NMR study of the electron transfer complex of plant ferredoxin and sulfite reductase: mapping the interaction sites of ferredoxin.
Plant ferredoxin serves as the physiological electron donor for sulfite reductase, which catalyzes the reduction of sulfite to sulfide. Ferredoxin and sulfite reductase form an electrostatically stabilized 1:1 complex for the intermolecular electron transfer. The protein-protein interaction between these proteins from maize leaves was analyzed by nuclear magnetic resonance spectroscopy. Chemical shift perturbation and cross-saturation experiments successfully mapped the location of two major interaction sites of ferredoxin: region 1 including Glu-29, Glu-30, and Asp-34 and region 2 including Glu-92, Glu-93, and Glu-94. The importance of these two acidic patches for interaction with sulfite reductase was confirmed by site-specific mutation of acidic ferredoxin residues in regions 1 and 2, separately and in combination, by which the ability of mutant ferredoxins to transfer electrons and bind to sulfite reductase was additively lowered. Taken together, this study gives a clear illustration of the molecular interaction between ferredoxin and sulfite reductase. We also present data showing that this interaction surface of ferredoxin significantly differs from that when ferredoxin-NADP(+) reductase is the interaction partner.
Institute for Protein Research, Osaka University, 3-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
Takashi
T
Saitoh
Takahisa
T
Ikegami
Masato
M
Nakayama
Keizo
K
Teshima
Hideo
H
Akutsu
Toshiharu
T
Hase
D001224:Aspartic Acid / Q000737:chemistry; D002846:Chromatography, Affinity; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D004579:Electron Transport; D005288:Ferredoxins / Q000737:chemistry*; D018698:Glutamic Acid / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D009154:Mutation; D009249:NADP / Q000737:chemistry; D010088:Oxidoreductases / Q000378:metabolism; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*; D011485:Protein Binding; D055672:Static Electricity; D013696:Temperature; D013997:Time Factors
D005288:Ferredoxins; D010940:Plant Proteins; D001224:Aspartic Acid; D018698:Glutamic Acid; D009249:NADP; D010088:Oxidoreductases; D050862:Oxidoreductases Acting on Sulfur Group Donors