Study of the properties of the frataxin from green and brown algae.

MARCHETTI ACOSTA, NOELIA; BARCHIESI, JULIETA; DIEGO FABIAN GOMEZ CASATI; BUSI, MARIA VICTORIA

Salta

Congreso; LV Reunión de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB),; 2019

SAIB

Fe-S clusters are among the oldest and mostversatile cofactors used by most living organisms. They are formed by atoms ofiron and inorganic sulfide. Although they can be synthesized non-enzymatically in vitro, their biosynthesis iscatalyzed by specific enzymes. Three complete systems responsible for thebiosynthesis of groups [Fe-S] were discovered in bacteria: NIF (nitrogen fixation),SUF (sulfur mobilization) and ISC (iron and sulfur cluster) and in eukaryotesthe presence of a ISC and SUF homologous system in mitochondria andchloroplasts, respectively. In this work we address the initialcharacterization of this pathway in algae. First, we performed theidentification  in silico  of gene andprotein sequences possibly related to the biogenesis of Fe-S clusters in greenand brown algae (Chlorella vulgarisand Ectocarpus siliculosus) using thePhytozome database (https://phytozome.jgi.doe.gov). After performing sequencealignements,  and considering  the similarity percentages found between sequences,one frataxin from E. siliculosus(EctsiFH24207) and two from C. vulgaris(ChlspFH134457 and ChlspFH20883) were selected to perform their functionalcharacterization. The recombinant proteins produced in bacteria were expressedand purified to homogeneity. We  evaluated their ability to attenuate theFenton reaction by measuring the inhibition of malondialdehyde production afterthe addition of thiobarbituric acid. As previously suggested, frataxin couldfunction as iron chaperone and in this way, its presence could attenuateoxidative damage by metals. Results showed that ChlspFH134457 attenuated theFenton reaction by 23% while EctsiFH24207 presented less atenuation. . Toassess whether overexpression decreases the sensitivity of E. coli cells tooxidative and metal stress, aliquots of liquid cultures were incubated in thepresence of  hydrogen peroxide, nickel,cadmium or zinc. Our results showed that the expressión of frataxin allowed thecells to grow better under oxidative conditions respect to the cells that donot express the recombinant frataxins. These results suggest that algae frataxinwould have a protective role against oxidative stress in algae.