The oxidase DsbA folds a protein with a nonconsecutive disulfide.
One of the last unsolved problems of molecular biology is how the sequential amino acid information leads to a functional protein. Correct disulfide formation within a protein is hereby essential. We present periplasmic ribonuclease I (RNase I) from Escherichia coli as a new endogenous substrate for the study of oxidative protein folding. One of its four disulfides is between nonconsecutive cysteines. In general view, the folding of proteins with nonconsecutive disulfides requires the protein disulfide isomerase DsbC. In contrast, our study with RNase I shows that DsbA is a sufficient catalyst for correct disulfide formation in vivo and in vitro. DsbA is therefore more specific than generally assumed. Further, we show that the redox potential of the periplasm depends on the presence of glutathione and the Dsb proteins to maintain it at-165 mV. We determined the influence of this redox potential on the folding of RNase I. Under the more oxidizing conditions of dsb(-) strains, DsbC becomes necessary to correct non-native disulfides, but it cannot substitute for DsbA. Altogether, DsbA folds a protein with a nonconsecutive disulfide as long as no incorrect disulfides are formed.
Messens
Joris
J
Brussels Center for Redox Biology, Vlaams Instituut voor Biotechnologie, Vrije Universiteit Brussel, 1050 Brussel, Belgium. joris.messens@vub.ac.be
Collet
Jean-Francois
JF
Van Belle
Karolien
K
Brosens
Elke
E
Loris
Remy
R
Wyns
Lode
L
D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019897:Periplasm / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013059:Spectrum Analysis, Raman
D004220:Disulfides; D029968:Escherichia coli Proteins; D010088:Oxidoreductases; D019704:Protein Disulfide-Isomerases