Identification and characterization of 1-Cys peroxiredoxin from Sulfolobus solfataricus and its involvement in the response to oxidative stress

Bcp2 was identified as a putative peroxiredoxin (Prx) in the genome databaseof the aerobic hyperthermophilic archaeon Sulfolobus solfataricus. Itsrole in oxidative stress was investigated by transcriptional analysis of RNAisolated from cultures that had been stressed with various oxidant agents.Its specific involvement was confirmed by a considerable increase in thebcp2 transcript following induction with H2O2. The 5¢ end of the transcriptwas mapped by primer extension analysis and the promoter region wascharacterized. bcp2 was cloned and expressed in Escherichia coli, therecombinant enzyme was purified and the predicted molecular mass wasconfirmed. Using dithiothreitol as an electron donor, this enzyme acts as acatalyst in H2O2 reduction and protects plasmid DNA from nicking bythe metal-catalysed oxidation system. Western blot analysis revealed thatthe Bpc2 expression was induced as a cellular adaptation in response to theaddition of exogenous stressors. The results obtained indicate that Bcp2plays an important role in the peroxide-scavaging system in S. solfataricus.Mutagenesis studies have shown that the only cysteine, Cys49, present inthe Bcp2 sequence, is involved in the catalysis. Lastly, the presence of thisCys in the sequence confirms that Bcp2 is the first archaeal 1-Cysteine peroxiredoxin(1-Cys Prx) so far identified.