FIG. 1.

Electron transport chains involved in energy generation under semiaerobic conditions in R. sphaeroides 7 min (A) and 30 min (B) after the addition of 1 mM H₂O₂. Arrows indicate electron flow. Thicker lines correspond to the anticipated higher electron flow. Known sites for generation of proton-motive force are shown. Expression of genes under no-stress conditions is set as background for comparisons (uncolored). Lack of color corresponds to expression that is not significantly changed from expression under no-stress conditions. Blue color corresponds to decreased expression (light blue, 0.33-0.5; bright blue, <0.33), and pink corresponds to increased expression (light pink, 2-3; pink, >3) of the corresponding genes. Proteins whose genes are expressed below reliable detection are not shown. DH, dehydrogenase; Q, quinone/quinol pool; LH, ligh-harvesting complex; RC, reaction center complex; cyt., cytochrome. The RC, LHI, and LHII complexes comprise the R. sphaeroides PS.