J. Biol. Chem., Vol. 267, Issue 36, 25644-25647, Dec, 1992
Visible light-inducible photolyase gene from the goldfish Carassius auratus
S Yasuhira and A Yasui
Research Institute for Tuberculosis and Cancer, Tohoku University, Sendai, Japan.
By introducing and expressing a cDNA library constructed from mRNA of the
cultured goldfish Carassius auratus cells in Escherichia coli, a gene
encoding photolyase of the vertebrate was isolated, the first example from
metazoa. The amino acid sequence deduced from the nucleotide sequence
differs significantly from those of microorganisms. Five out of 6
tryptophan residues strictly conserved in photolyases from microorganisms
and thought to play important roles in DNA and chromophore binding of the
enzyme are substituted by other residues of different characteristics. By
Northern analysis the expression of the photolyase gene was found to be
induced more than 10 times by exposure of the cells to visible light. These
results indicate a unique evolution of the photolyase gene and a novel
mechanism of gene regulation, in which visible light triggers the
production of the light- dependent enzyme for repair of DNA damages induced
by harmful ultraviolet part of sunlight.