Photolyases and Cryptochromes in UV-resistant Bacteria from High-altitude Andean Lakes

DANIEL ALONSO; ALBARRACIN VIRGINIA H.; LUCIANO R. PORTERO; FARIAS MARIA EUGENIA; FEDERICO ZANNIER

PHOTOCHEMISTRY AND PHOTOBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0031-8655

?High-Altitude Andean Lakes? (HAAL) are pristine environments harboring poly-extremophilic microbes that show combined adaptations to physical and chemical stress suchas large daily ambient thermal amplitude, extreme solar radiation levels, intense dryness,alkalinity, high concentrations of arsenic (up to 200 ppm) and dissolved salts. In this work,wecompared the UV resistance profiles, pigment content and photoreactivation abilities ofthree UV-resistant bacteria isolated from distinct niches from HAAL´s: i.e. Acinetobacter sp.Ver3 (water, Lake Verde; 4.400 m), Exiguobacterium sp. S17 (stromatolite, Lake Socompa,3,570 m) and Nesterenkonia sp. Act20 (soil, Lake Socompa, 3,570 m).UV resistance ability of HAAL´s strains indicate a clear adaptation to high radiationexposure encountered in their original habitat, which can be explained by genetic andphysiological mechanisms named as the UV-resistome. Thus, the UV-resistome depends onthe expression of a diverse set of genes devoted to evading or repairing the damage it provoked direct or indirectly. As pigment extraction and photoreactive assays indicate thepresence of photoactive molecules, we characterized more in detail proteins with homologyto photolyases/cryptochromes members (CPF). Phylogenetic analyses,sequence comparisonand 3D modelling with bonafide CPFs members was used to proof the presence of functionaldomains and key residues in the novel proteins.