The extremophilic Andean isolate Acinetobacter sp. Ver3 expresses two ferredoxin‐NADP + reductase isoforms with different catalytic properties

Abstract

Ferredoxin/flavodoxin-NADPH reductases (FPRs) catalyze the reversibleelectron transfer between NADPH and ferredoxin/flavodoxin. The Acinetobactersp. Ver3 isolated from high-altitude Andean lakes contains two isoenzymes,FPR1ver3 and FPR2ver3. Absorption spectra of these FPRs revealedtypical features of flavoproteins, consistent with the use of FAD as a prostheticgroup. Spectral differences indicate distinct electronic arrangements forthe flavin in each enzyme. Steady-state kinetic measurements show that theenzymes display catalytic efficiencies in the order of 1–6 microM/s, althoughFPR1ver3 exhibited higher kcat values compared to FPR2ver3. Whenflavodoxinver3 was used as a substrate, both reductases exhibited dissimilarbehavior. Moreover, only FPR1ver3 is induced by oxidative stimuli, indicatingthat the polyextremophile Ver3 has evolved diverse strategies to cope withoxidative environments.