletti M, Al Kassas R, Casalino M, Colonna B. The two-faced role of cad genes in the virulence of pathogenic Escherichia coli. Res Microbiol 2007; 158:487-93. [PMID: 17656072 DOI: 10.1016/j.resmic.2007.05.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/29/2007] [Accepted: 05/02/2007] [Indexed: 11/18/2022]
Abstract
In enterobacteria, acid stress induces expression of the cad system which is involved in maintaining intracellular pH at levels compatible with cell survival. Despite its crucial role, the cad operon is silenced in Shigella and in other pathogenic Escherichia coli. In the present review, we will address the question of why and how the cad locus has been sacrificed for the sake of optimal expression of virulence traits.
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Affiliation(s)
- Gianni Prosseda
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dip. Biologia Cellulare e dello Sviluppo, Sapienza-Università di Roma, Via dei Sardi 70, 00185 Rome, Italy
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16
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Arsène-Ploetze F, Kugler V, Martinussen J, Bringel F. Expression of the pyr operon of Lactobacillus plantarum is regulated by inorganic carbon availability through a second regulator, PyrR2, homologous to the pyrimidine-dependent regulator PyrR1. J Bacteriol 2006; 188:8607-16. [PMID: 17041052 PMCID: PMC1698236 DOI: 10.1128/jb.00985-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inorganic carbon (IC), such as bicarbonate or carbon dioxide, stimulates the growth of Lactobacillus plantarum. At low IC levels, one-third of natural isolated L. plantarum strains are nutritionally dependent on exogenous arginine and pyrimidine, a phenotype previously defined as high-CO2-requiring (HCR) prototrophy. IC enrichment significantly decreased the amounts of the enzymes in the pyrimidine biosynthetic pathway encoded by the pyrR1BCAa1Ab1DFE operon, as demonstrated by proteomic analysis. Northern blot and reverse transcription-PCR experiments demonstrated that IC levels regulated pyr genes mainly at the level of transcription or RNA stability. Two putative PyrR regulators with 62% amino acid identity are present in the L. plantarum genome. PyrR1 is an RNA-binding protein that regulates the pyr genes in response to pyrimidine availability by a mechanism of transcriptional attenuation. In this work, the role of PyrR2 was investigated by allelic gene replacement. Unlike the pyrR1 mutant, the DeltapyrR2 strain acquired a demand for both pyrimidines and arginine unless bicarbonate or CO2 was present at high concentrations, which is known as an HCR phenotype. Analysis of the IC- and pyrimidine-mediated regulation in pyrR1 and pyrR2 mutants suggested that only PyrR2 positively regulates the expression levels of the pyr genes in response to IC levels but had no effect on pyrimidine-mediated repression. A model is proposed for the respective roles of PyrR1 and PyrR2 in the pyr regulon expression.
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Affiliation(s)
- Florence Arsène-Ploetze
- UMR7156 Université Louis Pasteur/CNRS, Génétique Moléculaire, Génomique, Microbiologie, Département Microorganismes, Génomes, Environnement, 28 Rue Goethe, 67083 Strasbourg, France
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17
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Soksawatmaekhin W, Uemura T, Fukiwake N, Kashiwagi K, Igarashi K. Identification of the Cadaverine Recognition Site on the Cadaverine-Lysine Antiporter CadB. J Biol Chem 2006; 281:29213-20. [PMID: 16877381 DOI: 10.1074/jbc.m600754200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amino acid residues involved in cadaverine uptake and cadaverine-lysine antiporter activity were identified by site-directed mutagenesis of the CadB protein. It was found that Tyr(73), Tyr(89), Tyr(90), Glu(204), Tyr(235), Asp(303), and Tyr(423) were strongly involved in both uptake and excretion and that Tyr(55), Glu(76), Tyr(246), Tyr(310), Cys(370), and Glu(377) were moderately involved in both activities. Mutations of Trp(43), Tyr(57), Tyr(107), Tyr(366), and Tyr(368) mainly affected uptake activity, and Trp(41), Tyr(174), Asp(185), and Glu(408) had weak effects on uptake. The decrease in the activities of the mutants was reflected by an increase in the K(m) value. Mutation of Arg(299) mainly affected excretion, suggesting that Arg(299) is involved in the recognition of the carboxyl group of lysine. These results indicate that amino acid residues involved in both uptake and excretion, or solely in excretion, are located in the cytoplasmic loops and the cytoplasmic side of transmembrane segments, whereas residues involved in uptake were located in the periplasmic loops and the transmembrane segments. The SH group of Cys(370) seemed to be important for uptake and excretion, because both were inhibited by the existence of Cys(125), Cys(389), or Cys(394) together with Cys(370). The relative topology of 12 transmembrane segments was determined by inserting cysteine residues at various sites and measuring the degree of inhibition of transport through crosslinking with Cys(370). The results suggest that a hydrophilic cavity is formed by the transmembrane segments II, III, IV, VI, VII, X, XI, and XII.
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Affiliation(s)
- Waraporn Soksawatmaekhin
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
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18
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Kuper C, Jung K. CadC-Mediated Activation of the cadBA Promoter in Escherichia coli. J Mol Microbiol Biotechnol 2006; 10:26-39. [PMID: 16491024 DOI: 10.1159/000090346] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The transcriptional activator CadC in Escherichia coli, a member of the ToxR-like proteins, activates transcription of the cadBA operon encoding the lysine decarboxylase CadA and the lysine-cadaverine antiporter CadB. cadBA is induced under conditions of acidic external pH and exogenous lysine; anoxic conditions raise the expression level up to 10 times. To characterize the binding mechanism of CadC, procedures for the purification of this membrane-integrated protein and its reconstitution into proteoliposomes were established. The binding sites of CadC upstream of the cadBA promoter region were determined by in vitro DNaseI protection analysis. Two regions were protected during DNaseI digestion, one from -144 to -112 bp, designated Cad1, and another one from -89 to -59 bp, designated Cad2. Binding of purified CadC to Cad1 and Cad2 was further characterized by DNA-binding assays, indicating that CadC was able to bind to both DNA fragments. Genetic analysis with promoter-lacZ fusions confirmed that both sites, Cad1 and Cad2, are essential for activation of cadBA transcription. Moreover, these experiments revealed that binding of H-NS upstream of the CadC-binding sites is necessary for repression of cadBA expression at neutral pH and under aerobic conditions. Based on these results, a model for transcriptional regulation of the cadBA operon is proposed, according to which H-NS is involved in the formation of a repression complex under non-inducing conditions. This complex is dissolved by binding of CadC to Cad1 under inducing conditions. Upon binding of CadC to Cad2 cadBA expression is activated.
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Affiliation(s)
- Christoph Kuper
- Department of Biology I, Microbiology, Ludwig Maximilians University Munich, Munich, Germany
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19
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Sun L, Fukamachi T, Saito H, Kobayashi H. Carbon dioxide increases acid resistance in Escherichia coli. Lett Appl Microbiol 2005; 40:397-400. [PMID: 15892732 DOI: 10.1111/j.1472-765x.2005.01714.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
AIMS To investigate how carbon dioxide affects the acid resistance of Escherichia coli. METHODS AND RESULTS Escherichia coli W3110 was grown in minimal EG medium at pH 7.5, and cells were adapted at pH 5.5 at 37 degrees C with and without supply of carbon dioxide and nitrogen gases. The number of colonies grown on LB medium was measured after cells were challenged in minimal EG medium of pH 2.5 at 37 degrees C under various conditions. When carbon dioxide was supplied at both the acid adaptation and challenge stages, 94% of cells survived after the acid challenge for 1 h, while the survival rates were 50 and 67% when nitrogen gas and glutamate were supplied respectively. After the acid challenge for 3 h, the survival rate observed with the carbon dioxide gas supply was again 2.5-fold higher than those with the nitrogen gas supply. CONCLUSION Carbon dioxide was shown to participate in the maintenance of high viability under acidic conditions. SIGNIFICANCE AND IMPACT OF THE STUDY This study provides useful information for research into bacterial pathogenesis, fermentation and food preservation.
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Affiliation(s)
- L Sun
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
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20
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Abstract
Most current paradigms of microbial metabolism have been derived from studying cells grown under a variety of nutrient compositions in aqueous environments. With recent advances in genomics and experimental techniques, alternative forms of bacterial growth are increasingly being explored. When propagated on nutrient-rich semi-solid media, several species of bacteria undergo a morphological differentiation into swarmers that are capable of migrating on surfaces. Recent studies indicate that swarmer differentiation represents much more than a motility phenotype, as several clinically important attributes are also co-regulated. We demonstrate that migrating swarmer cells of Salmonella are metabolically differentiated compared to the vegetative swimmer cells grown in the same nutrient environment. Furthermore, once the cells have differentiated, the swarmers remain in this physiological state under conditions that do not promote the initial differentiation. The bacterium's capacity to override some of the classic paradigms of metabolic regulation established in aqueous environments represents a unique physiological response by the pathogen that may be advantageous in polymicrobial environments such as the host.
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Affiliation(s)
- Wook Kim
- Department of Microbiology and Infectious Diseases, University of Calgary, 3330 Hospital Dr. N.W., Calgary, Alberta T2N 4N1, Canada
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21
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Soksawatmaekhin W, Kuraishi A, Sakata K, Kashiwagi K, Igarashi K. Excretion and uptake of cadaverine by CadB and its physiological functions in Escherichia coli. Mol Microbiol 2004; 51:1401-12. [PMID: 14982633 DOI: 10.1046/j.1365-2958.2003.03913.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The functions of the putative cadaverine transport protein CadB were studied in Escherichia coli. CadB had both cadaverine uptake activity, dependent on proton motive force, and cadaverine excretion activity, acting as a cadaverine-lysine antiporter. The Km values for uptake and excretion of cadaverine were 20.8 and 303 microM respectively. Both cadaverine uptake and cadaverine-lysine antiporter activities of CadB were functional in cells. Cell growth of a polyamine-requiring mutant was stimulated slightly at neutral pH by the cadaverine uptake activity and greatly at acidic pH by the cadaverine-lysine antiporter activity. At acidic pH, the operon containing cadB and cadA, encoding lysine decarboxylase, was induced in the presence of lysine. This caused neutralization of the extracellular medium and made possible the production of CO(2) and cadaverine and aminopropylcadaverine instead of putrescine and spermidine. The induction of the cadBA operon also generated a proton motive force. When the cadBA operon was not induced, the expression of the speF-potE operon, encoding inducible ornithine decarboxylase and a putrescine-ornithine antiporter, was increased. The results indicate that the cadBA operon plays important roles in cellular regulation at acidic pH.
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Affiliation(s)
- Waraporn Soksawatmaekhin
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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22
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Abstract
Studies of bacterial adaptation to alkaline pH have been less extensive to date compared with those of acidic pH. Recent development of novel methods for global analysis of gene expression under various conditions revealed that many genes were induced at high pH. These data led us to question why so many genes are required for adaptation to alkaline pH. The internal pH of bacteria growing at extremely high pH remains unclear because the methods for measuring interior acidic deltapH developed to date are not so accurate, but it is generally accepted that cytoplasmic pH increases with medium alkalization, although the increase is lower than that of the change in medium pH. Therefore, activities of enzymes working in neutral cytoplasm may decrease with cytoplasmic alkalization under extreme alkaline conditions. Based on these findings, we propose in this article that genes whose products have an optimum activity at high pH are induced under alkaline stress to compensate for the decrease in activities of systems functioning at neutral pH.
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Affiliation(s)
- Hiromi Saito
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260–8675, Japan
| | - Hiroshi Kobayashi
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260–8675, Japan
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23
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Affiliation(s)
- E I Kozliak
- Department of Chemistry, University of North Dakota, P.O. Box 9024 Grand Forks, ND 58202-9024, USA
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24
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Kobayashi H, Saito H, Kakegawa T. Bacterial strategies to inhabit acidic environments. J GEN APPL MICROBIOL 2000; 46:235-243. [PMID: 12483574 DOI: 10.2323/jgam.46.235] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Bacteria can inhabit a wide range of environmental conditions, including extremes in pH ranging from 1 to 11. The primary strategy employed by bacteria in acidic environments is to maintain a constant cytoplasmic pH value. However, many data demonstrate that bacteria can grow under conditions in which pH values are out of the range in which cytoplasmic pH is kept constant. Based on these observations, a novel notion was proposed that bacteria have strategies to survive even if the cytoplasm is acidified by low external pH. Under these conditions, bacteria are obliged to use acid-resistant systems, implying that multiple systems having the same physiological role are operating at different cytoplasmic pH values. If this is true, it is quite likely that bacteria have genes that are induced by environmental stimuli under different pH conditions. In fact, acid-inducible genes often respond to another factor(s) besides pH. Furthermore, distinct genes might be required for growth or survival at acid pH under different environmental conditions because functions of many systems are dependent on external conditions. Systems operating at acid pH have been described to date, but numerous genes remain to be identified that function to protect bacteria from an acid challenge. Identification and analysis of these genes is critical, not only to elucidate bacterial physiology, but also to increase the understanding of bacterial pathogenesis.
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Affiliation(s)
- Hiroshi Kobayashi
- Faculty of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
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25
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Maestri O, Joset F. Regulation by external pH and stationary growth phase of the acetolactate synthase from Synechocystis PCC6803. Mol Microbiol 2000; 37:828-38. [PMID: 10972805 DOI: 10.1046/j.1365-2958.2000.02048.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Several characteristics identify the protein encoded by the alsS gene [sll1981 in Cyanobase (http://www.kazusa.or.jp/cyano/cyano. html)] of Synechocystis PCC6803 as an acetolactate synthase. The AlsS protein is about 60% homologous to the AlsS from Bacillus subtilis or other bacteria. These enzymes condense two pyruvates to form acetolactate, implicated in pH homeostasis via the acetoin-2, 3-butanediol pathway or in valine biosynthesis. Transcriptional fusions revealed that alsS was induced at the onset of stationary phase, as in B. subtilis, a situation leading to an increase in the pHout to above 11 in Synechocystis. This is the first cyanobacterial gene showing a dependence on pH for its expression. Induction was also obtained by the presence of > 100 mM Na+, the effect being prevented by amiloride, in agreement with Na+/H+ exchange in the pH homeostasis process. Homology of the Synechocystis AlsS protein to the close family of acetohydroxy acid synthases (including one in Synechocystis) is around 30%. These enzymes are involved in the parallel routes for valine/leucine and isoleucine biosynthesis. No phenotype of auxotrophy for any of these amino acids was associated with a null mutation in the Synechocystis alsS gene. The AlsS enzyme did not complement the isoleucine deficiency of an acetohydroxy acid synthase-deficient Escherichia coli mutant.
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Affiliation(s)
- O Maestri
- Laboratoire de Chimie Bactérienne, CNRS, Marseilles, France
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26
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Merrell DS, Camilli A. The cadA gene of Vibrio cholerae is induced during infection and plays a role in acid tolerance. Mol Microbiol 1999; 34:836-49. [PMID: 10564522 DOI: 10.1046/j.1365-2958.1999.01650.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Vibrio cholerae is a facultative pathogen of humans that must survive exposure to inorganic and organic acids in the stomach and small intestine. To learn more about the mechanisms by which this pathogen colonizes the intestinal tract, we used a recombinase gene fusion reporter to identify transcripts induced during infection in an adult rabbit model of cholera. One of the genes identified was cadA, which encodes an inducible lysine decarboxylase. CadA was also induced during infections of the suckling and adult mouse intestines, and in vitro under conditions of low pH and high lysine concentration. We show that V. cholerae is capable of mounting an acid tolerance response (ATR) to both inorganic and organic acid challenges. Mutational analyses revealed a significant role for cadA, but not for speF, which encodes an ornithine decarboxylase, in both inorganic and organic ATR. Potential roles for toxR, toxT and rpoS in ATR were examined, and it was found that toxR plays a ToxT-independent role in mediating organic ATR, whereas rpoS played no detectable role in either ATR. Transcriptional analysis showed that the toxR defect in ATR is not caused by decreased cadA transcription. Despite induction of cadA in these animal models, competition assays revealed that neither cadA nor speF alone or together were required for colonization of suckling or adult mice. However, acid-adapted wild-type V. cholerae exhibited a major competitive advantage over unadapted cells during colonization of suckling mice.
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Affiliation(s)
- D S Merrell
- Tufts University School of Medicine, Department of Molecular Biology and Microbiology, 136 Harrison Avenue, Boston, MA 02111, USA
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27
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Dilworth MJ, Glenn AR. Problems of adverse pH and bacterial strategies to combat it. NOVARTIS FOUNDATION SYMPOSIUM 1999; 221:4-14, discussion 14-8. [PMID: 10207910 DOI: 10.1002/9780470515631.ch2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
This chapter aims to survey the problems faced by bacteria found in environments of adverse pH, to review strategies used to combat those problems and to ask how those strategies are implemented. At acid or alkaline pH, bacteria are challenged not just by excess of H+ or OH- but also by excess of metal ions (aluminium, heavy metals at acidic pH, Na+ at alkaline pH), as well as shortages. Bacteria attempt to maintain their intracellular pH by minimizing membrane permeability to H+ and other ions, buffering the cytoplasm, ameliorating the external pH through catabolism or selective substrate utilization, and developing ionic pumping systems. The amelioration of pH depends on the availability of substrate, and is unlikely in most naturally stressful environments. Ion pumping is expensive energetically, although the cost to growth is unknown. The response to adverse pH involves sensing systems and responsive regulatory systems. The adaptive acid tolerance response is now well known in and other bacteria, but is there a widespread adaptive alkali tolerance response? What and where are the sensors? Whether they sense intracellular pH, extracellular pH or delta pH is unclear, although an external sensory input seems essential. Is there one major sensory system responsive to pH or multiple systems with back-up mechanisms? What and where are the regulators? Is there one central regulator controlling all the responses or are there cascades of responses?
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Affiliation(s)
- M J Dilworth
- Centre for Rhizobium Studies, School of Biological Sciences and Biotechnology, Murdoch University, Perth, Australia
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28
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Slonczewski JL, Blankenhorn D. Acid and base regulation in the proteome of Escherichia coli. NOVARTIS FOUNDATION SYMPOSIUM 1999; 221:75-83; discussions 83-92. [PMID: 10207914 DOI: 10.1002/9780470515631.ch6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Acid and base conditions have many significant effects on the growth of Escherichia coli. External and internal pH perturbations induce different classes of genes. pH-dependent regulation of genes intersects with other regulatory responses, e.g. oxygen level or osmolarity. 2D electrophoretic gels were used to compare global patterns of protein induction in Escherichia coli grown in complex media buffered at the acid or alkaline ends of the pH range for growth (pH 4.4 vs. pH 9.1). Preliminary results indicate new classes of acid- and base-dependent regulation, in some cases highly dependent on oxygen level. Other proteins are induced strongly at both extremes of pH, compared to pH 7. Current work continues to dissect the relationship between effects of pH, oxygen level and osmolarity.
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Affiliation(s)
- J L Slonczewski
- Department of Biology, Kenyon College, Gambier, OH 43022, USA
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29
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Lemonnier M, Lane D. Expression of the second lysine decarboxylase gene of Escherichia coli. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 3):751-760. [PMID: 9534244 DOI: 10.1099/00221287-144-3-751] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Certain amino acids are substrates for two decarboxylase enzymes in Escherichia coli, one inducible by anaerobic growth at low pH and the other constitutive. In the case of lysine, an inducible decarboxylase (CadA) has been extensively characterized, but evidence for the existence of a second lysine decarboxylase is fragmentary and uncertain. This paper confirms that a second lysine decarboxylase is encoded by a locus (ldc) previously suggested to be a lysine decarboxylase gene on the basis of sequence comparisons. Overexpression of the cloned gene provided sufficient quantities of enzyme in cell-free extracts for preliminary examination of the properties of the ldc gene product, Ldc. The enzyme is active over a broad range of pH with an optimum at 7.6, much higher than that of CadA, about 5.5. The temperature optimum for both enzymes is similar, at about 52 degrees C, but Ldc is more readily inactivated by heat than CadA. Expression of ldc from its own promoter was very weak for cells growing in a variety of media, although a low level of lysine decarboxylase was present in cells that carried the ldc region on an oligo-copy plasmid when these were grown in minimal-glucose medium. Northern analysis of RNA extracted from such cells revealed a transcript whose length corresponded to that of the ldc gene, suggesting that ldc is normally transcribed from a promoter immediately upstream. However, most of the ldc mRNA was shorter, indicating degradation or premature termination. The ldc upstream sequence promoted transcription of a lacZ gene to which it was fused. Introduction of the upstream sequence as an insert in a multicopy vector increased transcription of the resident lacZ fusion. The low level of expression in single copy, the emergence of expression when the gene is present at moderate copy number, and the derepression by the upstream sequence in trans imply that this second lysine decarboxylase gene may not be constitutive but subject to specific repression by a factor which remains to be identified.
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30
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Futatsugi L, Saito H, Kakegawa T, Kobayashi H. Growth of an Escherichia coli mutant deficient in respiration. FEMS Microbiol Lett 1997; 156:141-5. [PMID: 9368373 DOI: 10.1111/j.1574-6968.1997.tb12719.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
An Escherichia coli mutant deficient in genes for heme biosynthesis grew in medium of initial pH 8 containing 1% tryptone and glucose under aerobic growth conditions, and its doubling time was approximately 60 min at 37 degrees C. The growth rate was not increased under O2-limiting conditions. When the mutant was grown in medium of initial pH 6, growth stopped at the middle of the exponential growth phase. This could be overcome and the growth yield increased by the addition of 20 mM lysine to the growth medium. Lysine did not prevent the decrease in the medium pH as growth proceeded, making it unlikely that lysine decarboxylation stimulates growth by the alkalinization of the medium. These results indicate that respiration is not obligatory for growth under aerobic conditions, but growth without respiration at low pH requires a large amount of lysine.
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Affiliation(s)
- L Futatsugi
- Faculty of Pharmaceutical Sciences, Chiba University, Japan
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31
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Neely MN, Olson ER. Kinetics of expression of the Escherichia coli cad operon as a function of pH and lysine. J Bacteriol 1996; 178:5522-8. [PMID: 8808945 PMCID: PMC178378 DOI: 10.1128/jb.178.18.5522-5528.1996] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Escherichia coli cadBA genes are regulated at the transcriptional level by external pH and lysine. The membrane-localized CadC protein is required for activation of this operon under inducing conditions, which include acidic external pH, lysine, and oxygen limitation. To better understand the mechanism by which CadC functions, the kinetics of cadBA expression as a function of pH and lysine were examined. By primer extension assays, cadBA expression was detected within 4 min following exposure of cells to one of the inducing stimuli (low pH or lysine), provided that the cells had first been grown to steady state in the presence of the other inducing stimulus. The induction time was three to four times longer when both inducing stimuli were added simultaneously. cadBA expression was shut off within 4 min following a shift from acidic to neutral pH. Treatment of cells with chloramphenicol prevented induction by acidic pH and lysine. Transcription of lysP (encodes a lysine transporter) was also examined, since it is a negative regulator of cadBA expression in the absence of lysine. lysP expression was repressed by lysine but not influenced by pH. Putative transcription start sites for lysP and cadC were determined. Together, these data suggest that CadC senses the lysine- and pH-induced signals separately and that one of the roles of lysine in inducing cadBA may be to repress expression of lysP, thus eliminating the repressing effects of LysP.
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Affiliation(s)
- M N Neely
- Department of Biotechnology, Parke-Davis Pharmaceutical Research, Warner Lambert Inc., Ann Arbor, Michigan 48105, USA
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32
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Konings WN, Lolkema JS, Poolman B. The generation of metabolic energy by solute transport. Arch Microbiol 1995. [DOI: 10.1007/bf02529957] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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