In this issue of Cell, show that there is a disulfide relay system in the intermembrane space (IMS) of mitochondria that is comprised of the proteins Mia40 and Erv1. This disulfide relay system promotes the import and oxidative folding of proteins. Oxidized Mia40 traps newly imported proteins through mixed disulfide bridges. Subsequent isomerization of these disulfide bridges allows the importe...

Six rhodopsin mutants containing disulfide cross-links between different cytoplasmic regions were prepared: disulfide bond 1, between Cys65 (interhelical loop I-II) and Cys316 (end of helix VII); disulfide bond 2, between Cys246 (end of helix VI) and Cys312 (end of helix VII); disulfide bond 3, between Cys139 (end of helix III) and Cys248 (end of helix VI); disulfide bond 4, between Cys139 (end...

Thioredoxin contains a single disulfide bond that can be reduced without perturbing significantly the structure of the enzyme. Upon reduction of the disulfide, protein stability decreases. We have experimentally tested the expected linkage relationship between disulfide bond formation and protein stability for thioredoxin. In order to do this, it is necessary to measure the equilibrium constant...

The prediction of the location of disulfide bridges helps solving the protein folding problem. Most of previous works on disulfide connectivity pattern prediction use the prior knowledge of the bonding state of cysteines. In this study an effective method is proposed to predict disulfide connectivity pattern without the prior knowledge of cysteins’bonding state. To the best of our knowledge, wi...

The copper chaperone for superoxide dismutase 1 (Ccs1) provides an important cellular function against oxidative stress. Ccs1 is present in the cytosol and in the intermembrane space (IMS) of mitochondria. Its import into the IMS depends on the Mia40/Erv1 disulfide relay system, although Ccs1 is, in contrast to typical substrates, a multidomain protein and lacks twin Cx(n)C motifs. We report on...

The formation of disulfides in proteins entering the secretory pathway is catalysed by the protein disulfide isomerase (PDI) family of enzymes. These enzymes catalyse the introduction, reduction and isomerization of disulfides. To function continuously they require an oxidase to reform the disulfide at their active site. To determine how each family member can be recycled to catalyse disulfide ...

In Escherichia coli, the periplasmic disulfide oxidoreductase DsbA is thought to be a powerful but nonspecific oxidant, joining cysteines together the moment they enter the periplasm. DsbC, the primary disulfide isomerase, likely resolves incorrect disulfides. Given the reliance of protein function on correct disulfide bonds, it is surprising that no phenotype has been established for null muta...

Intramolecular disulfide bonds are understood to play a role in regulating protein stability and activity. Because disulfide bonds covalently link different components of a protein, they influence protein structure. However, the effects of disulfide bonds on fast (subpicosecond to approximately 100 ps) protein equilibrium structural fluctuations have not been characterized experimentally. Here,...

The combination of SDS-PAGE and MS is one of the most powerful and perhaps most frequently used gel-based proteomics approaches in protein identification. However, one drawback of this method is that separation takes place under denaturing and reducing (R) conditions and as a consequence, all proteins with identical apparent molecular mass (Mr) will run together. Therefore, low-abundant protein...

Pentamer formation by Vp1, the major capsid protein of simian virus 40, requires an interdigitation of structural elements from the Vp1 monomers [Liddington, R. C., Yan, Y., Moulai, J., Sahli, R., Benjamin, T. L. & Harrison, S. C. (1991) Nature (London) 354, 278-284]. Our analyses reveal that disulfide-linked Vp1 homooligomers are present in the simian virus 40-infected cytoplasm and that they ...