Figure 1. Fractionation of the thylakoid protein complexes by sucrose gradient ultracentrifugation.

Wild type (Wt) and isiA^- cells in mid-logarithmic growth (OD₇₃₀ ∼0.6–0.8) were collected, washed and resuspended to an OD₇₃₀ of 0.2 in either regular BG-11 (Fe+, control), or iron-free BG-11medium (iron depletion). Cells were further grown for 3 d (short-term iron depletion, FeS) or 10 d (long-term or extensive iron depletion, FeL). Thylakoid membranes were isolated and solubilized with mild detergent (dodecyl maltoside, with a 15∶1 detergent to Chl ratio). The thylakoid protein complexes were then separated by step sucrose gradient ultracentrifugation at 160,000×g for 16 h at 4°C.