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B6db references: 21597182

type Journal Article
authors Yoneyama H, Hori H, Lim SJ, Murata T, Ando T, Isogai E, Katsumata R.
title Isolation of a mutant auxotrophic for L-alanine and identification of three major aminotransferases that synthesize L-alanine in Escherichia coli
journal Biosci Biotechnol Biochem
sel selected
ui 21597182
year (2011)
volume 75
number 5
pages 930-8
abstract For Escherichia coli, it has been assumed that L-alanine is synthesized by alanine-valine transaminase (AvtA) in conjunction with an unknown alanine aminotransferase(s). We isolated alanine auxotrophs from a prototrophic double mutant deficient in AvtA and YfbQ, a novel alanine aminotransferase, by chemical mutagenesis. A shotgun cloning experiment identified two genes, uncharacterized yfdZ and serC, that complemented the alanine auxotrophy. When the yfdZ- or serC-mutation was introduced into the double mutant, one triple mutant (avtA yfbQ yfdZ) showed alanine auxotrophy, and another (avtA yfbQ serC), prototrophy. In addition, we found that four independent alanine auxotrophs possessed a point mutation in yfdZ but not in serC. We also found that yfdZ expression was induced in minimal medium. Furthermore, yfbQ-bearing plasmid conferred the ability to excrete alanine on the mutant lacking D-amino acid dehydrogenase-encoding gene, dadA. From these results, we concluded that E. coli synthesizes L-alanine by means of three aminotransferases, YfbQ, YfdZ, and AvtA.
last changed 2017/11/15 10:21

B6db references