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Burton M, Abanobi C, Wang KTC, Ma Y, Rasche ME. Substrate Specificity Analysis of Dihydrofolate/Dihydromethanopterin Reductase Homologs in Methylotrophic α-Proteobacteria. Front Microbiol 2018; 9:2439. [PMID: 30364315 PMCID: PMC6193120 DOI: 10.3389/fmicb.2018.02439] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 09/24/2018] [Indexed: 12/22/2022] Open
Abstract
Methane-producing archaea and methylotrophic bacteria use tetrahydromethanopterin (H4MPT) and/or tetrahydrofolate (H4F) as coenzymes in one-carbon (C1) transfer pathways. The α-proteobacterium Methylobacterium extorquens AM1 contains a dihydromethanopterin reductase (DmrA) and two annotated dihydrofolate reductases (DfrA and DfrB). DmrA has been shown to catalyze the final step of H4MPT biosynthesis; however, the functions of DfrA and DfrB have not been examined biochemically. Moreover, sequence alignment (BLAST) searches have recognized scores of proteins that share up to 99% identity with DmrA but are annotated as diacylglycerol kinases (DAGK). In this work, we used bioinformatics and enzyme assays to provide insight into the phylogeny and substrate specificity of selected Dfr and DmrA homologs. In a phylogenetic tree, DmrA and homologs annotated as DAGKs grouped together in one clade. Purified histidine-tagged versions of the annotated DAGKs from Hyphomicrobium nitrativorans and M. nodulans (respectively, sharing 69 and 84% identity with DmrA) showed only low activity in phosphorylating 1,2-dihexanoyl-sn-glycerol when compared with a commercial DAGK from Escherichia coli. However, the annotated DAGKs successfully reduced a dihydromethanopterin analog (dihydrosarcinapterin, H2SPT) with kinetic values similar to those determined for M. extorquens AM1 DmrA. DfrA and DfrB showed little or no ability to reduce H2SPT under the conditions studied; however, both catalyzed the NADPH-dependent reduction of dihydrofolate. These results provide the first evidence that DfrA and DfrB function as authentic dihydrofolate reductases, while DAGKs with greater than 69% identity to DmrA may be misannotated and are likely to function in H4MPT biosynthesis.
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Affiliation(s)
- Mark Burton
- Department of Chemistry and Biochemistry, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
| | - Chidinma Abanobi
- Department of Chemistry and Biochemistry, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
| | - Kate Tzu-Chi Wang
- Department of Chemistry and Biochemistry, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
| | - Yihua Ma
- Department of Chemistry and Biochemistry, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
| | - Madeline E Rasche
- Department of Chemistry and Biochemistry, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
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Chistoserdova L. Wide Distribution of Genes for Tetrahydromethanopterin/Methanofuran-Linked C1 Transfer Reactions Argues for Their Presence in the Common Ancestor of Bacteria and Archaea. Front Microbiol 2016; 7:1425. [PMID: 27679616 PMCID: PMC5020050 DOI: 10.3389/fmicb.2016.01425] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 08/29/2016] [Indexed: 12/14/2022] Open
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Ochsner AM, Sonntag F, Buchhaupt M, Schrader J, Vorholt JA. Methylobacterium extorquens: methylotrophy and biotechnological applications. Appl Microbiol Biotechnol 2014; 99:517-34. [PMID: 25432674 DOI: 10.1007/s00253-014-6240-3] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/14/2014] [Accepted: 11/16/2014] [Indexed: 01/06/2023]
Abstract
Methylotrophy is the ability to use reduced one-carbon compounds, such as methanol, as a single source of carbon and energy. Methanol is, due to its availability and potential for production from renewable resources, a valuable feedstock for biotechnology. Nature offers a variety of methylotrophic microorganisms that differ in their metabolism and represent resources for engineering of value-added products from methanol. The most extensively studied methylotroph is the Alphaproteobacterium Methylobacterium extorquens. Over the past five decades, the metabolism of M. extorquens has been investigated physiologically, biochemically, and more recently, using complementary omics technologies such as transcriptomics, proteomics, metabolomics, and fluxomics. These approaches, together with a genome-scale metabolic model, facilitate system-wide studies and the development of rational strategies for the successful generation of desired products from methanol. This review summarizes the knowledge of methylotrophy in M. extorquens, as well as the available tools and biotechnological applications.
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Affiliation(s)
- Andrea M Ochsner
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland
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Bobik TA, Morales EJ, Shin A, Cascio D, Sawaya MR, Arbing M, Yeates TO, Rasche ME. Structure of the methanofuran/methanopterin-biosynthetic enzyme MJ1099 from Methanocaldococcus jannaschii. Acta Crystallogr F Struct Biol Commun 2014; 70:1472-9. [PMID: 25372812 PMCID: PMC4231847 DOI: 10.1107/s2053230x1402130x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 09/25/2014] [Indexed: 11/10/2022] Open
Abstract
Prior studies have indicated that MJ1099 from Methanocaldococcus jannaschii has roles in the biosynthesis of tetrahydromethanopterin and methanofuran, two key cofactors of one-carbon (C1) metabolism in diverse organisms including the methanogenic archaea. Here, the structure of MJ1099 has been solved to 1.7 Å resolution using anomalous scattering methods. The results indicate that MJ1099 is a member of the TIM-barrel superfamily and that it is a homohexamer. Bioinformatic analyses identified a potential active site that is highly conserved among MJ1099 homologs and the key amino acids involved were identified. The results presented here should guide further studies of MJ1099 including mechanistic studies and possibly the development of inhibitors that target the methanogenic archaea in the digestive tracts of humans and that are a source of the greenhouse gas methane.
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Affiliation(s)
- Thomas A. Bobik
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Erick J. Morales
- Department of Chemistry and Biochemistry, California State University, Fullerton, CA 92834, USA
| | - Annie Shin
- Department of Energy Institute for Genomics and Proteomics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Duilio Cascio
- Department of Energy Institute for Genomics and Proteomics, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Michael R. Sawaya
- Department of Energy Institute for Genomics and Proteomics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Mark Arbing
- Department of Energy Institute for Genomics and Proteomics, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Todd O. Yeates
- Department of Energy Institute for Genomics and Proteomics, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Madeline E. Rasche
- Department of Chemistry and Biochemistry, California State University, Fullerton, CA 92834, USA
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Discovery and characterization of the first archaeal dihydromethanopterin reductase, an iron-sulfur flavoprotein from Methanosarcina mazei. J Bacteriol 2013; 196:203-9. [PMID: 23995635 DOI: 10.1128/jb.00457-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The microbial production of methane by methanogenic archaea is dependent on the synthesis of the pterin-containing cofactor tetrahydromethanopterin (H4MPT). The enzyme catalyzing the last step of H4MPT biosynthesis (dihydromethanopterin reductase) has not previously been identified in methane-producing microorganisms. Previous complementation studies with the methylotrophic bacterium Methylobacterium extorquens have indicated that an uncharacterized archaeal-flavoprotein-like flavoprotein (AfpA) from Methylobacillus flagellatus or Burkholderia xenovorans can replace the activity of a phylogenetically unrelated bacterial dihydromethanopterin reductase (DmrA). We propose that MM1854, a homolog of AfpA from Methanosarcina mazei, catalyzes the last step of H4MPT biosynthesis in methane-producing microorganisms. To test this hypothesis, a six-histidine (His6)-tagged version of MM1854 was produced. Bioinformatic analysis revealed the presence of one flavin mononucleotide (FMN)-binding site and two iron-sulfur cluster sites, consistent with an oxidoreductase enzyme. Purified His6-MM1854 occurred as a homodimer of 29-kDa subunits, and the UV-visible spectrum of the purified protein showed absorbance peaks at 380 and 460 nm, characteristic of oxidized FMN. NAD(P)H was incapable of directly reducing the flavin cofactor, but dithionite eliminated the FMN peaks, indicating successful electron transfer to MM1854. An electron transfer system of NADPH, spinach NADPH-ferredoxin oxidoreductase, and ferredoxin could also reduce the FMN peaks. A newly developed assay indicated that dithiothreitol-reduced MM1854 could transfer electrons to dihydromethanopterin. This assay was also effective with a heat-stable DmrX analog from Methanocaldococcus jannaschii (MJ0208). These results provide the first biochemical evidence that MM1854 and MJ0208 function as archaeal dihydromethanopterin reductases (DmrX) and that ferredoxin may serve as an electron donor.
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Matsen JB, Yang S, Stein LY, Beck D, Kalyuzhnaya MG. Global Molecular Analyses of Methane Metabolism in Methanotrophic Alphaproteobacterium, Methylosinus trichosporium OB3b. Part I: Transcriptomic Study. Front Microbiol 2013; 4:40. [PMID: 23565111 PMCID: PMC3615186 DOI: 10.3389/fmicb.2013.00040] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 02/17/2013] [Indexed: 11/20/2022] Open
Abstract
Methane utilizing bacteria (methanotrophs) are important in both environmental and biotechnological applications, due to their ability to convert methane to multicarbon compounds. However, systems-level studies of methane metabolism have not been carried out in methanotrophs. In this work we have integrated genomic and transcriptomic information to provide an overview of central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotroph. Particulate methane monooxygenase, PQQ-dependent methanol dehydrogenase, the H4MPT-pathway, and NAD-dependent formate dehydrogenase are involved in methane oxidation to CO2. All genes essential for operation of the serine cycle, the ethylmalonyl-CoA (EMC) pathway, and the citric acid (TCA) cycle were expressed. PEP-pyruvate-oxaloacetate interconversions may have a function in regulation and balancing carbon between the serine cycle and the EMC pathway. A set of transaminases may contribute to carbon partitioning between the pathways. Metabolic pathways for acquisition and/or assimilation of nitrogen and iron are discussed.
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Affiliation(s)
- Janet B Matsen
- Department of Chemical Engineering, University of Washington Seattle, WA, USA
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Testani JM, Dabelic R, Rasche ME. Chemical reduction of pterins to dihydropterins as substrates for enzymatic reactions. Anal Biochem 2006; 358:20-4. [PMID: 16962549 DOI: 10.1016/j.ab.2006.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 07/18/2006] [Accepted: 08/01/2006] [Indexed: 11/22/2022]
Abstract
Dihydropterins are important intermediates in various metabolic pathways, including the biosynthesis of tetrahydrofolate and tetrahydromethanopterin, a key coenzyme in the one-carbon metabolism of methanogenic Archaea. Some procedures for the reduction of pterins to dihydropterins may produce undesirable tetrahydropterin contaminants. This work describes a procedure for the rapid reduction of pterins to dihydropterins while minimizing tetrahydropterin production that may be particularly useful in producing substrates for enzyme reactions when the dihydropterin substrate cannot be purchased commercially.
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Affiliation(s)
- Jeffrey M Testani
- University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Kalyuzhnaya MG, Korotkova N, Crowther G, Marx CJ, Lidstrom ME, Chistoserdova L. Analysis of gene islands involved in methanopterin-linked C1 transfer reactions reveals new functions and provides evolutionary insights. J Bacteriol 2005; 187:4607-14. [PMID: 15968072 PMCID: PMC1151760 DOI: 10.1128/jb.187.13.4607-4614.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, the occurrence and chromosomal clustering of genes encoding C(1) transfer reactions linked to tetrahydromethanopterin (H(4)MPT) were analyzed in a variety of proteobacteria and in representatives of the Planctomycetes via genomic analysis or via partial sequencing by cosmid walking. Although a tendency for clustering was found common for the genes of interest, significant variations in gene order and the degree of clustering were uncovered both between and within different groups of Proteobacteria and between Proteobacteria and Planctomycetes. Phylogenetic analyses suggested that the evolution of genes encoding H(4)MPT-linked reactions in Proteobacteria involved lateral transfers within Proteobacteria and possibly between Proteobacteria and other phyla. Gene cluster comparisons revealed a number of novel genes potentially involved in the C(1) transfer reactions, and these were analyzed by mutation and expression analyses. Four genes, a homolog of pabB, and three genes conserved between methanogenic Archaea and Bacteria possessing H(4)MPT-linked functions, orfY, orf1, and afpA were shown to be involved in formaldehyde oxidation/detoxification, as judged by specific mutant phenotypes. In particular, pabB contributes to the biosynthesis of para-aminobenzoic acid, a precursor of both tetrahydrofolate and H(4)MPT, and afpA apparently encodes a novel dihydromethanopterin reductase, based on mutant complementation experiments.
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Affiliation(s)
- Marina G Kalyuzhnaya
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, USA
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Chistoserdova L, Rasche ME, Lidstrom ME. Novel dephosphotetrahydromethanopterin biosynthesis genes discovered via mutagenesis in Methylobacterium extorquens AM1. J Bacteriol 2005; 187:2508-12. [PMID: 15774894 PMCID: PMC1065231 DOI: 10.1128/jb.187.7.2508-2512.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Accepted: 12/14/2004] [Indexed: 11/20/2022] Open
Abstract
Methylobacterium extorquens AM1 was used to explore the genetics of dephosphotetrahydromethanopterin (dH(4)MPT) biosynthesis. Strains with mutations in eight "archaeal-type" genes linked on the chromosome of M. extorquens AM1 were analyzed for the ability to synthesize dH(4)MPT, and six were found to be dH(4)MPT negative. Putative functions of these genes in dH(4)MPT biosynthesis are discussed.
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Affiliation(s)
- Ludmila Chistoserdova
- 231 Wilcox Hall, Box 352125, Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA.
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Marx CJ, Van Dien SJ, Lidstrom ME. Flux analysis uncovers key role of functional redundancy in formaldehyde metabolism. PLoS Biol 2005; 3:e16. [PMID: 15660163 PMCID: PMC539335 DOI: 10.1371/journal.pbio.0030016] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 11/11/2004] [Indexed: 11/18/2022] Open
Abstract
Genome-scale analysis of predicted metabolic pathways has revealed the common occurrence of apparent redundancy for specific functional units, or metabolic modules. In many cases, mutation analysis does not resolve function, and instead, direct experimental analysis of metabolic flux under changing conditions is necessary. In order to use genome sequences to build models of cellular function, it is important to define function for such apparently redundant systems. Here we describe direct flux measurements to determine the role of redundancy in three modules involved in formaldehyde assimilation and dissimilation in a bacterium growing on methanol. A combination of deuterium and (14)C labeling was used to measure the flux through each of the branches of metabolism for growth on methanol during transitions into and out of methylotrophy. The cells were found to differentially partition formaldehyde among the three modules depending on the flux of methanol into the cell. A dynamic mathematical model demonstrated that the kinetic constants of the enzymes involved are sufficient to account for this phenomenon. We demonstrate the role of redundancy in formaldehyde metabolism and have uncovered a new paradigm for coping with toxic, high-flux metabolic intermediates: a dynamic, interconnected metabolic loop.
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Affiliation(s)
- Christopher J Marx
- 1Department of Microbiology, University of WashingtonSeattle, WashingtonUnited States of America
| | | | - Mary E Lidstrom
- 1Department of Microbiology, University of WashingtonSeattle, WashingtonUnited States of America
- 3Department of Chemical Engineering, University of WashingtonSeattle, WashingtonUnited States of America
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Buchenau B, Thauer RK. Tetrahydrofolate-specific enzymes in Methanosarcina barkeri and growth dependence of this methanogenic archaeon on folic acid or p-aminobenzoic acid. Arch Microbiol 2004; 182:313-25. [PMID: 15349715 DOI: 10.1007/s00203-004-0714-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Revised: 07/15/2004] [Accepted: 07/15/2004] [Indexed: 10/26/2022]
Abstract
Methanogenic archaea are generally thought to use tetrahydromethanopterin or tetrahydrosarcinapterin (H4SPT) rather than tetrahydrofolate (H4F) as a pterin C1 carrier. However, the genome sequence of Methanosarcina species recently revealed a cluster of genes, purN, folD, glyA and metF, that are predicted to encode for H4F-specific enzymes. We show here for folD and glyA from M. barkeri that this prediction is correct: FolD (bifunctional N5,N10-methylene-H4F dehydrogenase/N5,N10-methenyl-H4F cyclohydrolase) and GlyA (serine:H4F hydroxymethyltransferase) were heterologously overproduced in Escherichia coli, purified and found to be specific for methylene-H4F and H4F, respectively (apparent Km below 5 microM). Western blot analyses and enzyme activity measurements revealed that both enzymes were synthesized in M. barkeri. The results thus indicate that M. barkeri should contain H4F, which was supported by the finding that growth of M. barkeri was dependent on folic acid and that the vitamin could be substituted by p-aminobenzoic acid, a biosynthetic precursor of H4F. From the p-aminobenzoic acid requirement, an intracellular H4F concentration of approximately 5 M was estimated. Evidence is presented that the p-aminobenzoic acid taken up by the growing cells was not required for the biosynthesis of H4SPT, which was found to be present in the cells at a concentration above 3 mM. The presence of both H4SPT and H4F in M. barkeri is in agreement with earlier isotope labeling studies indicating that there are two separate C1 pools in these methanogens.
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Affiliation(s)
- Bärbel Buchenau
- Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, Marburg, Germany
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