Speaker: Dr. Ines Pereira (ITQB, Portugal)
A key reaction in microbial sulfur metabolism is the reduction of sulfite by the dissimilatory sulfite reductase, DsrAB. This enzyme is present in sulfate, thiosulfate and sulfite reducing organisms, and also in sulfur-oxidizers where it is thought to operate in reverse. The mechanism of sulfite reduction by DsrAB has long been the subject of controversy due to the in vitro formation of thiosulfate and trithionate, in contrast to the closely-related assimilatory enzyme that produces only sulfide.
Recent studies have identified the small protein DsrC and the DsrMKJOP membrane complex as physiological partners of DsrAB . In particular, a crystal structure of DsrAB in complex with DsrC suggested the direct involvement of the latter protein in sulfite reduction and led to the proposal of a new mechanism for this reaction .
I will present recent results on the role played by DsrC in sulfite reduction, which provide new insight into the reaction mechanism and the involvement of the DsrMKJOP complex in the whole process.
1- Pereira IAC, Ramos AR, Grein F, Marques MC, da Silva SM & Venceslau SS (2011) Front. Microbiol. 2:69
2- Oliveira TF, Vonrheim, Matias PM, Venceslau SS, Pereira IAC, Archer M (2008) J. Biol. Chem. 283: 34141