STUDY OF THE PROPERTIES OF THE FRATAXIN FROM GREEN AND BROWN ALGAE

GOMEZ CASATI, D.F.; MARCHETTI-ACOSTA, N.S.; BUSI, M.V.; BARCHIESI, J.

Salta

Congreso; LV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB) y XIV PABMB Congress; 2019

SAIB, Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Fe-S clusters are among the oldest and most versatile cofactors used by most living organisms. They are formed by atoms of iron and inorganic sulfide. Although they can be synthesized non-enzymatically in vitro, their biosynthesis is catalyzed by specific enzymes. Three complete systems responsible for the biosynthesis of groups [Fe-S] were discovered in bacteria: NIF (nitrogen fixation), SUF (sulfur mobilization) and ISC (iron and sulfur cluster) . On the other hand, in eukaryotes the presence of a ISC and SUF homologous system were detected in mitochondria and chloroplasts, respectively. In this work we address the initial characterization of this pathway in algae. First, we performed the identification in silico of gene and protein sequences possibly related to the biogenesis of Fe-S clusters in green and brown algae (Chlorella vulgaris and Ectocarpus siliculosus) using the Phytozome database (https://phytozome.jgi.doe.gov). After performing sequence alignments and considering the similarity percentages found between sequences, one frataxin from E. siliculosus (EctsiFH) and one from C. vulgaris (ChlspFH) were selected to perform their functional characterization. The recombinant proteins produced in bacteria were expressed and purified to homogeneity. We evaluated their ability to attenuate the Fenton reaction by measuring the inhibition of malondialdehyde production after the addition of thiobarbituric acid. As previously suggested, frataxin could function as iron chaperone and in this way, its presence could attenuate oxidative damage by metals. Results showed that ChlspFH attenuated the Fenton reaction by 23% while EctsiFH presented less attenuation. To assess whether overexpression decreases the sensitivity of E. coli cells to oxidative and metal stress, aliquots of liquid cultures were incubated in the presence of hydrogen peroxide, nickel, cadmium or zinc. Our results showed that the expression of frataxin allowed the cells to grow better under oxidative conditions respect to the cells that do not express the recombinant frataxins. These results suggest that algae frataxin would have a protective role against oxidative stress in algae