Characterization of a Chlamydomonas reinhardtii gene encoding a protein of the DNA photolyase/blue light photoreceptor family

Abstract

The organization and nucleotide sequence of a gene from Chlamydomonas reinhardtii encoding a member of the DNA photolyase/blue light photoreceptor protein family is reported. A region of over 7 kb encompassing the gene was sequenced. Northern analysis detected a single 4.2 kb mRNA. The gene consists of eight exons and seven introns, and encodes a predicted protein of 867 amino acids. The first 500 amino acids exhibit significant homology with previously sequenced DNA photolyases, showing the closest relationship to mustard (Sinapis alba) photolyase (43% identity). An even higher identity, 49%, is obtained when the Chlamydomonas gene product is compared to the putative blue-light photoreceptor (HY4) from Arabidopsis thaliana. Both the Chlamydomonas and the Arabidopsis proteins differ from the well characterized DNA photolyases in that they contain a carboxyl terminal extension of 367 and 181 amino acids, respectively. However, there is very little homology between the carboxyl terminal domains of the two proteins. A previously isolated Chlamydomonas mutant, phr1, which is deficient in DNA photolyase activity, especially in the nucleus, was shown by RFLP analysis not to be linked to the gene we have isolated. We propose this gene encodes a candidate Chlamydomonas blue light photoreceptor.

Light-Intensity-Dependent Expression of Lhc Gene Family Encoding Light-Harvesting Chlorophyll-a/b Proteins of Photosystem II in Chlamydomonas reinhardtii

“…This view is consistent with the results that the addition of DCMU and the deletion of the PS little affected the low-light accumulation. Although phytochrome has not been reported in C. reinhardtii, a protein with retinal as chromophore (chlamyopsin; Deininger et al, 1995) and a homolog of cryptochrome (CPH1; Small et al, 1995) have been identified. Kindle (1987) proposed that the light-induced expression of a Lhc gene is controlled by a system with a blue-light receptor rather than by a phytochrome in C. reinhardtii, although the photoreceptor has not yet been identified.…”

Blue Light Receptors and Signal Transduction

“…;Ahmad and Cashmore, 1993;Batschauer, 1993;Guo et al, 1998;Ninu et al, 1999), monocots (rice, barley, etc. ;Lin and Cashmore, 1996;Imaizumi et al, 2000;Perrotta et al, 2001), fern ( Adiantum capillus-veneris ;Kanegae and Wada, 1998;Imaizumi et al, 2000), moss ( Physcomitrella patens ;Imaizumi et al, 2001), and algae ( Chlamydomonas reinhardtii ; Small et al, 1995). Most plant species studied contain multiple cryptochromes.…”

“…But CRY1 and CRY2 mRNA levels have been recently shown by a DNA microarray analysis to oscillate with a circadian rhythm of relatively low amplitudes (Harmer et al, 2000). Tomato CRY1 and CRY2, and Chlamydomonas CPH1 gene showed no obvious light regulation for their mRNA expression (Small et al, 1995;Perrotta et al, 2000). On the other hand, white mustard SaPHR gene expression is light induced, and both developmental regulation and light regulation of mRNA expression have been reported for some fern cryptochrome genes (Batschauer, 1993;Imaizumi et al, 2000).…”

Cryptochrome: The Second Photoactive Pigment in the Eye and Its Role in Circadian Photoreception

“…Mutations in CRY2 confer a late-flowering phenotype (74). A CRY gene has been isolated from the alga Chlamydomonas reinhardtii (75) and five CRY genes were found in the fern Adiantum capillus-veneris (76). However, there are no genetic data on the functions of CRYs in these organisms.…”