TY - JOUR
T1 - Overexpression of the rhodanese PspE, a single cysteine-containing protein, restores disulphide bond formation to an Escherichia coli strain lacking DsbA
AU - Chng, Shu Sin
AU - Dutton, Rachel J.
AU - Denoncin, Katleen
AU - Vertommen, Didier
AU - Collet, Jean Francois
AU - Kadokura, Hiroshi
AU - Beckwith, Jonathan
PY - 2012/9
Y1 - 2012/9
N2 - Escherichia coli uses the DsbA/DsbB system for introducing disulphide bonds into proteins in the cell envelope. Deleting either dsbA or dsbB or both reduces disulphide bond formation but does not entirely eliminate it. Whether such background disulphide bond forming activity is enzyme-catalysed is not known. To identify possible cellular factors that might contribute to the background activity, we studied the effects of overexpressing endogenous proteins on disulphide bond formation in the periplasm. We find that overexpressing PspE, a periplasmic rhodanese, partially restores substantial disulphide bond formation to a dsbA strain. This activity depends on DsbC, the bacterial disulphide bond isomerase, but not on DsbB. We show that overexpressed PspE is oxidized to the sulphenic acid form and reacts with substrate proteins to form mixed disulphide adducts. DsbC either prevents the formation of these mixed disulphides or resolves these adducts subsequently. In the process, DsbC itself gets oxidized and proceeds to catalyse disulphide bond formation. Although this PspE/DsbC system is not responsible for the background disulphide bond forming activity, we suggest that it might be utilized in other organisms lacking the DsbA/DsbB system.
AB - Escherichia coli uses the DsbA/DsbB system for introducing disulphide bonds into proteins in the cell envelope. Deleting either dsbA or dsbB or both reduces disulphide bond formation but does not entirely eliminate it. Whether such background disulphide bond forming activity is enzyme-catalysed is not known. To identify possible cellular factors that might contribute to the background activity, we studied the effects of overexpressing endogenous proteins on disulphide bond formation in the periplasm. We find that overexpressing PspE, a periplasmic rhodanese, partially restores substantial disulphide bond formation to a dsbA strain. This activity depends on DsbC, the bacterial disulphide bond isomerase, but not on DsbB. We show that overexpressed PspE is oxidized to the sulphenic acid form and reacts with substrate proteins to form mixed disulphide adducts. DsbC either prevents the formation of these mixed disulphides or resolves these adducts subsequently. In the process, DsbC itself gets oxidized and proceeds to catalyse disulphide bond formation. Although this PspE/DsbC system is not responsible for the background disulphide bond forming activity, we suggest that it might be utilized in other organisms lacking the DsbA/DsbB system.
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U2 - 10.1111/j.1365-2958.2012.08157.x
DO - 10.1111/j.1365-2958.2012.08157.x
M3 - Article
C2 - 22809289
AN - SCOPUS:84865559539
VL - 85
SP - 996
EP - 1006
JO - Molecular Microbiology
JF - Molecular Microbiology
SN - 0950-382X
IS - 5
ER -