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

CATALANO DUPUY, D. L.; CECCARELLI, E. A.

Jaca, España

Simposio; 16th Symposium on Flavins and Flavoproteins; 2008

Comite Flavin y Flavoproteins de varias universidades

Ferredoxin-NADP(H) reductases (FNR) are flavoenzymes that deliver NADPH or lowpotential one-electron donors (ferredoxin, flavodoxin) to redox metabolisms in plastids,mitochondria and bacteria. There are differences in catalytic efficiencies among themembers of the FNR family. Whereas plant FNRs display turnover numbers related tothe needs of the photosynthesis, bacterial reductases are much less active. It is notknown how this catalytic improvement is accomplished but probably was obtained bysubtle changes in the protein structure and FAD conformation. The role of FNR in thebacterial metabolism has not been completely elucidated. Evidences indicate that one ofthe functions is related to oxidative stress protection. We found that FNR fromLeptospira 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 forLepFNR support the notion of a putative lateral gene transfer offering L. interrogansevolutionary advantages. However we have observed that ferredoxin from pea is not agood substrate for LepFNR. Looking for the physiological substrate of this reductasewe identified two ferredoxin genes (LFd1 and LFd2) from the bacterium genome. Bysequence and structural analyses we found that they are not plant-type Fds, the commonpartners of plastidic class FNRs. Our observations suggest a new function of FNR inbacteria.[1] Ceccarelli, E.A., Arakaki, A.K., Cortez, N., Carrillo N. (2004) Biochim. Biophys.Acta 1698, 155-165.[2] Nascimento, A.S., Catalano-Dupuy, D.L., Bernardes, A., de Oliveira, N.M., Santos,M.A., Ceccarelli, E.A., Polikarpov, I. (2007) BMC. Struct. Biol. 7, 69.