title: Cloning, characterization and transcriptional analysis of two phosphate acetyltransferase isoforms from Azotobacter vinelandii.
abstract: Acetate is abundant in soil contributing to a great extent on carbon cycling in nature. Phosphate acetyltransferase (Pta, EC 2.3.1.8) catalyzes the reversible transfer of the acetyl group from acetyl-P to CoA forming acetyl-CoA and inorganic phosphate, participating to acetate assimilation/dissimilation reactions. In the present study, we demonstrate that Azotobacter vinelandii, a nitrogen-fixing, free-living, soil bacterium, possesses two class II phosphate acetyltransferase isoforms, AvPTA-1 and AvPTA-2, with different kinetic properties. At the acetyl-CoA forming direction, AvPTA-1 has lower affinity for acetyl-P and higher affinity for CoA than AvPTA-2 while at the acetyl-P forming direction; activity was measured only for AvPTA-1. Quantification of their expression patterns by RT-qPCR indicated that both genes are expressed during exponential growth on glucose or acetate and are down-regulated in the stationary phase. The ammonium availability during acetate growth resulted in up-regulation of Avpta-2 expression only. Further, the gene expression patterns of other related gene transcripts were also investigated, in order to understand the influence of each pathway in the assimilation/dissimilation of acetate.
authors.affiliation: Department of Agricultural Biotechnology, Agricultural University of Athens, Iera Odos 75, 11855, Botanikos, Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Dimou
authors.forename: Anastasia
authors.initials: A
authors.lastname: Venieraki
authors.forename: Georgios
authors.initials: G
authors.lastname: Liakopoulos
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Katinakis
mesh_terms: D000085:Acetates / Q000378:metabolism; D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000201:enzymology* / Q000235:genetics*; D055162:Biocatalysis; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D015964:Gene Expression Regulation, Bacterial; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D010709:Phosphate Acetyltransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D000085:Acetates; D007527:Isoenzymes; D011994:Recombinant Proteins; D010709:Phosphate Acetyltransferase