|PROSITE documentation PDOC51176|
Dehydrogenases for the biosynthesis of L-tyrosine (Tyr) comprise prephenate dehydrogenase (EC 18.104.22.168) (PDH), arogenate dehydrogenase (EC 22.214.171.124) (ADH) and cyclohexadienyl dehydrogenase that can accept both prephenate and arogenate as substrate. These enzymes use a nicotinamide nucleotide as co-substrate and can be specific for NAD(+), for NADP(+) or can utilize either of these. Bacteria, archaea, plants and fungi possess one or more of these enzymes, which participate in two alternative pathways for the synthesis of Tyr. Prephenate, the common precursor, is formed from chorismate by chorismate mutase. PDH converts prephenate into p-hydroxyphenylpyruvate, which can yield Tyr according to pathway I. In the alternative pathway II, prephenate aminotransferase converts prephenate into arogenate (meaning 'giving rise to aromatics'). Conversion of arogenate can either yield Tyr by ADH, or phenylalanine (Phe) by arogenate dehydratase.
PDH in Tyr biosynthesis pathway I:
PDH Tyr aminotransferase prephenate ----------> p-hydroxyphenylpyruvate <==========> tyrosine
ADH in Tyr biosynthesis pathway II:
Prephenate aminotransferase ADH prephenate <===================> arogenate -----------------> tyrosine
Both PDH and ADH contain a catalytic PDH/ADH domain, which has a length of ~180 residues. A potential NAD(+) binding motif is located in the N-terminal part [1,2]. A central conserved histidine is important for the catalytic activity in the Escherichia coli PDH . Some PDH/ADH domain proteins have a C-terminal extension that may be involved in allosteric regulation [1,2,3,4].
Some proteins known to contain a prephenate/arogenate dehydrogenase domain:
The profile we developed covers the entire prephenate/arogenate dehydrogenase domain.Last update:
December 2005 / First entry.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Zhao G., Xia T., Ingram L.O., Jensen R.A.|
|Title||An allosterically insensitive class of cyclohexadienyl dehydrogenase from Zymomonas mobilis.|
|Source||Eur. J. Biochem. 212:157-165(1993).|
|2||Authors||Bonner C.A., Jensen R.A., Gander J.E., Keyhani N.O.|
|Title||A core catalytic domain of the TyrA protein family: arogenate dehydrogenase from Synechocystis.|
|Source||Biochem. J. 382:279-291(2004).|
|3||Authors||Christendat D., Saridakis V.C., Turnbull J.L.|
|Title||Use of site-directed mutagenesis to identify residues specific for each reaction catalyzed by chorismate mutase-prephenate dehydrogenase from Escherichia coli.|
|4||Authors||Rippert P., Matringe M.|
|Title||Purification and kinetic analysis of the two recombinant arogenate dehydrogenase isoforms of Arabidopsis thaliana.|
|Source||Eur. J. Biochem. 269:4753-4761(2002).|