RecA Protein from the Extremely Radioresistant Bacterium Deinococcus radiodurans : Expression, Purification, and Characterization

The RecA proteins of Deinococcus radiodurans and Escherichia coli promote DNA strand exchange via inverse pathways

“…RecBCD plays a critical role in recombinational processes in many bacteria. The Dr RecA protein is normally expressed at very low levels in Dr cells, and only transiently at high levels after exposure to heavy DNA damage (10,11). The ssDNA binding (SSB) gene of Dr is apparently disrupted, containing segments in different reading frames (6).…”

“…Nevertheless, the Dr RecA protein has been successfully expressed in Ec and purified from that source (10). In many respects, the Dr RecA protein is similar to other bacterial RecA proteins.…”

“…This situation has delayed the accurate cloning of the Dr SSB protein. The Ec SSB is nevertheless highly stimulatory in Dr RecA-mediated DNA strand exchange (10), and the Ec SSB is used in these experiments.…”

DNA Helicase Activity of the RecD Protein from Deinococcus radiodurans

“…The complete D. radiodurans genome has been sequenced, and orthologues of many familiar DNA repair proteins are readily identifiable (7). For example, a D. radiodurans recA gene is found, and the RecA protein has been characterized biochemically (8,9). However, the D. radiodurans genome apparently has neither recB nor recC genes, nor are there addAB-like genes (7).…”

Production of Superoxide Dismutase by Deinococcus radiophilus

“…Although it could be speculated that the unusual radio-resistance is attributed to their morphological characteristics (including a thick cell wall of several distinct layers and membrane-bound carotenoid pigment), one could easily assume that the operation of the efficient scavenging systems against the reactive oxygen species (ROS) and the repairing potential of the damaged cellular components that are mediated by toxic oxidants are highly engaged in the extreme radio-resistance of Deinococcus. Extensive studies on UV resistance in regard to the repairing genes for damaged DNA (Evans and Moseley, 1983;Gutman et al, 1993;Daly et al, 1994;Agostini et al, 1996;Narumi et al, 1997;Bauche and Laval, 1999;Kim et al, 2002) and the entire genome analysis of D. radiodurans that was reported in recent years (White et al, 1999;Makarova et al, 2001) would be insufficient to understand the radio-resistant nature of Deinococcus. Therefore, attention has been paid to the scavenging enzymes against the reactive oxygens in relation to the UV resistance.…”