Figure 8.

The Degradation of Cytochrome b₆f Complex Is Accelerated in the Presence of NO.

(A) and (B) Strain WT-S24 was transferred to nitrogen-free medium and supplemented 1 h later with water (no add), 1 mM SNP, 0.1 mM cPTIO, or 1 mM SNP plus 0.1 mM cPTIO. Samples, harvested at 10, 24, and 34 h, were assessed for changes in photosynthetic activity (Φ_PSII; [A]) and for the accumulation of cytochrome b₆f subunits, CCB3, and Rubisco (B). In (A), the maximum quantum yield of PSII F_v/F_m shows there is no NO-mediated inactivation of the PSII.

(C) Quantification of cytochrome f accumulation in the typical experiment shown in (B).

(D) Strain WT-S24 was transferred to nitrogen-free medium and supplemented at the time points indicated by arrows with water (no add), 0.1 mM GSNO, 0.1 mM cPTIO, or 0.1 mM GSNO plus 0.1 mM cPTIO. Aliquots of the cultures were harvested every hour for the measure of the photosynthetic activity (Φ_PSII).