Figure 4.

Variations of the Carboxysome Size and Carbon Fixation under Air/ML, CO₂, LL, and HL.

(A) Thin-section EM images showing individual carboxysomes in the Syn7942 wild-type cells under Air/ML, CO₂, LL, and HL treatments. Yellow arrows indicate the carboxysomes with spaces of low protein density under LL. More EM images are shown in Supplemental Figure 9. Scale bar = 1 μm.

(B) Changes in the carboxysome diameter under Air/ML, CO₂, LL and HL measured from EM (n = 33, 25, 27, and 51, respectively), with representative carboxysome images depicted above. Dashed lines indicate medians, and solid lines indicate means. Differences in the carboxysome diameter are significant between CO₂ and air (P = 1.92 × 10⁻¹⁴) and between LL and HL (P = 8.29 × 10⁻⁷), indicated as ***.

(C) Correlation between the carboxysome size and the Rubisco content per carboxysome under Air/ML, CO₂, LL, and HL.

(D) Correlation between the carboxysome size and CO₂ fixation per carboxysome. a.u., Arbitrary units.

(E) Correlation between the carboxysome size and CO₂ fixation per Rubisco of the carboxysomes. Carboxysome diameters and CO₂ fixation are presented as average ±sd, whereas the carboxysome total protein content and Rubisco content are shown as Peak value ± HWHM.