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Awadh AA, Le Gresley A, Forster-Wilkins G, Kelly AF, Fielder MD. Determination of metabolic activity in planktonic and biofilm cells of Mycoplasma fermentans and Mycoplasma pneumoniae by nuclear magnetic resonance. Sci Rep 2021; 11:5650. [PMID: 33707544 PMCID: PMC7952918 DOI: 10.1038/s41598-021-84326-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 02/03/2021] [Indexed: 01/31/2023] Open
Abstract
Mycoplasmas are fastidious microorganisms, typically characterised by their restricted metabolism and minimalist genome. Although there is reported evidence that some mycoplasmas can develop biofilms little is known about any differences in metabolism in these organisms between the growth states. A systematic metabolomics approach may help clarify differences associated between planktonic and biofilm associated mycoplasmas. In the current study, the metabolomics of two different mycoplasmas of clinical importance (Mycoplasma pneumoniae and Mycoplasma fermentans) were examined using a novel approach involving nuclear magnetic resonance spectroscopy and principle component analysis. Characterisation of metabolic changes was facilitated through the generation of high-density metabolite data and diffusion-ordered spectroscopy that provided the size and structural information of the molecules under examination. This enabled the discrimination between biofilms and planktonic states for the metabolomic profiles of both organisms. This work identified clear biofilm/planktonic differences in metabolite composition for both clinical mycoplasmas and the outcomes serve to establish a baseline understanding of the changes in metabolism observed in these pathogens in their different growth states. This may offer insight into how these organisms are capable of exploiting and persisting in different niches and so facilitate their survival in the clinical setting.
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Affiliation(s)
- Ammar A. Awadh
- grid.15538.3a0000 0001 0536 3773School of Life Sciences, Pharmacy and Chemistry, SEC Faculty, Kingston University London, Kingston Upon Thames, UK
| | - Adam Le Gresley
- grid.15538.3a0000 0001 0536 3773School of Life Sciences, Pharmacy and Chemistry, SEC Faculty, Kingston University London, Kingston Upon Thames, UK
| | - Gary Forster-Wilkins
- grid.15538.3a0000 0001 0536 3773School of Life Sciences, Pharmacy and Chemistry, SEC Faculty, Kingston University London, Kingston Upon Thames, UK
| | - Alison F. Kelly
- grid.15538.3a0000 0001 0536 3773School of Life Sciences, Pharmacy and Chemistry, SEC Faculty, Kingston University London, Kingston Upon Thames, UK
| | - Mark D. Fielder
- grid.15538.3a0000 0001 0536 3773School of Life Sciences, Pharmacy and Chemistry, SEC Faculty, Kingston University London, Kingston Upon Thames, UK
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2
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Branching Out: Alterations in Bacterial Physiology and Virulence Due to Branched-Chain Amino Acid Deprivation. mBio 2018; 9:mBio.01188-18. [PMID: 30181248 PMCID: PMC6123439 DOI: 10.1128/mbio.01188-18] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The branched-chain amino acids (BCAAs [Ile, Leu, and Val]) represent important nutrients in bacterial physiology, with roles that range from supporting protein synthesis to signaling and fine-tuning the adaptation to amino acid starvation. In some pathogenic bacteria, the adaptation to amino acid starvation includes induction of virulence gene expression: thus, BCAAs support not only proliferation during infection, but also the evasion of host defenses. The branched-chain amino acids (BCAAs [Ile, Leu, and Val]) represent important nutrients in bacterial physiology, with roles that range from supporting protein synthesis to signaling and fine-tuning the adaptation to amino acid starvation. In some pathogenic bacteria, the adaptation to amino acid starvation includes induction of virulence gene expression: thus, BCAAs support not only proliferation during infection, but also the evasion of host defenses. A body of research has accumulated over the years to describe the multifaceted physiological roles of BCAAs and the mechanisms bacteria use to maintain their intracellular levels. More recent studies have focused on understanding how fluctuations in their intracellular levels impact global regulatory pathways that coordinate the adaptation to nutrient limitation, especially in pathogenic bacteria. In this minireview, we discuss how these studies have refined the individual roles of BCAAs, shed light on how BCAA auxotrophy might promote higher sensitivity to exogenous BCAA levels, and revealed pathogen-specific responses to BCAA deprivation. These advancements improve our understanding of how bacteria meet their nutritional requirements for growth while simultaneously remaining responsive to changes in environmental nutrient availability to promote their survival in a range of environments.
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3
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Kaiser JC, King AN, Grigg JC, Sheldon JR, Edgell DR, Murphy MEP, Brinsmade SR, Heinrichs DE. Repression of branched-chain amino acid synthesis in Staphylococcus aureus is mediated by isoleucine via CodY, and by a leucine-rich attenuator peptide. PLoS Genet 2018; 14:e1007159. [PMID: 29357354 PMCID: PMC5794164 DOI: 10.1371/journal.pgen.1007159] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/01/2018] [Accepted: 12/18/2017] [Indexed: 01/06/2023] Open
Abstract
Staphylococcus aureus requires branched-chain amino acids (BCAAs; isoleucine, leucine, valine) for protein synthesis, branched-chain fatty acid synthesis, and environmental adaptation by responding to their availability via the global transcriptional regulator CodY. The importance of BCAAs for S. aureus physiology necessitates that it either synthesize them or scavenge them from the environment. Indeed S. aureus uses specialized transporters to scavenge BCAAs, however, its ability to synthesize them has remained conflicted by reports that it is auxotrophic for leucine and valine despite carrying an intact BCAA biosynthetic operon. In revisiting these findings, we have observed that S. aureus can engage in leucine and valine synthesis, but the level of BCAA synthesis is dependent on the BCAA it is deprived of, leading us to hypothesize that each BCAA differentially regulates the biosynthetic operon. Here we show that two mechanisms of transcriptional repression regulate the level of endogenous BCAA biosynthesis in response to specific BCAA availability. We identify a trans-acting mechanism involving isoleucine-dependent repression by the global transcriptional regulator CodY and a cis-acting leucine-responsive attenuator, uncovering how S. aureus regulates endogenous biosynthesis in response to exogenous BCAA availability. Moreover, given that isoleucine can dominate CodY-dependent regulation of BCAA biosynthesis, and that CodY is a global regulator of metabolism and virulence in S. aureus, we extend the importance of isoleucine availability for CodY-dependent regulation of other metabolic and virulence genes. These data resolve the previous conflicting observations regarding BCAA biosynthesis, and reveal the environmental signals that not only induce BCAA biosynthesis, but that could also have broader consequences on S. aureus environmental adaptation and virulence via CodY.
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Affiliation(s)
- Julienne C. Kaiser
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Alyssa N. King
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Jason C. Grigg
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica R. Sheldon
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - David R. Edgell
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
| | - Michael E. P. Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shaun R. Brinsmade
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Department of Microbiology and Immunology, Georgetown University, Washington, DC, United States of America
| | - David E. Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
- * E-mail:
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4
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Millman A, Dar D, Shamir M, Sorek R. Computational prediction of regulatory, premature transcription termination in bacteria. Nucleic Acids Res 2016; 45:886-893. [PMID: 27574119 PMCID: PMC5314783 DOI: 10.1093/nar/gkw749] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/08/2016] [Accepted: 08/18/2016] [Indexed: 11/26/2022] Open
Abstract
A common strategy for regulation of gene expression in bacteria is conditional transcription termination. This strategy is frequently employed by 5′UTR cis-acting RNA elements (riboregulators), including riboswitches and attenuators. Such riboregulators can assume two mutually exclusive RNA structures, one of which forms a transcriptional terminator and results in premature termination, and the other forms an antiterminator that allows read-through into the coding sequence to produce a full-length mRNA. We developed a machine-learning based approach, which, given a 5′UTR of a gene, predicts whether it can form the two alternative structures typical to riboregulators employing conditional termination. Using a large positive training set of riboregulators derived from 89 human microbiome bacteria, we show high specificity and sensitivity for our classifier. We further show that our approach allows the discovery of previously unidentified riboregulators, as exemplified by the detection of new LeuA leaders and T-boxes in Streptococci. Finally, we developed PASIFIC (www.weizmann.ac.il/molgen/Sorek/PASIFIC/), an online web-server that, given a user-provided 5′UTR sequence, predicts whether this sequence can adopt two alternative structures conforming with the conditional termination paradigm. This webserver is expected to assist in the identification of new riboswitches and attenuators in the bacterial pan-genome.
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Affiliation(s)
- Adi Millman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniel Dar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Maya Shamir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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5
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Zhang Z, Wu J, Lin W, Wang J, Yan H, Zhao W, Ma J, Ding J, Zhang P, Zhao GP. Subdomain II of α-isopropylmalate synthase is essential for activity: inferring a mechanism of feedback inhibition. J Biol Chem 2014; 289:27966-78. [PMID: 25128527 DOI: 10.1074/jbc.m114.559716] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The committed step of leucine biosynthesis, converting acetyl-CoA and α-ketoisovalerate into α-isopropylmalate, is catalyzed by α-isopropylmalate synthase (IPMS), an allosteric enzyme subjected to feedback inhibition by the end product L-leucine. We characterized the short form IPMS from Leptospira biflexa (LbIPMS2), which exhibits a catalytic activity comparable with that of the long form IPMS (LbIPMS1) and has a similar N-terminal domain followed by subdomain I and subdomain II but lacks the whole C-terminal regulatory domain. We found that partial deletion of the regulatory domain of LbIPMS1 resulted in a loss of about 50% of the catalytic activity; however, when the regulatory domain was deleted up to Arg-385, producing a protein that is almost equivalent to the intact LbIPMS2, about 90% of the activity was maintained. Moreover, in LbIPMS2 or LbIPMS1, further deletion of several residues from the C terminus of subdomain II significantly impaired or completely abolished the catalytic activity, respectively. These results define a complete and independently functional catalytic module of IPMS consisting of both the N-terminal domain and the two subdomains. Structural comparison of LbIPMS2 and the Mycobacterium tuberculosis IPMS revealed two different conformations of subdomain II that likely represent two substrate-binding states related to cooperative catalysis. The biochemical and structural analyses together with the previously published hydrogen-deuterium exchange data led us to propose a conformation transition mechanism for feedback inhibition mediated by subdomains I and II that might associated with alteration of the binding affinity toward acetyl-CoA.
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Affiliation(s)
- Zilong Zhang
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and Shanghai International Travel Healthcare Center, Shanghai Entry-Exit Inspection and Quarantine Bureau, Shanghai 200335, China
| | - Jian Wu
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Wei Lin
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Jin Wang
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Han Yan
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Wei Zhao
- Key Laboratory of Medical Molecular Virology affiliated to the Ministries of Education and Health, Shanghai Medical College, and Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jun Ma
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and
| | - Jianping Ding
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China,
| | - Peng Zhang
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China,
| | - Guo-Ping Zhao
- From the Chinese Academy of Sciences Key Laboratory of Synthetic Biology and Key Laboratory of Medical Molecular Virology affiliated to the Ministries of Education and Health, Shanghai Medical College, and Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China, Shanghai-Ministry of Science and Technology Key Laboratory for Health and Disease Genomics, Chinese National Human Genome Center, Shanghai 201203, China, Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong Special Administrative Region 999077, China, and
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6
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Rabinovitch-Deere CA, Oliver JWK, Rodriguez GM, Atsumi S. Synthetic biology and metabolic engineering approaches to produce biofuels. Chem Rev 2013; 113:4611-32. [PMID: 23488968 DOI: 10.1021/cr300361t] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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7
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Bachmann H, Starrenburg MJC, Molenaar D, Kleerebezem M, van Hylckama Vlieg JET. Microbial domestication signatures of Lactococcus lactis can be reproduced by experimental evolution. Genome Res 2011; 22:115-24. [PMID: 22080491 DOI: 10.1101/gr.121285.111] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Experimental evolution is a powerful approach to unravel how selective forces shape microbial genotypes and phenotypes. To this date, the available examples focus on the adaptation to conditions specific to the laboratory. The lactic acid bacterium Lactococcus lactis naturally occurs on plants and in dairy environments, and it is proposed that dairy strains originate from the plant niche. Here we investigate the adaptation of a L. lactis strain isolated from a plant to a dairy niche by propagating it for 1000 generations in milk. Two out of three independently evolved strains displayed significantly increased acidification rates and biomass yields in milk. Genome resequencing, revealed six, seven, and 28 mutations in the three strains, including point mutations in loci related to amino acid biosynthesis and transport and in the gene encoding MutL, which is involved in DNA mismatch repair. Two strains lost a conjugative transposon containing genes important in the plant niche but dispensable in milk. A plasmid carrying an extracellular protease was introduced by transformation. Although improving growth rate and growth yield significantly, the plasmid was rapidly lost. Comparative transcriptome and phenotypic analyses confirmed that major physiological changes associated with improved growth in milk relate to nitrogen metabolism and the loss or down-regulation of several pathways involved in the utilization of complex plant polymers. Reproducing the transition from the plant to the dairy niche through experimental evolution revealed several genome, transcriptome, and phenotype signatures that resemble those seen in strains isolated from either niche.
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8
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Smit BA, Engels WJM, Smit G. Branched chain aldehydes: production and breakdown pathways and relevance for flavour in foods. Appl Microbiol Biotechnol 2008; 81:987-99. [PMID: 19015847 PMCID: PMC7419363 DOI: 10.1007/s00253-008-1758-x] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 10/16/2008] [Accepted: 10/18/2008] [Indexed: 11/28/2022]
Abstract
Branched aldehydes, such as 2-methyl propanal and 2- and 3-methyl butanal, are important flavour compounds in many food products, both fermented and non-fermented (heat-treated) products. The production and degradation of these aldehydes from amino acids is described and reviewed extensively in literature. This paper reviews aspects influencing the formation of these aldehydes at the level of metabolic conversions, microbial and food composition. Special emphasis was on 3-methyl butanal and its presence in various food products. Knowledge gained about the generation pathways of these flavour compounds is essential for being able to control the formation of desired levels of these aldehydes.
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Affiliation(s)
- Bart A Smit
- Campina Innovation, Nieuwe Kanaal 7C, 6709PA Wageningen, The Netherlands
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9
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Abstract
Lactic acid bacteria (LAB) constitute a diverse group of Gram positive obligately fermentative microorganisms which include both beneficial and pathogenic strains. LAB generally have complex nutritional requirements and therefore they are usually associated with nutrient-rich environments such as animal bodies, plants and foodstuffs. Amino acids represent an important resource for LAB and their utilization serves a number of physiological roles such as intracellular pH control, generation of metabolic energy or redox power, and resistance to stress. As a consequence, the regulation of amino acid catabolism involves a wide set of both general and specific regulators and shows significant differences among LAB. Moreover, due to their fermentative metabolism, LAB amino acid catabolic pathways in some cases differ significantly from those described in best studied prokaryotic model organisms such as Escherichia coli or Bacillus subtilis. Thus, LAB amino acid catabolism constitutes an interesting case for the study of metabolic pathways. Furthermore, LAB are involved in the production of a great variety of fermented products so that the products of amino acid catabolism are also relevant for the safety and the quality of fermented products.
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Affiliation(s)
- María Fernández
- Instituto de Productos Lácteos de Asturias CSIC, Crta de Infiesto s/n, Villaviciosa, Asturias, Spain
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10
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Cocaign-Bousquet M, Garrigues C, Novak L, Lindley N, Loublere P. Rational development of a simple synthetic medium for the sustained growth ofLactococcus lactis. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1995.tb03131.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Activation of the diacetyl/acetoin pathway in Lactococcus lactis subsp. lactis bv. diacetylactis CRL264 by acidic growth. Appl Environ Microbiol 2008; 74:1988-96. [PMID: 18245243 DOI: 10.1128/aem.01851-07] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactococcus lactis subsp. lactis bv. diacetylactis strains are aroma-producing organisms used in starter cultures for the elaboration of dairy products. This species is essentially a fermentative microorganism, which cometabolizes glucose and citrate to yield aroma compounds through the diacetyl/acetoin biosynthetic pathway. Our previous results have shown that under acidic growth Lactococcus bv. diacetylactis CRL264 expresses coordinately the genes responsible for citrate transport and its conversion into pyruvate. In the present work the impact of acidic growth on glucose, citrate, and pyruvate metabolism of Lactococcus bv. diacetylactis CRL264 has been investigated by proteomic analysis. The results indicated that acid growth triggers the conversion of citrate, but not glucose, into alpha-acetolactate via pyruvate. Moreover, they showed that low pH has no influence on levels of lactate dehydrogenase and pyruvate dehydrogenase. Therefore, the influence of external pH on regulation of the diacetyl/acetoin biosynthetic pathway in Lactococcus bv. diacetylactis CRL264 has been analyzed at the transcriptional level. Expression of the als, aldB, aldC, and butBA genes encoding the enzymes involved in conversion of pyruvate into aroma compounds has been investigated by primer extension, reverse transcription-PCR analysis, and transcriptional fusions. The results support that this biosynthetic pathway is induced at the transcriptional level by acidic growth conditions, presumably contributing to lactococcal pH homeostasis by synthesis of neutral compounds and by decreasing levels of pyruvate.
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Botina SG, Tsygankov YD, Sukhodolets VV. Identification of industrial strains of lactic acid bacteria by methods of molecular genetic typing. RUSS J GENET+ 2006. [DOI: 10.1134/s1022795406120039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Hols P, Hancy F, Fontaine L, Grossiord B, Prozzi D, Leblond-Bourget N, Decaris B, Bolotin A, Delorme C, Dusko Ehrlich S, Guédon E, Monnet V, Renault P, Kleerebezem M. New insights in the molecular biology and physiology ofStreptococcus thermophilusrevealed by comparative genomics. FEMS Microbiol Rev 2005. [DOI: 10.1016/j.fmrre.2005.04.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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14
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den Hengst CD, van Hijum SAFT, Geurts JMW, Nauta A, Kok J, Kuipers OP. The Lactococcus lactis CodY regulon: identification of a conserved cis-regulatory element. J Biol Chem 2005; 280:34332-42. [PMID: 16040604 DOI: 10.1074/jbc.m502349200] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CodY of Lactococcus lactis MG1363 is a transcriptional regulator that represses the expression of several genes encoding proteins of the proteolytic system. DNA microarray analysis, comparing the expression profiles of L. lactis MG1363 and an isogenic strain in which codY was mutated, was used to determine the CodY regulon. In peptide-rich medium and exponentially growing cells, where CodY exerts strong repressing activity, the expression of over 30 genes was significantly increased upon removal of codY. The differentially expressed genes included those predominantly involved in amino acid transport and metabolism. In addition, several genes belonging to other functional categories were derepressed, stressing the pleiotropic role of CodY. Scrutinizing the transcriptome data with bioinformatics tools revealed the presence of a novel over-represented motif in the upstream regions of several of the genes derepressed in L. lactis MG1363DeltacodY. Evidence is presented that this 15-bp cis-sequence, AATTTTCWGAAAATT, serves as a high affinity binding site for CodY, as shown by electrophoretic mobility shift assays and DNase I footprinting analyses. The presence of this CodY-box is sufficient to evoke CodY-mediated regulation in vivo. A copy of this motif is also present in the upstream region of codY itself. It is shown that CodY regulates its own synthesis and requires the CodY-box and branched-chain amino acids to interact with its promoter.
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Affiliation(s)
- Chris D den Hengst
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN Haren and Friesland Foods Corporate Research, P. O. Box 87, 7400 AB Deventer, The Netherlands
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15
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Petranovic D, Guédon E, Sperandio B, Delorme C, Ehrlich D, Renault P. Intracellular effectors regulating the activity of the Lactococcus lactis CodY pleiotropic transcription regulator. Mol Microbiol 2005; 53:613-21. [PMID: 15228538 DOI: 10.1111/j.1365-2958.2004.04136.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CodY is a pleiotropic transcriptional regulator conserved in low-G+C Gram-positive bacteria. Two distinct signals have been shown independently to influence the activity of this regulator: the level of intracellular GTP in Bacillus subtilis and the level of intracellular branched-chain amino acids (BCAA) isoleucine, leucine and valine in Lactococcus lactis. Measurement of BCAA and GTP levels in several environmental conditions showed that L. lactis CodY responded to the intracellular BCAA concentrations but not to physiological fluctuations in intracellular GTP. In addition, we demonstrated that CodY from L. lactis did not respond to intracellular GTP even when complementing CodY activity in B. subtilis. However, L. lactis CodY activity could still be modulated in B. subtilis by adding a rich nitrogen source to the growth media. This finding suggests that only BCAA are sensed by L. lactis CodY, whereas both GTP and BCAA signals may be integrated by B. subtilis CodY. The difference in the function of CodY from B. subtilis and L. lactis seems to reflect the difference in the physiology of these two bacteria.
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Affiliation(s)
- Dina Petranovic
- Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas Cedex, France
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16
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Yasutake Y, Yao M, Sakai N, Kirita T, Tanaka I. Crystal structure of the Pyrococcus horikoshii isopropylmalate isomerase small subunit provides insight into the dual substrate specificity of the enzyme. J Mol Biol 2004; 344:325-33. [PMID: 15522288 DOI: 10.1016/j.jmb.2004.09.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Revised: 09/14/2004] [Accepted: 09/15/2004] [Indexed: 10/26/2022]
Abstract
Recent studies have implied that the isopropylmalate isomerase small subunit of the hyperthermophilic archaea Pyrococcus horikoshii (PhIPMI-s) functions as isopropylmalate isomerase in the leucine biosynthesis pathway, and as homoaconitase (HACN) in the lysine biosynthesis pathway via alpha-aminoadipic acid. PhIPMI is thus considered a key to understanding the fundamental metabolism of the earliest organisms. We describe for the first time the crystal structure of PhIPMI-s, which displays dual substrate specificity. The crystal structure unexpectedly shows that four molecules create an interlocked assembly with intermolecular disulfide linkages having a skewed 222 point-group symmetry. Although the overall fold of the PhIPMI-s monomer is related closely to domain 4 of the aconitase (ACN), one alpha-helix in the ACN structure is replaced by a short loop with relatively high temperature factor values. Because this region is essential for discriminating the structurally similar substrate based on interactions with its diversified gamma-moiety, the loop structure in the PhIPMI-s must be dependent on the presence of a substrate. The flexibility of the loop region might be a structural basis for recognizing both hydrophobic and hydrophilic gamma-moieties of two distinct substrates, isopropylmalate and homocitrate.
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Affiliation(s)
- Yoshiaki Yasutake
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-10, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan
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17
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van der Kaaij H, Desiere F, Mollet B, Germond JE. L-alanine auxotrophy of Lactobacillus johnsonii as demonstrated by physiological, genomic, and gene complementation approaches. Appl Environ Microbiol 2004; 70:1869-73. [PMID: 15006820 PMCID: PMC368417 DOI: 10.1128/aem.70.3.1869-1873.2004] [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: 11/20/2022] Open
Abstract
Using a chemically defined medium without L-alanine, Lactobacillus johnsonii was demonstrated to be strictly auxotrophic for that amino acid. A comparative genetic analysis showed that all known genes involved in L-alanine biosynthesis are absent from the genome of L. johnsonii. This auxotrophy was complemented by heterologous expression of the Bacillus subtilis L-alanine dehydrogenase.
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18
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Abstract
The chromosome structure of lactic acid bacteria has been investigated only recently. The development of pulsed-field gel electrophoresis (PFGE) combined with other DNA-based techniques enables whole-genome analysis of any bacterium, and has allowed rapid progress to be made in the knowledge of the lactic acid bacteria genome. Lactic acid bacteria possess one of the smallest eubacterial chromosomes. Depending on the species, the genome sizes range from 1.1 to 2.6 Mb. Combined physical and genetic maps of several species are already available or close to being achieved. Knowledge of the genomic structure of these organisms will serve as a basis for future genetic studies. Macrorestriction fingerprinting by PFGE is already one of the major tools for strain differentiation, identification of individual strains, and the detection of strain lineages. The genome data resulting from these studies will be of general application strain improvement.
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Affiliation(s)
- P Le Bourgeois
- Laboratoire de Microbiologie et Génétique Moléculaire du CNRS, Toulouse, France
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Chambellon E, Yvon M. CodY-regulated aminotransferases AraT and BcaT play a major role in the growth of Lactococcus lactis in milk by regulating the intracellular pool of amino acids. Appl Environ Microbiol 2003; 69:3061-8. [PMID: 12788699 PMCID: PMC161493 DOI: 10.1128/aem.69.6.3061-3068.2003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aminotransferases, which catalyze the last step of biosynthesis of most amino acids and the first step of their catabolism, may be involved in the growth of Lactococcus lactis in milk. Previously, we isolated two aminotransferases from L. lactis, AraT and BcaT, which are responsible for the transamination of aromatic amino acids, branched-chain amino acids, and methionine. In this study, we demonstrated that double inactivation of AraT and BcaT strongly reduced the growth of L. lactis in milk. Supplementation of milk with amino acids and keto acids that are substrates of both aminotransferases did not improve the growth of the double mutant. On the contrary, supplementation of milk with isoleucine or a dipeptide containing isoleucine almost totally inhibited the growth of the double mutant, while it did not affect or only slightly affected the growth of the wild-type strain. These results suggest that AraT and BcaT play a major role in the growth of L. lactis in milk by degrading the intracellular excess isoleucine, which is responsible for the growth inhibition. The growth inhibition by isoleucine is likely to be due to CodY repression of the proteolytic system, which is necessary for maximal growth of L. lactis in milk, since the growth of the CodY mutant was not affected by addition of isoleucine to milk. Moreover, we demonstrated that AraT and BcaT are part of the CodY regulon and therefore are regulated by nutritional factors, such as the carbohydrate and nitrogen sources.
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Affiliation(s)
- Emilie Chambellon
- Unité de Recherche de Biochimie et Structure des Protéines, INRA, 78352 Jouy-en-Josas, France
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20
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Kohlhaw GB. Leucine biosynthesis in fungi: entering metabolism through the back door. Microbiol Mol Biol Rev 2003; 67:1-15, table of contents. [PMID: 12626680 PMCID: PMC150519 DOI: 10.1128/mmbr.67.1.1-15.2003] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
After exploring evolutionary aspects of branched-chain amino acid biosynthesis, the review focuses on the extended leucine biosynthetic pathway as it operates in Saccharomyces cerevisiae. First, the genes and enzymes specific for the leucine pathway are considered: LEU4 and LEU9 (encoding the alpha-isopropylmalate synthase isoenzymes), LEU1 (isopropylmalate isomerase), and LEU2 (beta-isopropylmalate dehydrogenase). Emphasis is given to the unusual distribution of the branched-chain amino acid pathway enzymes between mitochondrial matrix and cytosol, on the newly defined role of Leu5p, and on regulatory mechanisms governing gene expression and enzyme activity, including new evidence for the metabolic importance of the regulation of alpha-isopropylmalate synthase by coenzyme A. Next, structure-function relationships of the transcriptional regulator Leu3p are addressed, defining its dual role as activator and repressor and discussing evidence in support of the self-masking model. Recent data pointing at a more extended Leu3p regulon are discussed. An overview of the layered controls of the extended leucine pathway is provided that includes a description of the newly recognized roles of Ilv5p and Bat1p in maintaining mitochondrial integrity. Finally, branched-chain amino acid biosynthesis and its regulation in other fungi are summarized, the question of leucine as metabolic signal is addressed, and possible directions of future research in this area are outlined.
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Affiliation(s)
- Gunter B Kohlhaw
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, USA.
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21
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Abstract
Carbohydrates are highly abundant biomolecules found extensively in nature. Besides playing important roles in energy storage and supply, they often serve as essential biosynthetic precursors or structural elements needed to sustain all forms of life. A number of unusual sugars that have certain hydroxyl groups replaced by a hydrogen, an amino group, or an alkyl side chain play crucial roles in determining the biological activity of the parent natural products in bacterial lipopolysaccharides or secondary metabolite antibiotics. Recent investigation of the biosynthesis of these monosaccharides has led to the identification of the gene clusters whose protein products facilitate the unusual sugar formation from the ubiquitous NDP-glucose precursors. This review summarizes the mechanistic studies of a few enzymes crucial to the biosynthesis of C-2, C-3, C-4, and C-6 deoxysugars, the characterization and mutagenesis of nucleotidyl transferases that can recognize and couple structural analogs of their natural substrates and the identification of glycosyltransferases with promiscuous substrate specificity. Information gleaned from these studies has allowed pathway engineering, resulting in the creation of new macrolides with unnatural deoxysugar moieties for biological activity screening. This represents a significant progress toward our goal of searching for more potent agents against infectious diseases and malignant tumors.
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Affiliation(s)
- Xuemei M He
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, USA.
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22
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Henrich B, Klein JR, Weber B, Delorme C, Renault P, Wegmann U. Food-grade delivery system for controlled gene expression in Lactococcus lactis. Appl Environ Microbiol 2002; 68:5429-36. [PMID: 12406734 PMCID: PMC129891 DOI: 10.1128/aem.68.11.5429-5436.2002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A food-grade system for the delivery of desired genes to Lactococcus lactis, their inducible expression, and their transfer to related strains was established. Based on the thermosensitive pG(+)host replicon, two types of plasmid vectors were constructed which contained sections of either the chromosomal leu operon of L. lactis or the tel operon from the lactococcal sex factor. Genes cloned into the leu or tel sequences of these vectors were delivered to the homologous regions of the chromosome or the sex factor through two single crossovers, leading to integration of the recombinant plasmids and subsequent excision of the vector portions. Inducible transcription of integrated genes was achieved by using the nisin-controlled expression (NICE) system. To establish the signal transduction genes nisRK in L. lactis, the vectors pLNG1363 (targeted to the chromosome) and pUK500 (targeted to the sex factor) were constructed. Fusions of six different peptidase genes (pep) from Lactobacillus delbrueckii with the nisin-inducible promoter P(nisA) were delivered to the sex factor with derivatives of the vector pUK300. Food-grade recombinants of L. lactis were constructed which had the nisRK genes and individual P(nisA)::pep fusions integrated either separately into the chromosome and the sex factor or simultaneously into the sex factor. With both types of recombinants, expression of P(nisA)::pep fusions after induction with nisin was demonstrated. Depending on the loci used for integration of nisRK, variable induction rates were observed. Furthermore, an engineered sex factor carrying a P(nisA)::pepI fusion was transfered by conjugation between two strains of L. lactis at a frequency of 4 x 10(-4).
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Affiliation(s)
- B Henrich
- Fachbereich Biologie, Abteilung Mikrobiologie, Universität Kaiserslautern, D-67653 Kaiserslautern, Germany.
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23
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Chia JS, Lee YY, Huang PT, Chen JY. Identification of stress-responsive genes in Streptococcus mutans by differential display reverse transcription-PCR. Infect Immun 2001; 69:2493-501. [PMID: 11254612 PMCID: PMC98184 DOI: 10.1128/iai.69.4.2493-2501.2001] [Citation(s) in RCA: 55] [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
Streptococcus mutans, which causes dental caries in the human oral cavity and occasionally causes infective endocarditis in the heart, withstands adverse environmental stress through diverse alterations in protein synthesis. Differential gene expression in response to environmental stress was analyzed by RNA fingerprinting using arbitrarily primed PCR with a panel of 11mer primers designed for differential display in Enterobacteriaceae. Dot and Northern blot hybridization confirmed that the transcription of several genes was up- or down-regulated following exposure to acid shock from pH 7.5 to 5.5. RNA of a gene designated AP-185 (acid-stress protein) was induced specifically by acid treatment, while RNA of GSP-781 (general-stress protein) was up-regulated significantly when bacteria were exposed to high osmolarity and temperature, as well as low pH. The deduced amino acid sequence of AP-185 shares homology (78% identity) with branched-chain amino acid aminotransferase. Cloning and sequence analysis of GSP-781 revealed a potential secreted protein of a molecular mass of about 43 kDa and with a pI predicted to be 5.5. Transcriptional levels of another gene, designated AR-186 (acid-repressed protein), which encodes putative aconitase, were repressed by acid treatment but were enhanced by plasma or serum components. Analogous results were identified in icd and citZ genes, and repression of these genes, along with AR-186, was also observed when they were exposed to high osmolarity and temperature. These results indicate that differential regulation of specific genes at the transcriptional level is triggered by different stress and that genes responsible for glutamate biosynthesis in the citrate pathway are coordinately regulated during the stress response of S. mutans.
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Affiliation(s)
- J S Chia
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China.
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24
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He X, Agnihotri G, Liu Hw HW. Novel enzymatic mechanisms in carbohydrate metabolism. Chem Rev 2000; 100:4615-62. [PMID: 11749360 DOI: 10.1021/cr9902998] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- X He
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712
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25
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Garault P, Letort C, Juillard V, Monnet V. Branched-chain amino acid biosynthesis is essential for optimal growth of Streptococcus thermophilus in milk. Appl Environ Microbiol 2000; 66:5128-33. [PMID: 11097879 PMCID: PMC92433 DOI: 10.1128/aem.66.12.5128-5133.2000] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactic acid bacteria are nutritionally demanding bacteria which need, among other things, amino acids for optimal growth. We identified the branched-chain amino acid (BCAA) biosynthesis pathway as an essential pathway for optimal growth of Streptococcus thermophilus in milk. Through random insertional mutagenesis, we isolated and characterized two mutants for which growth in milk is affected as a consequence of ilvB and ilvC gene interruptions. This situation demonstrates that the BCAA biosynthesis pathway is active in S. thermophilus. BCAA biosynthesis is necessary but not sufficient for optimal growth of S. thermophilus and is subject to retro-inhibition processes. The specificity of the BCAA biosynthesis pathway in S. thermophilus lies in the independent transcription of the ilvC gene encoding a keto acid reductoisomerase acting on acetolactate at the junction of the BCAA and acetoin biosynthesis pathways. The possible advantages for S. thermophilus of keeping this biosynthesis pathway active could be linked either to adaptation of the organism to milk, which is different than that of other dairy bacteria, or to the role of the pathway in maintaining the internal pH.
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Affiliation(s)
- P Garault
- Unité de Biochimie et Structure des Protéines, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas Cedex, France
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26
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Gosalbes MJ, Esteban CD, Galán JL, Pérez-Martínez G. Integrative food-grade expression system based on the lactose regulon of Lactobacillus casei. Appl Environ Microbiol 2000; 66:4822-8. [PMID: 11055930 PMCID: PMC92386 DOI: 10.1128/aem.66.11.4822-4828.2000] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lactose operon from Lactobacillus casei is regulated by very tight glucose repression and substrate induction mechanisms, which made it a tempting candidate system for the expression of foreign genes or metabolic engineering. An integrative vector was constructed, allowing stable gene insertion in the chromosomal lactose operon of L. casei. This vector was based on the nonreplicative plasmid pRV300 and contained two DNA fragments corresponding to the 3' end of lacG and the complete lacF gene. Four unique restriction sites were created, as well as a ribosome binding site that would allow the cloning and expression of new genes between these two fragments. Then, integration of the cloned genes into the lactose operon of L. casei could be achieved via homologous recombination in a process that involved two selection steps, which yielded highly stable food-grade mutants. This procedure has been successfully used for the expression of the E. coli gusA gene and the L. lactis ilvBN genes in L. casei. Following the same expression pattern as that for the lactose genes, beta-glucuronidase activity and diacetyl production were repressed by glucose and induced by lactose. This integrative vector represents a useful tool for strain improvement in L. casei that could be applied to engineering fermentation processes or used for expression of genes for clinical and veterinary uses.
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Affiliation(s)
- M J Gosalbes
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, 46100-Burjassot, Valencia, Spain
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27
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Goupil-Feuillerat N, Corthier G, Godon JJ, Ehrlich SD, Renault P. Transcriptional and translational regulation of alpha-acetolactate decarboxylase of Lactococcus lactis subsp. lactis. J Bacteriol 2000; 182:5399-408. [PMID: 10986242 PMCID: PMC110982 DOI: 10.1128/jb.182.19.5399-5408.2000] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The alpha-acetolactate decarboxylase (ALDC) gene, aldB, is the penultimate gene of the leu-ilv-ald operon, which encodes the three branched-chain amino acid (BCAA) biosynthesis genes in Lactococcus lactis. Its product plays a dual role in the cell: (i) it catalyzes the second step of the acetoin pathway, and (ii) it controls the pool of alpha-acetolactate during leucine and valine synthesis. It can be transcribed from the two promoters present upstream of the leu and ilv genes (P1 and P2) or independently under the control of its own promoter (P3). In this paper we show that the production of ALDC is limited by two mechanisms. First, the strength of P3 decreases greatly during starvation for BCAAs and under other conditions that generally provoke the stringent response. Second, although aldB is actively transcribed from P1 and P2 during BCAA starvation, ALDC is not significantly produced from these transcripts. The aldB ribosome binding site (RBS) appears to be entrapped in a stem-loop, which is itself part of a more complex RNA folding structure. The function of the structure was studied by mutagenesis, using translational fusions with luciferase genes to assess its activity. The presence of the single stem-loop entrapping the aldB RBS was responsible for a 100-fold decrease in the level of aldB translation. The presence of a supplementary secondary structure upstream of the stem-loop led to an additional fivefold decrease of aldB translation. Finally, the translation of the ilvA gene terminating in the latter structure decreased the level of translation of aldB fivefold more, leading to the complete extinction of the reporter gene activity. Since three leucines and one valine are present among the last six amino acids of the ilvA product, we propose that pausing of the ribosomes during translation could modulate the folding of the messenger, as a function of BCAA availability. The purpose of the structure-dependent regulation could be to ensure the minimal production of ALDC required for the control of the acetolactate pool during BCAA synthesis but to avoid its overproduction, which would dissipate acetolactate. Large amounts of ALDC, necessary for operation of the acetoin pathway, could be produced under favorable conditions from the P3 transcripts, which do not contain the secondary structures.
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Affiliation(s)
- N Goupil-Feuillerat
- Unité de Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy en Josas Cedex, France
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28
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Isolation and purification of acetolactate synthase and acetolactate decarboxylase from the culture ofLactococcus lactis. APPL BIOCHEM MICRO+ 2000. [DOI: 10.1007/bf02737903] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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29
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Yvon M, Chambellon E, Bolotin A, Roudot-Algaron F. Characterization and role of the branched-chain aminotransferase (BcaT) isolated from Lactococcus lactis subsp. cremoris NCDO 763. Appl Environ Microbiol 2000; 66:571-7. [PMID: 10653720 PMCID: PMC91865 DOI: 10.1128/aem.66.2.571-577.2000] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Lactococcus lactis, which is widely used as a starter in the cheese industry, the first step of aromatic and branched-chain amino acid degradation is a transamination which is catalyzed by two major aminotransferases. We have previously purified and characterized biochemically and genetically the aromatic aminotransferase, AraT. In the present study, we purified and studied the second enzyme, the branched-chain aminotransferase, BcaT. We cloned and sequenced the corresponding gene and used a mutant, along with the luciferase gene as the reporter, to study the role of the enzyme in amino acid metabolism and to reveal the regulation of gene transcription. BcaT catalyzes transamination of the three branched-chain amino acids and methionine and belongs to class IV of the pyridoxal 5'-phosphate-dependent aminotransferases. In contrast to most of the previously described bacterial BcaTs, which are hexameric, this enzyme is homodimeric. It is responsible for 90% of the total isoleucine and valine aminotransferase activity of the cell and for 50 and 40% of the activity towards leucine and methionine, respectively. The original role of BcaT was probably biosynthetic since expression of its gene was repressed by free amino acids and especially by isoleucine. However, in dairy strains, which are auxotrophic for branched-chain amino acids, BcaT functions only as a catabolic enzyme that initiates the conversion of major aroma precursors. Since this enzyme is still active under cheese-ripening conditions, it certainly plays a major role in cheese flavor development.
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Affiliation(s)
- M Yvon
- Unité de Recherche de Biochimie et Structure des Protéines, I.N.R. A., 78352 Jouy-en-Josas, France.
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30
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Kawaguchi H, Inagaki K, Matsunami H, Nakayama Y, Tano T, Tanaka H. Purification and characterization of 3-isopropylmalate dehydrogenase from Thiobacillus thiooxidans. J Biosci Bioeng 2000; 90:459-61. [PMID: 16232891 DOI: 10.1016/s1389-1723(01)80020-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2000] [Accepted: 07/10/2000] [Indexed: 11/17/2022]
Abstract
3-Isopropylmalate dehydrogenase was purified to homogeneity from the acidophilic autotroph Thiobacillus thiooxidans. The native enzyme was a dimer of molecular weight 40,000. The apparent K(m) values for 3-isopropylmalate and NAD+ were estimated to be 0.13 mM and 8.7 mM, respectively. The optimum pH for activity was 9.0 and the optimum temperature was 65 degrees C. The properties of the enzyme were similar to those of the Thiobacillus ferrooxidans enzyme, expect for substrate specificity. T. thiooxidans 3-isopropylmalate dehydrogenase could not utilize malate as a substrate.
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Affiliation(s)
- H Kawaguchi
- Department of Bioresources Chemistry, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan
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31
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KAWAGUCHI HIROSHI, INAGAKI KENJI, MATSUNAMI HIDEYUKI, NAKAYAMA YUMI, TANO TATSUO, TANAKA HIDEHIKO. Purification and Characterization of 3-Isopropylmalate Dehydrogenase from Thiobacillus thiooxidans. J Biosci Bioeng 2000. [DOI: 10.1263/jbb.90.459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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32
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Craster HL, Potter CA, Baumberg S. End-product control of expression of branched-chain amino acid biosynthesis genes in Streptomyces coelicolor A3(2): paradoxical relationships between DNA sequence and regulatory phenotype. MICROBIOLOGY (READING, ENGLAND) 1999; 145 ( Pt 9):2375-2384. [PMID: 10517590 DOI: 10.1099/00221287-145-9-2375] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The branched-chain protein amino acids isoleucine, valine and leucine can provide precursors for synthesis of complex polyketide secondary metabolites in streptomycetes; therefore the regulation of their own synthesis is of interest. DNA sequences upstream of ilvBNC, ilvD, leuA, leuB, ilvE and leuCD in Streptomyces coelicolor A3(2) have been obtained in this laboratory or as part of the S. coelicolor genome sequencing project. Upstream of ilvB and leuA, typical features of classical attenuator systems can be discerned, in particular hypothetical short ORFs with runs of Ile/Val/Leu and Leu codons, respectively. No such features are apparent upstream of other genes or gene clusters present. All five upstream regions were fused to xylE (encoding catechol dioxygenase, CO) as a reporter gene in the SCP2*-based low-copy-number vector pIJ2839. All wild-type regions showed strong depression of CO activity in the presence of all three branched-chain amino acids whether or not the attenuation features were present. By site-directed mutagenesis, the Ile/Val/Leu and Leu triplets in the putative attenuator peptides for ilvB and leuA were replaced by ones for other amino acids. In the case of ilvB, this had no effect at all; for leuA, the wild-type regulatory phenotype persisted in at least some experiments. It was concluded that (i) an unknown regulatory mechanism must be operating in the ilv/leu system of S. coelicolor A3(2) in place of classical attenuation; and (ii) it is unsafe to infer the functioning of a regulatory mechanism from sequence homologies alone.
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Affiliation(s)
| | - Chris A Potter
- School of Biology, University of Leeds, Leeds LS2 9JT, UK1
| | - Simon Baumberg
- School of Biology, University of Leeds, Leeds LS2 9JT, UK1
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33
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Cavin JF, Dartois V, Labarre C, Diviès C. Cloning of branched chain amino acid biosynthesis genes and assays of alpha-acetolactate synthase activities in Leuconostoc mesenteroides subsp. cremoris. Res Microbiol 1999; 150:189-98. [PMID: 10229948 DOI: 10.1016/s0923-2508(99)80035-7] [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: 11/18/2022]
Abstract
A genomic library from Leuconostoc mesenteroides subsp. cremoris (Lmc) in Escherichia coli was screened for alpha-acetolactate synthase (ALS) activity using a phenotypic test detecting the production of acetolactate or related C4 derivatives (diacetyl, acetoin or 2,3-butanediol) in the culture. Four recombinant E. coli clones, with plasmids containing overlapping DNA fragments and displaying anabolic ALS activity, were selected. This activity is encoded by an ilvB gene belonging to a putative operon which contains genes highly similar to the genes of the branched chain amino acid (BCAA) operon of Lactococcus lactis subsp. lactis. This putative BCAA operon is not functional as the ilvA gene is interrupted by a single mutation and the strain is auxotrophic for the three BCAAs. Only a very low anabolic ALS activity was present in cell-free extracts of Lmc and no transcript from the ilvB gene could be detected. Instability of ilvB expression in E. coli was the consequence of a frequent IS5 insertion sequence in this gene. Despite the detection of a high catabolic ALS activity in Lmc, no catabolic ALS activity gene could be found in the BCAA gene locus, indicating the presence of a catabolic als gene in the Lmc chromosome that could be absent or not expressed in the screened library.
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Affiliation(s)
- J F Cavin
- Laboratoire De Microbiologie UA INRA, ENSBANA, Université-de Bourgogne, Dijon, France.
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34
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Curic M, Stuer-Lauridsen B, Renault P, Nilsson D. A general method for selection of alpha-acetolactate decarboxylase-deficient Lactococcus lactis mutants to improve diacetyl formation. Appl Environ Microbiol 1999; 65:1202-6. [PMID: 10049884 PMCID: PMC91165 DOI: 10.1128/aem.65.3.1202-1206.1999] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enzyme acetolactate decarboxylase (Ald) plays a key role in the regulation of the alpha-acetolactate pool in both pyruvate catabolism and the biosynthesis of the branched-chain amino acids, isoleucine, leucine, and valine (ILV). This dual role of Ald, due to allosteric activation by leucine, was used as a strategy for the isolation of Ald-deficient mutants of Lactococcus lactis subsp. lactis biovar diacetylactis. Such mutants can be selected as leucine-resistant mutants in ILV- or IV-prototrophic strains. Most dairy lactococcus strains are auxotrophic for the three amino acids. Therefore, the plasmid pMC004 containing the ilv genes (encoding the enzymes involved in the biosynthesis of IV) of L. lactis NCDO2118 was constructed. Introduction of pMC004 into ILV-auxotrophic dairy strains resulted in an isoleucine-prototrophic phenotype. By plating the strains on a chemically defined medium supplemented with leucine but not valine and isoleucine, spontaneous leucine-resistant mutants were obtained. These mutants were screened by Western blotting with Ald-specific antibodies for the presence of Ald. Selected mutants lacking Ald were subsequently cured of pMC004. Except for a defect in the expression of Ald, the resulting strain, MC010, was identical to the wild-type strain, as shown by Southern blotting and DNA fingerprinting. The mutation resulting in the lack of Ald in MC010 occurred spontaneously, and the strain does not contain foreign DNA; thus, it can be regarded as food grade. Nevertheless, its application in dairy products depends on the regulation of genetically modified organisms. These results establish a strategy to select spontaneous Ald-deficient mutants from transformable L. lactis strains.
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Affiliation(s)
- M Curic
- Research and Development, Chr. Hansen A/S, DK-2970 Horsholm, Denmark
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35
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Tamakoshi M, Yamagishi A, Oshima T. The organization of the leuC, leuD and leuB genes of the extreme thermophile Thermus thermophilus. Gene 1998; 222:125-32. [PMID: 9813279 DOI: 10.1016/s0378-1119(98)00482-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
3-Isopropylmalate dehydrogenase is encoded by leuB gene while leuC and leuB genes encode the large and small subunits of isopropylmalate isomerase in leucine biosynthetic pathway, respectively. Organization of the leuB, leuC and leuD genes of an extreme thermophile, Thermus thermophilus, was investigated by sequence analysis. Location of the genes was also tested by complementation analysis of leu deficiency of the thermophile and Escherichia coli. The order was the leuC, leuD, and leuB genes and, in contrast to a previous report, they did not overlap with each other. Sequence analysis of the leuC and leuD genes suggested that cysteine residues for iron-sulfur binding and other amino acid residues involved in isomerase activity, which have been inferred from analysis of a related protein, aconitase, were highly conserved.
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Affiliation(s)
- M Tamakoshi
- Department of Molecular Biology, Tokyo University of Pharmacy & Life Science, 1432 Horinouchi, Hachioji, Tokyo 192-0392, Japan
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36
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Chen H, Guo Z, Liu HW. Biosynthesis of Yersiniose: Attachment of the Two-Carbon Branched-Chain Is Catalyzed by a Thiamine Pyrophosphate-Dependent Flavoprotein. J Am Chem Soc 1998. [DOI: 10.1021/ja983071v] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Huawei Chen
- Department of Chemistry University of Minnesota Minneapolis, Minnesota 55455
| | - Zhihong Guo
- Department of Chemistry University of Minnesota Minneapolis, Minnesota 55455
| | - Hung-wen Liu
- Department of Chemistry University of Minnesota Minneapolis, Minnesota 55455
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Martinussen J, Hammer K. The carB gene encoding the large subunit of carbamoylphosphate synthetase from Lactococcus lactis is transcribed monocistronically. J Bacteriol 1998; 180:4380-6. [PMID: 9721272 PMCID: PMC107444 DOI: 10.1128/jb.180.17.4380-4386.1998] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The biosynthesis of carbamoylphosphate is catalyzed by the heterodimeric enzyme carbamoylphosphate synthetase. The genes encoding the two subunits of this enzyme in procaryotes are normally transcribed as an operon, but the gene encoding the large subunit (carB) in Lactococcus lactis is shown to be transcribed as an isolated unit. Carbamoylphosphate is a precursor in the biosynthesis of both pyrimidine nucleotides and arginine. By mutant analysis, L. lactis is shown to possess only one carB gene; the same gene product is thus required for both biosynthetic pathways. Furthermore, arginine may satisfy the requirement for carbamoylphosphate in pyrimidine biosynthesis through degradation by means of the arginine deiminase pathway. The expression of the carB gene is subject to regulation at the level of transcription by pyrimidines, most probably by an attenuator mechanism. Upstream of the carB gene, an open reading frame showing a high degree of similarity to those of glutathione peroxidases from other organisms was identified.
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Affiliation(s)
- J Martinussen
- Department of Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark. jm@un,dty,dk
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38
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Chipman D, Barak Z, Schloss JV. Biosynthesis of 2-aceto-2-hydroxy acids: acetolactate synthases and acetohydroxyacid synthases. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1385:401-19. [PMID: 9655946 DOI: 10.1016/s0167-4838(98)00083-1] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Two groups of enzymes are classified as acetolactate synthase (EC 4. 1.3.18). This review deals chiefly with the FAD-dependent, biosynthetic enzymes which readily catalyze the formation of acetohydroxybutyrate from pyruvate and 2-oxobutyrate, as well as of acetolactate from two molecules of pyruvate (the ALS/AHAS group). These enzymes are generally susceptible to inhibition by one or more of the branched-chain amino acids which are ultimate products of the acetohydroxyacids, as well as by several classes of herbicides (sulfonylureas, imidazolinones and others). Some ALS/AHASs also catalyze the (non-physiological) oxidative decarboxylation of pyruvate, leading to peracetic acid; the possible relationship of this process to oxygen toxicity is considered. The bacterial ALS/AHAS which have been well characterized consist of catalytic subunits (around 60 kDa) and smaller regulatory subunits in an alpha2beta2 structure. In the case of Escherichia coli isozyme III, assembly and dissociation of the holoenzyme has been studied. The quaternary structure of the eukaryotic enzymes is less clear and in plants and yeast only catalytic polypeptides (homologous to those of bacteria) have been clearly identified. The presence of regulatory polypeptides in these organisms cannot be ruled out, however, and genes which encode putative ALS/AHAS regulatory subunits have been identified in some cases. A consensus sequence can be constructed from the 21 sequences which have been shown experimentally to represent ALS/AHAS catalytic polypeptides. Many other sequences fit this consensus, but some genes identified as putative 'acetolactate synthase genes' are almost certainly not ALS/AHAS. The solution of the crystal structures of several thiamin diphosphate (ThDP)-dependent enzymes which are homologous to ALS/AHAS, together with the availability of many amino acid sequences for the latter enzymes, has made it possible for two laboratories to propose similar, reasonable models for a dimer of catalytic subunits of an ALS/AHAS. A number of characteristics of these enzymes can now be better understood on the basis of such models: the nature of the herbicide binding site, the structural role of FAD and the binding of ThDP-Mg2+. The models are also guides for experimental testing of ideas concerning structure-function relationships in these enzymes, e.g. the nature of the substrate recognition site. Among the important remaining questions is how the enzyme suppresses alternative reactions of the intrinsically reactive hydroxyethylThDP enamine formed by the decarboxylation of the first substrate molecule and specifically promotes its condensation with 2-oxobutyrate or pyruvate.
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Affiliation(s)
- D Chipman
- Department of Life Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel.
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Matsunami H, Kawaguchi H, Inagaki K, Eguchi T, Kakinuma K, Tanaka H. Overproduction and substrate specificity of 3-isopropylmalate dehydrogenase from Thiobacillus ferrooxidans. Biosci Biotechnol Biochem 1998; 62:372-3. [PMID: 9532798 DOI: 10.1271/bbb.62.372] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We constructed an overexpression system in Escherichia coli of the leuB gene coding for 3-isopropylmalate dehydrogenase in Thiobacillus ferrooxidans. E. coli harboring the plasmid we constructed, pKK leuB1, produced 17-fold the enzyme protein of the expression system previously used for purification. The substrate specificity of the enzyme was analyzed with synthetic (2R, 3S)-3-alkylmalates. The 3-isopropylmalate dehydrogenase of Thiobacillus ferrooxidans had broad specificity toward the alkylmalates.
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Affiliation(s)
- H Matsunami
- Department of Bioresources Chemistry, Faculty of Agriculture, Okayama University, Japan
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Goupil-Feuillerat N, Cocaign-Bousquet M, Godon JJ, Ehrlich SD, Renault P. Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis. J Bacteriol 1997; 179:6285-93. [PMID: 9335274 PMCID: PMC179541 DOI: 10.1128/jb.179.20.6285-6293.1997] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The alpha-acetolactate decarboxylase gene aldB is clustered with the genes for the branched-chain amino acids (BCAA) in Lactococcus lactis subsp. lactis. It can be transcribed with BCAA genes under isoleucine regulation or independently of BCAA synthesis under the control of its own promoter. The product of aldB is responsible for leucine sensibility under valine starvation. In the presence of more than 10 microM leucine, the alpha-acetolactate produced by the biosynthetic acetohydroxy acid synthase IlvBN is transformed to acetoin by AldB and, consequently, is not available for valine synthesis. AldB is also involved in acetoin formation in the 2,3-butanediol pathway, initiated by the catabolic acetolactate synthase, AlsS. The differences in the genetic organization, the expression, and the kinetics parameters of these enzymes between L. lactis and Klebsiella terrigena, Bacillus subtilis, or Leuconostoc oenos suggest that this pathway plays a different role in the metabolism in these bacteria. Thus, the alpha-acetolactate decarboxylase from L. lactis plays a dual role in the cell: (i) as key regulator of valine and leucine biosynthesis, by controlling the acetolactate flux by a shift to catabolism; and (ii) as an enzyme catalyzing the second step of the 2,3-butanediol pathway.
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Affiliation(s)
- N Goupil-Feuillerat
- Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas, France
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41
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van Ham RC, Moya A, Latorre A. Putative evolutionary origin of plasmids carrying the genes involved in leucine biosynthesis in Buchnera aphidicola (endosymbiont of aphids). J Bacteriol 1997; 179:4768-77. [PMID: 9244264 PMCID: PMC179323 DOI: 10.1128/jb.179.15.4768-4777.1997] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
An 8.5-kb plasmid encoding genes (leuABCD) involved in leucine biosynthesis and a small plasmid of 1.74 kb of yet unknown function were found in the intracellular symbiont, Buchnera aphidicola, of two divergent aphid species, Thelaxes suberi and Tetraneura caerulescens, respectively. The leuABCD-carrying plasmid (pBTs1) was amplified from total aphid DNA by inverse long PCR, using outwardly oriented oligonucleotide primers specific to leuA. The resulting 8.2-kb PCR fragment as well as the 1.74-kb plasmid (pBTc1) were cloned and sequenced. pBTs1 differed from a previously described B. aphidicola plasmid (pRPE) of the aphid Rhopalosiphum padi by the presence of a small heat shock gene (ibp) and in the order of the leuABCD and repA genes. Comparison of both leucine plasmids to the small plasmid pBTc1 revealed extensive similarity with respect to putative replication functions as well as in the presence of a highly conserved open reading frame that was found to be homologous to Escherichia coli YqhA and Haemophilus influenzae HI0507 and which may encode an integral membrane protein. The three B. aphidicola plasmids most likely evolved from a common ancestral replicon, which in turn may be distantly related to IncFII plasmids. Phylogenetic affiliations of the B. aphidicola strains of the two aphid species were assessed by sequencing of their 16S rRNA genes. Evaluation of the distribution of the leuABCD-encoding plasmids within a phylogenetic framework suggests independent origins for pBTs1 and pRPE from an ancestral replicon resembling pBTc1. The implications for symbiotic essential amino acid biosynthesis and provisioning are discussed.
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Affiliation(s)
- R C van Ham
- Department of Genetics, University of Valencia, Spain
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Antelmann H, Bernhardt J, Schmid R, Mach H, Völker U, Hecker M. First steps from a two-dimensional protein index towards a response-regulation map for Bacillus subtilis. Electrophoresis 1997; 18:1451-63. [PMID: 9298659 DOI: 10.1002/elps.1150180820] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Data on the identification of proteins of Bacillus subtilis on two-dimensional (2-D) gels as well as their regulation are summarized and the identification of 56 protein spots is included. The pattern of proteins synthesized in Bacillus subtilis during exponential growth, during starvation for glucose or phosphate, or after the imposition of stresses like heat shock, salt- and ethanol stress as well as oxidative stress was analyzed. N-terminal sequencing of protein spots allowed the identification of 93 proteins on 2-D gels, which are required for the synthesis of amino acids and nucleotides, the generation of ATP, for glycolyses, the pentose phosphate cycle, the citric acid cycle as well as for adaptation to a variety of stress conditions. A computer-aided analysis of the 2-D gels was used to monitor the synthesis profile of more than 130 protein spots. Proteins performing housekeeping functions during exponential growth displayed a reduced synthesis rate during stress and starvation, whereas spots induced during stress and starvation were classified as specific stress proteins induced by a single stimulus or a group of related stimuli, or as general stress proteins induced by a variety of entirely different stimuli. The analysis of mutants in global regulators was initiated in order to establish a response regulation map for B. subtilis. These investigations demonstrated that the alternative sigma factor sigma B is involved in the regulation of almost all of the general stress proteins and that the phoPR two-component system is required for the induction of a large part but not all of the proteins induced by phosphate starvation.
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Affiliation(s)
- H Antelmann
- Ernst-Moritz-Arndt-Universität Greifswald, Institut für Mikrobiologie und Molekularbiologie, Germany
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43
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Boumerdassi H, Monnet C, Desmazeaud M, Corrieu G. Isolation and properties of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 mutants producing diacetyl and acetoin from glucose. Appl Environ Microbiol 1997; 63:2293-9. [PMID: 9172349 PMCID: PMC168522 DOI: 10.1128/aem.63.6.2293-2299.1997] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Following treatment with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine, three mutants of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 that produced diacetyl and acetoin from glucose were isolated. The lactate dehydrogenase activity of these mutants was strongly attenuated, and the mutants produced less lactate than the parental strain. The kinetic properties of lactate dehydrogenase of strain CNRZ 483 and the mutants revealed differences in the affinity of the enzyme for pyruvate, NADH, and fructose-1,6-diphosphate. When cultured aerobically, strain CNRZ 483 transformed 2.3% of glucose to acetoin and produced no diacetyl or 2,3-butanediol. Under the same conditions, mutants 483L1, 483L2, and 483L3 transformed 42.0, 78.9, and 75.8%, respectively, of glucose to C4 compounds (diacetyl, acetoin, and 2,3-butanediol). Anaerobically, strain CNRZ 483 produced no C4 compounds, while mutants 483L1, 483L2, and 483L3 transformed 2.0, 37.0, and 25.8% of glucose to acetoin and 2,3-butanediol. In contrast to the parental strain, the NADH balance showed that the mutants regenerated most of the NAD via NADH oxidase under aerobic conditions and by ethanol production under anaerobic conditions.
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Affiliation(s)
- H Boumerdassi
- Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Institut National de la Recherche Agronomique, Thiverval Grignon, France
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44
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Monnet C, Schmitt P, Divies C. Development and Use of a Screening Procedure for Production of (alpha)-Acetolactate by Lactococcus lactis subsp. lactis biovar diacetylactis Strains. Appl Environ Microbiol 1997; 63:793-5. [PMID: 16535527 PMCID: PMC1389533 DOI: 10.1128/aem.63.2.793-795.1997] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A method was developed to screen and isolate mutagenized Lactococcus lactis subsp. lactis biovar diacetylactis strains accumulating (alpha)-acetolactate. This compound is accumulated by (alpha)-acetolactate decarboxylase-deficient strains and undergoes spontaneous degradation into diacetyl on agar plates. The diacetyl produced is detected by a colorimetric reaction yielding a red halo around the colonies.
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45
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Asayama M, Kabasawa M, Shirai M. A novel genetic organization: the leuA-rpoD1 locus in the cyanobacterium Microcystis aeruginosa K-81. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1350:15-20. [PMID: 9003451 DOI: 10.1016/s0167-4781(96)00191-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We cloned and sequenced the region upstream of rpoD1, which encodes a principal sigma factor in the cyanobacterium Microcystis aeruginosa K-81. An open reading frame (orf1, 1599 bp) was discovered, the deduced amino-acid sequence of which (533 aa, 58, 016 Da) exhibits homology to another bacterial leuA gene product, 2-isopropylmalate synthase. The leuA (orf1) gene specifically complemented an E. coli leuA mutant. The 5'-upstream region of leuA did not contain possible leader peptide or stem-loop structures for attenuation. These findings indicate that the genetic structure of the leuA-rpoD1 locus in M. aeruginosa K-81 significantly differs from those of known leuA and rpoD loci found in other bacteria.
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Affiliation(s)
- M Asayama
- Laboratory of Molecular Microbiology, School of Agriculture, Ibaraki University, Japan
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46
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Garmyn D, Monnet C, Martineau B, Guzzo J, Cavin JF, Diviès C. Cloning and sequencing of the gene encoding alpha-acetolactate decarboxylase from Leuconostoc oenos. FEMS Microbiol Lett 1996; 145:445-50. [PMID: 8978099 DOI: 10.1111/j.1574-6968.1996.tb08614.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The alsD gene encoding alpha-acetolactate decarboxylase was isolated from a genomic library of Leuconostoc oenos, using a screening procedure developed on microtiter plates. The nucleotide sequence of alsD encodes a putative protein of 239 amino acids showing significant similarity with other bacterial alpha-acetolactate decarboxylases. Upstream from alsD lies an open reading frame (alsS) which is highly similar to bacterial genes coding for catabolic alpha-acetolactate synthases. Northern (RNA) blotting analyses indicated the presence of a 2.4-kb dicistronic transcript of alsS and alsD. This suggests that the alsS and alsD genes are organized in a single operon.
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Affiliation(s)
- D Garmyn
- Laboratoire de Microbiologie, ENSBANA, Université de Bourgogne, Dijon, France.
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47
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Affiliation(s)
- Dennis H. Flint
- E. I. du Pont de Nemours and Co., Central Research and Development, Experimental Station, P.O. Box 80328, Wilmington, Delaware 19880-0328
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48
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Kok J. Inducible gene expression and environmentally regulated genes in lactic acid bacteria. Antonie Van Leeuwenhoek 1996; 70:129-45. [PMID: 8879404 DOI: 10.1007/bf00395930] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Relatively recently, a number of genes and operons have been identified in lactic acid bacteria that are inducible and respond to environmental factors. Some of these genes/operons had been isolated and analysed because of their importance in the fermentation industry and, consequently, their transcription was studied and found to be regulatable. Examples are the lactose operon, the operon for nisin production, and genes in the proteolytic pathway of Lactococcus lactis, as well as xylose metabolism in Lactobacillus pentosus. Some other operons were specifically targetted with the aim to compare their mode of regulation with known regulatory mechanisms in other well-studied bacteria. These studies, dealing with the biosynthesis of histidine, tryptophan, and of the branched chain amino acids in L. lactis, have given new insights in gene regulation and in the occurrence of auxotrophy in these bacteria. Also, nucleotide sequence analyses of a number of lactococcal bacteriophages was recently initiated to, among other things, specifically learn more about regulation of the phage life cycle. Yet another approach in the analysis of regulated genes is the 'random' selection of genetic elements that respond to environmental stimuli and the first of such sequences from lactic acid bacteria have been identified and characterized. The potential of these regulatory elements in fundamental research and practical (industrial) applications will be discussed.
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Affiliation(s)
- J Kok
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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49
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Davidson BE, Kordias N, Dobos M, Hillier AJ. Genomic organization of lactic acid bacteria. Antonie Van Leeuwenhoek 1996; 70:161-83. [PMID: 8879406 DOI: 10.1007/bf00395932] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Current knowledge of the genomes of the lactic acid bacteria, Lactococcus lactis and Streptococcus thermophilus, and members of the genera Lactobacillus, Leuconostoc, Pediococcus and Carnobacterium, is reviewed. The genomes contain a chromosome within the size range of 1.8 to 3.4 Mbp. Plasmids are common in Lactococcus lactis (most strains carry 4-7 different plasmids), some of the lactobacilli and pediococci, but they are not frequently present in S. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus or the intestinal lactobacilli. Five IS elements have been found in L. lactis and most strains carry multiple copies of at least two of them; some strains also carry a 68-kbp conjugative transposon. IS elements have been found in the genera Lactobacillus and Leuconostoc, but not in S. thermophilus. Prophages are also a normal component of the L. lactis genome and lysogeny is common in the lactobacilli, however it appears to be rare in S. thermophilus. Physical and genetic maps for two L. lactis subsp. lactis strains, two L. lactis subsp. cremoris strains and S. thermophilus A054 have been constructed and each reveals the presence of six rrn operons clustered in less than 40% of the chromosome. The L. lactis subsp. cremoris MG1363 map contains 115 genetic loci and the S. thermophilus map has 35. The maps indicate significant plasticity in the L. lactis subsp. cremoris chromosome in the form of a number of inversions and translocations. The cause(s) of these rearrangements is (are) not known. A number of potentially powerful genetic tools designed to analyse the L. lactis genome have been constructed in recent years. These tools enable gene inactivation, gene replacement and gene recovery experiments to be readily carried out with this organism, and potentially with other lactic acid bacteria and Gram-positive bacteria. Integration vectors based on temperate phage attB sites and the random insertion of IS elements have also been developed for L. lactis and the intestinal lactobacilli. In addition, a L. lactis sex factor that mobilizes the chromosome in a manner reminiscent to that seen with Escherichia coli Hfr strains has been discovered and characterized. With the availability of this new technology, research into the genome of the lactic acid bacteria is poised to undertake a period of extremely rapid information accrual.
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Affiliation(s)
- B E Davidson
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia
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50
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Cocaign-Bousquet M, Garrigues C, Loubiere P, Lindley ND. Physiology of pyruvate metabolism in Lactococcus lactis. Antonie Van Leeuwenhoek 1996; 70:253-67. [PMID: 8879410 DOI: 10.1007/bf00395936] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Lactococcus lactis, a homofermentative lactic acid bacterium, has been studied extensively over several decades to obtain sometimes conflicting concepts relating to the growth behaviour. In this review some of the data will be examined with respect to pyruvate metabolism. It will be demonstrated that the metabolic transformation of pyruvate can be predicted if the growth-limiting constraints are adequately established. In general lactate remains the major product under conditions in which sugar metabolism via a homolactic fermentation can satisfy the energy requirements necessary to assimilate anabolic substrates from the medium. In contrast, alternative pathways are involved when this energy supply becomes limiting or when the normal pathways can no longer maintain balanced carbon flux. Pyruvate occupies an important position within the metabolic network of L. lactis and the control of pyruvate distribution within the various pathways is subject to co-ordinated regulation by both gene expression mechanisms and allosteric modulation of enzyme activity.
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Affiliation(s)
- M Cocaign-Bousquet
- Centre de Bioingnierie Gilbert Durand, UMR CNRS, Institut National des Sciences Appliques, Complexe Scientifique de Rangueil, Toulouse, France
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