Characterization of heme oxygenase and ferredoxin-NADP+ reductase in Leptospira biflexa

PORRINI, LUCÍA; CATALANO DUPUY, DANIELA L; CECCARELLI, EDUARDO A

Córdoba

Congreso; 52 th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2016

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Heme oxygenase (HO) catalyzes the degradation of heme to biliverdin, iron and carbon monoxide employing oxygen and reducing equivalents. HO is important for heme-iron utilization in bacteria and contributes to virulence in Leptospira interrogans. We found that a plastidic type, high efficiently ferredoxin-NADP+ reductase (FNR) provides the electrons for the functioning of HO in L. interrogans without the requirement of ferredoxin.Interestingly, phylogenetic analyses revealed that HOs and FNRs are grouped differentially among pathogenic and saprophytic Leptospira species, providing evidence of some function specialization. We have studied the electron transfer between HO and FNR in the saprophyte Leptospira biflexa. Structural and functional differences between the enzymes from the saprophyte and its close related pathogen can provide relevant information.LepBiHO and LepBiFNR were cloned, overexpressed and purified. The structural and enzymatic properties of both enzymes were studied. We found that LepBiHO catalyzed the NADPH/LepBiFNR dependent oxidation of heme without the need of ferredoxin with high catalytic efficiency. However, the reaction ended at an intermediate stage of the normal heme degradation pathway, with no production of biliverdin. Our findings contribute to the understanding of the heme degradation pathway in Leptospira, a key target for therapeutic applications.