Searching for the role of the plastidic-type Ferredoxin-NADP(H) reductase in Leptospira interrogans.

CATALANO DUPUY, DANIELA L.; CECCARELLI, EDUARDO A

Jaca, España.

Simposio; 16th International Symposium on Flavins and Flavoproteins.; 2008

Uniiversidad de Zaragoza

Ferredoxin-NADP(H) reductases (FNR) are flavoenzymes that deliver NADPH or low potential one-electron donors (ferredoxin, flavodoxin) to redox metabolisms in plastids, mitochondria and bacteria. There are differences in catalytic efficiencies among the members of the FNR family. Whereas plant FNRs display turnover numbers related to the needs of the photosynthesis, bacterial reductases are much less active. It is not known how this catalytic improvement is accomplished but probably was obtained by subtle changes in the protein structure and FAD conformation. The role of FNR in the bacterial metabolism has not been completely elucidated. Evidences indicate that one of the functions is related to oxidative stress protection. We found that FNR from Leptospira interrogans (LepFNR), a parasitic bacterium of animals and humans, belongs to the plastidic class of FNRs at variance of all other bacterial enzymes [1; 2]. The typical structural and biochemical characteristics of plastidic FNRs revealed for LepFNR support the notion of a putative lateral gene transfer offering L. interrogans evolutionary advantages. However we have observed that ferredoxin from pea is not a good substrate for LepFNR. Looking for the physiological substrate of this reductase we identified two ferredoxin genes (LFd1 and LFd2) from the bacterium genome. By sequence and structural analyses we found that they are not plant-type Fds, the common partners of plastidic class FNRs. Our observations suggest a new function of FNR in bacteria.