Insights into the stress response and sulfur metabolism revealed by proteome analysis of a Chlorobium tepidum mutant lacking the Rubisco-like protein
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- Hanson, T.E. & Tabita, F.R. Photosynthesis Research (2003) 78: 231. doi:10.1023/B:PRES.0000006829.41444.3d
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A significant fraction of the proteome of Chlorobium tepidum is altered in a mutant strain of the green sulfur bacterium C. tepidum (Ω::RLP) lacking the Rubisco-like protein (RLP). Additionally, a number of stress proteins display altered abundance or migration in strain Ω::RLP, including a thioredoxin, a putative Hsp20 family chaperonin, and GroEL. Changes in protein abundance are closely correlated to mRNA abundance in the case of two other stress proteins, a thiol-specific antioxidant protein homolog (Tsa/AhpC) and an iron only superoxide dismutase (Fe-SOD). Strain Ω::RLP is more resistant to hydrogen peroxide exposure than strain WT2321, providing evidence that the stress proteins are functional. Strain Ω::RLP is also defective in thiosulfate oxidation, but is able to oxidize sulfide as well as the wild-type strain. Based on studies with periplasm-enriched extracts of strain Ω::RLP, the loss of thiosulfate oxidation capability correlates with undetectable levels of the SoxY protein, a component of the predicted thiosulfate oxidation complex. These results provide further indications that sulfur oxidation capacity and the response to stress are linked in C. tepidum, with the RLP playing a major role.