1
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McCann JR, Rawls JF. Essential Amino Acid Metabolites as Chemical Mediators of Host-Microbe Interaction in the Gut. Annu Rev Microbiol 2023; 77:479-497. [PMID: 37339735 PMCID: PMC11188676 DOI: 10.1146/annurev-micro-032421-111819] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Amino acids are indispensable substrates for protein synthesis in all organisms and incorporated into diverse aspects of metabolic physiology and signaling. However, animals lack the ability to synthesize several of them and must acquire these essential amino acids from their diet or perhaps their associated microbial communities. The essential amino acids therefore occupy a unique position in the health of animals and their relationships with microbes. Here we review recent work connecting microbial production and metabolism of essential amino acids to host biology, and the reciprocal impacts of host metabolism of essential amino acids on their associated microbes. We focus on the roles of the branched-chain amino acids (valine, leucine, and isoleucine) and tryptophan on host-microbe communication in the intestine of humans and other vertebrates. We then conclude by highlighting research questions surrounding the less-understood aspects of microbial essential amino acid synthesis in animal hosts.
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Affiliation(s)
- Jessica R McCann
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, North Carolina, USA; ,
| | - John F Rawls
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, North Carolina, USA; ,
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2
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Liang YF, Long ZX, Zhang YJ, Luo CY, Yan LT, Gao WY, Li H. The chemical mechanisms of the enzymes in the branched-chain amino acids biosynthetic pathway and their applications. Biochimie 2021; 184:72-87. [PMID: 33607240 DOI: 10.1016/j.biochi.2021.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/04/2021] [Accepted: 02/10/2021] [Indexed: 12/27/2022]
Abstract
l-Valine, l-isoleucine, and l-leucine are three key proteinogenic amino acids, and they are also the essential amino acids required for mammalian growth, possessing important and to some extent, special physiological and biological functions. Because of the branched structures in their carbon chains, they are also named as branched-chain amino acids (BCAAs). This review will highlight the advance in studies of the enzymes involved in the biosynthetic pathway of BCAAs, concentrating on their chemical mechanisms and applications in screening herbicides and antibacterial agents. The uses of some of these enzymes in lab scale organic synthesis are also discussed.
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Affiliation(s)
- Yan-Fei Liang
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Zi-Xian Long
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Ya-Jian Zhang
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Cai-Yun Luo
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Le-Tian Yan
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China
| | - Wen-Yun Gao
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China.
| | - Heng Li
- College of Life Sciences, National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi'an, 710069, China.
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3
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Shu H, Zhang W, Yun Y, Chen W, Zhong Q, Hu Y, Chen H, Chen W. Metabolomics study on revealing the inhibition and metabolic dysregulation in Pseudomonas fluorescens induced by 3-carene. Food Chem 2020; 329:127220. [PMID: 32516715 DOI: 10.1016/j.foodchem.2020.127220] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 05/25/2020] [Accepted: 05/31/2020] [Indexed: 11/16/2022]
Abstract
3-Carene is a monoterpenoid that has an effective inhibitory ability against Pseudomonas fluorescens (P. fluorescens) which can induce a range of food contamination problems. In this study, ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based metabolomics was used to elucidate the antimicrobial mechanism of 3-carene in P. fluorescens. Multivariate analysis of the metabolite data revealed significant differences in the potential metabolite profiles between groups. The results of univariate analysis showed that significant changes in 42 metabolites were observed after treatment with 3-carene for 12 h when compared to the control group. Moreover, 3-carene treatment resulted in disturbances in many metabolic processes, including amino acid metabolism, pantothenate and coenzyme A (CoA) biosynthesis and the tricarboxylic acid (TCA) cycle. These results provide a new insight into the antimicrobial mechanisms of 3-carene in P. fluorescens and enhance our understanding of the antimicrobial mechanism from a metabolic perspective.
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Affiliation(s)
- Huizhen Shu
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Weimin Zhang
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Yonghuan Yun
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Weijun Chen
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Chunguang Agro-product Processing Institute, Wenchang 571333, China
| | - Qiuping Zhong
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Yueying Hu
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Haiming Chen
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Huachuang Institute of Areca Research-Hainan, Haikou 570226, China.
| | - Wenxue Chen
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Chunguang Agro-product Processing Institute, Wenchang 571333, China.
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4
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Amorim Franco TM, Blanchard JS. Bacterial Branched-Chain Amino Acid Biosynthesis: Structures, Mechanisms, and Drugability. Biochemistry 2017; 56:5849-5865. [PMID: 28977745 DOI: 10.1021/acs.biochem.7b00849] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The eight enzymes responsible for the biosynthesis of the three branched-chain amino acids (l-isoleucine, l-leucine, and l-valine) were identified decades ago using classical genetic approaches based on amino acid auxotrophy. This review will highlight the recent progress in the determination of the three-dimensional structures of these enzymes, their chemical mechanisms, and insights into their suitability as targets for the development of antibacterial agents. Given the enormous rise in bacterial drug resistance to every major class of antibacterial compound, there is a clear and present need for the identification of new antibacterial compounds with nonoverlapping targets to currently used antibacterials that target cell wall, protein, mRNA, and DNA synthesis.
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Affiliation(s)
- Tathyana M Amorim Franco
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10805, United States
| | - John S Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10805, United States
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5
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Henry CS, Rotman E, Lathem WW, Tyo KEJ, Hauser AR, Mandel MJ. Generation and Validation of the iKp1289 Metabolic Model for Klebsiella pneumoniae KPPR1. J Infect Dis 2017; 215:S37-S43. [PMID: 28375518 PMCID: PMC5790149 DOI: 10.1093/infdis/jiw465] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Klebsiella pneumoniae has a reputation for causing a wide range of infectious conditions, with numerous highly virulent and antibiotic-resistant strains. Metabolic models have the potential to provide insights into the growth behavior, nutrient requirements, essential genes, and candidate drug targets in these strains. Here we develop a metabolic model for KPPR1, a highly virulent strain of K. pneumoniae. We apply a combination of Biolog phenotype data and fitness data to validate and refine our KPPR1 model. The final model displays a predictive accuracy of 75% in identifying potential carbon and nitrogen sources for K. pneumoniae and of 99% in predicting nonessential genes in rich media. We demonstrate how this model is useful in studying the differences in the metabolic capabilities of the low-virulence MGH 78578 strain and the highly virulent KPPR1 strain. For example, we demonstrate that these strains differ in carbohydrate metabolism, including the ability to metabolize dulcitol as a primary carbon source. Our model makes numerous other predictions for follow-up verification and analysis.
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Affiliation(s)
- Christopher S Henry
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne
| | | | | | - Keith E J Tyo
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois
| | - Alan R Hauser
- Department of Microbiology-Immunology
- Division of Infectious Diseases, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, and
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6
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Cofactor specificity motifs and the induced fit mechanism in class I ketol-acid reductoisomerases. Biochem J 2015; 468:475-84. [PMID: 25849365 DOI: 10.1042/bj20150183] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/07/2015] [Indexed: 11/17/2022]
Abstract
Although most sequenced members of the industrially important ketol-acid reductoisomerase (KARI) family are class I enzymes, structural studies to date have focused primarily on the class II KARIs, which arose through domain duplication. In the present study, we present five new crystal structures of class I KARIs. These include the first structure of a KARI with a six-residue β2αB (cofactor specificity determining) loop and an NADPH phosphate-binding geometry distinct from that of the seven- and 12-residue loops. We also present the first structures of naturally occurring KARIs that utilize NADH as cofactor. These results show insertions in the specificity loops that confounded previous attempts to classify them according to loop length. Lastly, we explore the conformational changes that occur in class I KARIs upon binding of cofactor and metal ions. The class I KARI structures indicate that the active sites close upon binding NAD(P)H, similar to what is observed in the class II KARIs of rice and spinach and different from the opening of the active site observed in the class II KARI of Escherichia coli. This conformational change involves a decrease in the bending of the helix that runs between the domains and a rearrangement of the nicotinamide-binding site.
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7
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Influence of valine and other amino acids on total diacetyl and 2,3-pentanedione levels during fermentation of brewer's wort. Appl Microbiol Biotechnol 2013; 97:6919-30. [PMID: 23677441 PMCID: PMC3708283 DOI: 10.1007/s00253-013-4955-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 04/22/2013] [Accepted: 04/24/2013] [Indexed: 11/18/2022]
Abstract
Undesirable butter-tasting vicinal diketones are produced as by-products of valine and isoleucine biosynthesis during wort fermentation. One promising method of decreasing diacetyl production is through control of wort valine content since valine is involved in feedback inhibition of enzymes controlling the formation of diacetyl precursors. Here, the influence of valine supplementation, wort amino acid profile and free amino nitrogen content on diacetyl formation during wort fermentation with the lager yeast Saccharomyces pastorianus was investigated. Valine supplementation (100 to 300 mg L−1) resulted in decreased maximum diacetyl concentrations (up to 37 % lower) and diacetyl concentrations at the end of fermentation (up to 33 % lower) in all trials. Composition of the amino acid spectrum of the wort also had an impact on diacetyl and 2,3-pentanedione production during fermentation. No direct correlation between the wort amino acid concentrations and diacetyl production was found, but rather a negative correlation between the uptake rate of valine (and also other branched-chain amino acids) and diacetyl production. Fermentation performance and yeast growth were unaffected by supplementations. Amino acid addition had a minor effect on higher alcohol and ester composition, suggesting that high levels of supplementation could affect the flavour profile of the beer. Modifying amino acid profile of wort, especially with respect to valine and the other branched-chain amino acids, may be an effective way of decreasing the amount of diacetyl formed during fermentation.
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8
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Zhang YJ, Rubin EJ. Feast or famine: the host-pathogen battle over amino acids. Cell Microbiol 2013; 15:1079-87. [PMID: 23521858 DOI: 10.1111/cmi.12140] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/08/2013] [Accepted: 03/11/2013] [Indexed: 01/28/2023]
Abstract
Intracellular bacterial pathogens often rely on their hosts for essential nutrients. Host cells, in turn, attempt to limit nutrient availability, using starvation as a mechanism of innate immunity. Here we discuss both host mechanisms of amino acid starvation and the diverse adaptations of pathogens to their nutrient-deprived environments. These processes provide both key insights into immune subversion and new targets for drug development.
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Affiliation(s)
- Yanjia J Zhang
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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9
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Growth inhibition of pathogenic bacteria by sulfonylurea herbicides. Antimicrob Agents Chemother 2012; 57:1513-7. [PMID: 23263008 DOI: 10.1128/aac.02327-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Emerging resistance to current antibiotics raises the need for new microbial drug targets. We show that targeting branched-chain amino acid (BCAA) biosynthesis using sulfonylurea herbicides, which inhibit the BCAA biosynthetic enzyme acetohydroxyacid synthase (AHAS), can exert bacteriostatic effects on several pathogenic bacteria, including Burkholderia pseudomallei, Pseudomonas aeruginosa, and Acinetobacter baumannii. Our results suggest that targeting biosynthetic enzymes like AHAS, which are lacking in humans, could represent a promising antimicrobial drug strategy.
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10
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Gedi V, Yoon MY. Bacterial acetohydroxyacid synthase and its inhibitors - a summary of their structure, biological activity and current status. FEBS J 2012; 279:946-63. [DOI: 10.1111/j.1742-4658.2012.08505.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Choi JD, Gedi V, Pham CN, Ryu KH, Lee HS, Kim GH, Yoon MY. Site-directed mutagenesis of catalytic and regulatory subunits of Mycobacterium tuberculosis acetohydroxyacid synthase. Enzyme Microb Technol 2010. [DOI: 10.1016/j.enzmictec.2009.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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El-Sayed AS. Microbial l-methioninase: production, molecular characterization, and therapeutic applications. Appl Microbiol Biotechnol 2010; 86:445-67. [DOI: 10.1007/s00253-009-2303-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 10/08/2009] [Accepted: 10/10/2009] [Indexed: 10/19/2022]
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13
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Kingsbury JM, McCusker JH. Cytocidal amino acid starvation of Saccharomyces cerevisiae and Candida albicans acetolactate synthase (ilv2{Delta}) mutants is influenced by the carbon source and rapamycin. MICROBIOLOGY-SGM 2009; 156:929-939. [PMID: 20019084 DOI: 10.1099/mic.0.034348-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The isoleucine and valine biosynthetic enzyme acetolactate synthase (Ilv2p) is an attractive antifungal drug target, since the isoleucine and valine biosynthetic pathway is not present in mammals, Saccharomyces cerevisiae ilv2Delta mutants do not survive in vivo, Cryptococcus neoformans ilv2 mutants are avirulent, and both S. cerevisiae and Cr. neoformans ilv2 mutants die upon isoleucine and valine starvation. To further explore the potential of Ilv2p as an antifungal drug target, we disrupted Candida albicans ILV2, and demonstrated that Ca. albicans ilv2Delta mutants were significantly attenuated in virulence, and were also profoundly starvation-cidal, with a greater than 100-fold reduction in viability after only 4 h of isoleucine and valine starvation. As fungicidal starvation would be advantageous for drug design, we explored the basis of the starvation-cidal phenotype in both S. cerevisiae and Ca. albicans ilv2Delta mutants. Since the mutation of ILV1, required for the first step of isoleucine biosynthesis, did not suppress the ilv2Delta starvation-cidal defects in either species, the cidal phenotype was not due to alpha-ketobutyrate accumulation. We found that starvation for isoleucine alone was more deleterious in Ca. albicans than in S. cerevisiae, and starvation for valine was more deleterious than for isoleucine in both species. Interestingly, while the target of rapamycin (TOR) pathway inhibitor rapamycin further reduced S. cerevisiae ilv2Delta starvation viability, it increased Ca. albicans ilv1Delta and ilv2Delta viability. Furthermore, the recovery from starvation was dependent on the carbon source present during recovery for S. cerevisiae ilv2Delta mutants, reminiscent of isoleucine and valine starvation inducing a viable but non-culturable-like state in this species, while Ca. albicans ilv1Delta and ilv2 Delta viability was influenced by the carbon source present during starvation, supporting a role for glucose wasting in the Ca. albicans cidal phenotype.
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Affiliation(s)
- Joanne M Kingsbury
- Department of Molecular Genetics and Microbiology, Box 3020, Duke University Medical Center, Durham, NC 27710, USA
| | - John H McCusker
- Department of Molecular Genetics and Microbiology, Box 3020, Duke University Medical Center, Durham, NC 27710, USA
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14
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Vyazmensky M, Zherdev Y, Slutzker A, Belenky I, Kryukov O, Barak Z, Chipman DM. Interactions between large and small subunits of different acetohydroxyacid synthase isozymes of Escherichia coli. Biochemistry 2009; 48:8731-7. [PMID: 19653643 DOI: 10.1021/bi9009488] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The large, catalytic subunits (LSUs; ilvB, ilvG and ilvI, respectively) of enterobacterial acetohydroxyacid synthases isozymes (AHAS I, II and III) have molecular weights approximately 60 kDa and are paralogous with a family of other thiamin diphosphate dependent enzymes. The small, regulatory subunits (SSUs) of AHAS I and AHAS III (ilvN and ilvH) are required for valine inhibition, but ilvN and ilvH can only confer valine sensitivity on their own LSUs. AHAS II is valine resistant. The LSUs have only approximately 15, <<1 and approximately 3%, respectively, of the activity of their respective holoenzymes, but the holoenzymes can be reconstituted with complete recovery of activity. We have examined the activation of each of the LSUs by SSUs from different isozymes and ask to what extent such activation is specific; that is, is effective nonspecific interaction possible between LSUs and SSUs of different isozymes? To our surprise, the AHAS II SSU ilvM is able to activate the LSUs of all three of the isozymes, and the truncated AHAS III SSUs ilvH-Delta80, ilvH-Delta86 and ilvH-Delta89 are able to activate the LSUs of both AHAS I and AHAS III. However, none of the heterologously activated enzymes have any feedback sensitivity. Our results imply the existence of a common region in all three LSUs to which regulatory subunits may bind, as well as a similarity between the surfaces of ilvM and the other SSUs. This surface must be included within the N-terminal betaalphabetabetaalphabeta-domain of the SSUs, probably on the helical face of this domain. We suggest hypotheses for the mechanism of valine inhibition, and reject one involving induced dissociation of subunits.
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Affiliation(s)
- Maria Vyazmensky
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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15
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Nelson DR, Duxbury T. The distribution of acetohydroxyacid synthase in soil bacteria. Antonie Van Leeuwenhoek 2007; 93:123-32. [PMID: 17624809 DOI: 10.1007/s10482-007-9186-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Accepted: 06/18/2007] [Indexed: 11/26/2022]
Abstract
Most bacteria possess the enzyme acetohydroxyacid synthase, which is used to produce branched-chain amino acids. Enteric bacteria contain several isozymes suited to different conditions, but the distribution of acetohydroxyacid synthase in soil bacteria is largely unknown. Growth experiments confirmed that Escherichia coli, Salmonella enterica serotype Typhimurium, and Enterobacter aerogenes contain isozymes of acetohydroxyacid synthase, allowing the bacteria to grow in the presence of valine (which causes feedback inhibition of AHAS I) or the sulfonylurea herbicide triasulfuron (which inhibits AHAS II) although a slight lag phase was observed in growth in the latter case. Several common soil isolates were inhibited by triasulfuron, but Pseudomonas fluorescens and Rhodococcus erythropolis were not inhibited by any combination of triasulfuron and valine. The extent of sulfonylurea-sensitive acetohydroxyacid synthase in soil was revealed when 21 out of 27 isolated bacteria in pure culture were inhibited by triasulfuron, the addition of isoleucine and/or valine reversing the effect in 19 cases. Primers were designed to target the genes encoding the large subunits (ilvB, ilvG and ilvI) of acetohydroxyacid synthase from available sequence data and a approximately 355 bp fragment in Bacillus subtilis, Arthrobacter globiformis, E. coli and S. enterica was subsequently amplified. The primers were used to create a small clone library of sequences from an agricultural soil. Phylogenetic analysis revealed significant sequence variation, but all 19 amino acid sequences were most closely related to published large subunit acetohydroxyacid synthase amino acid sequences within several phyla including the Proteobacteria and Actinobacteria. The results suggested the majority of soil microorganisms contain only one functional acetohydroxyacid synthase enzyme sensitive to sulfonylurea herbicides.
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Affiliation(s)
- Darryl R Nelson
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW, 2006, Australia.
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16
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Vinogradov M, Kaplun A, Vyazmensky M, Engel S, Golbik R, Tittmann K, Uhlemann K, Meshalkina L, Barak Z, Hübner G, Chipman DM. Monitoring the acetohydroxy acid synthase reaction and related carboligations by circular dichroism spectroscopy. Anal Biochem 2005; 342:126-33. [PMID: 15958189 DOI: 10.1016/j.ab.2005.03.049] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 03/27/2005] [Accepted: 03/28/2005] [Indexed: 11/22/2022]
Abstract
Acetohydroxy acid synthase (AHAS) and related enzymes catalyze the production of chiral compounds [(S)-acetolactate, (S)-acetohydroxybutyrate, or (R)-phenylacetylcarbinol] from achiral substrates (pyruvate, 2-ketobutyrate, or benzaldehyde). The common methods for the determination of AHAS activity have shortcomings. The colorimetric method for detection of acyloins formed from the products is tedious and does not allow time-resolved measurements. The continuous assay for consumption of pyruvate based on its absorbance at 333 nm, though convenient, is limited by the extremely small extinction coefficient of pyruvate, which results in a low signal-to-noise ratio and sensitivity to interfering absorbing compounds. Here, we report the use of circular dichroism spectroscopy for monitoring AHAS activity. This method, which exploits the optical activity of reaction products, displays a high signal-to-noise ratio and is easy to perform both in time-resolved and in commercial modes. In addition to AHAS, we examined the determination of activity of glyoxylate carboligase. This enzyme catalyzes the condensation of two molecules of glyoxylate to chiral tartronic acid semialdehyde. The use of circular dichroism also identifies the product of glyoxylate carboligase as being in the (R) configuration.
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Affiliation(s)
- Michael Vinogradov
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel
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17
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Zabalza A, González EM, Arrese-Igor C, Royuela M. Fermentative metabolism is induced by inhibiting different enzymes of the branched-chain amino acid biosynthesis pathway in pea plants. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:7486-93. [PMID: 16159177 DOI: 10.1021/jf050654x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The inhibition of branched-chain amino acid (BCAA) biosynthesis was evaluated in pea plants in relation to the ability for induction of fermentative metabolism under aerobic conditions. Chlorsulfuron and imazethapyr (inhibitors of acetolactate synthase, ALS, EC 4.1.3.18) produced a strong induction of pyruvate decarboxylase (PDC, EC 4.1.1.1) and alcohol dehydrogenase (ADH, EC 1.1.1.1) activities and a lesser induction of lactate dehydrogenase (LDH, EC 1.1.1.27) and alanine aminotransferase (AlaAT, EC 2.6.1.2) activities in roots. Inhibition of the second enzyme of the BCAA biosynthesis (ketol-acid reductoisomerase, KARI, EC 1.1.1.86) by Hoe 704 (2-dimethylphosphinoyl-2-hydroxyacetic acid) and CPCA (1,1-cyclopropanedicarboxylic acid) enhanced fermentative enzyme activities including PDC, ADH, and AlaAT. Fermentative metabolism induction occurring with ALS- and KARI-inhibitors was related to a higher expression of PDC. In the case of KARI inhibition, it is proposed that fermentation induction is due to an inhibition of ALS activity resulted from an increase in acetolactate concentration. Fermentative metabolism induction in roots, or at least ethanolic fermentation, appeared to be a general physiological response to the BCAA biosynthesis inhibition.
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Affiliation(s)
- Ana Zabalza
- Departamento Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadia, Pamplona, Spain
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18
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Affiliation(s)
- Diana M Downs
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA
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19
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Schmitz G, Downs DM. Reduced transaminase B (IlvE) activity caused by the lack of yjgF is dependent on the status of threonine deaminase (IlvA) in Salmonella enterica serovar Typhimurium. J Bacteriol 2004; 186:803-10. [PMID: 14729707 PMCID: PMC321505 DOI: 10.1128/jb.186.3.803-810.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The YjgF/YER057c/UK114 family is a highly conserved class of proteins that is represented in the three domains of life. Thus far, a biochemical function demonstrated for these proteins in vivo or in vitro has yet to be defined. In several organisms, strains lacking a YjgF homolog have a defect in branched-chain amino acid biosynthesis. This study probes the connection between yjgF and isoleucine biosynthesis in Salmonella enterica. In strains lacking yjgF the specific activity of transaminase B, catalyzing the last step in the synthesis of isoleucine, was reduced. In the absence of yjgF, transaminase B activity could be restored by inhibiting threonine deaminase, the first enzymatic step in isoleucine biosynthesis. Strains lacking yjgF showed an increased sensitivity to sulfometruron methyl, a potent inhibitor of acetolactate synthase. Based on work described here and structural reports in the literature, we suggest a working model in which YjgF has a role in protecting the cell from toxic effects of imbalanced ketoacid pools.
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Affiliation(s)
- George Schmitz
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Gaston S, Ribas-Carbo M, Busquets S, Berry JA, Zabalza A, Royuela M. Changes in mitochondrial electron partitioning in response to herbicides inhibiting branched-chain amino acid biosynthesis in soybean. PLANT PHYSIOLOGY 2003; 133:1351-9. [PMID: 14576285 PMCID: PMC281629 DOI: 10.1104/pp.103.027805] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Revised: 06/20/2003] [Accepted: 07/01/2003] [Indexed: 05/18/2023]
Abstract
The adaptation of the respiratory metabolism in roots of soybean (Glycine max L. Merr. cv Ransom) treated with herbicides that inhibit the enzyme acetolactate synthase (ALS) was analyzed. A new gas phase dual-inlet mass spectrometry system for simultaneous measurement of 34O2 to 32O2 and O2 to N2 ratios has been developed. This system is more accurate than previously described systems, allows measurements of much smaller oxygen gradients, and, as a consequence, works with tissues that have lower respiration rates. ALS inhibition caused an increase of the alternative oxidase (AOX) protein and an accumulation of pyruvate. The combination of these two effects is likely to induce the activation of the alternative pathway and its participation in the total respiration. Moreover, the start of the alternative pathway activation and the increase of AOX protein were before the decline in the activity of cytochrome pathway. The possible role of AOX under ALS inhibition is discussed.
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Affiliation(s)
- Susana Gaston
- Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
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Gaston S, Zabalza A, González EM, Arrese-Igor C, Aparicio-Tejo PM, Royuela M. Imazethapyr, an inhibitor of the branched-chain amino acid biosynthesis, induces aerobic fermentation in pea plants. PHYSIOLOGIA PLANTARUM 2002; 114:524-532. [PMID: 11975725 DOI: 10.1034/j.1399-3054.2002.1140404.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Acetolactate synthase (ALS; EC 4.1.3.18) inhibition is the primary mechanism of action of imazethapyr (IM). However, the precise mechanisms that links ALS inhibition with plant death have not been elucidated. Supply of IM to pea (Pisum sativum L) plants produced an immediate cessation of growth, caused a 50% inhibition of the in vivo ALS activity within 1 day of treatment, and a remarkable accumulation (2.7-times) of free amino acids after 3 days. Carbohydrates (soluble and starch) were accumulated in both leaves and roots. Accumulation of soluble sugars in roots preceded that of starch in leaves, suggesting that the accumulation of carbohydrates in leaves is not the reason for the arrested root growth. A transient pyruvate accumulation was observed in roots, 1 day after the onset of IM supply. This was coincident with an increase in pyruvate decarboxylase (EC 4.1.1.1), and later increases in alcohol dehydrogenase (EC 1.1.1.1), lactate dehydrogenase (EC 1.1.1.27), and alanine amino transferase (EC 2.6.1.2) activities. This enhancement of fermentative activities was coincident with a slight decrease in aerobic respiration. The overall data suggest that the impairment of ALS activity may lead to a fermentative metabolism that may be involved in growth inhibition and plant death.
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Affiliation(s)
- Susana Gaston
- Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain
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Kaplun A, Chipman DM, Barak Z. Isoleucine starvation caused by sulfometuron methyl in Salmonella typhimurium measured by translational frameshifting. MICROBIOLOGY (READING, ENGLAND) 2002; 148:713-717. [PMID: 11882705 DOI: 10.1099/00221287-148-3-713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The authors have developed a tool for the study of inhibitor-induced amino acid starvation in bacteria which exploits the phenomenon of translational frameshifting. The inhibition of acetohydroxyacid synthase II by the herbicide sulfometuron methyl (SMM) has complex effects on branched-chain amino acid biosynthesis. Experiments were done with Salmonella typhimurium containing a plasmid with an isoleucine codon in a 'shifty' region, prone to translational frameshifting. SMM did not cause translational frameshifting in minimal medium under conditions that inhibit growth. A 20-fold higher concentration of SMM was required to cause starvation for isoleucine, e.g. in the presence of valine. This starvation was reflected in translational frameshifting correlated with inhibition of growth. These observations support the authors' previous suggestions based on other techniques. The method used here could be generalized for the study of complex metabolic effects related to amino acids.
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Affiliation(s)
- Alexander Kaplun
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel1
| | - David M Chipman
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel1
| | - Ze'ev Barak
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel1
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Epelbaum S, Chipman DM, Barak Z. Analysis of intracellular metabolites as tool for studying branched-chain amino acid biosynthesis and its inhibition in bacteria. Methods Enzymol 2001; 324:10-23. [PMID: 10989413 DOI: 10.1016/s0076-6879(00)24214-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- S Epelbaum
- Central Research and Development Department, E.I. duPont de Nemours and Company, Wilmington, Delaware 19880-0173, USA
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PospıÌÅ¡il S, Kopecký J, PÅikrylová V, SpıÌžek J. Overproduction of 2-ketoisovalerate and monensin production by regulatory mutants ofStreptomyces cinnamonensisresistant to 2-ketobutyrate and amino acids. FEMS Microbiol Lett 1999. [DOI: 10.1111/j.1574-6968.1999.tb13469.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Epelbaum S, LaRossa RA, VanDyk TK, Elkayam T, Chipman DM, Barak Z. Branched-chain amino acid biosynthesis in Salmonella typhimurium: a quantitative analysis. J Bacteriol 1998; 180:4056-67. [PMID: 9696751 PMCID: PMC107399 DOI: 10.1128/jb.180.16.4056-4067.1998] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/1998] [Accepted: 05/30/1998] [Indexed: 11/20/2022] Open
Abstract
We report here the first quantitative study of the branched-chain amino acid biosynthetic pathway in Salmonella typhimurium LT2. The intracellular levels of the enzymes of the pathway and of the 2-keto acid intermediates were determined under various physiological conditions and used for estimation of several of the fluxes in the cells. The results led to a revision of previous ideas concerning the way in which multiple acetohydroxy acid synthase (AHAS) isozymes contribute to the fitness of enterobacteria. In wild-type LT2, AHAS isozyme I provides most of the flux to valine, leucine, and pantothenate, while isozyme II provides most of the flux to isoleucine. With acetate as a carbon source, a strain expressing AHAS II only is limited in growth because of the low enzyme activity in the presence of elevated levels of the inhibitor glyoxylate. A strain with AHAS I only is limited during growth on glucose by the low tendency of this enzyme to utilize 2-ketobutyrate as a substrate; isoleucine limitation then leads to elevated threonine deaminase activity and an increased 2-ketobutyrate/2-ketoisovalerate ratio, which in turn interferes with the synthesis of coenzyme A and methionine. The regulation of threonine deaminase is also crucial in this regard. It is conceivable that, because of fundamental limitations on the specificity of enzymes, no single AHAS could possibly be adequate for the varied conditions that enterobacteria successfully encounter.
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Affiliation(s)
- S Epelbaum
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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Van Dyk TK, Ayers BL, Morgan RW, Larossa RA. Constricted flux through the branched-chain amino acid biosynthetic enzyme acetolactate synthase triggers elevated expression of genes regulated by rpoS and internal acidification. J Bacteriol 1998; 180:785-92. [PMID: 9473030 PMCID: PMC106955 DOI: 10.1128/jb.180.4.785-792.1998] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The first common enzyme of isoleucine and valine biosynthesis, acetolactate synthase (ALS), is specifically inhibited by the herbicide sulfometuron methyl (SM). To further understand the physiological consequences of flux alterations at this point in metabolism, Escherichia coli genes whose expression was induced by partial inhibition of ALS were sought. Plasmid-based fusions of random E. coli DNA fragments to Photorhabdus luminescens luxCDABE were screened for bioluminescent increases in actively growing liquid cultures slowed 25% by the addition of SM. From more than 8,000 transformants, 12 unique SM-inducible promoter-lux fusions were identified. The lux reporter genes were joined to seven uncharacterized open reading frames, f253a, f415, frvX, o513, o521, yciG, and yohF, and five known genes, inaA, IdcC, osmY, poxB, and sohA. Inactivation of the rpoS-encoded sigma factor, sigmaS, reduced basal expression levels of six of these fusions 10- to 200-fold. These six genes defined four new members of the sigmaS regulon, f253a, IdcC, yciG, and yohF, and included two known members, osmY and poxB. Furthermore, the weak acid salicylate, which causes cytoplasmic acidification, also induced increased bioluminescence from seven SM-inducible promoter-lux fusion-containing strains, namely, those with fusions of the sigmaS-controlled genes and inaA. The pattern of gene expression changes suggested that restricted ALS activity may result in intracellular acidification and induction of the sigmaS-dependent stress response.
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Affiliation(s)
- T K Van Dyk
- Central Research and Development Department, DuPont Co., Wilmington, Delaware 19880-0173, USA.
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Inoue H, Inagaki K, Eriguchi SI, Tamura T, Esaki N, Soda K, Tanaka H. Molecular characterization of the mde operon involved in L-methionine catabolism of Pseudomonas putida. J Bacteriol 1997; 179:3956-62. [PMID: 9190812 PMCID: PMC179205 DOI: 10.1128/jb.179.12.3956-3962.1997] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A 15-kb region of Pseudomonas putida chromosomal DNA containing the mde operon and an upstream regulatory gene (mdeR) has been cloned and sequenced. The mde operon contains two structural genes involved in L-methionine degradative metabolism: the already-identified mdeA, which encodes L-methionine gamma-lyase (H. Inoue, K. Inagaki, M. Sugimoto, N. Esaki, K. Soda, and H. Tanaka. J. Biochem. (Tokyo) 117:1120-1125, 1995), and mdeB, which encodes a homologous protein to the homodimeric-type E1 component of pyruvate dehydrogenase complex. A rho-independent terminator was present just downstream of mdeB, and open reading frames corresponding to other components of alpha-keto acid dehydrogenase complex were not found. When MdeB was overproduced in Escherichia coli, the cell extract showed the E1 activity with high specificity for alpha-ketobutyrate rather than pyruvate. These results suggest that MdeB plays an important role in the metabolism of alpha-ketobutyrate produced by MdeA from L-methionine. Accordingly, mdeB encodes a novel E1 component, alpha-ketobutyrate dehydrogenase E1 component, of an unknown alpha-keto acid dehydrogenase complex in P. putida. In addition, we found that the mdeR gene was located on the opposite strand and began at 127 bp from the translational start site of mdeA. The mdeR gene product has been identified as a member of the leucine-responsive regulatory protein (Lrp) family and revealed to act as an essential positive regulator allowing the expression of the mdeAB operon.
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Affiliation(s)
- H Inoue
- Department of Bioresources Chemistry, Faculty of Agriculture, Okayama University, Okayama-shi, Japan
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