LepFNR IS THE REDUCTANT FOR HEME DEGRADATION BY Leptospira interrogans HEME OXYGENASE

SOLDANO, ANABEL; CECCARELLI, EDUARDO A.; CATALANO DUPUY, DANIELA L.

Ciudad Autónoma de Buenos Aires

Congreso; Reunión Anual de SAIB 2013; 2013

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

LepFNR IS THE REDUCTANT FOR HEME DEGRADATION BY Leptospira interrogans HEME OXYGENASE Soldano A, Ceccarelli EA, Catalano Dupuy DL. Instituto de Biología Molecular y Celular de Rosario, CONICET, UNR. E-mail: soldano@ibr-conicet.gov.ar Like most pathogens, Leptospira interrogans requires an iron source for bacterial metabolism and growth during infection. Within mammalian hosts, free iron is negligible because it is mostly bound to high affinity proteins. However, L. interrogans has evolved to acquire iron from host hemoglobin. A crucial protein involved in this process is the heme oxygenase (LepHO), which cleavages the porphyrin of heme and release iron, biliverdin and carbon monoxide. Heme breakdown by bacterial heme oxygenases requires molecular oxygen and an electron source derived from NADPH supplied by ferredoxin-NADP+ reductase (FNR) and ferredoxin (Fd). The observed Fd dependence led us to test FNR and Fd as potential reducing partners of LepHO. Thereby, we studied the LepHO cleavage of heme macrocycle by optical absorption spectroscopy. We established that the plastidic-type ferredoxin-NADP+ reductase from L. interrogans (LepFNR), acts as the physiological electron donor without the participation of a ferredoxin. We characterized the interaction between LepHO and LepFNR determining the dissociation constant of LepHO-LepFNR complex. We found that in the presence of NADPH, LepFNR and ferrozine, LepHO releases ferrous iron. Our results indicate that LepFNR and LepHO are involved in the heme-iron utilization pathway, through which L. interrogans can successfully acquire iron from host for its own survival.