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ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(4): 270–275
CN 31-1940/Q
Cloning and Characterization of b-Carotene Ketolase Gene
Promoter in Haematococcus pluvialis
Chun-Xiao MENG1,2, Chang-Ying TENG1, Peng JIANG1, Song QIN1*, and
Cheng-Kui TSENG1
1Institute of Oceanology, Chinese Academy of Sciences, Qingdao
266071, China;
2Graduate School of the Chinese Academy of Sciences, Beijing 100039,
China
Abstract The unicellular green alga Haematococcus pluvialis
accumulates a highly valuable ketocarotenoid, astaxanthin, under various
environmental stresses. b-carotene ketolase (BKT) plays a key role in astaxanthin
biosynthesis in H. pluvialis. In this paper, an approximate 700 bp 5‘-flanking
region of the bkt gene containing a putative promoter was cloned through
walking upstream. The results of the sequence analysis showed that this bkt
5‘-flanking region might have cis-acting elements such as sterol
regulatory element (SRE-1)-like motifs, the C-repeat/dehydration responsive
element (DRE) and al-3
proximal element (APE)-like motifs, except for typical TATA and CCAAT boxes.
The results of the b-galactosidase assay and the transient expression of lacZ driven
by a series of sequential deletions revealed that a minimal promoter-like
region might exist from –630 to –408 bp, and the highest promoter activity was
observed to span the positions from –630 to –308 bp. The results of the
site-directed mutagenesis of a C-repeat/DRE and two APE-like motifs in a
promoter-like region (–630 to –308 bp) suggested that two APE-like motifs might
be essential for transcriptional control of the bkt gene.
Key words Haematococcus pluvialis; astaxanthin; b-carotene
ketolase gene (bkt); cis-acting element; promoter
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Received: November 26, 2004 Accepted: February 21,
2005
This research was supported by a grant from the National Natural
Science Foundation of China (No. 30470156)
*Corresponding author: Tel, 86-532-2898500; Fax, 86-532-2880645;
E-mail, [email protected]