Gene cloning and expression profile of a novel carotenoid hydroxylase (CYP97C) from the green alga Haematococcus pluvialis

Abstract

A full-length complementary DNA (cDNA) sequence of epsilon-ring CHY (designated Haecyp97c) was cloned from the green alga Haematococcus pluvialis by reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends methods. The Haecyp97c cDNA sequence was 1,995 base pairs (bp) in length, which contained a 1,620-bp open reading frame, a 46-bp 5'-untranslated region (UTR), and a 329-bp 3'-UTR with the characteristic of the poly (A) tail. The deduced protein had a calculated molecular mass of 58.71 kDa with an estimated isoelectric point of 7.94. Multiple alignment analysis revealed that the deduced amino acid sequence of HaeCYP97C shared high identity of 72-85 % with corresponding CYP97Cs from other eukaryotes. The catalytic motifs of cytochrome P450s were detected in the amino acid sequence of HaeCYP97C. The transcriptional levels of Haecyp97c and xanthophylls accumulation under high light (HL) stress have been examined. The results revealed that Haecyp97c transcript was strongly increased after 13-28 h under HL stress. Meanwhile, the concentrations of chlorophylls, carotenes, and lutein were decreased, and zeaxanthin and astaxanthin concentrations were increased rapidly, respectively. These facts indicated that HaeCYP97C was perhaps involved in xanthophyll biosynthesis, which plays an important role in adaption to HL for H. pluvialis.