Effect of cobalt ions on the soluble proteome of a Rhodobacter sphaeroides carotenoidless mutant

Rhodobacter sphaeroides strain R26.1 showed tolerance to Co2+ ions, up to 10 mM concentration. Interestingly the bacteriochlorophyll biosynthesis was found to decrease upon addition of such metal in the growth medium. Analysis of R. sphaeroides proteome from cells grown in control and in Co2+ enriched media was performed by two dimensional electrophoresis (2DE) followed by mass spectrometry. Proteome and functional analyses of differentially expressed proteins in cobalt response clearly highlighted the involvement of several metabolic pathways, and in particular of some enzymes involved in tetrapyrrole biosynthesis pathway.