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Appl. Environ. Microbiol., Apr 1995, 1298-1302, Vol 61, No. 4
A Abou-Zeid, GJW Euverink, GI Hessels, RA Jensen and L Dijkhuizen
Auxotrophic mutants of the actinomycete Amycolatopsis methanolica requiring
l-Phe or l-Tyr were isolated and identified as strains lacking prephenate
dehydratase (strain GH71) or arogenate dehydrogenase (strain GH70),
respectively. A. methanolica thus employs single pathways only for the
biosynthesis of these aromatic amino acids. Anion-exchange chromatography
of extracts revealed two peaks with Phe as well as Tyr aminotransferase
(AT) activity (Phe/Tyr ATI and Phe/Tyr ATII) and three peaks with
prephenate AT activity (Ppa ATI to Ppa ATIII). Phe/Tyr ATI and Ppa ATI
coeluted and appear to function as the A. methanolica branched-chain amino
acid AT. Ppa ATII probably functions as the aspartate AT. Mutant studies
showed that Phe/Tyr ATII is the dominant AT in l-Phe biosynthesis and in
l-Tyr catabolism but not in l-Tyr biosynthesis. Biochemical studies showed
that Ppa ATIII is highly specific for prephenate and provided evidence that
Ppa ATIII is the dominant AT in l-Tyr biosynthesis.
Copyright © 1995, American Society for Microbiology
Biosynthesis of l-Phenylalanine and l-Tyrosine in the Actinomycete Amycolatopsis methanolica
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands, and Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
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