Dissecting the Native Architecture and Dynamics of Cyanobacterial Photosynthetic Machinery

The structural dynamics and flexibility of cell membranes play fundamental roles in the functions of the cells, i.e., signaling, energy transduction, and physiological adaptation. The cyanobacterial thylakoid membrane represents a model membrane that can conduct both oxygenic photosynthesis and respiration simultaneously. In this study, we conducted direct visualization of the global organization and mobility of photosynthetic complexes in thylakoid membranes from a model cyanobacterium, Synechococcus elongatus PCC 7942, using high-resolution atomic force, confocal, and total internal reflection fluorescence microscopy. We visualized the native arrangement and dense packing of photosystem I （PSI）, photosystem II （PSlI）, and cytochrome （Cyt） befwithin thylakoid membranes at the molecular level. Furthermore, we func- tionally tagged PSI, PSlI, Cyt bef, and ATP synthase individually with fluorescent proteins, and revealed the heterogeneous distribution of these four photosynthetic complexes and determined their dynamic features within the crowding membrane environment using live-cell fluorescence imaging. We characterized red light-induced clustering localization and adjustable diffusion of photosynthetic complexes in thylakoid membranes, representative of the reorganization of photosynthetic apparatus in response to environmental changes. Understanding the organization and dynamics of photosynthetic membranes is essential for rational design and construction of artificial photosynthetic systems to undarpin bioenergy development. Knowledge of cyanobacterial thylakoid membranes could also be extended to other cell membranes, such as chloroplast and mitochondrial membranes.

Cryoelectron Microscopy Delineates the In Situ Structure of the Thylakoid Network

Photosynthesis is conceivably the most important biological process on Earth.By performing oxygenic photosynthesis,cyanobacteria,algae,and plants can use solar energy to power their metabolism and produce sugars and oxygen for life on the planet.These photosynthetic organisms have evolved a specialized intracellular membrane system,the thylakoid membrane,inside the cytoplasmic membrane to carry out the reactions of photosynthesis.

Photosynthesis in Phytoplankton: Insights from the Newly Discovered Biological Inorganic Carbon Pumps

Aquatic C02 assimilation results in storage in the oceans of〜24%of anthropogenic C02(〜40 petagrams per annum)released into the atmosphere and makes significant contributions to the global carbon cycle.These processes are executed predominantly in phytoplankton in the oceans(including cyanobacteria),which account for nearly 50%of global primary productivity(~50 gigatons per annum)(Field et al.,1998).