Carotenoid hydroxylase from Haematococcus pluvialis: cDNA sequence, regulation and functional complementation

A cDNA homologous to p-carotene hydroxylase from Arabidopsis thaliana was i solated from the green alga Haematococcus pluvialis. The predicted amino ac id sequence for this enzyme shows homology to the three known plant p-carot ene hydroxylases from Arabidopsis thaliana and from Capsicum annuum (38% id entity) and to prokaryote carotenoid hydroxylases (32-34% identities). Hete rologous complementation using E. coli strains which were genetically engin eered to produce carotenoids indicated that the H. pluvialis beta-carotene hydroxylase was able to catalyse not only the conversion of beta-carotene t o zeaxanthin but also the conversion of canthaxanthin to astaxanthin. Furth ermore, Northern blot analysis revealed increased p-carotene hydroxylase mR NA steady state levels after induction of astaxanthin biosynthesis. In acco rdance with the latter results, it is proposed that the carotenoid hydroxyl ase characterized in the present publication is involved in the biosynthesi s of astaxanthin during cyst cell formation of H. pluvialis. (C) 1999 Elsev ier Science B.V. All rights reserved.