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Katrin Henze - One of the best experts on this subject based on the ideXlab platform.
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Acetate:succinate CoA-Transferase in the hydrogenosomes of Trichomonas vaginalis: identification and characterization.
Journal of Biological Chemistry, 2007Co-Authors: Koen W. A. Van Grinsven, Mark van der Giezen, William Martin, Aloysius G M Tielens, Silke Rosnowsky, Susanne W. H. Van Weelden, Simone Pütz, Jaap J. Van Hellemond, Katrin HenzeAbstract:Acetate:succinate CoA-Transferases (ASCT) are acetate-producing enzymes in hydrogenosomes, anaerobically functioning mitochondria and in the aerobically functioning mitochondria of trypanosomatids. Although acetate is produced in the hydrogenosomes of a number of anaerobic microbial eukaryotes such as Trichomonas vaginalis, no acetate producing enzyme has ever been identified in these organelles. Acetate production is the last unidentified enzymatic reaction of hydrogenosomal carbohydrate metabolism. We identified a gene encoding an enzyme for acetate production in the genome of the hydrogenosome-containing protozoan parasite T. vaginalis. This gene shows high similarity to Saccharomyces cerevisiae acetyl-CoA hydrolase and Clostridium kluyveri succinyl-CoA:CoA-Transferase. Here we demonstrate that this protein is expressed and is present in the hydrogenosomes where it functions as the T. vaginalis acetate:succinate CoA-Transferase (TvASCT). Heterologous expression of TvASCT in CHO cells resulted in the expression of an active ASCT. Furthermore, homologous overexpression of the TvASCT gene in T. vaginalis resulted in an equivalent increase in ASCT activity. It was shown that the CoA Transferase activity is succinate-dependent. These results demonstrate that this acetyl-CoA hydrolase/Transferase homolog functions as the hydrogenosomal ASCT of T. vaginalis. This is the first hydrogenosomal acetate-producing enzyme to be identified. Interestingly, TvASCT does not share any similarity with the mitochondrial ASCT from Trypanosoma brucei, the only other eukaryotic succinate-dependent acetyl-CoA-Transferase identified so far. The trichomonad enzyme clearly belongs to a distinct class of acetate:succinate CoA-Transferases. Apparently, two completely different enzymes for succinate-dependent acetate production have evolved independently in ATP-generating organelles.
T. Joseph Kappock - One of the best experts on this subject based on the ideXlab platform.
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Crystal Structures of Acetobacter aceti Succinyl-Coenzyme A (CoA):Acetate CoA-Transferase Reveal Specificity Determinants and Illustrate the Mechanism Used by Class I CoA-Transferases.
Biochemistry, 2012Co-Authors: Elwood A. Mullins, T. Joseph KappockAbstract:Coenzyme A (CoA)-Transferases catalyze transthioesterification reactions involving acyl-CoA substrates, using an active-site carboxylate to form covalent acyl anhydride and CoA thioester adducts. Mechanistic studies of class I CoA-Transferases suggested that acyl-CoA binding energy is used to accelerate rate-limiting acyl transfers by compressing the substrate thioester tightly against the catalytic glutamate [White, H., and Jencks, W. P. (1976) J. Biol. Chem. 251, 1688–1699]. The class I CoA-Transferase succinyl-CoA:acetate CoA-Transferase is an acetic acid resistance factor (AarC) with a role in a variant citric acid cycle in Acetobacter aceti. In an effort to identify residues involved in substrate recognition, X-ray crystal structures of a C-terminally His6-tagged form (AarCH6) were determined for several wild-type and mutant complexes, including freeze-trapped acetylglutamyl anhydride and glutamyl-CoA thioester adducts. The latter shows the acetate product bound to an auxiliary site that is required ...
J B Gibbs - One of the best experts on this subject based on the ideXlab platform.
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protein prenylation in eukaryotic microorganisms genetics biology and biochemistry
Molecular Microbiology, 1994Co-Authors: C A Omer, J B GibbsAbstract:Summary Modrfication of proteins at C-terminal cysteine residue(s) by the isoprenoids farnesyl (C15) and geranylgeranyl (C20) is essential for the biological function of a number of eukaryotic proteins including fungal mating factors and the small, GTP-binding proteins of the Ras superfamily. Three distinct enzymes, conserved between yeast and mammals, have been identified that prenylate proteins: farnesyl protein Transferase, geranylgeranyl protein Transferase type I and geranylgeranyl protein Transferase type II. Each prenyl protein Transferase has its own protein substrate specificity. Much has been learned about the biology, genetics and biochemistry of protein prenylation and prenyl protein Transferases through studies of eukaryotic microorganisms, particularly Saccharo-myces cerevisiae. The functional Importance of protein prenylation was first demonstrated with fungal mating factors. The initial genetic analysis of prenyl protein Transferases was in S. cerewisiae with the isolation and subsequent characterization of mutations in the RAM1, RAM2, CDC43 and BET2 genes, each of which encodes a prenyl protein Transferase subunit. We review here these and other studies on protein prenylation in eukaryotic microbes and how they relate to and have contributed to our knowledge about protein prenylation in all eukaryotic cells.
Phillip B Hylemon - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of two bile acid coenzyme a Transferases from clostridium scindens a bile acid 7α dehydroxylating intestinal bacterium
Journal of Lipid Research, 2012Co-Authors: Jason M Ridlon, Phillip B HylemonAbstract:The human bile acid pool composition is composed of both primary bile acids (cholic acid and chenodeoxycholic acid) and secondary bile acids (deoxycholic acid and lithocholic acid). Secondary bile acids are formed by the 7α-dehydroxylation of primary bile acids carried out by intestinal anaerobic bacteria. We have previously described a multistep biochemical pathway in Clostridium scindens that is responsible for bile acid 7α-dehydroxylation. We have identified a large (12 kb) bile acid inducible (bai) operon in this bacterium that encodes eight genes involved in bile acid 7α-dehydroxylation. However, the function of the baiF gene product in this operon has not been elucidated. In the current study, we cloned and expressed the baiF gene in E. coli and discovered it has bile acid CoA Transferase activity. In addition, we discovered a second bai operon encoding three genes. The baiK gene in this operon was expressed in E. coli and found to encode a second bile acid CoA Transferase. Both bile acid CoA Transferases were determined to be members of the type III family by amino acid sequence comparisons. Both bile acid CoA Transferases had broad substrate specificity, except the baiK gene product, which failed to use lithocholyl-CoA as a CoA donor. Primary bile acids are ligated to CoA via an ATP-dependent mechanism during the initial steps of 7α-dehydroxylation. The bile acid CoA Transferases conserve the thioester bond energy, saving the cell ATP molecules during bile acid 7α-dehydroxylation. ATP-dependent CoA ligation is likely quickly supplanted by ATP-independent CoA transfer.
Alexei Savchenko - One of the best experts on this subject based on the ideXlab platform.
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substrate recognition by a colistin resistance enzyme from moraxella catarrhalis
ACS Chemical Biology, 2018Co-Authors: Peter J. Stogios, Georgina Cox, Haley L. Zubyk, Elena Evdokimova, Zdzislaw Wawrzak, Gerard D. Wright, Alexei SavchenkoAbstract:Lipid A phosphoethanolamine (PEtN) Transferases render bacteria resistant to the last resort antibiotic colistin. The recent discoveries of pathogenic bacteria harboring plasmid-borne PEtN Transferase (mcr) genes have illustrated the serious potential for wide dissemination of these resistance elements. The origin of mcr-1 is traced to Moraxella species co-occupying environmental niches with Enterobacteriaceae. Here, we describe the crystal structure of the catalytic domain of the chromosomally encoded colistin resistance PEtN Transferase, ICRMc (for intrinsic colistin resistance) of Moraxella catarrhalis. The ICRMc structure in complex with PEtN reveals key molecular details including specific residues involved in catalysis and PEtN binding. It also demonstrates that ICRMc catalytic domain dimerization is required for substrate binding. Our structure-guided phylogenetic analysis provides sequence signatures defining potentially colistin-active representatives in this enzyme family. Combined, these result...
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Substrate Recognition by a Colistin Resistance Enzyme from Moraxella catarrhalis
2018Co-Authors: Peter J. Stogios, Georgina Cox, Haley L. Zubyk, Elena Evdokimova, Zdzislaw Wawrzak, Gerard D. Wright, Alexei SavchenkoAbstract:Lipid A phosphoethanolamine (PEtN) Transferases render bacteria resistant to the last resort antibiotic colistin. The recent discoveries of pathogenic bacteria harboring plasmid-borne PEtN Transferase (mcr) genes have illustrated the serious potential for wide dissemination of these resistance elements. The origin of mcr-1 is traced to Moraxella species co-occupying environmental niches with Enterobacteriaceae. Here, we describe the crystal structure of the catalytic domain of the chromosomally encoded colistin resistance PEtN Transferase, ICRMc (for intrinsic colistin resistance) of Moraxella catarrhalis. The ICRMc structure in complex with PEtN reveals key molecular details including specific residues involved in catalysis and PEtN binding. It also demonstrates that ICRMc catalytic domain dimerization is required for substrate binding. Our structure-guided phylogenetic analysis provides sequence signatures defining potentially colistin-active representatives in this enzyme family. Combined, these results advance the molecular and mechanistic understanding of PEtN Transferases and illuminate their origins
