Fig. 2: Structural stability and photosynthetic capacity of isolated chloroplasts after CTP treatment.

a Schematic illustration of chloroplast’s structure and membrane. Chloroplast is constructed of a lipid bilayer membrane structure. The complexes of the translocon at the outer and inner envelope membrane of chloroplasts (TOC and TIC) mediate preprotein translocation across the chloroplast membrane. The sequence of the transmembrane domain (TMD) on TOC34, a 34-kDa integral membrane protein, is utilized as the source for chloroplast transit. Schematics is created in BioRender. Kim, H. (2024) BioRender.com/c78y188. b Chemical structure of CTP (MFAFQYLLVM). c Cumulated chlorophyll released from the destroyed chloroplasts for 14 days assessed by measuring absorbance 430 nm. Data were expressed as mean ± S.D. (n = 5 biological independent chloroplasts). Statistical significance for the comparison between chloroplast and chloroplast (+CTP) on each day was determined by unpaired, two-tailed t-test. P = 0.081 (day 0), P = 0.9240 (day 1), P = 0.0013 (day 3), P < 0.001 (day 5), P < 0.001 (day 7), P < 0.001 (day 10), P < 0.001 (day 14). d Comparison of oxygen levels of each chloroplast without (left) and with light exposure (right) at each time point under hypoxic conditions (1% pO₂). Data were expressed as mean ± S.D. (n = 3 biological independent chloroplasts). a–d: statical significant differences (P < 0.05) in one-way ANOVA with two-sided Duncan’s multiple range test with adjustments for multiple comparisons. w/o light: P = 1.0 (time: 0 h), P < 0.001 (time: 5 h), P < 0.001 (time: 10 h), P < 0.001 (time: 20 h). w/ light: P = 1.0 (time: 0 h), P < 0.001 (time: 5 h), P < 0.001 (time: 10 h), P < 0.001 (time: 20 h). e Effects of CTP on the Y(II) (left) and ETR (right). Magnified Y(II) kinetics from 0 to 200 PAR in the Y(II) graph. Data were expressed as mean ± S.D. (n = 3 biological independent chloroplasts). f Schematic illustration of PS II complex structure including OEC ((Mn)₄CaO₅) and 3 extrinsic proteins (PsbO, PsbP, and PsbQ). g SDS-PAGE profile of each PS II complex at 14 days after isolation. Each lane and sample treatments are described in Methods. Schematics is created in BioRender. Kim, H. (2024) BioRender.com/r70l387. h Comparison of band intensity of PsbO, PsbP, and PsbQ subunit in each PS II complex according to g. Filled bar: w/o light. Empty bar: w/ light. Each protein level is expressed as relative band intensity quantified by Image J. Data were expressed as mean ± S.D. (n = 3 biological independent PS II). i Comparison of oxygen levels of each PS II at each time point under hypoxic conditions. Data were expressed as mean ± S.D. (n = 3 biological independent PS II). a–d: statical significant differences (P < 0.05) in one-way ANOVA with two-sided Duncan’s multiple range test with adjustments for multiple comparisons. P = 1.0 (time: 0 h), P < 0.001 (time: 5 h), P < 0.001 (time: 10 h), P < 0.001 (time: 20 h). Statistical significance was determined by unpaired, two-tailed t-test in c and h. Source data are provided as a Source Data file.