Mj. Peak et al., EXTREME RESISTANCE TO THERMALLY-INDUCED DNA BACKBONE BREAKS IN THE HYPERTHERMOPHILIC ARCHAEON PYROCOCCUS-FURIOSUS, Journal of bacteriology, 177(21), 1995, pp. 6316-6318
Pyrococcus furiosus is a hyperthermophilic archaeon that grows optimal
ly at 100 degrees C. It is not conceivable that these organisms could
survive with genomic DNA that was subject to thermal destruction, yet
the mechanisms protecting the genomes of this and other hyperthermophi
les against such destruction are obscure. We have determined the effec
t of elevated temperatures up to 110 degrees C on the molecular weight
of DNA in intact P. furiosus cells, compared with the effect of eleva
ted temperatures on DNA in the mesothermophilic bacterium Escherichia
coli. At 100 degrees C, DNA in P. furiosus cells is about 20 times mor
e resistant to thermal breakage than that in E. coli tells, and six ti
mes fewer breaks were found in P. furiosus DNA after exposure to 110 d
egrees C for 30 min than in E. coli DNA at 95 degrees C. Our hypothesi
s for this remarkable stability of DNA in a hyperthermophile is that t
his hyperthermophile possesses DNA-binding proteins that protect again
st hydrolytic damage, as well as other endogenous protective mechanism
s and DNA repair enzyme systems.