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Borchert AJ, Bleem AC, Lim HG, Rychel K, Dooley KD, Kellermyer ZA, Hodges TL, Palsson BO, Beckham GT. Machine learning analysis of RB-TnSeq fitness data predicts functional gene modules in Pseudomonas putida KT2440. mSystems 2024; 9:e0094223. [PMID: 38323821 PMCID: PMC10949508 DOI: 10.1128/msystems.00942-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 01/07/2024] [Indexed: 02/08/2024] Open
Abstract
There is growing interest in engineering Pseudomonas putida KT2440 as a microbial chassis for the conversion of renewable and waste-based feedstocks, and metabolic engineering of P. putida relies on the understanding of the functional relationships between genes. In this work, independent component analysis (ICA) was applied to a compendium of existing fitness data from randomly barcoded transposon insertion sequencing (RB-TnSeq) of P. putida KT2440 grown in 179 unique experimental conditions. ICA identified 84 independent groups of genes, which we call fModules ("functional modules"), where gene members displayed shared functional influence in a specific cellular process. This machine learning-based approach both successfully recapitulated previously characterized functional relationships and established hitherto unknown associations between genes. Selected gene members from fModules for hydroxycinnamate metabolism and stress resistance, acetyl coenzyme A assimilation, and nitrogen metabolism were validated with engineered mutants of P. putida. Additionally, functional gene clusters from ICA of RB-TnSeq data sets were compared with regulatory gene clusters from prior ICA of RNAseq data sets to draw connections between gene regulation and function. Because ICA profiles the functional role of several distinct gene networks simultaneously, it can reduce the time required to annotate gene function relative to manual curation of RB-TnSeq data sets. IMPORTANCE This study demonstrates a rapid, automated approach for elucidating functional modules within complex genetic networks. While Pseudomonas putida randomly barcoded transposon insertion sequencing data were used as a proof of concept, this approach is applicable to any organism with existing functional genomics data sets and may serve as a useful tool for many valuable applications, such as guiding metabolic engineering efforts in other microbes or understanding functional relationships between virulence-associated genes in pathogenic microbes. Furthermore, this work demonstrates that comparison of data obtained from independent component analysis of transcriptomics and gene fitness datasets can elucidate regulatory-functional relationships between genes, which may have utility in a variety of applications, such as metabolic modeling, strain engineering, or identification of antimicrobial drug targets.
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Affiliation(s)
- Andrew J. Borchert
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Alissa C. Bleem
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Agile BioFoundry, Emeryville, California, USA
| | - Hyun Gyu Lim
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
- Joint BioEnergy Institute, Emeryville, California, USA
- Department of Biological Engineering, Inha University, Incheon, Korea
| | - Kevin Rychel
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
| | - Keven D. Dooley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Agile BioFoundry, Emeryville, California, USA
| | - Zoe A. Kellermyer
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Tracy L. Hodges
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Agile BioFoundry, Emeryville, California, USA
| | - Bernhard O. Palsson
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
- Joint BioEnergy Institute, Emeryville, California, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
- Department of Pediatrics, University of California, San Diego, California, USA
| | - Gregg T. Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Agile BioFoundry, Emeryville, California, USA
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2
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Harrison SA, Webb WL, Rammu H, Lane N. Prebiotic Synthesis of Aspartate Using Life's Metabolism as a Guide. Life (Basel) 2023; 13:life13051177. [PMID: 37240822 DOI: 10.3390/life13051177] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 04/29/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
A protometabolic approach to the origins of life assumes that the conserved biochemistry of metabolism has direct continuity with prebiotic chemistry. One of the most important amino acids in modern biology is aspartic acid, serving as a nodal metabolite for the synthesis of many other essential biomolecules. Aspartate's prebiotic synthesis is complicated by the instability of its precursor, oxaloacetate. In this paper, we show that the use of the biologically relevant cofactor pyridoxamine, supported by metal ion catalysis, is sufficiently fast to offset oxaloacetate's degradation. Cu2+-catalysed transamination of oxaloacetate by pyridoxamine achieves around a 5% yield within 1 h, and can operate across a broad range of pH, temperature, and pressure. In addition, the synthesis of the downstream product β-alanine may also take place in the same reaction system at very low yields, directly mimicking an archaeal synthesis route. Amino group transfer supported by pyridoxal is shown to take place from aspartate to alanine, but the reverse reaction (alanine to aspartate) shows a poor yield. Overall, our results show that the nodal metabolite aspartate and related amino acids can indeed be synthesised via protometabolic pathways that foreshadow modern metabolism in the presence of the simple cofactor pyridoxamine and metal ions.
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Affiliation(s)
- Stuart A Harrison
- Centre for Life's Origins and Evolution (CLOE), Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - William L Webb
- Centre for Life's Origins and Evolution (CLOE), Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Hanadi Rammu
- Centre for Life's Origins and Evolution (CLOE), Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Nick Lane
- Centre for Life's Origins and Evolution (CLOE), Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
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3
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Howieson VM, Zeng J, Kloehn J, Spry C, Marchetti C, Lunghi M, Varesio E, Soper A, Coyne AG, Abell C, van Dooren GG, Saliba KJ. Pantothenate biosynthesis in Toxoplasma gondii tachyzoites is not a drug target. INTERNATIONAL JOURNAL FOR PARASITOLOGY: DRUGS AND DRUG RESISTANCE 2023; 22:1-8. [PMID: 37004488 PMCID: PMC10102396 DOI: 10.1016/j.ijpddr.2023.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 03/08/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023]
Abstract
Toxoplasma gondii is a pervasive apicomplexan parasite that can cause severe disease and death in immunocompromised individuals and the developing foetus. The treatment of toxoplasmosis often leads to serious side effects and novel drugs and drug targets are therefore actively sought. In 2014, Mageed and colleagues suggested that the T. gondii pantothenate synthetase, the enzyme responsible for the synthesis of the vitamin B5 (pantothenate), the precursor of the important cofactor, coenzyme A, is a good drug target. Their conclusion was based on the ability of potent inhibitors of the M. tuberculosis pantothenate synthetase to inhibit the proliferation of T. gondii tachyzoites. They also reported that the inhibitory effect of the compounds could be antagonised by supplementing the medium with pantothenate, supporting their conclusion that the compounds were acting on the intended target. Contrary to these observations, we find that compound SW314, one of the compounds used in the Mageed et al. study and previously shown to be active against M. tuberculosis pantothenate synthetase in vitro, is inactive against the T. gondii pantothenate synthetase and does not inhibit tachyzoite proliferation, despite gaining access into the parasite in situ. Furthermore, we validate the recent observation that the pantothenate synthetase gene in T. gondii can be disrupted without detrimental effect to the survival of the tachyzoite-stage parasite in the presence or absence of extracellular pantothenate. We conclude that the T. gondii pantothenate synthetase is not essential during the tachyzoite stage of the parasite and it is therefore not a target for drug discovery against T. gondii tachyzoites.
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Leggett A, Li DW, Bruschweiler-Li L, Sullivan A, Stoodley P, Brüschweiler R. Differential metabolism between biofilm and suspended Pseudomonas aeruginosa cultures in bovine synovial fluid by 2D NMR-based metabolomics. Sci Rep 2022; 12:17317. [PMID: 36243882 PMCID: PMC9569359 DOI: 10.1038/s41598-022-22127-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/10/2022] [Indexed: 01/10/2023] Open
Abstract
Total joint arthroplasty is a common surgical procedure resulting in improved quality of life; however, a leading cause of surgery failure is infection. Periprosthetic joint infections often involve biofilms, making treatment challenging. The metabolic state of pathogens in the joint space and mechanism of their tolerance to antibiotics and host defenses are not well understood. Thus, there is a critical need for increased understanding of the physiological state of pathogens in the joint space for development of improved treatment strategies toward better patient outcomes. Here, we present a quantitative, untargeted NMR-based metabolomics strategy for Pseudomonas aeruginosa suspended culture and biofilm phenotypes grown in bovine synovial fluid as a model system. Significant differences in metabolic pathways were found between the suspended culture and biofilm phenotypes including creatine, glutathione, alanine, and choline metabolism and the tricarboxylic acid cycle. We also identified 21 unique metabolites with the presence of P. aeruginosa in synovial fluid and one uniquely present with the biofilm phenotype in synovial fluid. If translatable in vivo, these unique metabolite and pathway differences have the potential for further development to serve as targets for P. aeruginosa and biofilm control in synovial fluid.
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Affiliation(s)
- Abigail Leggett
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA
| | - Da-Wei Li
- Campus Chemical Instrument Center, The Ohio State University, Columbus, OH, USA
| | - Lei Bruschweiler-Li
- Campus Chemical Instrument Center, The Ohio State University, Columbus, OH, USA
| | - Anne Sullivan
- College of Medicine, Wexner Medical Center, Columbus, OH, USA
- Department of Orthopaedics, The Ohio State University, Columbus, OH, USA
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA.
- Department of Orthopaedics, The Ohio State University, Columbus, OH, USA.
- Department of Microbiology, The Ohio State University, Columbus, OH, USA.
- National Biofilm Innovation Centre (NBIC) and National Centre for Advanced Tribology at Southampton (nCATS), Mechanical Engineering, University of Southampton, Southampton, UK.
| | - Rafael Brüschweiler
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA.
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
- Campus Chemical Instrument Center, The Ohio State University, Columbus, OH, USA.
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA.
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5
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Lu S, Zhou C, Guo X, Du Z, Cheng Y, Wang Z, He X. Enhancing fluxes through the mevalonate pathway in Saccharomyces cerevisiae by engineering the HMGR and β-alanine metabolism. Microb Biotechnol 2022; 15:2292-2306. [PMID: 35531990 PMCID: PMC9328733 DOI: 10.1111/1751-7915.14072] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/26/2022] [Indexed: 11/29/2022] Open
Abstract
Mevalonate (MVA) pathway is the core for terpene and sterol biosynthesis, whose metabolic flux influences the synthesis efficiency of such compounds. Saccharomyces cerevisiae is an attractive chassis for the native active MVA pathway. Here, the truncated form of Enterococcus faecalis MvaE with only 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity was found to be the most effective enzyme for MVA pathway flux using squalene as the metabolic marker, resulting in 431-fold and 9-fold increases of squalene content in haploid and industrial yeast strains respectively. Furthermore, a positive correlation between MVA metabolic flux and β-alanine metabolic activity was found based on a metabolomic analysis. An industrial strain SQ3-4 with high MVA metabolic flux was constructed by combined engineering HMGR activity, NADPH regeneration, cytosolic acetyl-CoA supply and β-alanine metabolism. The strain was further evaluated as the chassis for terpenoids production. Strain SQ3-4-CPS generated from expressing β-caryophyllene synthase in SQ3-4 produced 11.86 ± 0.09 mg l-1 β-caryophyllene, while strain SQ3-5 resulted from down-regulation of ERG1 in SQ3-4 produced 408.88 ± 0.09 mg l-1 squalene in shake flask cultivations. Strain SQ3-5 produced 4.94 g l-1 squalene in fed-batch fermentation in cane molasses medium, indicating the promising potential for cost-effective production of squalene.
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Affiliation(s)
- Surui Lu
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049China
| | - Chenyao Zhou
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049China
| | - Xuena Guo
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
| | - Zhengda Du
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049China
| | - Yanfei Cheng
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
| | - Zhaoyue Wang
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
| | - Xiuping He
- CAS Key Laboratory of Microbial Physiological and Metabolic EngineeringState Key Laboratory of MycologyInstitute of MicrobiologyChinese Academy of SciencesBeijing100101China
- College of Life SciencesUniversity of Chinese Academy of SciencesBeijing100049China
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6
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Nordstedt NP, Jones ML. Genomic Analysis of Serratia plymuthica MBSA-MJ1: A Plant Growth Promoting Rhizobacteria That Improves Water Stress Tolerance in Greenhouse Ornamentals. Front Microbiol 2021; 12:653556. [PMID: 34046022 PMCID: PMC8144289 DOI: 10.3389/fmicb.2021.653556] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/14/2021] [Indexed: 12/26/2022] Open
Abstract
Water stress decreases the health and quality of horticulture crops by inhibiting photosynthesis, transpiration, and nutrient uptake. Application of plant growth promoting rhizobacteria (PGPR) can increase the growth, stress tolerance, and overall quality of field and greenhouse grown crops subjected to water stress. Here, we evaluated Serratia plymuthica MBSA-MJ1 for its ability to increase plant growth and quality of Petunia × hybrida (petunia), Impatiens walleriana (impatiens), and Viola × wittrockiana (pansy) plants recovering from severe water stress. Plants were treated weekly with inoculum of MBSA-MJ1, and plant growth and quality were evaluated 2 weeks after recovery from water stress. Application of S. plymuthica MBSA-MJ1 increased the visual quality and shoot biomass of petunia and impatiens and increased the flower number of petunia after recovery from water stress. In addition, in vitro characterizations showed that MBSA-MJ1 is a motile bacterium with moderate levels of antibiotic resistance that can withstand osmotic stress. Further, comprehensive genomic analyses identified genes putatively involved in bacterial osmotic and oxidative stress responses and the synthesis of osmoprotectants and vitamins that could potentially be involved in increasing plant water stress tolerance. This work provides a better understanding of potential mechanisms involved in beneficial plant-microbe interactions under abiotic stress using a novel S. plymuthica strain as a model.
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Affiliation(s)
- Nathan P Nordstedt
- Department of Horticulture and Crop Science, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, United States
| | - Michelle L Jones
- Department of Horticulture and Crop Science, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, United States
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7
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Suresh A, Srinivasarao S, Khetmalis YM, Nizalapur S, Sankaranarayanan M, Gowri Chandra Sekhar KV. Inhibitors of pantothenate synthetase of Mycobacterium tuberculosis - a medicinal chemist perspective. RSC Adv 2020; 10:37098-37115. [PMID: 35521286 PMCID: PMC9057165 DOI: 10.1039/d0ra07398a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 09/30/2020] [Indexed: 01/27/2023] Open
Abstract
Tuberculosis (TB), one of the most prevalent infections, is on the rise today. Although there are drugs available in the market to combat this lethal disorder, there are several shortcomings with the current drug regimen, such as prolonged treatment period, drug resistance, high cost, etc. Hence, it is inevitable for the current researchers across the globe to embark on new strategies for TB drug discovery, which will yield highly active low cost drugs with a shorter treatment period. To achieve this, novel strategies need to be adopted to discover new drugs. Pantothenate Synthetase (PS) is one such striking drug target in Mycobacterium tuberculosis (MTB). It was observed that the pantothenate biosynthetic pathway is crucial for the pathogenicity of MTB. Pantothenate is absent in mammals and needs to be obtained from dietary sources. Hence, the pantothenate biosynthesis pathway is an impending target for emerging new therapeutics to treat TB. Worldwide, several approaches have been implemented by researchers in the quest for these inhibitors such as high-throughput screening, simulating the reaction intermediate pantoyl adenylate, use of vibrant combinatorial chemistry, hybridization approach, virtual screening of databases, inhibitors based on the crystal structure of MTB PS, etc. The present review recapitulates current developments in PS inhibitors, important analogues of numerous metabolic intermediates, and newly established inhibitors with innumerable chemical structures.
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Affiliation(s)
- Amaroju Suresh
- Department of Chemistry, Birla Institute of Technology & Science-Pilani Hyderabad Campus, Medchal District Hyderabad-500078 Telangana India +91 40 66303527
| | - Singireddi Srinivasarao
- Department of Chemistry, Birla Institute of Technology & Science-Pilani Hyderabad Campus, Medchal District Hyderabad-500078 Telangana India +91 40 66303527
| | - Yogesh Mahadu Khetmalis
- Department of Chemistry, Birla Institute of Technology & Science-Pilani Hyderabad Campus, Medchal District Hyderabad-500078 Telangana India +91 40 66303527
| | | | - Murugesan Sankaranarayanan
- Medicinal Chemistry Research Laboratory, Department of Pharmacy, Birla Institute of Technology & Science-Pilani Pilani Campus Pilani 333031 Rajasthan India
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López-Sámano M, Beltrán LFLA, Sánchez-Thomas R, Dávalos A, Villaseñor T, García-García JD, García-de Los Santos A. A novel way to synthesize pantothenate in bacteria involves β-alanine synthase present in uracil degradation pathway. Microbiologyopen 2020; 9:e1006. [PMID: 32112625 PMCID: PMC7142369 DOI: 10.1002/mbo3.1006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 01/05/2020] [Accepted: 01/15/2020] [Indexed: 11/07/2022] Open
Abstract
Pantothenate is an indispensable vitamin precursor of the synthesis of coenzyme A (CoA), a key metabolite required in over 100 metabolic reactions. β-Alanine (β-ala) is an indispensable component of pantothenate. Due to the metabolic relevance of this pathway, we assumed that orthologous genes for ß-alanine synthesis would be present in the genomes of bacteria, archaea, and eukaryotes. However, comparative genomic studies revealed that orthologous gene replacement and loss of synteny occur at high frequency in panD genes. We have previously reported the atypical plasmid-encoded location of the pantothenate pathway genes panC and panB (two copies) in R. etli CFN42. This study also revealed the unexpected absence of a panD gene encoding the aspartate decarboxylase enzyme (ADC), required for the synthesis of β-ala. The aim of this study was to identify the source of β-alanine in Rhizobium etli CFN42. In this study, we present a bioinformatic analysis and an experimental validation demonstrating that the source of β-ala in this R. etli comes from β-alanine synthase, the last enzyme of the uracil degradation pathway.
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Affiliation(s)
- Mariana López-Sámano
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autonoma de México, Cuernavaca, Morelos, México
| | | | - Rosina Sánchez-Thomas
- Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", Tlalpan, México
| | - Araceli Dávalos
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autonoma de México, Cuernavaca, Morelos, México
| | - Tomás Villaseñor
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, UNAM, Cuernavaca, México
| | | | - Alejandro García-de Los Santos
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autonoma de México, Cuernavaca, Morelos, México
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9
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Lloyd CJ, King ZA, Sandberg TE, Hefner Y, Olson CA, Phaneuf PV, O’Brien EJ, Sanders JG, Salido RA, Sanders K, Brennan C, Humphrey G, Knight R, Feist AM. The genetic basis for adaptation of model-designed syntrophic co-cultures. PLoS Comput Biol 2019; 15:e1006213. [PMID: 30822347 PMCID: PMC6415869 DOI: 10.1371/journal.pcbi.1006213] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 03/13/2019] [Accepted: 02/07/2019] [Indexed: 11/18/2022] Open
Abstract
Understanding the fundamental characteristics of microbial communities could have far reaching implications for human health and applied biotechnology. Despite this, much is still unknown regarding the genetic basis and evolutionary strategies underlying the formation of viable synthetic communities. By pairing auxotrophic mutants in co-culture, it has been demonstrated that viable nascent E. coli communities can be established where the mutant strains are metabolically coupled. A novel algorithm, OptAux, was constructed to design 61 unique multi-knockout E. coli auxotrophic strains that require significant metabolite uptake to grow. These predicted knockouts included a diverse set of novel non-specific auxotrophs that result from inhibition of major biosynthetic subsystems. Three OptAux predicted non-specific auxotrophic strains—with diverse metabolic deficiencies—were co-cultured with an L-histidine auxotroph and optimized via adaptive laboratory evolution (ALE). Time-course sequencing revealed the genetic changes employed by each strain to achieve higher community growth rates and provided insight into mechanisms for adapting to the syntrophic niche. A community model of metabolism and gene expression was utilized to predict the relative community composition and fundamental characteristics of the evolved communities. This work presents new insight into the genetic strategies underlying viable nascent community formation and a cutting-edge computational method to elucidate metabolic changes that empower the creation of cooperative communities. Many basic characteristics underlying the establishment of cooperative growth in bacterial communities have not been studied in detail. The presented work sought to understand the adaptation of syntrophic communities by first employing a new computational method to generate a comprehensive catalog of E. coli auxotrophic mutants. Many of the knockouts in the catalog had the predicted effect of disabling a major biosynthetic process. As a result, these strains were predicted to be capable of growing when supplemented with many different individual metabolites (i.e., a non-specific auxotroph), but the strains would require a high amount of metabolic cooperation to grow in community. Three such non-specific auxotroph mutants from this catalog were co-cultured with a proven auxotrophic partner in vivo and evolved via adaptive laboratory evolution. In order to successfully grow, each strain in co-culture had to evolve under a pressure to grow cooperatively in its new niche. The non-specific auxotrophs further had to adapt to significant homeostatic changes in cell’s metabolic state caused by knockouts in metabolic genes. The genomes of the successfully growing communities were sequenced, thus providing unique insights into the genetic changes accompanying the formation and optimization of the viable communities. A computational model was further developed to predict how finite protein availability, a fundamental constraint on cell metabolism, could impact the composition of the community (i.e., the relative abundances of each community member).
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Affiliation(s)
- Colton J. Lloyd
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
| | - Zachary A. King
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
| | - Troy E. Sandberg
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
| | - Ying Hefner
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
| | - Connor A. Olson
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
| | - Patrick V. Phaneuf
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, United States of America
| | - Edward J. O’Brien
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, United States of America
| | - Jon G. Sanders
- Department of Pediatrics, University of California, San Diego, La Jolla, United States of America
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, United States of America
| | - Rodolfo A. Salido
- Department of Pediatrics, University of California, San Diego, La Jolla, United States of America
| | - Karenina Sanders
- Department of Pediatrics, University of California, San Diego, La Jolla, United States of America
| | - Caitriona Brennan
- Department of Pediatrics, University of California, San Diego, La Jolla, United States of America
| | - Gregory Humphrey
- Department of Pediatrics, University of California, San Diego, La Jolla, United States of America
| | - Rob Knight
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
- Department of Pediatrics, University of California, San Diego, La Jolla, United States of America
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, United States of America
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, United States of America
| | - Adam M. Feist
- Department of Bioengineering, University of California, San Diego, La Jolla, United States of America
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
- * E-mail:
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10
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Lalaouna D, Eyraud A, Devinck A, Prévost K, Massé E. GcvB small RNA uses two distinct seed regions to regulate an extensive targetome. Mol Microbiol 2018; 111:473-486. [PMID: 30447071 DOI: 10.1111/mmi.14168] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2018] [Indexed: 01/01/2023]
Abstract
GcvB small RNA is described as post-transcriptional regulator of 1-2% of all mRNAs in Escherichia coli and Salmonella Typhimurium. At least 24 GcvB:mRNA interactions have been validated in vivo, establishing the largest characterized sRNA targetome. By performing MS2-affinity purification coupled with RNA sequencing (MAPS) technology, we identified seven additional mRNAs negatively regulated by GcvB in E. coli. Contrary to the vast majority of previously known targets, which pair to the well-conserved GcvB R1 region, we validated four mRNAs targeted by GcvB R3 region. This indicates that base-pairing through R3 seed sequence seems relatively common. We also noticed unusual GcvB pairing sites in the coding sequence of two target mRNAs. One of these target mRNAs has a pairing site displaying a unique ACA motif, suggesting that GcvB could hijack a translational enhancer element. The second target mRNA is likely regulated via an active RNase E-mediated mRNA degradation mechanism. Remarkably, we confirmed the importance of the sRNA sponge SroC in the fine-tuning control of GcvB activity in function of growth conditions such as growth phase and nutrient availability.
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Affiliation(s)
- David Lalaouna
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Alex Eyraud
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Aurélie Devinck
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Karine Prévost
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Eric Massé
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
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11
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Arnott ZLP, Nozaki S, Monteiro DCF, Morgan HE, Pearson AR, Niki H, Webb ME. The Mechanism of Regulation of Pantothenate Biosynthesis by the PanD-PanZ·AcCoA Complex Reveals an Additional Mode of Action for the Antimetabolite N-Pentyl Pantothenamide (N5-Pan). Biochemistry 2017; 56:4931-4939. [PMID: 28832133 PMCID: PMC5724930 DOI: 10.1021/acs.biochem.7b00509] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The
antimetabolite pentyl pantothenamide has broad spectrum antibiotic
activity but exhibits enhanced activity against Escherichia
coli. The PanDZ complex has been proposed to regulate the
pantothenate biosynthetic pathway in E. coli by limiting
the supply of β-alanine in response to coenzyme A concentration.
We show that formation of such a complex between activated aspartate
decarboxylase (PanD) and PanZ leads to sequestration of the pyruvoyl
cofactor as a ketone hydrate and demonstrate that both PanZ overexpression-linked
β-alanine auxotrophy and pentyl pantothenamide toxicity are
due to formation of this complex. This both demonstrates that the
PanDZ complex regulates pantothenate biosynthesis in a cellular context
and validates the complex as a target for antibiotic development.
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Affiliation(s)
- Zoe L P Arnott
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds , Leeds LS2 9JT, U.K.,Hamburg Center for Ultrafast Imaging, Institute of Nanostructure and Solid State Physics, University of Hamburg , Luruper Chaussee 149, Hamburg 22761, Germany
| | - Shingo Nozaki
- Microbial Genetics Laboratory, Genetics Strains Research Center, National Institute of Genetics , 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Diana C F Monteiro
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds , Leeds LS2 9JT, U.K.,Hamburg Center for Ultrafast Imaging, Institute of Nanostructure and Solid State Physics, University of Hamburg , Luruper Chaussee 149, Hamburg 22761, Germany
| | - Holly E Morgan
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds , Leeds LS2 9JT, U.K
| | - Arwen R Pearson
- Hamburg Center for Ultrafast Imaging, Institute of Nanostructure and Solid State Physics, University of Hamburg , Luruper Chaussee 149, Hamburg 22761, Germany
| | - Hironori Niki
- Microbial Genetics Laboratory, Genetics Strains Research Center, National Institute of Genetics , 1111 Yata, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, Graduate University for Advanced Studies (Sokendai) , 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Michael E Webb
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds , Leeds LS2 9JT, U.K
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12
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Irnov I, Wang Z, Jannetty ND, Bustamante JA, Rhee KY, Jacobs-Wagner C. Crosstalk between the tricarboxylic acid cycle and peptidoglycan synthesis in Caulobacter crescentus through the homeostatic control of α-ketoglutarate. PLoS Genet 2017; 13:e1006978. [PMID: 28827812 PMCID: PMC5578688 DOI: 10.1371/journal.pgen.1006978] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/31/2017] [Accepted: 08/15/2017] [Indexed: 11/18/2022] Open
Abstract
To achieve robust replication, bacteria must integrate cellular metabolism and cell wall growth. While these two processes have been well characterized, the nature and extent of cross-regulation between them is not well understood. Here, using classical genetics, CRISPRi, metabolomics, transcriptomics and chemical complementation approaches, we show that a loss of the master regulator Hfq in Caulobacter crescentus alters central metabolism and results in cell shape defects in a nutrient-dependent manner. We demonstrate that the cell morphology phenotype in the hfq deletion mutant is attributable to a disruption of α-ketoglutarate (KG) homeostasis. In addition to serving as a key intermediate of the tricarboxylic acid (TCA) cycle, KG is a by-product of an enzymatic reaction required for the synthesis of peptidoglycan, a major component of the bacterial cell wall. Accumulation of KG in the hfq deletion mutant interferes with peptidoglycan synthesis, resulting in cell morphology defects and increased susceptibility to peptidoglycan-targeting antibiotics. This work thus reveals a direct crosstalk between the TCA cycle and cell wall morphogenesis. This crosstalk highlights the importance of metabolic homeostasis in not only ensuring adequate availability of biosynthetic precursors, but also in preventing interference with cellular processes in which these intermediates arise as by-products.
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Affiliation(s)
- Irnov Irnov
- Microbial Sciences Institute, Yale University, West Haven, CT, United States of America
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, United States of America
| | - Zhe Wang
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, United States of America
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medical College, New York, NY, United States of America
| | - Nicholas D. Jannetty
- Microbial Sciences Institute, Yale University, West Haven, CT, United States of America
- Howard Hughes Medical Institute, Yale University, New Haven, CT, United States of America
| | - Julian A. Bustamante
- Howard Hughes Medical Institute, Yale University, New Haven, CT, United States of America
| | - Kyu Y. Rhee
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, United States of America
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medical College, New York, NY, United States of America
| | - Christine Jacobs-Wagner
- Microbial Sciences Institute, Yale University, West Haven, CT, United States of America
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, United States of America
- Howard Hughes Medical Institute, Yale University, New Haven, CT, United States of America
- Department of Microbial Pathogenesis, Yale School of Medicine, Yale University, New Haven, CT, United States of America
- * E-mail:
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13
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Abstract
Pantothenate is vitamin B5 and is the key precursor for the biosynthesis of coenzyme A (CoA), a universal and essential cofactor involved in a myriad of metabolic reactions, including the synthesis of phospholipids, the synthesis and degradation of fatty acids, and the operation of the tricarboxylic acid cycle. CoA is also the only source of the phosphopantetheine prosthetic group for enzymes that shuttle intermediates between the active sites of enzymes involved in fatty acid, nonribosomal peptide, and polyketide synthesis. Pantothenate can be synthesized de novo and/or transported into the cell through a pantothenatepermease. Pantothenate uptake is essential for those organisms that lack the genes to synthesize this vitamin. The intracellular levels of CoA are controlled by the balance between synthesis and degradation. In particular, CoA is assembled in five enzymatic steps, starting from the phosphorylation of pantothenate to phosphopantothenatecatalyzed by pantothenate kinase, the product of the coaA gene. In some bacteria, the production of phosphopantothenate by pantothenate kinase is the rate limiting and most regulated step in the biosynthetic pathway. CoA synthesis additionally networks with other vitamin-associated pathways, such as thiamine and folic acid.
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14
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Stuecker TN, Bramhacharya S, Hodge-Hanson KM, Suen G, Escalante-Semerena JC. Phylogenetic and amino acid conservation analyses of bacterial L-aspartate-α-decarboxylase and of its zymogen-maturation protein reveal a putative interaction domain. BMC Res Notes 2015; 8:354. [PMID: 26276430 PMCID: PMC4537548 DOI: 10.1186/s13104-015-1314-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/03/2015] [Indexed: 11/16/2022] Open
Abstract
Background All organisms must synthesize the enzymatic cofactor coenzyme A (CoA) from the precursor pantothenate. Most bacteria can synthesize pantothenate de novo by the condensation of pantoate and β-alanine. The synthesis of β-alanine is catalyzed by l-aspartate-α-decarboxylase (PanD), a pyruvoyl enzyme that is initially synthesized as a zymogen (pro-PanD). Active PanD is generated by self-cleavage of pro-PanD at Gly24-Ser25 creating the active-site pyruvoyl moiety. In Salmonella enterica, this cleavage requires PanM, an acetyl-CoA sensor related to the Gcn5-like N-acetyltransferases. PanM does not acetylate pro-PanD, but the recent publication of the three-dimensional crystal structure of the PanM homologue PanZ in complex with the PanD zymogen of Escherichia coli provides validation to our predictions and provides a framework in which to further examine the cleavage mechanism. In contrast, PanD from bacteria lacking PanM efficiently cleaved in the absence of PanM in vivo. Results Using phylogenetic analyses combined with in vivo phenotypic investigations, we showed that two classes of bacterial l-aspartate-α-decarboxylases exist. This classification is based on their posttranslational activation by self-cleavage of its zymogen. Class I l-aspartate-α-decarboxylase zymogens require the acetyl-CoA sensor PanM to be cleaved into active PanD. This class is found exclusively in the Gammaproteobacteria. Class II l-aspartate-α-decarboxylase zymogens self cleave efficiently in the absence of PanM, and are found in a wide number of bacterial phyla. Several members of the Euryarchaeota and Crenarchaeota also contain Class II l-aspartate-α-decarboxylases. Phylogenetic and amino acid conservation analyses of PanM revealed a conserved region of PanM distinct from conserved regions found in related Gcn5-related acetyltransferase enzymes (Pfam00583). This conserved region represents a putative domain for interactions with l-aspartate-α-decarboxylase zymogens. This work may inform future biochemical and structural studies of pro-PanD-PanM interactions. Conclusions Experimental results indicate that S. enterica and C. glutamicuml-aspartate-α-decarboxylases represent two different classes of homologues of these enzymes. Class I homologues require PanM for activation, while Class II self cleave in the absence of PanM. Computer modeling of conserved amino acids using structure coordinates of PanM and l-aspartate-α-decarboxylase available in the protein data bank (RCSB PDB) revealed a putative site of interactions, which may help generate models to help understand the molecular details of the self-cleavage mechanism of l-aspartate-α-decarboxylases. Electronic supplementary material The online version of this article (doi:10.1186/s13104-015-1314-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tara N Stuecker
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA. .,Department of Biological Sciences, University of Arkansas, 850 W. Dickson St., SCEN 601, Fayettevile, AR, 72701, USA.
| | - Shanti Bramhacharya
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA. .,Microsoft Corporation, 7000 State Highway 161, Irving, TX, 75039, USA.
| | - Kelsey M Hodge-Hanson
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA. .,Department of Microbiology, University of Georgia, Biological Sciences Building, 120 Cedar Street, Athens, GA, 30602, USA.
| | - Garret Suen
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Jorge C Escalante-Semerena
- Department of Microbiology, University of Georgia, 212C, Biological Sciences Building, 120 Cedar Street, Athens, GA, 30602, USA.
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15
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AspC-mediated aspartate metabolism coordinates the Escherichia coli cell cycle. PLoS One 2014; 9:e92229. [PMID: 24670900 PMCID: PMC3966765 DOI: 10.1371/journal.pone.0092229] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 02/19/2014] [Indexed: 01/08/2023] Open
Abstract
Background The fast-growing bacterial cell cycle consists of at least two independent cycles of chromosome replication and cell division. To ensure proper cell cycles and viability, chromosome replication and cell division must be coordinated. It has been suggested that metabolism could affect the Escherichia coli cell cycle, but the idea is still lacking solid evidences. Methodology/Principle Findings We found that absence of AspC, an aminotransferase that catalyzes synthesis of aspartate, led to generation of small cells with less origins and slow growth. In contrast, excess AspC was found to exert the opposite effect. Further analysis showed that AspC-mediated aspartate metabolism had a specific effect in the cell cycle, as only extra aspartate of the 20 amino acids triggered production of bigger cells with more origins per cell and faster growth. The amount of DnaA protein per cell was found to be changed in response to the availability of AspC. Depletion of (p)ppGpp by ΔrelAΔspoT led to a slight delay in initiation of replication, but did not change the replication pattern found in the ΔaspC mutant. Conclusion/Significances The results suggest that AspC-mediated metabolism of aspartate coordinates the E. coli cell cycle through altering the amount of the initiator protein DnaA per cell and the division signal UDP-glucose. Furthermore, AspC sequence conservation suggests similar functions in other organisms.
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16
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Schmidt BJ, Ebrahim A, Metz TO, Adkins JN, Palsson BØ, Hyduke DR. GIM3E: condition-specific models of cellular metabolism developed from metabolomics and expression data. ACTA ACUST UNITED AC 2013; 29:2900-8. [PMID: 23975765 DOI: 10.1093/bioinformatics/btt493] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
MOTIVATION Genome-scale metabolic models have been used extensively to investigate alterations in cellular metabolism. The accuracy of these models to represent cellular metabolism in specific conditions has been improved by constraining the model with omics data sources. However, few practical methods for integrating metabolomics data with other omics data sources into genome-scale models of metabolism have been developed. RESULTS GIM(3)E (Gene Inactivation Moderated by Metabolism, Metabolomics and Expression) is an algorithm that enables the development of condition-specific models based on an objective function, transcriptomics and cellular metabolomics data. GIM(3)E establishes metabolite use requirements with metabolomics data, uses model-paired transcriptomics data to find experimentally supported solutions and provides calculations of the turnover (production/consumption) flux of metabolites. GIM(3)E was used to investigate the effects of integrating additional omics datasets to create increasingly constrained solution spaces of Salmonella Typhimurium metabolism during growth in both rich and virulence media. This integration proved to be informative and resulted in a requirement of additional active reactions (12 in each case) or metabolites (26 or 29, respectively). The addition of constraints from transcriptomics also impacted the allowed solution space, and the cellular metabolites with turnover fluxes that were necessarily altered by the change in conditions increased from 118 to 271 of 1397. AVAILABILITY GIM(3)E has been implemented in Python and requires a COBRApy 0.2.x. The algorithm and sample data described here are freely available at: http://opencobra.sourceforge.net/ CONTACTS brianjamesschmidt@gmail.com
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Affiliation(s)
- Brian J Schmidt
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA and Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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17
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Rothmann M, Kang M, Villa R, Ntai I, La Clair JJ, Kelleher NL, Chapman E, Burkart MD. Metabolic perturbation of an essential pathway: evaluation of a glycine precursor of coenzyme A. J Am Chem Soc 2013; 135:5962-5. [PMID: 23550886 DOI: 10.1021/ja400795m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pantetheine and its corresponding disulfide pantethine play a key role in metabolism as building blocks of coenzyme A (CoA), an essential cofactor utilized in ~4% of primary metabolism and central to fatty acid, polyketide, and nonribosomal peptide synthases. Using a combination of recombinant engineering and chemical synthesis, we show that the disulfide of N-pantoylglycyl-2-aminoethanethiol (GlyPan), with one fewer carbon than pantetheine, can rescue a mutant E. coli strain MG1655ΔpanC lacking a functional pantothenate synthetase. Using mass spectrometry, we show that the GlyPan variant is accepted by the downstream CoA biosynthetic machinery, ultimately being incorporated into essential acyl carrier proteins. These findings point to further flexibility in CoA-dependent pathways and offer the opportunity to incorporate orthogonal analogues.
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Affiliation(s)
- Michael Rothmann
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, USA
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18
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Abstract
Pantothenate, commonly referred to as vitamin B(5), is an essential molecule in the metabolism of living organisms and forms the core of coenzyme A. Unlike humans, some bacteria and plants are capable of de novo biosynthesis of pantothenate, making this pathway a potential target for drug development. Francisella tularensis subsp. tularensis Schu S4 is a zoonotic bacterial pathogen that is able to synthesize pantothenate but is lacking the known ketopantoate reductase (KPR) genes, panE and ilvC, found in the canonical Escherichia coli pathway. Described herein is a gene encoding a novel KPR, for which we propose the name panG (FTT1388), which is conserved in all sequenced Francisella species and is the sole KPR in Schu S4. Homologs of this KPR are present in other pathogenic bacteria such as Enterococcus faecalis, Coxiella burnetii, and Clostridium difficile. Both the homologous gene from E. faecalis V583 (EF1861) and E. coli panE functionally complemented Francisella novicida lacking any KPR. Furthermore, panG from F. novicida can complement an E. coli KPR double mutant. A Schu S4 ΔpanG strain is a pantothenate auxotroph and was genetically and chemically complemented with panG in trans or with the addition of pantolactone. There was no virulence defect in the Schu S4 ΔpanG strain compared to the wild type in a mouse model of pneumonic tularemia. In summary, we characterized the pantothenate pathway in Francisella novicida and F. tularensis and identified an unknown and previously uncharacterized KPR that can convert 2-dehydropantoate to pantoate, PanG.
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19
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Nozaki S, Webb ME, Niki H. An activator for pyruvoyl-dependent l-aspartate α-decarboxylase is conserved in a small group of the γ-proteobacteria including Escherichia coli. Microbiologyopen 2012; 1:298-310. [PMID: 23170229 PMCID: PMC3496974 DOI: 10.1002/mbo3.34] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 07/14/2012] [Accepted: 07/19/2012] [Indexed: 11/11/2022] Open
Abstract
In bacteria, β-alanine is formed via the action of l-aspartate α-decarboxylase (PanD) which is one of the small class of pyruvoyl-dependent enzymes. The pyruvoyl cofactor in these enzymes is formed via the intramolecular rearrangement of a serine residue in the peptide backbone leading to chain cleavage and formation of the covalently-bound cofactor from the serine residue. This reaction was previously thought to be uncatalysed. Here we show that in Escherichia coli, PanD is activated by the putative acetyltransferase YhhK, subsequently termed PanZ. Activation of PanD both in vivo and in vitro is PanZ-dependent. PanZ binds to PanD, and we demonstrate that a PanZ(N45A) site-directed mutant is unable to enhance cleavage of the proenzyme PanD despite retaining affinity for PanD. This suggests that the putative acetyltransferases domain of PanZ may be responsible for activation to enhance the processing of PanD. Although panD is conserved among most bacteria, the panZ gene is conserved only in E. coli-related enterobacterial species including Shigella, Salmonella, Klebsiella and Yersinia. These bacteria are found predominantly in the gut flora where pantothenate is abundant and regulation of PanD by PanZ allows these organisms to closely regulate production of β-alanine and hence pantothenate in response to metabolic demand.
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Affiliation(s)
- Shingo Nozaki
- Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
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20
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Abstract
UNLABELLED Coenzyme A (CoA) is essential for cellular chemistry in all forms of life. The pantothenate moiety of CoA is generated from the condensation of pantoate and β-alanine. β-Alanine is formed by decarboxylation of l-aspartate catalyzed by PanD, a pyruvoyl enzyme that is synthesized by the cell as an inactive precursor (pro-PanD). Maturation of pro-PanD into PanD occurs via a self-cleavage event at residue Ser25, which forms the catalytic pyruvoyl moiety. We recently reported that Salmonella enterica PanM was necessary for pro-PanD maturation, both in vitro and in vivo. Notably, PanM is annotated as a Gcn5-like N-acetyltransferase (GNAT), which suggested that lysine acetylation might be part of the mechanism of maturation. Here we show that PanM lacks acetyltransferase activity and that acetyl-CoA stimulates its activity. Results of experiments with nonhydrolyzable ethyl-CoA and genetically encoded acetyl-lysine-containing PanD support the conclusion that PanM-dependent pro-PanD maturation does not involve an acetyl transfer event. We also show that CoA binding to PanM is needed for in vivo activity and that disruption of CoA binding prevents PanM from interacting with PanD. We conclude that PanM is a GNAT homologue that lost its acetyltransferase activity and evolved a new function as an acetyl-CoA sensor that can trigger the maturation of pro-PanD. IMPORTANCE Nε-lysine acetylation is increasingly being recognized as a widespread and important form of posttranslational regulation in bacteria. The acetyltransferases that catalyze these reactions are poorly characterized in bacteria. Based on annotation, most bacterial genomes contain several acetyltransferases, but the physiological roles of only a handful have been determined. Notably, a subset of putative acetyltransferases lack residues that are critical for activity in most biochemically characterized acetyltransferases. We show that one such putative acetyltransferase, PanM (formerly YhhK), lacks acetyltransferase activity but functions instead as an acetyl-coenzyme A (CoA) sensor. This work establishes the possibility that, like PanM, other putative acetyltransferases may have evolved new functions while retaining the ability to sense acetyl-CoA.
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21
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Stuecker TN, Hodge KM, Escalante-Semerena JC. The missing link in coenzyme A biosynthesis: PanM (formerly YhhK), a yeast GCN5 acetyltransferase homologue triggers aspartate decarboxylase (PanD) maturation in Salmonella enterica. Mol Microbiol 2012; 84:608-19. [PMID: 22497218 PMCID: PMC3345047 DOI: 10.1111/j.1365-2958.2012.08046.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Coenzyme A (CoA) is an essential cofactor for all forms of life. The biochemistry underpinning the assembly of CoA in Escherichia coli and other enterobacteria is well understood, except for the events leading to maturation of the L-aspartate-α-decarboxylase (PanD) enzyme that converts pantothenate to β-alanine. PanD is synthesized as pro-PanD, which undergoes an auto-proteolytic cleavage at residue Ser25 to yield the catalytic pyruvoyl moiety of the enzyme. Since 1990, it has been known that E. coli yhhK strains are pantothenate auxotrophs, but the role of YhhK in pantothenate biosynthesis remained an enigma. Here we show that Salmonella enterica yhhK strains are also pantothenate auxotrophs. In vivo and in vitro evidence shows that YhhK interacts directly with PanD, and that such interactions accelerate pro-PanD maturation. We also show that S. enterica yhhK strains accumulate pro-PanD, and that not all pro-PanD proteins require YhhK for maturation. For example, the Corynebacterium glutamicum panD(+) gene corrected the pantothenate auxotrophy of a S. enterica yhhK strain, supporting in vitro evidence obtained by others that some pro-PanD proteins autocleave at faster rates. We propose the name PanM for YhhK to reflect its role as a trigger of pro-PanD maturation by stabilizing pro-PanD in an autocleavage-prone conformation.
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Affiliation(s)
- Tara N. Stuecker
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, WI 53706-1521 USA
| | - Kelsey M. Hodge
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, WI 53706-1521 USA
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22
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Chakrabarti KS, Thakur KG, Gopal B, Sarma SP. X-ray crystallographic and NMR studies of pantothenate synthetase provide insights into the mechanism of homotropic inhibition by pantoate. FEBS J 2010; 277:697-712. [PMID: 20059543 DOI: 10.1111/j.1742-4658.2009.07515.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural basis for the homotropic inhibition of pantothenate synthetase by the substrate pantoate was investigated by X-ray crystallography and high-resolution NMR spectroscopic methods. The tertiary structure of the dimeric N-terminal domain of Escherichia coli pantothenate synthetase, determined by X-ray crystallography to a resolution of 1.7 A, showed a second molecule of pantoate bound in the ATP-binding pocket. Pantoate binding to the ATP-binding site induced large changes in structure, mainly for backbone and side chain atoms of residues in the ATP binding HXGH(34-37) motif. Sequence-specific NMR resonance assignments and solution secondary structure of the dimeric N-terminal domain, obtained using samples enriched in (2)H, (13)C, and (15)N, indicated that the secondary structural elements were conserved in solution. Nitrogen-15 edited two-dimensional solution NMR chemical shift mapping experiments revealed that pantoate, at 10 mm, bound at these two independent sites. The solution NMR studies unambiguously demonstrated that ATP stoichiometrically displaced pantoate from the ATP-binding site. All NMR and X-ray studies were conducted at substrate concentrations used for enzymatic characterization of pantothenate synthetase from different sources [Jonczyk R & Genschel U (2006) J Biol Chem 281, 37435-37446]. As pantoate binding to its canonical site is structurally conserved, these results demonstrate that the observed homotropic effects of pantoate on pantothenate biosynthesis are caused by competitive binding of this substrate to the ATP-binding site. The results presented here have implications for the design and development of potential antibacterial and herbicidal agents.
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23
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Kastenmüller G, Schenk ME, Gasteiger J, Mewes HW. Uncovering metabolic pathways relevant to phenotypic traits of microbial genomes. Genome Biol 2009; 10:R28. [PMID: 19284550 PMCID: PMC2690999 DOI: 10.1186/gb-2009-10-3-r28] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 02/12/2009] [Accepted: 03/10/2009] [Indexed: 01/20/2023] Open
Abstract
Identifying the biochemical basis of microbial phenotypes is a main objective of comparative genomics. Here we present a novel method using multivariate machine learning techniques for comparing automatically derived metabolic reconstructions of sequenced genomes on a large scale. Applying our method to 266 genomes directly led to testable hypotheses such as the link between the potential of microorganisms to cause periodontal disease and their ability to degrade histidine, a link also supported by clinical studies.
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Affiliation(s)
- Gabi Kastenmüller
- Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße, D-85764 Neuherberg, Germany
| | - Maria Elisabeth Schenk
- Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße, D-85764 Neuherberg, Germany
| | - Johann Gasteiger
- Computer-Chemie-Centrum, Universität Erlangen-Nürnberg, Nägelsbachstraße, D-91052 Erlangen, Germany
- Molecular Networks GmbH, Henkestraße 91, D-91052 Erlangen, Germany
| | - Hans-Werner Mewes
- Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße, D-85764 Neuherberg, Germany
- Chair for Genome-oriented Bioinformatics, Technische Universität München, Life and Food Science Center Weihenstephan, Am Forum 1, D-85354 Freising-Weihenstephan, Germany
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Olzhausen J, Schübbe S, Schüller HJ. Genetic analysis of coenzyme A biosynthesis in the yeast Saccharomyces cerevisiae: identification of a conditional mutation in the pantothenate kinase gene CAB1. Curr Genet 2009; 55:163-73. [PMID: 19266201 DOI: 10.1007/s00294-009-0234-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 02/16/2009] [Accepted: 02/16/2009] [Indexed: 11/26/2022]
Abstract
Coenzyme A (CoA) is a ubiquitous cofactor required for numerous enzymatic carbon group transfer reactions. CoA biosynthesis requires contributions from various amino acids with pantothenate as an important intermediate which can be imported from the medium or synthesized de novo. Investigating function and expression of structural genes involved in CoA biosynthesis of the yeast Saccharomyces cerevisiae, we show that deletion of ECM31 and PAN6 results in mutants requiring pantothenate while loss of PAN5 (related to panE from E. coli) still allows prototrophic growth. A temperature-sensitive mutant defective for fatty acid synthase activity could be functionally complemented by a gene significantly similar to eukaryotic pantothenate kinases (YDR531W). Enzymatic studies and heterologous complementation of this mutation by bacterial and mammalian genes showed that YDR531W encodes a genuine pantothenate kinase (new gene designation: CAB1, "coenzyme A biosynthesis"). A G351S missense mutation within CAB1 was identified to cause the conditional phenotype of the mutant initially studied. Similar to CAB1, genes YIL083C, YKL088W, YGR277C and YDR106C responsible for late CoA biosynthesis turned out as essential. Null mutants could be complemented by their bacterial counterparts coaBC, coaD and coaE, respectively. Comparative expression analyses showed that some CoA biosynthetic genes are weakly de-repressed with ethanol as a carbon source compared with glucose.
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Affiliation(s)
- Judith Olzhausen
- Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt Universität Greifswald, Germany
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25
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Potential application of N-carbamoyl-beta-alanine amidohydrolase from Agrobacterium tumefaciens C58 for beta-amino acid production. Appl Environ Microbiol 2008; 75:514-20. [PMID: 19011069 DOI: 10.1128/aem.01128-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An N-carbamoyl-beta-alanine amidohydrolase of industrial interest from Agrobacterium tumefaciens C58 (beta car(At)) has been characterized. Beta car(At) is most active at 30 degrees C and pH 8.0 with N-carbamoyl-beta-alanine as a substrate. The purified enzyme is completely inactivated by the metal-chelating agent 8-hydroxyquinoline-5-sulfonic acid (HQSA), and activity is restored by the addition of divalent metal ions, such as Mn(2+), Ni(2+), and Co(2+). The native enzyme is a homodimer with a molecular mass of 90 kDa from pH 5.5 to 9.0. The enzyme has a broad substrate spectrum and hydrolyzes nonsubstituted N-carbamoyl-alpha-, -beta-, -gamma-, and -delta-amino acids, with the greatest catalytic efficiency for N-carbamoyl-beta-alanine. Beta car(At) also recognizes substrate analogues substituted with sulfonic and phosphonic acid groups to produce the beta-amino acids taurine and ciliatine, respectively. Beta car(At) is able to produce monosubstituted beta(2)- and beta(3)-amino acids, showing better catalytic efficiency (k(cat)/K(m)) for the production of the former. For both types of monosubstituted substrates, the enzyme hydrolyzes N-carbamoyl-beta-amino acids with a short aliphatic side chain better than those with aromatic rings. These properties make beta car(At) an outstanding candidate for application in the biotechnology industry.
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Chakauya E, Coxon KM, Wei M, Macdonald MV, Barsby T, Abell C, Smith AG. Towards engineering increased pantothenate (vitamin B(5)) levels in plants. PLANT MOLECULAR BIOLOGY 2008; 68:493-503. [PMID: 18726075 DOI: 10.1007/s11103-008-9386-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 07/31/2008] [Indexed: 05/26/2023]
Abstract
Pantothenate (vitamin B(5)) is the precursor of the 4'-phosphopantetheine moiety of coenzyme A and acyl-carrier protein. It is made by plants and microorganisms de novo, but is a dietary requirement for animals. The pantothenate biosynthetic pathway is well-established in bacteria, comprising four enzymic reactions catalysed by ketopantoate hydroxymethyltransferase (KPHMT), L: -aspartate-alpha-decarboxylase (ADC), pantothenate synthetase (PS) and ketopantoate reductase (KPR) encoded by panB, panD, panC and panE genes, respectively. In higher plants, the genes encoding the first (KPHMT) and last (PS) enzymes have been identified and characterised in several plant species. Commercially, pantothenate is chemically synthesised and used in vitamin supplements, feed additives and cosmetics. Biotransformation is an attractive alternative production system that would circumvent the expensive procedures of separating racemic intermediates. We explored the possibility of manipulating pantothenate biosynthesis in plants. Transgenic oilseed rape (Brassica napus) lines were generated in which the E. coli KPHMT and PS genes were expressed under a strong constitutive CaMV35SS promoter. No significant change of pantothenate levels in PS transgenic lines was observed. In contrast plants expressing KPHMT had elevated pantothenate levels in leaves, flowers siliques and seed in the range of 1.5-2.5 fold increase compared to the wild type plant. Seeds contained the highest vitamin content, indicating that they might be the ideal target for production purposes.
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Affiliation(s)
- Ereck Chakauya
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
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Schnackerz KD, Andersen G, Dobritzsch D, Piskur J. Degradation of pyrimidines in Saccharomyces kluyveri: transamination of beta-alanine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2008; 27:794-9. [PMID: 18600542 DOI: 10.1080/15257770802145983] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Beta-alanine is an intermediate in the reductive degradation of uracil. Recently we have identified and characterized the Saccharomyces kluyveri PYD4 gene and the corresponding enzyme beta -alanine aminotransferase ((Sk)Pyd4p), highly homologous to eukaryotic gamma-aminobutyrate aminotransferase (GABA-AT). S. kluyveri has two aminotransferases, GABA aminotransferase ((Sk)Uga1p) with 80% and (Sk)Pyd4p with 55% identity to S. cerevisiae GABA-AT. (Sk)Pyd4p is a typical pyridoxal phosphate-dependent aminotransferase, specific for alpha-ketoglutarate (alpha KG), beta-alanine (BAL) and gamma-aminobutyrate (GABA), showing a ping-pong kinetic mechanism involving two half-reactions and substrate inhibition. (Sk)Uga1p accepts only alpha KG and GABA but not BAL, thus only (Sk)Pydy4p belongs to the uracil degradative pathway.
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Affiliation(s)
- K D Schnackerz
- Cell- and Organism Biology, Lund University, Lund, Sweden.
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28
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Abstract
The linear biosynthetic pathway leading from alpha-ketoisovalerate to pantothenate (vitamin B5) and on to CoA comprises eight steps in the Bacteria and Eukaryota. Genes for up to six steps of this pathway can be identified by sequence homology in individual archaeal genomes. However, there are no archaeal homologs to known isoforms of pantothenate synthetase (PS) or pantothenate kinase. Using comparative genomics, we previously identified two conserved archaeal protein families as the best candidates for the missing steps. Here we report the characterization of the predicted PS gene from Methanosarcina mazei, which encodes a hypothetical protein (MM2281) with no obvious homologs outside its own family. When expressed in Escherichia coli, MM2281 partially complemented an auxotrophic mutant without PS activity. Purified recombinant MM2281 showed no PS activity on its own, but the enzyme enabled substantial synthesis of [14C]4'-phosphopantothenate from [14C]beta-alanine, pantoate and ATP when coupled with E. coli pantothenate kinase. ADP, but not AMP, was detected as a coproduct of the coupled reaction. MM2281 also transferred the 14C-label from [14C]beta-alanine to pantothenate in the presence of pantoate and ADP, presumably through isotope exchange. No exchange took place when pantoate was removed or ADP replaced with AMP. Our results indicate that MM2281 represents a novel type of PS that forms ADP and is strongly inhibited by its product pantothenate. These properties differ substantially from those of bacterial PS, and may explain why PS genes, in contrast to other pantothenate biosynthetic genes, were not exchanged horizontally between the Bacteria and Archaea.
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Affiliation(s)
- Silvia Ronconi
- Lehrstuhl für Genetik, Technische Universität München, Freising, Germany
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29
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Abstract
Pantothenic acid, a precursor of coenzyme A (CoA), is essential for the growth of pathogenic microorganisms. Since the structure of pantothenic acid was determined, many analogues of this essential metabolite have been prepared. Several have been demonstrated to exert an antimicrobial effect against a range of microorganisms by inhibiting the utilization of pantothenic acid, validating pantothenic acid utilization as a potential novel antimicrobial drug target. This review commences with an overview of the mechanisms by which various microorganisms acquire the pantothenic acid they require for growth, and the universal CoA biosynthesis pathway by which pantothenic acid is converted into CoA. A detailed survey of studies that have investigated the inhibitory activity of analogues of pantothenic acid and other precursors of CoA follows. The potential of inhibitors of both pantothenic acid utilization and biosynthesis as novel antibacterial, antifungal and antimalarial agents is discussed, focusing on inhibitors and substrates of pantothenate kinase, the enzyme catalysing the rate-limiting step of CoA biosynthesis in many organisms. The best strategies are considered for identifying inhibitors of pantothenic acid utilization and biosynthesis that are potent and selective inhibitors of microbial growth and that may be suitable for use as chemotherapeutic agents in humans.
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Affiliation(s)
- Christina Spry
- School of Biochemistry and Molecular Biology, The Australian National University, Canberra, Australia
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30
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Schnackerz KD, Dobritzsch D. Amidohydrolases of the reductive pyrimidine catabolic pathway purification, characterization, structure, reaction mechanisms and enzyme deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:431-44. [PMID: 18261476 DOI: 10.1016/j.bbapap.2008.01.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 01/07/2008] [Accepted: 01/09/2008] [Indexed: 12/26/2022]
Abstract
In the reductive pyrimidine catabolic pathway uracil and thymine are converted to beta-alanine and beta-aminoisobutyrate. The amidohydrolases of this pathway are responsible for both the ring opening of dihydrouracil and dihydrothymine (dihydropyrimidine amidohydrolase) and the hydrolysis of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyrate (beta-alanine synthase). The review summarizes what is known about the properties, kinetic parameters, three-dimensional structures and reaction mechanisms of these proteins. The two amidohydrolases of the reductive pyrimidine catabolic pathway have unrelated folds, with dihydropyrimidine amidohydrolase belonging to the amidohydrolase superfamily while the beta-alanine synthase from higher eukaryotes belongs to the nitrilase superfamily. beta-Alanine synthase from Saccharomyces kluyveri is an exception to the rule and belongs to the Acyl/M20 family.
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31
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Jonczyk R, Ronconi S, Rychlik M, Genschel U. Pantothenate synthetase is essential but not limiting for pantothenate biosynthesis in Arabidopsis. PLANT MOLECULAR BIOLOGY 2008; 66:1-14. [PMID: 17932772 DOI: 10.1007/s11103-007-9248-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 09/23/2007] [Indexed: 05/15/2023]
Abstract
Pantothenate (vitamin B5) is the universal precursor for coenzyme A (CoA), an essential cofactor that is required in the metabolism of carbohydrates and fatty acids. The final step of bacterial and eukaryotic pantothenate biosynthesis is catalyzed by pantothenate synthetase (PTS), which is encoded by a single gene in Arabidopsis thaliana (AtPTS). There was debate whether PTS represents the only mode of pantothenate production because previous biochemical evidence pointed to an additional pantothenate pathway in plants. Here we show that insertional mutant alleles of AtPTS confer a recessive embryo-lethal phenotype with mutant embryos arrested at the preglobular stage. Exogenous pantothenate was required for normal seed development and germination and also facilitated the remaining life cycle. Complementation of the mutant phenotype was likewise achieved by heterologous expression of E. coli PTS (panC). The panC transgene increased the total PTS activity in leaves by up to 500-fold but did not affect the steady-state level of pantothenate, indicating that PTS is essential but not limiting for pantothenate production. The auxotrophic AtPTS knockout phenotype suggests that the embryo and possibly all other tissues are autonomous for the biosynthesis of pantothenate. This view is consistent with the near-ubiquitous expression of AtPTS as judged by promoter:beta-glucuronidase analysis. Given the high demand for CoA during storage oil accumulation, we analyzed transcript and metabolite patterns of CoA biosynthesis in seeds. The data indicate that the pantothenate and CoA contents follow distinct developmental programs and that both transcriptional and posttranslational control mechanisms are important for CoA homeostasis.
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Affiliation(s)
- Rafal Jonczyk
- Lehrstuhl für Genetik, Technische Universität München, Am Hochanger 8, 85350 Freising, Germany
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32
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Lundgren S, Andersen B, Piškur J, Dobritzsch D. Crystallization and preliminary X-ray data analysis of beta-alanine synthase from Drosophila melanogaster. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:874-7. [PMID: 17909293 PMCID: PMC2339735 DOI: 10.1107/s1744309107042984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 09/03/2007] [Indexed: 11/11/2022]
Abstract
Beta-alanine synthase catalyzes the last step in the reductive degradation pathway for uracil and thymine, which represents the main clearance route for the widely used anticancer drug 5-fluorouracil. Crystals of the recombinant enzyme from Drosophila melanogaster, which is closely related to the human enzyme, were obtained by the hanging-drop vapour-diffusion method. They diffracted to 3.3 A at a synchrotron-radiation source, belong to space group C2 (unit-cell parameters a = 278.9, b = 95.0, c = 199.3 A, beta = 125.8 degrees) and contain 8-10 molecules per asymmetric unit.
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Affiliation(s)
- Stina Lundgren
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Birgit Andersen
- Department of Organism and Cell Biology, Lund University, Lund, Sweden
| | - Jure Piškur
- Department of Organism and Cell Biology, Lund University, Lund, Sweden
| | - Doreen Dobritzsch
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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33
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Seetharamappa J, Oke M, Liu H, McMahon SA, Johnson KA, Carter L, Dorward M, Zawadzki M, Overton IM, van Niekirk CAJ, Graham S, Botting CH, Taylor GL, White MF, Barton GJ, Coote PJ, Naismith JH. Purification, crystallization and data collection of methicillin-resistant Staphylococcus aureus Sar2676, a pantothenate synthetase. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:488-91. [PMID: 17554169 PMCID: PMC2335074 DOI: 10.1107/s1744309107020362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2007] [Accepted: 04/24/2007] [Indexed: 11/10/2022]
Abstract
Sar2676, a pantothenate synthetase with a molecular weight of 31 419 Da from methicillin-resistant Staphylococcus aureus, has been expressed, purified and crystallized at 293 K. The protein crystallizes in a primitive triclinic lattice, with unit-cell parameters a = 45.3, b = 60.5, c = 117.6 A, alpha = 87.2, beta = 81.2, gamma = 68.4 degrees . A complete data set has been collected to 2.3 A resolution at the ESRF. Consideration of the likely solvent content suggested the asymmetric unit to contain four molecules. This has been confirmed by molecular-replacement phasing calculations, which give a solution with four monomers using a monomer of pantothenate synthetase from Escherichia coli (PDB code 1iho), which is 41% identical to Sar2676, as a search model.
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Affiliation(s)
- Jaldappagari Seetharamappa
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
- Department of Chemistry, Karnatak University, Pavate Nagar, Dharwad 580 003, Karnataka State, India
| | - Muse Oke
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Huanting Liu
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Stephen A. McMahon
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Kenneth A. Johnson
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Lester Carter
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Mark Dorward
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Michal Zawadzki
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Ian M. Overton
- Scottish Structural Facility and School of Life Sciences Research, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - C. A. Johannes van Niekirk
- Scottish Structural Facility and School of Life Sciences Research, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Shirley Graham
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Catherine H. Botting
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Garry L. Taylor
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Malcolm F. White
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - Geoffrey J. Barton
- Scottish Structural Facility and School of Life Sciences Research, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland
| | - Peter J. Coote
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
| | - James H. Naismith
- Scottish Structural Facility and Centre for Biomolecular Sciences, The University, St Andrews KY16 9ST, Scotland
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Webb ME, Marquet A, Mendel RR, Rébeillé F, Smith AG. Elucidating biosynthetic pathways for vitamins and cofactors. Nat Prod Rep 2007; 24:988-1008. [PMID: 17898894 DOI: 10.1039/b703105j] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The elucidation of the pathways to the water-soluble vitamins and cofactors has provided many biochemical and chemical challenges. This is a reflection both of their complex chemical nature, and the fact that they are often made in small amounts, making detection of the enzyme activities and intermediates difficult. Here we present an orthogonal review of how these challenges have been overcome using a combination of methods, which are often ingenious. We make particular reference to some recent developments in the study of biotin, pantothenate, folate, pyridoxol, cobalamin, thiamine, riboflavin and molybdopterin biosynthesis.
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Affiliation(s)
- Michael E Webb
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
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35
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Abstract
Metabolism encompasses the biochemical basis of life and as such spans all biological disciplines. Many decades of basic research, primarily in microbes, have resulted in extensive characterization of metabolic components and regulatory paradigms. With this basic knowledge in hand and the technologies currently available, it has become feasible to move toward an understanding of microbial metabolism as a system rather than as a collection of component parts. Insight into the system will be generated by continued efforts to rigorously define metabolic components combined with renewed efforts to discover components and connections using in vivo-driven approaches. On the tail of a detailed understanding of components and connections that comprise metabolism will come the ability to generate a comprehensive mathematical model that describes the system. While microbes provide the logical organism for this work, the value of such a model would span biological disciplines. Described herein are approaches that can provide insight into metabolism and caveats of their use. The goal of this review is to emphasize that in silico, in vitro, and in vivo approaches must be used in combination to achieve a full understanding of microbial metabolism.
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Affiliation(s)
- Diana M Downs
- Department of Bacteriology, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
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36
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Tuck KL, Saldanha SA, Birch LM, Smith AG, Abell C. The design and synthesis of inhibitors of pantothenate synthetase. Org Biomol Chem 2006; 4:3598-610. [PMID: 16990935 DOI: 10.1039/b609482a] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pantothenate synthetase catalyses the ATP-dependent condensation of D-pantoate and beta-alanine to form pantothenate. Ten analogues of the reaction intermediate pantoyl adenylate, in which the phosphodiester is replaced by either an ester or sulfamoyl group, were designed as potential inhibitors of the enzyme. The esters were all modest competitive inhibitors, the sulfamoyls were more potent, consistent with their closer structural similarity to the pantoyl adenylate intermediate.
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Affiliation(s)
- Kellie L Tuck
- University Chemical Laboratory, Lensfield Road, Cambridge, UK CB2 1EW
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37
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Coenye T, Vandamme P. Displacement of ɛ-proteobacterial core genes by horizontally transferred homologous genes. Res Microbiol 2005; 156:738-47. [PMID: 15950129 DOI: 10.1016/j.resmic.2005.01.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 01/13/2005] [Accepted: 01/28/2005] [Indexed: 11/15/2022]
Abstract
The introduction of novel genes by horizontal gene transfer (HGT) is considered an alternative mechanism for genetic adaptation, leading to diversification and speciation. The goal of this study was to determine which genes that are present in all sequenced epsilon-proteobacterial genomes were acquired by HGT. In our approach we used BLAST analysis to reduce the number of genes that subsequently needed to be analysed using more in-depth phylogenetic methods, including neighbour-joining and maximum likelihood. Among the 991 core genes found in all five completed epsilon-proteobacterial genome sequences, we identified 30 genes that were probably acquired by HGT. It is proposed that these genes displaced an ancestral core gene with a similar function. Although it was not possible to identify putative donor taxa for all acquired genes, it was clear that genes were acquired from a wide range of Bacteria, including Spirochaetes, Firmicutes, Actinobacteria, mycoplasmas and several subdivisions of the Proteobacteria. We did not observe HGT from Archaea to the epsilon-Proteobacteria. The majority of acquired genes were operational genes involved in transport, metabolism, signal transduction and energy production and conversion.
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Affiliation(s)
- Tom Coenye
- Laboratorium voor Microbiologie, Universiteit Ghent, Ghent, Belgium.
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38
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Herrmann G, Selmer T, Jessen HJ, Gokarn RR, Selifonova O, Gort SJ, Buckel W. Two beta-alanyl-CoA:ammonia lyases in Clostridium propionicum. FEBS J 2005; 272:813-21. [PMID: 15670161 DOI: 10.1111/j.1742-4658.2004.04518.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The fermentation of beta-alanine by Clostridium propionicum proceeds via activation to the CoA-thiol ester, followed by deamination to acryloyl-CoA, which is also an intermediate in the fermentation of l-alanine. By shifting the organism from the carbon and energy source alpha-alanine to beta-alanine, the enzyme beta-alanyl-CoA:ammonia lyase is induced 300-fold (approximately 30% of the soluble protein). The low basal lyase activity is encoded by the acl1 gene, whereas the almost identical acl2 gene (six amino acid substitutions) is responsible for the high activity after growth on beta-alanine. The deduced beta-alanyl-CoA:ammonia lyase proteins are related to putative beta-aminobutyryl-CoA ammonia lyases involved in lysine fermentation and found in the genomes of several anaerobic bacteria. beta-Alanyl-CoA:ammonia lyase 2 was purified to homogeneity and characterized as a heteropentamer composed of 16 kDa subunits. The apparent K(m) value for acryloyl-CoA was measured as 23 +/- 4 microm, independent of the concentration of the second substrate ammonia; k(cat)/K(m) was calculated as 10(7) m(-1) x s(-1). The apparent K(m) for ammonia was much higher, 70 +/- 5 mm at 150 microm acryloyl-CoA with a much lower k(cat)/K(m) of 4 x 10(3) m(-1) x s(-1). In the reverse reaction, a K(m) of 210 +/- 30 microM was obtained for beta-alanyl-CoA. The elimination of ammonia was inhibited by 70% at 100 mm ammonium chloride. The content of beta-alanyl-CoA:ammonia lyase in beta-alanine grown cells is about 100 times higher than that required to sustain the growth rate of the organism. It is therefore suggested that the enzyme is needed to bind acryloyl-CoA, in order to keep the toxic free form at a very low level. A formula was derived for the calculation of isomerization equilibra between L-alanine/beta-alanine or D-lactate/3-hydroxypropionate.
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Affiliation(s)
- Gloria Herrmann
- Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Marburg, Germany
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39
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Ottenhof HH, Ashurst JL, Whitney HM, Saldanha SA, Schmitzberger F, Gweon HS, Blundell TL, Abell C, Smith AG. Organisation of the pantothenate (vitamin B5) biosynthesis pathway in higher plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 37:61-72. [PMID: 14675432 DOI: 10.1046/j.1365-313x.2003.01940.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Pantothenate (vitamin B5) is the precursor for the biosynthesis of the phosphopantetheine moiety of coenzyme A and acyl carrier protein, and is synthesised in Escherichia coli by four enzymic reactions. Ketopantoate hydroxymethyltransferase (KPHMT) and pantothenate synthetase (PtS) catalyse the first and last steps, respectively. Two genes encoding KPHMT and one for PtS were identified in the Arabidopsis thaliana genome, and cDNAs for all three genes were amplified by PCR. The cDNAs were able to complement their respective E. coli auxotrophs, demonstrating that they encoded functional enzymes. Subcellular localisation of the proteins was investigated using green fluorescent protein (GFP) fusions and confocal microscopy. The two KPHMT-GFP fusion proteins were targeted exclusively to mitochondria, whereas PtS-GFP was found in the cytosol. This implies that there must be transporters for pathway intermediates. KPHMT enzyme activity could be measured in purified mitochondria from both pea leaves and Arabidopsis suspension cultures. We investigated whether Arabidopsis encoded homologues of the remaining two pantothenate biosynthesis enzymes from E. coli, l-aspartate-alpha-decarboxylase (ADC) and ketopantoate reductase (KPR). No homologue of ADC could be identified using either conventional blast or searches with the program fugue in which the structure of the E. coli ADC was compared to all the annotated proteins in Arabidopsis. ADC also appears to be absent from the genome of the yeast, Saccharomyces cerevisiae, by the same criteria. In contrast, a putative Arabidopsis oxidoreductase with some similarity to KPR was identified with fugue.
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Lundgren S, Gojković Z, Piskur J, Dobritzsch D. Yeast β-Alanine Synthase Shares a Structural Scaffold and Origin with Dizinc-dependent Exopeptidases. J Biol Chem 2003; 278:51851-62. [PMID: 14534321 DOI: 10.1074/jbc.m308674200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta-Alanine synthase (beta AS) is the final enzyme of the reductive pyrimidine catabolic pathway, which is responsible for the breakdown of pyrimidine bases, including several anticancer drugs. In eukaryotes, beta ASs belong to two subfamilies, which exhibit a low degree of sequence similarity. We determined the structure of beta AS from Saccharomyces kluyveri to a resolution of 2.7 A. The subunit of the homodimeric enzyme consists of two domains: a larger catalytic domain with a dizinc metal center, which represents the active site of beta AS, and a smaller domain mediating the majority of the intersubunit contacts. Both domains exhibit a mixed alpha/beta-topology. Surprisingly, the observed high structural homology to a family of dizinc-dependent exopeptidases suggests that these two enzyme groups have a common origin. Alterations in the ligand composition of the metal-binding site can be explained as adjustments to the catalysis of a different reaction, the hydrolysis of an N-carbamyl bond by beta AS compared with the hydrolysis of a peptide bond by exopeptidases. In contrast, there is no resemblance to the three-dimensional structure of the functionally closely related N-carbamyl-d-amino acid amidohydrolases. Based on comparative structural analysis and observed deviations in the backbone conformations of the eight copies of the subunit in the asymmetric unit, we suggest that conformational changes occur during each catalytic cycle.
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Affiliation(s)
- Stina Lundgren
- Division of Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-17177 Stockholm, Sweden
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von Delft F, Inoue T, Saldanha SA, Ottenhof HH, Schmitzberger F, Birch LM, Dhanaraj V, Witty M, Smith AG, Blundell TL, Abell C. Structure of E. coli ketopantoate hydroxymethyl transferase complexed with ketopantoate and Mg2+, solved by locating 160 selenomethionine sites. Structure 2003; 11:985-96. [PMID: 12906829 DOI: 10.1016/s0969-2126(03)00158-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We report the crystal structure of E. coli ketopantoate hydroxymethyltransferase (KPHMT) at 1.9 A resolution, in complex with its product, ketopantoate. KPHMT catalyzes the first step in the biosynthesis of pantothenate (vitamin B(5)), the precursor of coenzyme A and the acyl carrier protein cofactor. The structure of the decameric enzyme was solved by multiwavelength anomalous dispersion to locate 160 selenomethionine sites and phase 560 kDa of protein, making it the largest structure solved by this approach. KPHMT adopts the (betaalpha)(8) barrel fold and is a member of the phosphoenolpyruvate/pyruvate superfamily. The active site contains a ketopantoate bidentately coordinated to Mg(2+). Similar binding is likely for the substrate, alpha-ketoisovalerate, orienting the C3 for deprotonation.
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Affiliation(s)
- Frank von Delft
- Department of Biochemistry, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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Rubio A, Downs DM. Elevated levels of ketopantoate hydroxymethyltransferase (PanB) lead to a physiologically significant coenzyme A elevation in Salmonella enterica serovar Typhimurium. J Bacteriol 2002; 184:2827-32. [PMID: 11976313 PMCID: PMC135036 DOI: 10.1128/jb.184.10.2827-2832.2002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pantothenate is the product of the ATP-dependent condensation of pantoate and beta-alanine and is a direct precursor of coenzyme A. A connection exists between pantothenate biosynthesis and thiamine biosynthesis in Salmonella enterica serovar Typhimurium since derivatives of a purF mutant that can grow (on glucose medium) in the absence of thiamine excrete pantothenate. We show here that the causative mutation in three such mutants was the addition of a CG base pair upstream of the panB gene. This base addition brings the spacing between the -10 and -35 hexamers of the promoter to a consensus spacing of 17 bp and results in increased transcription of the pan operon. Furthermore, overexpression of PanB caused by this mutation, or by other means, was necessary and sufficient to increase pantothenate production and allow PurF-independent thiamine synthesis on glucose medium.
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Affiliation(s)
- Aileen Rubio
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53706, USA
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von Delft F, Lewendon A, Dhanaraj V, Blundell TL, Abell C, Smith AG. The crystal structure of E. coli pantothenate synthetase confirms it as a member of the cytidylyltransferase superfamily. Structure 2001; 9:439-50. [PMID: 11377204 DOI: 10.1016/s0969-2126(01)00604-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Pantothenate synthetase (EC 6.3.2.1) is the last enzyme of the pathway of pantothenate (vitamin B(5)) synthesis. It catalyzes the condensation of pantoate with beta-alanine in an ATP-dependent reaction. RESULTS We describe the overexpression, purification, and crystal structure of recombinant pantothenate synthetase from E. coli. The structure was solved by a selenomethionine multiwavelength anomalous dispersion experiment and refined against native data to a final R(cryst) of 22.6% (R(free) = 24.9%) at 1.7 A resolution. The enzyme is dimeric, with two well-defined domains per protomer: the N-terminal domain, a Rossmann fold, contains the active site cavity, with the C-terminal domain forming a hinged lid. CONCLUSIONS The N-terminal domain is structurally very similar to class I aminoacyl-tRNA synthetases and is thus a member of the cytidylyltransferase superfamily. This relationship has been used to suggest the location of the ATP and pantoate binding sites and the nature of hinge bending that leads to the ternary enzyme-pantoate-ATP complex.
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Affiliation(s)
- F von Delft
- Department of Biochemistry, 80 Tennis Court Road, CB2 1GA, Cambridge, United Kingdom
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Gojković Z, Sandrini MP, Piskur J. Eukaryotic beta-alanine synthases are functionally related but have a high degree of structural diversity. Genetics 2001; 158:999-1011. [PMID: 11454750 PMCID: PMC1461717 DOI: 10.1093/genetics/158.3.999] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
beta-Alanine synthase (EC 3.5.1.6), which catalyzes the final step of pyrimidine catabolism, has only been characterized in mammals. A Saccharomyces kluyveri pyd3 mutant that is unable to grow on N-carbamyl-beta-alanine as the sole nitrogen source and exhibits diminished beta-alanine synthase activity was used to clone analogous genes from different eukaryotes. Putative PYD3 sequences from the yeast S. kluyveri, the slime mold Dictyostelium discoideum, and the fruit fly Drosophila melanogaster complemented the pyd3 defect. When the S. kluyveri PYD3 gene was expressed in S. cerevisiae, which has no pyrimidine catabolic pathway, it enabled growth on N-carbamyl-beta-alanine as the sole nitrogen source. The D. discoideum and D. melanogaster PYD3 gene products are similar to mammalian beta-alanine synthases. In contrast, the S. kluyveri protein is quite different from these and more similar to bacterial N-carbamyl amidohydrolases. All three beta-alanine synthases are to some degree related to various aspartate transcarbamylases, which catalyze the second step of the de novo pyrimidine biosynthetic pathway. PYD3 expression in yeast seems to be inducible by dihydrouracil and N-carbamyl-beta-alanine, but not by uracil. This work establishes S. kluyveri as a model organism for studying pyrimidine degradation and beta-alanine production in eukaryotes.
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Affiliation(s)
- Z Gojković
- Section of Molecular Microbiology, BioCentrum DTU, DK-2800 Lyngby, Denmark
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Frodyma M, Rubio A, Downs DM. Reduced flux through the purine biosynthetic pathway results in an increased requirement for coenzyme A in thiamine synthesis in Salmonella enterica serovar typhimurium. J Bacteriol 2000; 182:236-40. [PMID: 10613889 PMCID: PMC94266 DOI: 10.1128/jb.182.1.236-240.2000] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Work presented here establishes a connection between cellular coenzyme A (CoA) levels and thiamine biosynthesis in Salmonella enterica serovar Typhimurium. Prior work showed that panE mutants (panE encodes ketopantoate reductase) had a conditional requirement for thiamine or pantothenate. Data presented herein show that the nutritional requirement of panE mutants for either thiamine or pantothenate is manifest only when flux through the purine biosynthetic pathway is reduced. Further, the data show that under the above conditions it is the lack of thiamine pyrophosphate, and not decreased CoA levels, that directly prevents growth.
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Affiliation(s)
- M Frodyma
- Department of Bacteriology, University of Wisconsin-Madison, Madison 53706, USA
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Genschel U, Powell CA, Abell C, Smith AG. The final step of pantothenate biosynthesis in higher plants: cloning and characterization of pantothenate synthetase from Lotus japonicus and Oryza sativum (rice). Biochem J 1999; 341 ( Pt 3):669-78. [PMID: 10417331 PMCID: PMC1220405 DOI: 10.1042/0264-6021:3410669] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have isolated a Lotus japonicus cDNA for pantothenate (vitamin B(5)) synthetase (PS) by functional complementation of an Escherichia coli panC mutant (AT1371). A rice (Oryza sativum) expressed sequence tag, identified by sequence similarity to PS, was also able to complement the E. coli auxotroph, as was an open reading frame from Saccharomyces cerevisiae (baker's yeast). The Lotus and rice cDNAs encode proteins of approx. 34 kDa, which are 65% similar at the amino acid level and do not appear to encode N-terminal extensions by comparison with PS sequences from other organisms. Furthermore, analysis of genomic sequence flanking the coding sequence for PS in Lotus suggests the original cDNA is full-length. The Lotus and rice PSs are therefore likely to be cytosolic. Southern analysis of Lotus genomic DNA indicates that there is a single gene for PS. Recombinant PS from Lotus, overexpressed in E. coli AT1371, is a dimer. The enzyme requires d-pantoate, beta-alanine and ATP for activity and has a higher affinity for pantoate (K(m) 45 microM) than for beta-alanine (K(m) 990 microM). Uncompetitive substrate inhibition becomes significant at pantoate concentrations above 1 mM. The enzyme displays optimal activity at about 0.5 mM pantoate (k(cat) 0.63 s(-1)) and at pH 7.8. Neither oxopantoate nor pantoyl-lactone can replace pantoate as substrate. Antibodies raised against recombinant PS detected a band of 34 kDa in Western blots of Lotus proteins from both roots and leaves. The implications of these findings for pantothenate biosynthesis in plants are discussed.
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Affiliation(s)
- U Genschel
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, U.K
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Sahm H, Eggeling L. D-Pantothenate synthesis in Corynebacterium glutamicum and use of panBC and genes encoding L-valine synthesis for D-pantothenate overproduction. Appl Environ Microbiol 1999; 65:1973-9. [PMID: 10223988 PMCID: PMC91285 DOI: 10.1128/aem.65.5.1973-1979.1999] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
D-Pantothenate is synthesized via four enzymes from ketoisovalerate, which is an intermediate of branched-chain amino acid synthesis. We quantified three of these enzyme activities in Corynebacterium glutamicum and determined specific activities ranging from 0.00014 to 0.001 micromol/min mg (protein)-1. The genes encoding the ketopantoatehydroxymethyl transferase and the pantothenate synthetase were cloned, sequenced, and functionally characterized. These studies suggest that panBC constitutes an operon. By using panC, an assay system was developed to quantify D-pantothenate. The wild type of C. glutamicum was found to accumulate 9 micrograms of this vitamin per liter. A strain was constructed (i) to abolish L-isoleucine synthesis, (ii) to result in increased ketoisovalerate formation, and (iii) to enable its further conversion to D-pantothenate. The best resulting strain has ilvA deleted from its chromosome and has two plasmids to overexpress genes of ketoisovalerate (ilvBNCD) and D-pantothenate (panBC) synthesis. With this strain a D-pantothenate accumulation of up to 1 g/liter is achieved, which is a 10(5)-fold increase in concentration compared to that of the original wild-type strain. From the series of strains analyzed it follows that an increased ketoisovalerate availability is mandatory to direct the metabolite flux into the D-pantothenate-specific part of the pathway and that the availability of beta-alanine is essential for D-pantothenate formation.
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Affiliation(s)
- H Sahm
- Institut für Biotechnologie, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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Hoppensack A, Rehm BH, Steinbüchel A. Analysis of 4-phosphopantetheinylation of polyhydroxybutyrate synthase from Ralstonia eutropha: generation of beta-alanine auxotrophic Tn5 mutants and cloning of the panD gene region. J Bacteriol 1999; 181:1429-35. [PMID: 10049372 PMCID: PMC93530 DOI: 10.1128/jb.181.5.1429-1435.1999] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The postulated posttranslational modification of the polyhydroxybutyrate (PHA) synthase from Ralstonia eutropha by 4-phosphopantetheine was investigated. Four beta-alanine auxotrophic Tn5-induced mutants of R. eutropha HF39 were isolated, and two insertions were mapped in an open reading frame with strong similarity to the panD gene from Escherichia coli, encoding L-aspartate-1-decarboxylase (EC 4.1.1.15), whereas two other insertions were mapped in an open reading frame (ORF) with strong similarity to the NAD(P)+ transhydrogenase (EC 1.6.1.1) alpha 1 subunit, encoded by the pntAA gene from Escherichia coli. The panD gene was cloned by complementation of the panD mutant of R. eutropha Q20. DNA sequencing of the panD gene region (3,312 bp) revealed an ORF of 365 bp, encoding a protein with 63 and 67% amino acid sequence similarity to PanD from E. coli and Bacillus subtilis, respectively. Subcloning of only this ORF into vectors pBBR1MCS-3 and pBluescript KS- led to complementation of the panD mutants of R. eutropha and E. coli SJ16, respectively. panD-encoded L-aspartate-1-decarboxylase was further confirmed by an enzymatic assay. Upstream of panD, an ORF with strong similarity to pntAA from E. coli, encoding NAD(P)+ transhydrogenase subunit alpha 1 was found; downstream of panD, two ORFs with strong similarity to pntAB and pntB, encoding subunits alpha 2 and beta of the NAD(P)+ transhydrogenase, respectively, were identified. Thus, a hitherto undetermined organization of pan and pnt genes was found in R. eutropha. Labeling experiments using one of the R. eutropha panD mutants and [2-14C]beta-alanine provided no evidence that R. eutropha PHA synthase is covalently modified by posttranslational attachment of 4-phosphopantetheine, nor did the E. coli panD mutant exhibit detectable labeling of functional PHA synthase from R. eutropha.
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Affiliation(s)
- A Hoppensack
- Institut für Mikrobiologie der Westfälischen Wilhelms-Universität Münster, D-48149 Münster, Germany
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Abstract
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715-1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
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Affiliation(s)
- M K Berlyn
- Department of Biology and School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520-8104, USA.
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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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