Flavodoxin-Mediated Electron Transfer from Photosystem I to Ferredoxin-NADP+ Reductase in Anabaena: Role of Flavodoxin Hydrophobic Residues in Protein-Protein Interactions
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- 作者：Guillermina Goñ ; i ; Ana Serrano ; Susana Frago ; Manuel Hervá ; s ; José ; Ramó ; n Peregrina ; Miguel A. De la Rosa ; Carlos Gó ; mez-Moreno ; José ; A. Navarro ; Milagros Medina
- 刊名：Biochemistry
- 出版年：2008
- 出版时间：January 29, 2008
- 年：2008
- 卷：47
- 期：4
- 页码：1207 - 1217
- 全文大小：915K
- 年卷期：v.47,no.4(January 29, 2008)
- ISSN：1520-4995
文摘
Three surface hydrophobic residues located at the Anabaena flavodoxin (Fld) putative complexinterface with its redox partners were replaced by site-directed mutagenesis. The effects of thesereplacements on Fld interaction with both its physiological electron donor, photosystem I (PSI), and itselectron acceptor, ferredoxin-NADP+ reductase (FNR), were analyzed. Trp57, Ile59, and Ile92 contributedto the optimal orientation and tightening of the FNR:Fld and PSI:Fld complexes. However, these sidechains did not appear to be involved in crucial specific interactions, but rather contributed to the obtainmentof the optimal orientation and distance of the redox centers required for efficient electron transfer. Thissupports the idea that the interaction of Fld with its partners is less specific than that of ferredoxin andthat more than one orientation is efficient for electron transfer in these transient complexes. Additionally,for some of the analyzed processes, WT Fld seems not to be the most optimized molecular species.Therefore, subtle changes at the isoalloxazine environment not only influence the Fld binding abilities,but also modulate the electron exchange processes by producing different orientations and distances betweenthe redox centers. Finally, the weaker apoflavodoxin interaction with FNR suggests that the solvent-accessible region of FMN plays a role either in complex formation with FNR or in providing the adequateconformation of the FNR binding region in Fld.