Complex metabolic reactions in cells are distributed in organelle modular compartments. Reactions in organelles have been reproduced in vitro by reconstituting functional protein machinery into membrane systems. We tested harvest organelle design, if switchable, to provide both a sustainable energy source and means to induce bladder response.[1] ATP (ATP) sinter agent and two light converters (plant-derived photochemical system II and proteorhodopsin derived from bacteria) enable ATP synthesis. It depends on two optical conversion devices, and it enables optical control to dynamically control ATP synthesis. Red light and green light interfere with ATP synthesis. We encapsulated giant vesicle light synthesizing organelle to form one cell line and showed two ATP dependent responses, optical control of carbon fixation and actin polymerization, changing the morphology of the vesicle. We hope to develop a full biomimetic vesicular system with a regulatory network showing switchable photosynthetic organelle homeostasis.
We applied fluorescence spectromicroscopy to Arabidopsis mesophyll protoplasts in order to observe in vivo changes in fluorescence spectra of granal and stromal thylakoid regions during the state transition, a photoprotection method. [2] State transition in chloroplasts of plants, is an important regulatory mechanism to maintain the excitation balance between PSI and PSII in the thylakoid membrane. Light-harvesting complex II (LHCII) plays a key role as the regulated energy distributor between PSI and PSII. The microscopic fluorescence spectra obtained from a few sections with different depths were decomposed into PSI and PSII spectra and self-absorption effects were removed. We determined amplitude changes of PSI and PSII in fluorescence spectra solely due to state transition. Subdomain analysis of granal and stromal thylakoid regions clarified variant behaviors in the different regions.
[1] Lee et al. Nature Biotechnology 2018, 36, 530–535.
[2] Kim et al. Plant Cell & Physiology 2015, 56, 759-768