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Laux M, Ciapina LP, de Carvalho FM, Gerber AL, Guimarães APC, Apolinário M, Paes JES, Jonck CR, de Vasconcelos ATR. Living in mangroves: a syntrophic scenario unveiling a resourceful microbiome. BMC Microbiol 2024; 24:228. [PMID: 38943070 PMCID: PMC11212195 DOI: 10.1186/s12866-024-03390-6] [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: 12/22/2023] [Accepted: 06/19/2024] [Indexed: 07/01/2024] Open
Abstract
BACKGROUND Mangroves are complex and dynamic coastal ecosystems under frequent fluctuations in physicochemical conditions related to the tidal regime. The frequent variation in organic matter concentration, nutrients, and oxygen availability, among other factors, drives the microbial community composition, favoring syntrophic populations harboring a rich and diverse, stress-driven metabolism. Mangroves are known for their carbon sequestration capability, and their complex and integrated metabolic activity is essential to global biogeochemical cycling. Here, we present a metabolic reconstruction based on the genomic functional capability and flux profile between sympatric MAGs co-assembled from a tropical restored mangrove. RESULTS Eleven MAGs were assigned to six Bacteria phyla, all distantly related to the available reference genomes. The metabolic reconstruction showed several potential coupling points and shortcuts between complementary routes and predicted syntrophic interactions. Two metabolic scenarios were drawn: a heterotrophic scenario with plenty of carbon sources and an autotrophic scenario with limited carbon sources or under inhibitory conditions. The sulfur cycle was dominant over methane and the major pathways identified were acetate oxidation coupled to sulfate reduction, heterotrophic acetogenesis coupled to carbohydrate catabolism, ethanol production and carbon fixation. Interestingly, several gene sets and metabolic routes similar to those described for wastewater and organic effluent treatment processes were identified. CONCLUSION The mangrove microbial community metabolic reconstruction reflected the flexibility required to survive in fluctuating environments as the microhabitats created by the tidal regime in mangrove sediments. The metabolic components related to wastewater and organic effluent treatment processes identified strongly suggest that mangrove microbial communities could represent a resourceful microbial model for biotechnological applications that occur naturally in the environment.
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Affiliation(s)
- Marcele Laux
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha Petrópolis, Rio de Janeiro, 25651-075, Brazil
| | - Luciane Prioli Ciapina
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha Petrópolis, Rio de Janeiro, 25651-075, Brazil.
| | - Fabíola Marques de Carvalho
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha Petrópolis, Rio de Janeiro, 25651-075, Brazil
| | - Alexandra Lehmkuhl Gerber
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha Petrópolis, Rio de Janeiro, 25651-075, Brazil
| | - Ana Paula C Guimarães
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha Petrópolis, Rio de Janeiro, 25651-075, Brazil
| | - Moacir Apolinário
- Petróleo Brasileiro S. A., Centro de Pesquisa Leopoldo Américo Miguez de Mello, Rio de Janeiro, RJ, Brasil
| | - Jorge Eduardo Santos Paes
- Petróleo Brasileiro S. A., Centro de Pesquisa Leopoldo Américo Miguez de Mello, Rio de Janeiro, RJ, Brasil
| | - Célio Roberto Jonck
- Petróleo Brasileiro S. A., Centro de Pesquisa Leopoldo Américo Miguez de Mello, Rio de Janeiro, RJ, Brasil
| | - Ana Tereza R de Vasconcelos
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Avenida Getúlio Vargas 333, Quitandinha Petrópolis, Rio de Janeiro, 25651-075, Brazil
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2
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Characterization and directed evolution of propionyl-CoA carboxylase and its application in succinate biosynthetic pathway with two CO2 fixation reactions. Metab Eng 2020; 62:42-50. [DOI: 10.1016/j.ymben.2020.08.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/18/2020] [Accepted: 08/24/2020] [Indexed: 11/20/2022]
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Jiang H, Rao KS, Yee VC, Kraus JP. Characterization of four variant forms of human propionyl-CoA carboxylase expressed in Escherichia coli. J Biol Chem 2005; 280:27719-27. [PMID: 15890657 DOI: 10.1074/jbc.m413281200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Propionyl-CoA carboxylase (PCC) is a biotin-dependent mitochondrial enzyme that catalyzes the conversion of propionyl-CoA to D-methylmalonyl-CoA. PCC consists of two heterologous subunits, alpha PCC and beta PCC, which are encoded by the nuclear PCCA and PCCB genes, respectively. Deficiency of PCC results in a metabolic disorder, propionic acidemia, which is sufficiently severe to cause neonatal death. We have purified three PCCs containing pathogenic mutations in the beta subunit (R165W, E168K, and R410W) and one PCCB polymorphism (A497V) to homogeneity to elucidate the potential structural and functional effects of these substitutions. We observed no significant difference in Km values for propionyl-CoA between wild-type and the variant enzymes, which indicated that these substitutions had no effect on the affinity of the enzyme for this substrate. Furthermore, the kinetic studies indicated that mutation R410W was not involved in propionyl-CoA binding in contrast to a previous report. The three mutant PCCs had half the catalytic efficiency of wild-type PCC as judged by the kcat/Km ratios. No significant differences have been observed in molecular mass or secondary structure among these enzymes. However, the variant PCCs were less thermostable than the wild-type. Following incubation at 47 degrees C, blue native-PAGE revealed a lower oligomeric form (alpha2beta2) in the three mutants not detectable in wild-type and the polymorphism. Interestingly, the lower oligomeric form was also observed in the corresponding crude Escherichia coli extracts. Our biochemical data and the structural analysis using a beta PCC homology model indicate that the pathogenic nature of these mutations is more likely to be due to a lack of assembly rather than disruption of catalysis. The strong favorable effect of the co-expressed chaperone proteins on PCC folding, assembly, and activity suggest that propionic acidemia may be amenable to chaperone therapy.
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Affiliation(s)
- Hua Jiang
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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Hall PR, Wang YF, Rivera-Hainaj RE, Zheng X, Pustai-Carey M, Carey PR, Yee VC. Transcarboxylase 12S crystal structure: hexamer assembly and substrate binding to a multienzyme core. EMBO J 2003; 22:2334-47. [PMID: 12743028 PMCID: PMC156002 DOI: 10.1093/emboj/cdg244] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2003] [Revised: 03/20/2003] [Accepted: 03/24/2003] [Indexed: 11/13/2022] Open
Abstract
Transcarboxylase from Propionibacterium shermanii is a 1.2 MDa multienzyme complex that couples two carboxylation reactions, transferring CO(2)(-) from methylmalonyl-CoA to pyruvate, yielding propionyl-CoA and oxaloacetate. The 1.9 A resolution crystal structure of the central 12S hexameric core, which catalyzes the first carboxylation reaction, has been solved bound to its substrate methylmalonyl-CoA. Overall, the structure reveals two stacked trimers related by 2-fold symmetry, and a domain duplication in the monomer. In the active site, the labile carboxylate group of methylmalonyl-CoA is stabilized by interaction with the N-termini of two alpha-helices. The 12S domains are structurally similar to the crotonase/isomerase superfamily, although only domain 1 of each 12S monomer binds ligand. The 12S reaction is similar to that of human propionyl-CoA carboxylase, whose beta-subunit has 50% sequence identity with 12S. A homology model of the propionyl-CoA carboxylase beta-subunit, based on this 12S crystal structure, provides new insight into the propionyl-CoA carboxylase mechanism, its oligomeric structure and the molecular basis of mutations responsible for enzyme deficiency in propionic acidemia.
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Affiliation(s)
- Pamela R Hall
- Department of Molecular Cardiology and Center for Structural Biology, Lerner Research Institute, Cleveland Clinic Foundation, OH 44195, USA
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5
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Kimura E. Metabolic engineering of glutamate production. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2003; 79:37-57. [PMID: 12523388 DOI: 10.1007/3-540-45989-8_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Since the discovery of Corynebacterium glutamicum as an efficient glutamate-overproducing microorganism in 1957, the production of L-amino acids by the fermentative method has become one of the most important research-target of industrial microbiology. Several research groups have developed metabolic engineering principles for L-amino acid-producing C. glutamicum strains over the last four decades. The mechanism of L-glutamate-overproduction by the microorganism is very unique and interesting. L-Glutamate overproduction by this bacterium, a biotin auxotroph, is induced by a biotin limitation and suppressed by an excess of biotin. Addition of a surfactant or penicillin is known to induce L-glutamate overproduction under excess biotin. After the development of the general molecular biology tools such as cloning vectors and DNA transfer technique, genes encoding biosynthetic enzymes were isolated. With those genes and tools, recombinant DNA technology can be applied in analysis of biosynthetic pathways and strain construction of C. glutamicum. In this review, key points of the L-glutamate biosynthetic pathways are summarized and the recent studies about triggering mechanism of L-glutamate overproduction by C. glutamicum are introduced. Then the metabolic flux analysis of L-glutamate overproduction is explored.
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Affiliation(s)
- Eiichiro Kimura
- Fermentation & Biotechnology Laboratories, Ajinomoto Co., Inc., 1-1 suzuki-cho, Kawasaki-ku, Kawasaki-shi, 210-8681 Japan.
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6
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Zheng X, Rivera-Hainaj RE, Zheng Y, Pusztai-Carey M, Hall PR, Yee VC, Carey PR. Substrate binding induces a cooperative conformational change in the 12S subunit of transcarboxylase: Raman crystallographic evidence. Biochemistry 2002; 41:10741-6. [PMID: 12196011 DOI: 10.1021/bi020422g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 12S subunit of transcarboxylase is a 338 000 Da hexamer that transfers carboxlylate from methylmalonyl-CoA (MM-CoA) to biotin; in turn, the biotin transfers the carboxylate to pyruvate on another subunit, the 5S. Here, Raman difference microscopy is used to study the binding of substrate and product, and their analogues, to single crystals of 12S. A single crystal is the medium of choice because it provides Raman data of unprecedented quality. Crystalline ligand-protein complexes were formed by cocrystallization or by the soaking in/soaking out method. Raman difference spectra were obtained by subtracting the spectrum of the apo crystal from that of a crystal with the substrate or product bound. Raman difference spectra from crystals with the substrate bound are dominated by bands from the protein's amide bonds and aromatic side chain residues. In contrast, Raman difference spectra involving the product, propionyl-CoA, are dominated by modes from the ligand. These results show that substrate binding triggers a conformational change in 12S, whereas product binding does not. The conformational change involves an increase in the amount of alpha-helix since markers for this secondary structure are prominent in the difference spectra of the substrate complex. The number of MM-CoA ligands bound per 12S hexamer can be gauged from the intensity of the MM-CoA Raman features and the fact that the protein concentration in the crystals is known from X-ray crystallographic data. Most crystal samples had six MM-CoAs per hexamer although a few, from different soaking experiments, contained only 1-2. However, both sets of crystals showed the same degree of protein conformational change, indicating that the change induced by the substrate is cooperative. This effect allowed us to record the Raman spectrum of bound MM-CoA without interference from protein modes; the Raman spectrum of a 12S crystal containing 2 MM-CoA ligands per hexamer was subtracted from the Raman spectrum of a 12S crystal containing six MM-CoA ligands per hexamer. The conformational change is reversible and can be controlled by soaking out or soaking in the ligand, using either concentrated ammonium sulfate solutions or the solution used in the crystallization trials. Malonyl-CoA also binds to 12S crystals and brings about conformational changes identical to those seen for MM-CoA; in addition, butyryl-CoA binds and behaves in a manner similar to propionyl-CoA. These data implicate the -COO- group on MM-CoA (that is transferred to biotin in the reaction on the intact enzyme) as the agent bringing about the cooperative conformational change in 12S.
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Affiliation(s)
- Xiaojing Zheng
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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7
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Roessner CA, Huang KX, Warren MJ, Raux E, Scott AI. Isolation and characterization of 14 additional genes specifying the anaerobic biosynthesis of cobalamin (vitamin B12) in Propionibacterium freudenreichii (P. shermanii). MICROBIOLOGY (READING, ENGLAND) 2002; 148:1845-1853. [PMID: 12055304 DOI: 10.1099/00221287-148-6-1845] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A search for genes encoding enzymes involved in cobalamin (vitamin B12) production in the commercially important organism Propionibacterium freudenreichii (P. shermanii) has resulted in the isolation of an additional 14 genes encoding enzymes responsible for 17 steps of the anaerobic B12 pathway in this organism. All of the genes believed to be necessary for the biosynthesis of adenosylcobinamide from uroporphyrinogen III have now been isolated except two (cbiA and an as yet unidentified gene encoding cobalt reductase). Most of the genes are contained in two divergent operons, one of which, in turn, is closely linked to the operon encoding the B12-dependent enzyme methylmalonyl-CoA mutase. The close linkage of the three genes encoding the subunits of transcarboxylase to the hemYHBXRL gene cluster is reported. The functions of the P. freudenreichii B12 pathway genes are discussed, and a mechanism for the regulation of cobalamin and propionic acid production by oxygen in this organism is proposed.
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Affiliation(s)
- Charles A Roessner
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA1
| | - Ke-Xue Huang
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA1
| | - Martin J Warren
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK2
| | - Evelyne Raux
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK2
| | - A Ian Scott
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA1
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Rivera-Hainaj RE, Pusztai-Carey M, Venkat Reddy D, Choowongkomon K, Sönnichsen FD, Carey PR. Characterization of the carboxylate delivery module of transcarboxylase: following spontaneous decarboxylation of the 1.3S-CO2- subunit by NMR and FTIR spectroscopies. Biochemistry 2002; 41:2191-7. [PMID: 11841210 DOI: 10.1021/bi0116442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Transcarboxylase (TC) is a multisubunit enzyme that catalyzes the transfer of a carboxylate group from methylmalonyl-CoA (MMCoA) to pyruvate. The CO2- group is shuttled between the MMCoA and pyruvate binding sites by a biotin cofactor, covalently linked to the 1.3S subunit. Fully carboxylated 1.3S can be prepared in vitro using 1.3S, MMCoA, and catalytic amounts of the TC's MMCoA-binding subunit. The 1.3S-CO2- intermediate decarboxylates spontaneously over a period of hours, and this process was characterized by 1D and 2D NMR and FTIR spectroscopies. The NMR data yielded a first-order kinetic constant of 1.4 x 10(-3) min(-1) for the spontaneous decarboxylation. This rate was calculated from the 1D NMR spectrum by measuring the reappearance of biotin's ureido NH protons and the disappearance of peaks at 6.99 and 7.67 ppm assigned to Asn-8 and/or Asn-24 from the 1.3S's N-terminus. The latter peaks are absent in the 1D spectrum of non-carboxylated 1.3S due to exchange between two or more conformations within the N-terminus causing line broadening. It is proposed that interactions between the biotin-CO2- and the N-terminal amino acids perturb this conformational equilibrium causing some N-terminal residues to appear in the 1D NMR spectrum of the carboxylated form. Further details are apparent from a comparison of the 2D spectra of the 1.3S-CO2- and 1.3S proteins, where carboxylation causes several peaks from the C-terminal half to shift as well as the appearance of resonances due to some residues located at the N-terminal half of the protein. FTIR difference spectra were used also to follow spontaneous decarboxylation of the 1.3S-CO2-. For the carboxylated 1.3S, the difference spectra provided the vibrational signature of the CO2- on the biotin ring. A doublet was identified at 1695 and 1699 cm(-1) that increased in intensity with increasing t. This is assigned to an antisymmetric stretching vibration of the CO2- group bound to biotin on the 1.3S protein. Its position and profile provide further evidence for interactions occurring between the biotin-CO2- group and the 1.3S protein. These studies demonstrate the highly mobile, "poised" nature of the 1.3S protein engineered for its role as a CO2- translocator.
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Affiliation(s)
- Rosa E Rivera-Hainaj
- Department of Biochemistry and Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4935, USA
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9
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McKean AL, Ke J, Song J, Che P, Achenbach S, Nikolau BJ, Wurtele ES. Molecular characterization of the non-biotin-containing subunit of 3-methylcrotonyl-CoA carboxylase. J Biol Chem 2000; 275:5582-90. [PMID: 10681539 DOI: 10.1074/jbc.275.8.5582] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biotin enzyme, 3-methylcrotonyl-CoA carboxylase (MCCase) (3-methylcrotonyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1. 4), catalyzes a pivotal reaction required for both leucine catabolism and isoprenoid metabolism. MCCase is a heteromeric enzyme composed of biotin-containing (MCC-A) and non-biotin-containing (MCC-B) subunits. Although the sequence of the MCC-A subunit was previously determined, the primary structure of the MCC-B subunit is unknown. Based upon sequences of biotin enzymes that use substrates structurally related to 3-methylcrotonyl-CoA, we isolated the MCC-B cDNA and gene of Arabidopsis. Antibodies directed against the bacterially produced recombinant protein encoded by the MCC-B cDNA react solely with the MCC-B subunit of the purified MCCase and inhibit MCCase activity. The primary structure of the MCC-B subunit shows the highest similarity to carboxyltransferase domains of biotin enzymes that use methyl-branched thiol esters as substrate or products. The single copy MCC-B gene of Arabidopsis is interrupted by nine introns. MCC-A and MCC-B mRNAs accumulate in all cell types and organs, with the highest accumulation occurring in rapidly growing and metabolically active tissues. In addition, these two mRNAs accumulate coordinately in an approximately equal molar ratio, and they each account for between 0.01 and 0.1 mol % of cellular mRNA. The sequence of the Arabidopsis MCC-B gene has enabled the identification of animal paralogous MCC-B cDNAs and genes, which may have an impact on the molecular understanding of the lethal inherited metabolic disorder methylcrotonylglyciuria.
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Affiliation(s)
- A L McKean
- Department of Biochemistry, Iowa State University, Ames, Iowa 50011, USA
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Mukhopadhyay B, Stoddard SF, Wolfe RS. Purification, regulation, and molecular and biochemical characterization of pyruvate carboxylase from Methanobacterium thermoautotrophicum strain deltaH. J Biol Chem 1998; 273:5155-66. [PMID: 9478969 DOI: 10.1074/jbc.273.9.5155] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We discovered that Methanobacterium thermoautotrophicum strain DeltaH possessed pyruvate carboxylase (PYC), and this biotin prototroph required exogenously supplied biotin to exhibit detectable amounts of PYC activity. The enzyme was highly labile and was stabilized by 10% inositol in buffers to an extent that allowed purification to homogeneity and characterization. The purified enzyme was absolutely dependent on ATP, Mg2+ (or Mn2+ or Co2+), pyruvate, and bicarbonate for activity; phosphoenolpyruvate could not replace pyruvate, and acetyl-CoA was not required. The enzyme was inhibited by ADP and alpha-ketoglutarate but not by aspartate or glutamate. ATP was inhibitory at high concentrations. The enzyme, unlike other PYCs, exhibited nonlinear kinetics with respect to bicarbonate and was inhibited by excess Mg2+, Mn2+, or Co2+. The 540-kDa enzyme of A4B4 composition contained a non-biotinylated 52-kDa subunit (PYCA) and a 75-kDa biotinylated subunit (PYCB). The pycB gene was probably monocistronic and followed by a putative gene of a DNA-binding protein on the opposite strand. The pycA was about 727 kilobase pairs away from pycB on the chromosome and was probably co-transcribed with the biotin ligase gene (birA). PYCA and PYCB showed substantial sequence identities (33-62%) to, respectively, the biotin carboxylase and biotin carboxyl carrier + carboxyltransferase domains or subunits of known biotin-dependent carboxylases/decarboxylases. We discovered that PYCB and probably the equivalent domains or subunits of all biotin-dependent carboxylases harbored the serine/threonine dehydratase types of pyridoxal-phosphate attachment site. Our results and the existence of an alternative oxaloacetate synthesizing enzyme phosphoenolpyruvate carboxylase in M. thermoautotrophicum strain DeltaH (Kenealy, W. R., and Zeikus, J. G. (1982) FEMS Microbiol. Lett. 14, 7-10) raise several questions for future investigations.
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Affiliation(s)
- B Mukhopadhyay
- Department of Microbiology, University of Illinois, Urbana, Illinois 61801, USA.
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Bott M, Pfister K, Burda P, Kalbermatter O, Woehlke G, Dimroth P. Methylmalonyl-CoA decarboxylase from Propionigenium modestum--cloning and sequencing of the structural genes and purification of the enzyme complex. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 250:590-9. [PMID: 9428714 DOI: 10.1111/j.1432-1033.1997.0590a.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Methylmalonyl-CoA decarboxylase catalyses the only energy-conserving step during succinate fermentation by Propionigenium modestum: the decarboxylation of (S)-methylmalonyl-CoA to propionyl-CoA is coupled to the vectorial transport of Na+ across the cytoplasmic membrane, thereby creating a sodium ion motive force that is used for ATP synthesis. By taking advantage of the sequence similarity between the beta-subunits of other Na+-transport decarboxylases, a portion of the P. modestum beta-subunit gene was amplified by PCR with degenerated primers. The cloned PCR product then served as homologous probe for cloning suitable fragments from genomic DNA. Sequence analysis of a 3.7-kb region identified four genes which probably form a transcriptional unit, mmdADCB. Remarkably, a mmdE gene which is present in the homologous mmdADECB cluster from Veillonella parvula and encodes the 6-kDa epsilon-subunit, is missing in P. modestum. By sequence comparisons, the following functions could be assigned to the P. modestum proteins: MmdA (56.1 kDa; alpha-subunit), carboxyltransferase; MmdB (41.2 kDa; beta-subunit), carboxybiotin-carrier-protein decarboxylase; MmdC (13.1 kDa; gamma-subunit), biotin carrier protein. MmdD (14.2 kDa; delta-subunit) presumably is essential for the assembly of the complex, as shown for the corresponding V. parvula protein. Methylmalonyl-CoA decarboxylase was solubilized from membranes of P. modestum with n-dodecylmaltoside and enriched 15-fold by affinity chromatography on monomeric avidin resin. The purified protein was composed of four subunits, three of which were identified by N-terminal sequence analysis as MmdA, MmdD, and MmdC. The purified enzyme exhibited a specific activity of up to 25 U/mg protein and an apparent Km value for (S)-methylmalonyl-CoA of approximately 12 microM. Compared to the five-subunit complex of V. parvula, the four-subunit enzyme of P. modestum appeared to be more labile, presumably a consequence of the lack of the epsilon-subunit.
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Affiliation(s)
- M Bott
- Mikrobiologisches Institut der Eidgenössischen Technischen Hochschule Zürich, Switzerland
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12
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Koo JH, Jung SB, Byun HS, Kim YS. Cloning and sequencing of genes encoding malonate decarboxylase in Acinetobacter calcoaceticus. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1354:49-54. [PMID: 9375791 DOI: 10.1016/s0167-4781(97)00134-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Malonate decarboxylase from Acinetobacter calcoaceticus was isolated and characterized (Kim, Y.S., Byun, H.S., J. Biol. Chem. 269 (1994) 29636-29641), and its subunits were reanalyzed recently to be alpha, beta, gamma, and delta. The genes for the subunits, MdcA (548 a.a.), B (295 a.a.), C (238 a.a.), and D (102 a.a.), of the enzyme have been cloned by using oligonucleotide primers deduced from amino acid sequences of peptides isolated from the purified enzyme, and sequenced to be clustered in an operon in the order of A-D-B-C. The operon was found to encode more genes than mdcABCD. The Escherichia coli, transformed with the vector containing the insert mdcADBC and about 1.7 kb of an upstream region, expressed the four subunits of the enzyme but the proteins did not show enzyme activity. It indicates that, like the enzymes from Malonomonas rubra and Klebsiella pneumoniae, more genes are needed for the formation of the functional malonate decarboxylase.
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Affiliation(s)
- J H Koo
- Department of Biochemistry, College of Science, Bioproducts Research Center, Yonsei University, Seoul, South Korea
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Kimura E, Abe C, Kawahara Y, Nakamatsu T, Tokuda H. A dtsR gene-disrupted mutant of Brevibacterium lactofermentum requires fatty acids for growth and efficiently produces L-glutamate in the presence of an excess of biotin. Biochem Biophys Res Commun 1997; 234:157-61. [PMID: 9168981 DOI: 10.1006/bbrc.1997.6613] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A dtsR gene encoding a homolog of the beta subunit of some biotin-containing enzymes suppresses a detergent-sensitive mutation of Brevibacterium lactofermentum (E. Kimura et al., 1996, Biosci. Biotech. Biochem. 60, 1565-1570), which has been used for the fermentative production of L-glutamate. When the dtsR gene was disrupted, the organism exhibited strict fatty acid auxotrophy; oleate or oleate ester, but not palmitate ester or stearate ester, supported the growth of the delta dtsR mutant. Immunoblotting with an anti-DtsR antibody revealed that no intact DtsR was present in the cytosol of the delta dtsR mutant. In the presence of an excess of biotin, the wild type strain did not produce L-glutamate whereas the delta dtsR mutant efficiently produced it. The mechanism underlying the efficient production of L-glutamate by the delta dtsR mutant is discussed as to the possible role of dtsR in fatty acid metabolism.
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Affiliation(s)
- E Kimura
- Technology Laboratory, Ajinomoto Co., Inc., Kawasaki, Japan.
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14
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Affiliation(s)
- P Dimroth
- Mikrobiologisches Institut, Eidgenössische Technische Hochschule, Zürich, Switzerland
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