Genetic and Molecular Characterization of a DASH Cryptochrome Homologous Gene from Antarctic Diatom Phaeodactylum tricornutum ICE-H

Abstract

DASH-type cryptochromes (cry-DASH) belong to cryptochrome/photolyase family (CPF), that includes photolyases with the capability to repair UVB-induced DNA lesions and cryptochromes acting as photoreceptors without photorepair activity. However, recent studies demonstrated that cry-DASH can repair cyclobutane pyrimidine dimers (CPDs) in damaged single-stranded DNA (ssDNA). Up to now, cry-DASHs have been investigated in prokaryotes and eukaryotes. However, the characteristics and role of cry-DASH in Antarctic diatom were not elucidated. Here, a cry-DASH sequence (Pticry-DASH) of the Antarctic diatom Phaeodactylum tricornutum ICE-H was retrieved from the transcriptome data, amplified by RT-PCR, cloned, and then expressed in Escherichia coli. The phylogenetic analysis indicated that Pticry-DASH is most closely related to cry-DASH. The gene expression of Pticry-DASH under abiotic stress was investigated by RT-PCR. Significant transcript accumulation was revealed after exposure to UVB, blue light, high-intensity light, and high temperature. The Pticry-DASH was expressed in E. coli, purified and its activity was measured. Photo-reactivation experiments confirmed that Pticry-DASH can repair CPDs in ssDNA lesions. Taken together for the first time the cry-DASH has been identified in the Antarctic diatom. The properties and peculiarities of Pticry-DASH including UVB-induced CPDs repair function may promote the exploitation of Antarctic resources.