Structure and functional properties of the cold-adapted catalase from Acinetobacter sp. Ver3 native of the Atacama plateau in northern Argentina

SARTORIO, MARIANA G.; GONZALEZ, JAVIER M.; CORTEZ, NESTOR R.

Congreso; Biofísica en tiempos de COVID-19 : Primeras Jornadas Virtuales SAB 2020; 2020

Sociedad Argentina de Biofísica

Heme catalases remove hydrogen peroxide by catalyzing its dismutation into water andmolecular oxygen, thereby protecting the cell from oxidative damage. The Atacamaplateau in northern Argentina, located at 4,000 meters above sea level, is a desertic areacharacterized by extreme UV radiation, high salinity, and a wide temperature amplitudebetween day and night. Here, we cloned, expressed and puri􏰀ed the heme catalaseKatE1 from an Acinetobacter sp. Atacama isolate, aiming to investigate its extremophilicproperties. Our kinetic and stability assays indicate that KatE1 is maximally active at 50°C in alkaline media, with nearly unchanged speci􏰀c activity between 0 °C and 40 °C, inthe pH range 5.5 to 11.0. In addition, we solved its three-dimensional crystallographicstructure, disclosing minimal structural di􏰁erences compared with mesophilic andthermophilic surrogates, except for a conserved methionine residue on the distal hemeside, which we propose comprises a molecular adaptation to oxidative damage.AcknowldegmentsWe thank synchrotron SOLEIL, L. Diacovich, D. Albanesi, S. Klinke and L. Otero for crystal growth and datacollection. This work was supported by CONICET and ANPCyT, grants PICT 2015-1492 to N.C. and PICT2017-4590 to J.M.G. To the memory of late Dr. Néstor Cortez, our beloved colleague and friend.