Structure of plant photosystem I-plastocyanin complex reveals strong hydrophobic interactions. Issue 12 (25th June 2021)

• Record Type: Journal Article
• Authors: Caspy, Ido; Fadeeva, Mariia; Kuhlgert, Sebastian; Borovikova-Sheinker, Anna; Klaiman, Daniel; Masrati, Gal; Drepper, Friedel; Ben-Tal, Nir; Hippler, Michael; Nelson, Nathan
• Is Part Of: Biochemical journal. Volume 478:Issue 12(2021)
• Page Start: 2371
• Page End: 2384
• Publication Date: 2021-06-25
• Subjects: cryo-electron microscopy -- electron transfer -- membrane proteins -- photosystems -- plant biology; Biochemistry -- Periodicals; 572
• DOI: 10.1042/BCJ20210267
• Languages: English
• ISSNs: 0264-6021

Abstract

Abstract : Photosystem I is defined as plastocyanin-ferredoxin oxidoreductase. Taking advantage of genetic engineering, kinetic analyses and cryo-EM, our data provide novel mechanistic insights into binding and electron transfer between PSI and Pc. Structural data at 2.74 Å resolution reveals strong hydrophobic interactions in the plant PSI–Pc ternary complex, leading to exclusion of water molecules from PsaA–PsaB/Pc interface once the PSI–Pc complex forms. Upon oxidation of Pc, a slight tilt of bound oxidized Pc allows water molecules to accommodate the space between Pc and PSI to drive Pc dissociation. Such a scenario is consistent with the six times larger dissociation constant of oxidized as compared with reduced Pc and mechanistically explains how this molecular machine optimized electron transfer for fast turnover.