1
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Wang Y, Dong W, Chu L, Zhao H, He L, Sheng X. A combination of proteomics, genetics, and physiology provides insights into the acid-tolerance phenotype of Pseudomonas pergaminensis F77. Microbiol Res 2024; 278:127545. [PMID: 37952350 DOI: 10.1016/j.micres.2023.127545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/29/2023] [Accepted: 11/04/2023] [Indexed: 11/14/2023]
Abstract
Acid tolerance is crucial for the effective and persistent mineral weathering by acid-producing bacteria. Here, the molecular basis of the acid tolerance of mineral-weathering Pseudomonas pergaminensis F77 was identified using proteomics analysis of the strain under acid stress. Then, the acid tolerance of strain F77 and its mutants with deletion of the acid tolerance-related genes orf03767, mcp, resR, nueR, yegD, and fxsA, which are involved in the two-component systems, DNA repair, nucleotide binding, and membrane parts, were compared. Finally, the acid tolerance-related physiological mechanisms of strain F77 and its mutants F77ΔnueR and F77ΔresR under acidic conditions were characterized. The significantly upregulated proteins in the acid-adapted and acid-challenged strain F77 included the proteins involved in metabolic pathways associated with ATPase, membrane components, organic acid transmembrane transporters, response to stimulus, nucleotide binding, ABC transporters, and two-component systems. The cell numbers decreased by 24-100% at pH ≤ 4.50, while the membrane fluidity increased by 22-61% at pH ≤ 5.50 for the mutants F77ΔnueR and F77ΔresR, compared with that of strain F77. The intracellular H+-ATPase activities decreased by 29-33% for the mutant F77ΔnueR at pH ≤ 4.50% and 33-79% for the mutant F77ΔresR at all tested pHs (pH ≤ 7.00); meanwhile, the ratios of intracellular NAD+/NADH decreased by 71-91% for the mutant F77ΔresR at all tested pHs (pH ≤ 7.00), compared with that of strain F77. Furthermore, the intracellular putrescine concentrations were reduced by 40-70% for the mutant F77ΔresR at all tested pHs (pH ≤ 7.00) compared with that of strain F77. Our findings suggested that multiple proteins and metabolic pathways were associated with bacterial acid tolerance and revealed that nueR and resR were involved in acid tolerance based on their modulation of multiple acid tolerance-related physiological functions in strain F77.
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Affiliation(s)
- Yuanli Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China; College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, China
| | - Wen Dong
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Lingfeng Chu
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Hui Zhao
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Linyan He
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
| | - Xiafang Sheng
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
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2
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Frelet-Barrand A. Lactococcus lactis, an Attractive Cell Factory for the Expression of Functional Membrane Proteins. Biomolecules 2022; 12:biom12020180. [PMID: 35204681 PMCID: PMC8961550 DOI: 10.3390/biom12020180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/17/2022] [Accepted: 01/21/2022] [Indexed: 01/27/2023] Open
Abstract
Membrane proteins play key roles in most crucial cellular processes, ranging from cell-to-cell communication to signaling processes. Despite recent improvements, the expression of functionally folded membrane proteins in sufficient amounts for functional and structural characterization remains a challenge. Indeed, it is still difficult to predict whether a protein can be overproduced in a functional state in some expression system(s), though studies of high-throughput screens have been published in recent years. Prokaryotic expression systems present several advantages over eukaryotic ones. Among them, Lactococcus lactis (L. lactis) has emerged in the last two decades as a good alternative expression system to E. coli. The purpose of this chapter is to describe L. lactis and its tightly inducible system, NICE, for the effective expression of membrane proteins from both prokaryotic and eukaryotic origins.
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Affiliation(s)
- Annie Frelet-Barrand
- FEMTO-ST Institute, UMR 6174, CNRS, Université Bourgogne Franche-Comté, 15B Avenue des Montboucons, CEDEX, 25030 Besançon, France
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3
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Wirtz L, Eder M, Brand AK, Jung H. HutT functions as the major L-histidine transporter in Pseudomonas putida KT2440. FEBS Lett 2021; 595:2113-2126. [PMID: 34245008 DOI: 10.1002/1873-3468.14159] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 11/06/2022]
Abstract
Histidine is an important carbon and nitrogen source of γ-proteobacteria and can affect bacteria-host interactions. The mechanisms of histidine uptake are only partly understood. Here, we analyze functional properties of the putative histidine transporter HutT of the soil bacterium Pseudomonas putida. The hutT gene is part of the histidine utilization operon, and the gene product belongs to the amino acid-polyamine-organocation (APC) family of secondary transporters. Deletion of hutT severely impairs growth of P. putida on histidine, suggesting that the encoded transporter is the major histidine uptake system of P. putida. Transport experiments with cells and purified and reconstituted protein indicate that HutT functions as a high-affinity histidine : proton symporter with high specificity for the amino acid. Substitution analyses identified amino acids crucial for HutT function.
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Affiliation(s)
- Larissa Wirtz
- Division of Microbiology, Department of Biology 1, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Michelle Eder
- Division of Microbiology, Department of Biology 1, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Anna-Katharina Brand
- Division of Microbiology, Department of Biology 1, Ludwig Maximilians University Munich, Martinsried, Germany
| | - Heinrich Jung
- Division of Microbiology, Department of Biology 1, Ludwig Maximilians University Munich, Martinsried, Germany
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4
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Hernandez-Valdes JA, Dalglish MM, Hermans J, Kuipers OP. Development of Lactococcus lactis Biosensors for Detection of Sulfur-Containing Amino Acids. Front Microbiol 2020; 11:1654. [PMID: 32760389 PMCID: PMC7375092 DOI: 10.3389/fmicb.2020.01654] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/25/2020] [Indexed: 11/24/2022] Open
Abstract
The sulfur-containing amino acids methionine and cysteine play an important role in food industry. These amino acids are used to confer a sulfur smell or meat-related aroma to food products. Besides their use as food additives, methionine and cysteine participate in flavor formation in dairy fermentations. For instance, the characteristic aroma of Cheddar cheeses is derived from methionine. Therefore, bacterial strains with the ability to overproduce and secrete these amino acids are relevant for the food industry. In addition, the quantification of these compounds in food matrices is a laborious task that involves sample preparation and specific analytical methods such as high-performance liquid chromatography. The ability of bacteria to naturally sense metabolites has successfully been exploited to develop biosensors. The presence of a specific metabolite is sensed by the biosensors, and it is subsequently translated into the expression of one or more reporter genes. In this study we aim to develop biosensors to detect methionine and cysteine, which are produced and secreted by wild-type Lactococcus lactis strains. We employed two strategies to create L. lactis biosensors, the first one is based on the methionine auxotrophy of this bacterium and the second strategy is based on a cysteine-responsive promoter. The characterization of the biosensors showed their specific response to the presence of these amino acids. Subsequently, we applied the methionine biosensor to quantify the presence of methionine in bacterial supernatants of wild-type L. lactis that naturally secretes methionine to benchmark the performance of our biosensors. The methionine biosensor responded linearly to the amounts of methionine present in the bacterial supernatants, i.e., the increases in the biosensor cell densities were proportional to the amounts of methionine present in the supernatants. The biosensors developed in this study tackle the limitations of amino acid quantification and the selection of strains with secretion of amino acids. These biosensors may eventually be used for screening of engineered strains to increase methionine and cysteine production, and may facilitate the detection of these amino acids in complex food matrices.
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Affiliation(s)
- Jhonatan A. Hernandez-Valdes
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | | | - Jos Hermans
- Analytical Biochemistry, Department of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Oscar P. Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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5
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Pols T, Singh S, Deelman-Driessen C, Gaastra BF, Poolman B. Enzymology of the pathway for ATP production by arginine breakdown. FEBS J 2020; 288:293-309. [PMID: 32306469 PMCID: PMC7818446 DOI: 10.1111/febs.15337] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/06/2020] [Accepted: 04/15/2020] [Indexed: 01/02/2023]
Abstract
In cells, the breakdown of arginine to ornithine and ammonium ion plus carbon dioxide is coupled to the generation of metabolic energy in the form of ATP. The arginine breakdown pathway is minimally composed of arginine deiminase, ornithine transcarbamoylase, carbamate kinase, and an arginine/ornithine antiporter; ammonia and carbon dioxide most likely diffuse passively across the membrane. The genes for the enzymes and transporter have been cloned and expressed, and the proteins have been purified from Lactococcus lactis IL1403 and incorporated into lipid vesicles for sustained production of ATP. Here, we study the kinetic parameters and biochemical properties of the individual enzymes and the antiporter, and we determine how the physicochemical conditions, effector composition, and effector concentration affect the enzymes. We report the KM and VMAX values for catalysis and the native oligomeric state of all proteins, and we measured the effect of pathway intermediates, pH, temperature, freeze-thaw cycles, and salts on the activity of the cytosolic enzymes. We also present data on the protein-to-lipid ratio and lipid composition dependence of the antiporter.
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Affiliation(s)
- Tjeerd Pols
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Shubham Singh
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Cecile Deelman-Driessen
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Bauke F Gaastra
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Bert Poolman
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
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6
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Lysis of a Lactococcus lactis Dipeptidase Mutant and Rescue by Mutation in the Pleiotropic Regulator CodY. Appl Environ Microbiol 2020; 86:AEM.02937-19. [PMID: 32005740 PMCID: PMC7117943 DOI: 10.1128/aem.02937-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 01/22/2020] [Indexed: 12/13/2022] Open
Abstract
Lactococcus lactis subsp. cremoris MG1363 is a model for the lactic acid bacteria (LAB) used in the dairy industry. The proteolytic system, consisting of a proteinase, several peptide and amino acid uptake systems, and a host of intracellular peptidases, plays a vital role in nitrogen metabolism and is of eminent importance for flavor formation in dairy products. The dipeptidase PepV functions in the last stages of proteolysis. A link between nitrogen metabolism and peptidoglycan (PG) biosynthesis was underlined by the finding that deletion of the dipeptidase gene pepV (creating strain MGΔpepV) resulted in a prolonged lag phase when the mutant strain was grown with a high concentration of glycine. In addition, most MGΔpepV cells lyse and have serious defects in their shape. This phenotype is due to a shortage of alanine, since adding alanine can rescue the growth and shape defects. Strain MGΔpepV is more resistant to vancomycin, an antibiotic targeting peptidoglycan d-Ala-d-Ala ends, which confirmed that MGΔpepV has an abnormal PG composition. A mutant of MGΔpepV was obtained in which growth inhibition and cell shape defects were alleviated. Genome sequencing showed that this mutant has a single point mutation in the codY gene, resulting in an arginine residue at position 218 in the DNA-binding motif of CodY being replaced by a cysteine residue. Thus, this strain was named MGΔpepVcodY R218C Transcriptome sequencing (RNA-seq) data revealed a dramatic derepression in peptide uptake and amino acid utilization in MGΔpepVcodY R218C A model of the connections among PepV activity, CodY regulation, and PG synthesis of L. lactis is proposed.IMPORTANCE Precise control of peptidoglycan synthesis is essential in Gram-positive bacteria for maintaining cell shape and integrity as well as resisting stresses. Although neither the dipeptidase PepV nor alanine is essential for L. lactis MG1363, adequate availability of either ensures proper cell wall synthesis. We broaden the knowledge about the dipeptidase PepV, which acts as a linker between nitrogen metabolism and cell wall synthesis in L. lactis.
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7
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Hernandez-Valdes JA, van Gestel J, Kuipers OP. A riboswitch gives rise to multi-generational phenotypic heterogeneity in an auxotrophic bacterium. Nat Commun 2020; 11:1203. [PMID: 32139702 PMCID: PMC7058034 DOI: 10.1038/s41467-020-15017-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/13/2020] [Indexed: 12/26/2022] Open
Abstract
Auxotrophy, the inability to produce an organic compound essential for growth, is widespread among bacteria. Auxotrophic bacteria rely on transporters to acquire these compounds from their environment. Here, we study the expression of both low- and high-affinity transporters of the costly amino acid methionine in an auxotrophic lactic acid bacterium, Lactococcus lactis. We show that the high-affinity transporter (Met-transporter) is heterogeneously expressed at low methionine concentrations, resulting in two isogenic subpopulations that sequester methionine in different ways: one subpopulation primarily relies on the high-affinity transporter (high expression of the Met-transporter) and the other subpopulation primarily relies on the low-affinity transporter (low expression of the Met-transporter). The phenotypic heterogeneity is remarkably stable, inherited for tens of generations, and apparent at the colony level. This heterogeneity results from a T-box riboswitch in the promoter region of the met operon encoding the high-affinity Met-transporter. We hypothesize that T-box riboswitches, which are commonly found in the Lactobacillales, may play as-yet unexplored roles in the predominantly auxotrophic lifestyle of these bacteria.
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Affiliation(s)
- Jhonatan A Hernandez-Valdes
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, Netherlands
| | - Jordi van Gestel
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Oscar P Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG, Groningen, Netherlands.
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8
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Beck MH, Flaiz M, Bengelsdorf FR, Dürre P. Induced heterologous expression of the arginine deiminase pathway promotes growth advantages in the strict anaerobe Acetobacterium woodii. Appl Microbiol Biotechnol 2019; 104:687-699. [DOI: 10.1007/s00253-019-10248-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/30/2019] [Accepted: 11/05/2019] [Indexed: 01/12/2023]
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9
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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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10
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Arimoto T, Yambe R, Morisaki H, Umezawa H, Kataoka H, Matsui S, Kuwata H. Influence of excess branched-chain amino acid uptake by Streptococcus mutans in human host cells. FEMS Microbiol Lett 2018; 365:4733272. [PMID: 29240953 DOI: 10.1093/femsle/fnx273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 12/11/2017] [Indexed: 11/12/2022] Open
Abstract
Oral streptococci, including cariogenic bacterium Streptococcus mutans, comprise a large percentage of human supragingival plaque, which contacts both tooth surfaces and gingiva. Eukaryotic cells are able to take up macromolecules and particles, including bacteria, by endocytosis. Increasing evidence indicates endocytosis may be used as an entry process by bacteria. We hypothesized that some endocytosed bacteria might survive and obtain nutrients, such as amino acids, until they are killed. To verify this hypothesis, we focused on bacterial utilization of branched-chain amino acids (BCAAs; isoleucine, leucine and valine) in host cells. A branched-chain aminotransferase, IlvE (EC 2.6.1.42), has been suggested to play an important role in internal synthesis of BCAAs in S. mutans UA159. Therefore, we constructed an ilvE-deficient S. mutans 109c strain and confirmed that it had similar growth behavior as reported previously. 14C radioactive leucine uptake assays showed that ilvE-deficient S. mutans took up more leucine both inside and outside of host cells. We further clarified that a relative decrease of BCAAs in host cells caused enhanced endocytic and autophagic activity. In conclusion, S. mutans is endocytosed by host cells and may survive and obtain nutrients, such as BCAAs, inside the cells, which might affect cellular functions of host cells.
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Affiliation(s)
- Takafumi Arimoto
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Rei Yambe
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Hirobumi Morisaki
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Haruka Umezawa
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Hideo Kataoka
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Shohei Matsui
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan.,Division of Community-Based Comprehensive Dentistry, Department of Special Needs Dentistry, Showa University School of Dentisty, Tokyo 142-8555, Japan
| | - Hirotaka Kuwata
- Department of Oral Microbilogy and Immunology, Showa University School of Dentisty, Tokyo 142-8555, Japan
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11
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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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12
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Rong JC, Cha QQ, Ren XB, Xie BB, Song XY. Complete genome sequence of Pseudoalteromonas espejiana DSM9414 T, an amino-acid-requiring strain from seawater. Mar Genomics 2017; 38:21-23. [PMID: 28869183 DOI: 10.1016/j.margen.2017.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Revised: 08/20/2017] [Accepted: 08/20/2017] [Indexed: 10/19/2022]
Abstract
Strain DSM9414, the type strain of Pseudoalteromonas espejiana, is a Gram-negative, and amino-acid-requiring stain isolated from seawater off the coast of Northern California. In this study, we report the complete genome sequence of Pseudoalteromonas espejiana DSM9414T. The genome (4,500,451bp; 40.3% G+C) is composed of two circular chromosomes: chromosome I is 3,720,756bp with 40.4% G+C content and chromosome II is 779,695bp with 39.8% G+C content. Genomic analysis showed that chromosome I encodes a complete set of ABC transporters responsible for branched-chain amino acids, whose homologous proteins were not discovered in other Pseudoalteromonas genomes released. This result indicated the tight dependence of extracellular amino acids for strain DSM9414T, which is consistent with its phenotype. The complete genome sequence of P. espejiana provides further genetic insights into the diversity of dependence on extracellular amino acids for Pseudoalteromonas species.
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Affiliation(s)
- Jin-Cheng Rong
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China
| | - Qian-Qian Cha
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China
| | - Xue-Bing Ren
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China; Institute of Marine Science and Technology, Shandong University, Jinan 250100, China
| | - Bin-Bin Xie
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China; Institute of Marine Science and Technology, Shandong University, Jinan 250100, China
| | - Xiao-Yan Song
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Jinan 250100, China.
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13
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Azizan KA, Ressom HW, Mendoza ER, Baharum SN. 13C based proteinogenic amino acid (PAA) and metabolic flux ratio analysis of Lactococcus lactis reveals changes in pentose phosphate (PP) pathway in response to agitation and temperature related stresses. PeerJ 2017; 5:e3451. [PMID: 28695065 PMCID: PMC5501154 DOI: 10.7717/peerj.3451] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 05/19/2017] [Indexed: 11/20/2022] Open
Abstract
Lactococcus lactis subsp. cremoris MG1363 is an important starter culture for dairy fermentation. During industrial fermentations, L. lactis is constantly exposed to stresses that affect the growth and performance of the bacterium. Although the response of L. lactis to several stresses has been described, the adaptation mechanisms at the level of in vivo fluxes have seldom been described. To gain insights into cellular metabolism, 13C metabolic flux analysis and gas chromatography mass spectrometry (GC-MS) were used to measure the flux ratios of active pathways in the central metabolism of L. lactis when subjected to three conditions varying in temperature (30°C, 37°C) and agitation (with and without agitation at 150 rpm). Collectively, the concentrations of proteinogenic amino acids (PAAs) and free fatty acids (FAAs) were compared, and Pearson correlation analysis (r) was calculated to measure the pairwise relationship between PAAs. Branched chain and aromatic amino acids, threonine, serine, lysine and histidine were correlated strongly, suggesting changes in flux regulation in glycolysis, the pentose phosphate (PP) pathway, malic enzyme and anaplerotic reaction catalysed by pyruvate carboxylase (pycA). Flux ratio analysis revealed that glucose was mainly converted by glycolysis, highlighting the stability of L. lactis’ central carbon metabolism despite different conditions. Higher flux ratios through oxaloacetate (OAA) from pyruvate (PYR) reaction in all conditions suggested the activation of pyruvate carboxylate (pycA) in L. lactis, in response to acid stress during exponential phase. Subsequently, more significant flux ratio differences were seen through the oxidative and non-oxidative pentose phosphate (PP) pathways, malic enzyme, and serine and C1 metabolism, suggesting NADPH requirements in response to environmental stimuli. These reactions could play an important role in optimization strategies for metabolic engineering in L. lactis. Overall, the integration of systematic analysis of amino acids and flux ratio analysis provides a systems-level understanding of how L. lactis regulates central metabolism under various conditions.
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Affiliation(s)
- Kamalrul Azlan Azizan
- Metabolomics Research Laboratory, Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor, Malaysia
| | - Habtom W Ressom
- Departments of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, D.C., United States of America
| | - Eduardo R Mendoza
- Institute of Mathematics, University of the Philippines Diliman, Quezon City, Metro Manila, Philippines.,Membrane Biochemistry Group, Max Planck Institute of Biochemistry, Planegg, Germany
| | - Syarul Nataqain Baharum
- Metabolomics Research Laboratory, Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor, Malaysia
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14
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Noens EEE, Lolkema JS. Convergent evolution of the arginine deiminase pathway: the ArcD and ArcE arginine/ornithine exchangers. Microbiologyopen 2017; 6:e00412. [PMID: 27804281 PMCID: PMC5300872 DOI: 10.1002/mbo3.412] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 11/10/2022] Open
Abstract
The arginine deiminase (ADI) pathway converts L-arginine into L-ornithine and yields 1 mol of ATP per mol of L-arginine consumed. The L-arginine/L-ornithine exchanger in the pathway takes up L-arginine and excretes L-ornithine from the cytoplasm. Analysis of the genomes of 1281 bacterial species revealed the presence of 124 arc gene clusters encoding the pathway. About half of the clusters contained the gene encoding the well-studied L-arginine/L-ornithine exchanger ArcD, while the other half contained a gene, termed here arcE, encoding a membrane protein that is not a homolog of ArcD. The arcE gene product of Streptococcus pneumoniae was shown to take up L-arginine and L-ornithine with affinities of 0.6 and 1 μmol/L, respectively, and to catalyze metabolic energy-independent, electroneutral exchange. ArcE of S. pneumoniae could replace ArcD in the ADI pathway of Lactococcus lactis and provided the cells with a growth advantage. In contrast to ArcD, ArcE catalyzed translocation of the pathway intermediate L-citrulline with high efficiency. A short version of the ADI pathway is proposed for L-citrulline catabolism and the presence of the evolutionary unrelated arcD and arcE genes in different organisms is discussed in the context of the evolution of the ADI pathway.
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Affiliation(s)
- Elke E. E. Noens
- Molecular MicrobiologyGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenGroningenThe Netherlands
| | - Juke S. Lolkema
- Molecular MicrobiologyGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenGroningenThe Netherlands
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15
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Relative Rates of Amino Acid Import via the ABC Transporter GlnPQ Determine the Growth Performance of Lactococcus lactis. J Bacteriol 2015; 198:477-85. [PMID: 26553850 DOI: 10.1128/jb.00685-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/04/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The GlnPQ transporter from Lactococcus lactis has the remarkable feature of having two substrate-binding domains (SBDs) fused to the N terminus of the transmembrane domain (TMD), and thus four SBDs are present in the homodimeric complex. Although X-ray structures and ligand binding data are available for both SBDs, little is known of how different amino acids compete with each other for transport via GlnPQ. Here we show GlnPQ has a broader substrate specificity than previously thought, with the ability to take up asparagine, glutamine, and glutamic acid, albeit via different routes and with different affinities. Asparagine and glutamine compete with each other at the level of binding to SBD1 and SBD2 (with differences in dissociation constant), but at the same time SBD1 and SBD2 compete with each other at the level of interaction with the translocator domain (with differences in affinity constant and rate of transport). Although glutamine transport via SBD1 is outcompeted by physiological concentrations of asparagine, SBD2 ensures high rates of import of the essential amino acid glutamine. Taken together, this study demonstrates that even in the presence of competing asparagine concentrations, GlnPQ has a high capacity to transport glutamine, which matches the high needs of the cell for glutamine and glutamate. IMPORTANCE GlnPQ is an ATP-binding cassette (ABC) transporter for glutamine, glutamic acid, and asparagine. The system is essential in various Gram-positive bacteria, including L. lactis and several pathogens. Here we show how the amino acids compete with each other for binding to the multiple SBDs of GlnPQ and how these SBDs compete with each other for substrate delivery to the transporter. Overall, our results show that GlnPQ has evolved to transport diverse substrates via different paths and to optimally acquire the abundant and essential amino acid glutamine.
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16
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ArcD1 and ArcD2 Arginine/Ornithine Exchangers Encoded in the Arginine Deiminase Pathway Gene Cluster of Lactococcus lactis. J Bacteriol 2015; 197:3545-53. [PMID: 26324452 DOI: 10.1128/jb.00526-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/25/2015] [Indexed: 01/26/2023] Open
Abstract
UNLABELLED The arginine deiminase (ADI) pathway gene cluster in Lactococcus lactis contains two copies of a gene encoding an l-arginine/l-ornithine exchanger, the arcD1 and arcD2 genes. The physiological function of ArcD1 and ArcD2 was studied by deleting the two genes. Deletion of arcD1 resulted in loss of the growth advantage observed in the presence of high l-arginine in different growth media. Uptake of l-arginine and l-ornithine by resting cells was reduced to the low level observed for an ArcD1/ArcD2 double deletion mutant. Deletion of the arcD2 gene did not affect the growth enhancement, and uptake activities were slightly reduced. Nevertheless, recombinant expression of ArcD2 in the ArcD1/ArcD2 double mutant did recover the growth advantage. Kinetic characterization of ArcD1 and ArcD2 showed high affinities for both l-arginine and l-ornithine (Km in the micromolar range). A difference between the two transporters was the significantly lower affinity of ArcD2 for the cationic amino acids l-ornithine, l-lysine, and l-histidine. In contrast, the affinity of ArcD2 was higher for the neutral amino acid l-alanine. Moreover, ArcD2 efficiently translocated l-alanine, while ArcD1 did not. Both transporters revealed affinities in the mM range for agmatine, cadaverine, histamine, and putrescine. These amines bind but are not translocated. It is concluded that ArcD1 is the main l-arginine/l-ornithine exchanger in the ADI pathway and that ArcD2 is not functionally expressed in the media used. ArcD2 is proposed to function together with the arcT gene that encodes a putative transaminase and is found adjacent to the arcD2 gene. IMPORTANCE The arginine deiminase (ADI) pathway gene cluster in Lactococcus lactis contains two copies of a gene encoding an l-arginine/l-ornithine exchanger, the arcD1 and arcD2 genes. The physiological function of ArcD1 and ArcD2 was studied by deleting the two genes. It is concluded that ArcD1 is the main l-arginine/l-ornithine exchanger in the ADI pathway. ArcD2 is proposed to function as a l-arginine/l-alanine exchanger in a pathway together with the arcT gene, which is found adjacent to the arcD2 gene in the ADI gene cluster.
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17
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Ricciardi A, Ianniello R, Parente E, Zotta T. Modified chemically defined medium for enhanced respiratory growth ofLactobacillus caseiandLactobacillus plantarumgroups. J Appl Microbiol 2015; 119:776-85. [DOI: 10.1111/jam.12894] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/27/2015] [Accepted: 06/20/2015] [Indexed: 11/29/2022]
Affiliation(s)
- A. Ricciardi
- Scuola di Scienze Agrarie, Forestali, Alimentari e Ambientali; Università degli Studi della Basilicata; Potenza Italy
| | - R.G. Ianniello
- Scuola di Scienze Agrarie, Forestali, Alimentari e Ambientali; Università degli Studi della Basilicata; Potenza Italy
| | - E. Parente
- Scuola di Scienze Agrarie, Forestali, Alimentari e Ambientali; Università degli Studi della Basilicata; Potenza Italy
- Istituto di Scienze dell'Alimentazione-CNR; Avellino Italy
| | - T. Zotta
- Istituto di Scienze dell'Alimentazione-CNR; Avellino Italy
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18
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Physiology and substrate specificity of two closely related amino acid transporters, SerP1 and SerP2, of Lactococcus lactis. J Bacteriol 2014; 197:951-8. [PMID: 25535271 DOI: 10.1128/jb.02471-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The serP1 and serP2 genes found adjacently on the chromosome of Lactococcus lactis strains encode two members of the amino acid-polyamine-organocation (APC) superfamily of secondary transporters that share 61% sequence identity. SerP1 transports L-serine, L-threonine, and L-cysteine with high affinity. Affinity constants (Km) are in the 20 to 40 μM range. SerP2 is a DL-alanine/DL-serine/glycine transporter. The preferred substrate appears to be DL-alanine for which the affinities were found to be 38 and 20 μM for the D and L isomers, respectively. The common substrate L-serine is a high-affinity substrate of SerP1 and a low-affinity substrate of SerP2 with affinity constants of 18 and 356 μM, respectively. Growth experiments demonstrate that SerP1 is the main L-serine transporter responsible for optimal growth in media containing free amino acids as the sole source of amino acids. SerP2 is able to replace SerP1 in this role only in medium lacking the high-affinity substrates L-alanine and glycine. SerP2 plays an adverse role for the cell by being solely responsible for the uptake of toxic D-serine. The main function of SerP2 is in cell wall biosynthesis through the uptake of D-alanine, an essential precursor in peptidoglycan synthesis. SerP2 has overlapping substrate specificity and shares 42% sequence identity with CycA of Escherichia coli, a transporter whose involvement in peptidoglycan synthesis is well established. No evidence was obtained for a role of SerP1 and SerP2 in the excretion of excess amino acids during growth of L. lactis on protein/peptide-rich media.
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19
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Cavanagh D, Fitzgerald GF, McAuliffe O. From field to fermentation: the origins of Lactococcus lactis and its domestication to the dairy environment. Food Microbiol 2014; 47:45-61. [PMID: 25583337 DOI: 10.1016/j.fm.2014.11.001] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/22/2014] [Accepted: 11/01/2014] [Indexed: 11/18/2022]
Abstract
Lactococcus lactis is an organism of substantial economic importance, used extensively in the production of fermented foods and widely held to have evolved from plant strains. The domestication of this organism to the milk environment is associated with genome reduction and gene decay, and the acquisition of specific genes involved in protein and lactose utilisation by horizontal gene transfer. In recent years, numerous studies have focused on uncovering the physiology and molecular biology of lactococcal strains from the wider environment for exploitation in the dairy industry. This in turn has facilitated comparative genome analysis of lactococci from different environments and provided insight into the natural phenotypic and genetic diversity of L. lactis. This diversity may be exploited in dairy fermentations to develop products with improved quality and sensory attributes. In this review, we discuss the classification of L. lactis and the problems that arise with phenotype/genotype designation. We also discuss the adaptation of non-dairy lactococci to milk, the traits associated with this adaptation and the potential application of non-dairy lactococci to dairy fermentations.
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Affiliation(s)
- Daniel Cavanagh
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland; Department of Microbiology, University College Cork, Co. Cork, Ireland.
| | | | - Olivia McAuliffe
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
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20
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Kevvai K, Kütt ML, Nisamedtinov I, Paalme T. Utilization of (15)N-labelled yeast hydrolysate in Lactococcus lactis IL1403 culture indicates co-consumption of peptide-bound and free amino acids with simultaneous efflux of free amino acids. Antonie van Leeuwenhoek 2014; 105:511-22. [PMID: 24389760 DOI: 10.1007/s10482-013-0103-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 12/19/2013] [Indexed: 11/26/2022]
Abstract
Lactococcus lactis subsp. lactis IL1403 was grown in medium containing unlabelled free amino acids and (15)N-labelled yeast hydrolysate to gain insight into the role of peptides as a source of amino acids under conditions where free amino acids are abundant. A mathematical model was composed to estimate the fluxes of free and peptide-derived amino acids into and out of the intracellular amino acid pool. We observed co-consumption of peptides and free amino acids and a considerable efflux of most free amino acids during growth. We did not observe significant differences between the peptide consumption patterns of essential and non-essential amino acids, which suggests that the incorporation of a particular amino acid is more dependent on its availability in a readily assimilated form than the organism's auxotrophy for it. For most amino acids the contribution of peptide-bound forms to the formation of biomass was initially between 30 and 60 % with the remainder originating from free amino acids. During the later stages of fermentation we observed a decrease in the utilization of peptide-bound amino acids, thus indicating that the more readily assimilated peptides are gradually exhausted from the medium during growth.
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Affiliation(s)
- Kaspar Kevvai
- Competence Centre of Food and Fermentation Technologies, Akadeemia tee 15a, 12618, Tallinn, Estonia,
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21
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Lactobacillus reuteri-specific immunoregulatory gene rsiR modulates histamine production and immunomodulation by Lactobacillus reuteri. J Bacteriol 2013; 195:5567-76. [PMID: 24123819 DOI: 10.1128/jb.00261-13] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human microbiome-derived strains of Lactobacillus reuteri potently suppress proinflammatory cytokines like human tumor necrosis factor (TNF) by converting the amino acid l-histidine to the biogenic amine histamine. Histamine suppresses mitogen-activated protein (MAP) kinase activation and cytokine production by signaling via histamine receptor type 2 (H2) on myeloid cells. Investigations of the gene expression profiles of immunomodulatory L. reuteri ATCC PTA 6475 highlighted numerous genes that were highly expressed during the stationary phase of growth, when TNF suppression is most potent. One such gene was found to be a regulator of genes involved in histidine-histamine metabolism by this probiotic species. During the course of these studies, this gene was renamed the Lactobacillus reuteri-specific immunoregulatory (rsiR) gene. The rsiR gene is essential for human TNF suppression by L. reuteri and expression of the histidine decarboxylase (hdc) gene cluster on the L. reuteri chromosome. Inactivation of rsiR resulted in diminished TNF suppression in vitro and reduced anti-inflammatory effects in vivo in a trinitrobenzene sulfonic acid (TNBS)-induced mouse model of acute colitis. A L. reuteri strain lacking an intact rsiR gene was unable to suppress colitis and resulted in greater concentrations of serum amyloid A (SAA) in the bloodstream of affected animals. The PhdcAB promoter region targeted by rsiR was defined by reporter gene experiments. These studies support the presence of a regulatory gene, rsiR, which modulates the expression of a gene cluster known to mediate immunoregulation by probiotics at the transcriptional level. These findings may point the way toward new strategies for controlling gene expression in probiotics by dietary interventions or microbiome manipulation.
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22
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Characterization and molecular mechanism of AroP as an aromatic amino acid and histidine transporter in Corynebacterium glutamicum. J Bacteriol 2013; 195:5334-42. [PMID: 24056108 DOI: 10.1128/jb.00971-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Corynebacterium glutamicum is equipped with abundant membrane transporters to adapt to a changing environment. Many amino acid transporters have been identified in C. glutamicum, but histidine uptake has not been investigated in detail. Here, we identified the aromatic amino acid transporter encoded by aroP as a histidine transporter in C. glutamicum by a combination of the growth and histidine uptake features. Characterization of histidine uptake showed that AroP has a moderate affinity for histidine, with a Km value of 11.40 ± 2.03 μM, and histidine uptake by AroP is competitively inhibited by the aromatic amino acids. Among the four substrates, AroP exhibits a stronger preference for tryptophan than for tyrosine, phenylalanine, and histidine. Homology structure modeling and molecular docking were performed to predict the substrate binding modes and conformational changes during substrate transport. These results suggested that tryptophan is best accommodated in the binding pocket due to shape compatibility, strong hydrophobic interactions, and the lowest binding energy, which is consistent with the observed substrate preference of AroP. Furthermore, the missense mutations of the putative substrate binding sites verified that Ser24, Ala28, and Gly29 play crucial roles in substrate binding and are highly conserved in the Gram-positive bacteria. Finally, the expression of aroP is not significantly affected by extracellular histidine or aromatic amino acids, indicating that the physiological role of AroP may be correlated with the increased fitness of C. glutamicum to assimilate extracellular amino acid for avoiding the high energy cost of amino acid biosynthesis.
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23
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Trip H, Lolkema J. Amino Acid Transport Assays in Resting Cells of Lactococcus lactis. Bio Protoc 2013. [DOI: 10.21769/bioprotoc.793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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