Fig. 4: The attachment of PsaSOD1/2 subunits to the stromal side of the PSI core. | Nature Communications

Fig. 4: The attachment of PsaSOD1/2 subunits to the stromal side of the PSI core.

From: The cryo-EM structure of Photosystem I from Chromera velia with a bound superoxide dismutase heterodimer

Fig. 4

a The PsaSOD1/2 heterodimer stably binds to the PsaCDE triad of PSI via an N-terminal extension (linker, highlighted in orange). b The linker of PsaSOD1 is buried in a groove that is formed by stromal parts of PsaD, PsaL, PsaI, PsaB, and FCPb, engaging in hydrophobic, charged, and polar interactions with a total buried surface area of 4675 Å2. c PsaSOD2 is the catalytically active site with Fe bound to three histidines and one aspartate, while PsaSOD1 has lost its Fe cofactor due to a mutation of one histidine to threonine, resulting in unfavorable coordination for Fe. d PsaSOD1 has two N-linked glycosylation sites at the SOD domain and in the N-terminal linker region; both glycosylation sites were confirmed by MS analysis (Supplementary Fig. 10). The conserved NXS/T motif, with the sugar chains, are shown with density. Color coding follows the same scheme as in Fig. 1.

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