Extensive remodeling of a cyanobacterial photosynthetic apparatus in far-red light

TLDR

Cyanobacteria are unique among bacteria in performing oxygenic photosynthesis, often together with nitrogen fixation, and are major primary producers in many ecosystems. Far‑red light induces replacement of core subunits of photosystems I and II and phycobilisomes with proteins encoded by a 21‑gene cluster that includes a knotless red/far‑red phytochrome and two response regulators. The far‑red acclimation of Leptolyngbya sp. JSC‑1 triggers synthesis of chlorophylls d and f, alters expression of ~2,900 genes, and boosts light harvesting in the 700–750 nm range while increasing oxygen evolution.

Abstract

Cyanobacteria are unique among bacteria in performing oxygenic photosynthesis, often together with nitrogen fixation and, thus, are major primary producers in many ecosystems. The cyanobacterium, Leptolyngbya sp. strain JSC-1, exhibits an extensive photoacclimative response to growth in far-red light that includes the synthesis of chlorophylls d and f. During far-red acclimation, transcript levels increase more than twofold for ~900 genes and decrease by more than half for ~2000 genes. Core subunits of photosystem I, photosystem II, and phycobilisomes are replaced by proteins encoded in a 21-gene cluster that includes a knotless red/far-red phytochrome and two response regulators. This acclimative response enhances light harvesting for wavelengths complementary to the growth light (λ = 700 to 750 nanometers) and enhances oxygen evolution in far-red light.