A high non-photochemical quenching(NPQ) appeared below the phase transition temperature when Microcystis aeruginosa PCC7806 cells were exposed to saturated light for a short time.This suggested that a component of NPQ...A high non-photochemical quenching(NPQ) appeared below the phase transition temperature when Microcystis aeruginosa PCC7806 cells were exposed to saturated light for a short time.This suggested that a component of NPQ,independent from state transition or photo-inhibition,had been generated in the PSII complex;this was a fast component responding to high intensity light.Glutaraldehyde(GA),commonly used to stabilize membrane protein conformations,resulted in more energy transfer to PSII reaction centers,affecting the energy absorption and dissipation process rather than the transfer process of phycobilisome(PBS).In comparison experiments with and without GA,the rapid light curves(RLCs) and fluorescence induction dynamics of the fast phase showed that excess excitation energy was dissipated by conformational change in the photosynthetic pigment proteins on the thylakoid membrane(PPPTM).Based on deconvolution of NPQ relaxation kinetics,we concluded that the fast quenching component(NPQ f) was closely related to PPPTM conformational change,as it accounted for as much as 39.42% of the total NPQ.We hypothesize therefore,that NPQ f induced by PPPTM conformation is an important adaptation mechanism for Microcystis blooms under high-intensity light during summer and autumn.展开更多
CYCLIC electron transport around photosystem I (PS I ) is considered physiologically important not only for its coupled formation of ATP, but also for its function on protection of the photosynthetic apparatus against...CYCLIC electron transport around photosystem I (PS I ) is considered physiologically important not only for its coupled formation of ATP, but also for its function on protection of the photosynthetic apparatus against photoinhibition. However, due to the difficulty of its measurement, we know little about its operation in vivo.展开更多
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...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.展开更多
基金supported by the National Basic Research Program of China(Grant No. 2008CB418002)the National Major Programs of Water Body Pollution Control and Remediation (Grant Nos. 2009ZX07104-005 and 2009ZX07106-001)
文摘A high non-photochemical quenching(NPQ) appeared below the phase transition temperature when Microcystis aeruginosa PCC7806 cells were exposed to saturated light for a short time.This suggested that a component of NPQ,independent from state transition or photo-inhibition,had been generated in the PSII complex;this was a fast component responding to high intensity light.Glutaraldehyde(GA),commonly used to stabilize membrane protein conformations,resulted in more energy transfer to PSII reaction centers,affecting the energy absorption and dissipation process rather than the transfer process of phycobilisome(PBS).In comparison experiments with and without GA,the rapid light curves(RLCs) and fluorescence induction dynamics of the fast phase showed that excess excitation energy was dissipated by conformational change in the photosynthetic pigment proteins on the thylakoid membrane(PPPTM).Based on deconvolution of NPQ relaxation kinetics,we concluded that the fast quenching component(NPQ f) was closely related to PPPTM conformational change,as it accounted for as much as 39.42% of the total NPQ.We hypothesize therefore,that NPQ f induced by PPPTM conformation is an important adaptation mechanism for Microcystis blooms under high-intensity light during summer and autumn.
文摘CYCLIC electron transport around photosystem I (PS I ) is considered physiologically important not only for its coupled formation of ATP, but also for its function on protection of the photosynthetic apparatus against photoinhibition. However, due to the difficulty of its measurement, we know little about its operation in vivo.
文摘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.
