Watching the Native Supramolecular Architecture of Photosynthetic Membrane in Red Algae

Abstract

The architecture of the entire photosynthetic membrane network determines, at the supramolecular level, the physiological roles of the photosynthetic protein complexes involved. So far, a precise picture of the native configuration of red algal thylakoids is still lacking. In this work, we investigated the supramolecular architectures of phycobilisomes (PBsomes) and native thylakoid membranes from the unicellular red alga Porphyridium cruentum using atomic force microscopy (AFM) and transmission electron microscopy. The topography of single PBsomes was characterized by AFM imaging on both isolated and membranecombined PBsomes complexes. The native organization of thylakoid membranes presented variable arrangements of PBsomes on the membrane surface. It indicates that different light illuminations during growth allow diverse distribution of PBsomes upon the isolated photosynthetic membranes from P. cruentum, random arrangement or rather ordered arrays, to be observed. Furthermore, the distributions of PBsomes on the membrane surfaces are mostly crowded. This is the first investigation using AFM to visualize the native architecture of PBsomes and their crowding distribution on the thylakoid membrane from P. cruentum. Various distribution patterns of PBsomes under different light conditions indicate the photoadaptation of thylakoid membranes, probably promoting the energy-harvesting efficiency. These results provide important clues on the supramolecular architecture of red algal PBsomes and the diverse organizations of thylakoid membranes in vivo.

FRAP Analysis on Red Alga Reveals the Fluorescence Recovery Is Ascribed to Intrinsic Photoprocesses of Phycobilisomes than Large-Scale Diffusion

“…However, recent investigations have shown that the thylakoid membrane in the unicellular red alga P. cruentum exhibits dense crowding of PBsome complexes [27], [28]. In addition to determining the arrangements of PBsomes on the thylakoid membrane, the supramolecular crowding has also profound implications for the dynamic behavior of PBsomes in P. cruentum : the rapid and long-range movement of PBsomes may be inhibited by the dense packing of membrane surface, and the limited free vertical spacing between opposite thylakoid layers, as well as remarkable steric hindrance, taking into account the large size of individual PBsomes.…”

Direct characterization of the native structure and mechanics of cyanobacterial carboxysomes

“…The structures of isolated β-carboxysomes were characterized using negative staining TEM as described previously. 65 , 66 Samples were stained with 3% uranyl acetate. Images were recorded using a FEI Tecnai G2 Spirit BioTWIN FEI transmission electron microscope.…”

Unfolding pathway and intermolecular interactions of the cytochrome subunit in the bacterial photosynthetic reaction center

“…The resulting photosynthetic membranes were then immobilized on freshly cleaved mica substrate for AFM imaging. AFM has demonstrated its extraordinary power in high-resolution imaging of native photosynthetic membranes [ 17 , [22] , [23] , [24] , [25] ] and force measurements to delineate the mechanical unfolding of photosynthetic antenna membrane complexes [ 26 ]. AFM screening showed that the isolated photosynthetic membranes appear as two-dimensional patches with the sizes larger than 150 nm ( Fig.…”