A cDNA encoding a DHQ synthase (3-dehydroquinate synthase) [EC 4.6.1.3] from tomato has been identified by complementing a 3-dehydroquinate synthase-deficient Escherichia coli strain (Bischoff et al, 1996). The deduced amino acid sequence contains a putative N-terminal plastid-specific transit peptide (Bischoff et al, 1996). The sequence of the mature enzyme more closely resembles those of the corresponding bacterial enzymes than the fungal enzymes (Bischoff et al, 1996).

In Pisum sativum DHQ dehydratase (dehydroquinase) [EC 4.4.1.10] occurs as a bifunctional enzyme, with dehydroquinase and shikimate dehydrogenase [EC 1.1.1.25] activities (Deka et al, 1994). The dehydroquinase domain is homologous to all other type I dehydroquinases, and is N-terminal (Deka et al, 1994). Similarly, a Nicotiana tabacum cDNA encoding a bifunctional protein having catalytic domains for dehydroquinase and shikimate dehydrogenase has been cloned and sequenced (Bonner and Jensen, 1994). This cDNA complements the Escherichia coli aroD and aroE auxotrophs (Bonner and Jensen, 1994). The two catalytic domains exhibit greater amino acid identity with prokaryote homologues than with yeast and fungal homologues (Bonner and Jensen, 1994).

Bischoff M, Rosler J, Raesecke HR, Gorlach J, Amrhein N, Schmid J 1996 Cloning of a cDNA encoding a 3-dehydroquinate synthase from a higher plant, and analysis of the organ-specific and elicitor-induced expression of the corresponding gene. Plant Mol. Biol. 31: 69-76.

Bonner CA, Jensen RA 1994 Cloning of cDNA encoding the bifunctional dehydroquinase/shikimate dehydrogenase of aromatic amino acid biosynthesis in Nicotiana tabacum. Biochem. J. 302: 11-14.

Deka RK, Anton IA, Dunbar B, Coggins JR 1994 The characterisation of the shikimate pathway enzyme dehydroquinase from Pisum sativum. FEBS Lett. 349: 397-402.