Research Article

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

Science  12 Sep 2014:
Vol. 345, Issue 6202, pp. 1312-1317
DOI: 10.1126/science.1256963

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Making sure leftover light gets in

Bacteria that harvest sunlight through photosynthesis are everywhere and are vital for absorbing carbon dioxide. Like plants in a jungle, these cells have to compete for access to light. Gan et al. found that one species of such cyanobacteria, Leptolyngbya, survives on the scraps of leftover light that other photosynthetic cells can't use. When the light is crowded out by competing organisms, Leptolyngbya changes the pathways in its cells that make the light-harvesting molecules and remodels them into structures that can use redder light at longer wavelengths that is unused by other cells.

Science, this issue p. 1312

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.

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