ENHANCED TOLERANCE OF Escherichia coli TO THERMAL AND OXIDATIVE STRESS

RIMMAUDO L, ARAN M, MASELLI G, MORA GARCÍA S, WOLOSIUK RA.

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2012

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

2-Cys peroxiredoxins (2-Cys Prx) are peroxidases devoid of prosthetic groups that mediate in defence against oxidative stress and peroxide activation of signaling pathways. The associated activities -peroxidase and chaperone- have been assigned to multiple cytoprotective functions. At heat shock temperatures, 2- Cys Prx assembles into oligomeric structures, which possess higher chaperone activity than the decamer found at lower temperatures. To gain insight into the ability of 2-Cys Prx to withstand thermal and oxidative stress, we screened a library of mutants prepared by directed evolution of 2-Cys Prx (AhpC) for tolerance to temperature and oxidants. Thus, we isolated a mutant of AhpC that allowed the survival of the host cells at 53°C, i.e. 8 °C higher than the wild type protein.We also observed that cells were more tolerant to thermal and oxidative stress when transformed with Picrophilus torridus AhpC, from an archea that grows in extreme acidic and hot habitats. Congruent with these results, both mutant and archea AhpC were thermostable while wild type AhpC denaturated irreversible upon increasing temperature. The approach of directed evolution opens the possibility to improve AhpC for increased tolerance to thermal and oxidative stress that could be adapted to the development of organisms more resistant to extreme environments.