DNA Repair: Lessons from the Evolution of Ionizing- Radiation-Resistant Prokaryotes – Fact and Theory

摘要: At the outset, I believe that concept of ionizing-radiation (IR) resistance needs to be clarified in a tangible manner for readers this chapter. propose following general definition adopted previous paper (Sghaier et al., 2008): An ionizing-radiation-resistant prokaryotes (IRRP) is any vegetative prokaryote can thrive after exposure high, acute IR (generally, with D10 value dose necessary effect 90% reduction Colony Forming Units greater than 1 kGy) using efficient physiological, genetic and proteic protection repair mechanisms fully amend its DNA DSBs. has been observed broad range prokaryotic groups (Kopylov 1993), including hyperthermophilic Archaea (P. abyssi, P. furiosus, Thermococcus marinus, radiotolerans gammatolerans) (DiRuggiero 1997; Jolivet 2003a; 2003b; 2004), halophilic (Halobacterium sp.) (Kottemann 2005), Deinococcus-Thermus group (many Deinococcus sp. Truepera radiovictrix) (Albuquerque Actinobacteria (Rubrobacter radiotolerans, Rubrobacter xylanophilus Kineococcus radiotolerans) (Yoshinaka 1973; Ferreira 1999; Phillips 2002; Chen Proteobacteria (Methylobacterium Acinetobacter radioresistens) (Ito Iizuka, 1971; Nishimura 1994), Cyanobacteria (Chroococcidiopsis (Billi 2000), Sphingobacteria (Hymenobacter actinosclerus) (Collins 2000). However, exception Pyrococcus, very little information available regarding comparative genomics above-mentioned prokaryotes. D. radiodurans current gold-medallist among completely sequenced genome (Liolios 2006; Liolios 2010), more 100 DSBs per chromosome, induced by IR, without loss viability (Moseley, 1983; White 1999). After breaking 3.2 Mb into 20−30 kb pieces high fascinatingly reassembles such 3 hr later restructured nonrearranged chromosomes are present (Galhardo Rosenberg, 2009). Nine interrelated explanations extreme have proposed: (i) binding IrrI (DR0171) genomic repeat sequences might prevent exhaustive chromosomal degradation irr (Udupa (ii)