Degradation of pyrimidines in Saccharomyces kluyveri: transamination of beta-alanine.
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.
Schnackerz
K D
KD
Cell- and Organism Biology, Lund University, Lund, Sweden. schnacke@biozentrum.uni-wuerzburg.de
Andersen
G
G
Dobritzsch
D
D
Piskur
J
J
D000612:4-Aminobutyrate Transaminase / Q000378:metabolism; D000586:Amination; D051263:D-Alanine Transaminase / Q000378:metabolism; D007700:Kinetics; D011743:Pyrimidines / Q000378:metabolism*; D012440:Saccharomyces / Q000201:enzymology / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D015091:beta-Alanine / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D011743:Pyrimidines; D015091:beta-Alanine; D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; D051263:D-Alanine Transaminase; C030986:pyrimidine