Abstract
It has been suggested that Deinococcus radiodurans possesses a DNA damage response mechanism. However, little is known about the molecular basis for the control of the inducible proteins. We found that, like in E. coli, RecA is the sole protein required for LexA cleavage. We also found that the co-protease activity rather than recombination activity of RecA contributes to the high proficient DNA repair in D. radiodurans. Interestingly, it has been shown that the D. radiodurans genome encodes different two LexA homologues (LexA and LexA2). We analyzed the function of these genes by generating gene disruption strains. The lexA2 disruptant strain exhibited much higher resistance than the wild-type, suggesting that DNA repair genes are down-regulated by LexA2. Furthermore, to gain insight into contributions of LexA and LexA2 in the DNA damage response mechanism, we examined the gene dosage effects of lexA and lexA2. [J Radiat Res 44:412 (2003)]
