Identification of the N- and C-Terminal Substrate Binding Segments of Ferredoxin-NADP+ Reductase by NMR
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- 作者：Masahiro Maeda ; Young Ho Lee ; Takahisa Ikegami ; Kohsuke Tamura ; Masaru Hoshino ; Toshio Yamazaki ; Masato Nakayama ; Toshiharu Hase ; and Yuji Goto
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：August 9, 2005
- 年：2005
- 卷：44
- 期：31
- 页码：10644 - 10653
- 全文大小：583K
- 年卷期：v.44,no.31(August 9, 2005)
- ISSN：1520-4995
文摘
Ferredoxin-NADP+ reductase (FNR) catalyzes the reduction of NADP+ through the formationof an electron transfer complex with ferredoxin. To gain insight into the interaction of this enzyme withsubstrates at both ends of the polypeptide chain, we performed NMR analyses of a 314-residue maizeleaf FNR with a nearly complete assignment of the backbone resonances. The chemical shift perturbationupon formation of the complex indicated that a flexible N-terminal region of FNR contributed to theinteraction with maize ferredoxin, and an analysis of N-terminally truncated mutants of FNR confirmedthe importance of this region for the binding of ferredoxin. Comparison between the spectra of FNR inthe NADP+- and inhibitor-bound states also revealed that the nicotinamide moiety of NADP+ was accessibleto the C-terminal Tyr314. We propose that the formation of the catalytic competent complex of FNR andsubstrates is achieved through the interaction of the N- and C-terminal segments with ferredoxin andNADP+, respectively. Since the ends of the polypeptide chain act as flexible regions of proteins, theymay contribute to the search of a larger space for a binding partner and to the opening of active sites.