Fig. 6. A schematic model for NDH-1-mediated PSI CET in response to different levels of light exposure.

The color scheme is as follows: NdhV, deep blue; NdhS, yellow; NdhO, marine; the rest of NDH-1L and NDH-1MS, gray; Fd, teal; and PSI, green. The electron transfer pathway [2Fe-2S]-N6a-N6b-N2-PQ and the reduction of PQ to PQH₂ are denoted by sky-blue and orange arrows, respectively. The high-light intensity increases the level of photoreduced Fd from PSI (orange arrow between PSI to Fd) and the level of Fd bound to the NDH-1 complex (black arrow between Fd and NDH-1L or NDH-1MS). Positive regulation of NDH-CET by NdhV is indicated by a green arrow.