The soluble, periplasmic domain of OmpA folds as an independent unit and displays chaperone activity by reducing the self-association propensity of the unfolded OmpA transmembrane β-barrel.

ABSTRACT: OmpA is one of only a few transmembrane proteins whose folding and stability have been investigated in detail. However, only half of the OmpA mass encodes its transmembrane β-barrel; the remaining sequence is a soluble domain that is localized to the periplasmic side of the outer membrane. To understand how the OmpA periplasmic domain contributes to the stability and folding of the full-length OmpA protein, we cloned, expressed, purified and studied the OmpA periplasmic domain independently of the OmpA transmembrane β-barrel region. Our experiments showed that the OmpA periplasmic domain exists as an independent folding unit with a free energy of folding equal to -6.2 (±0.1) kcal mol(-1) at 25°C. Using circular dichroism, we determined that the OmpA periplasmic domain adopts a mixed alpha/

SUBMITTER: Danoff EJ 

PROVIDER: S-EPMC3169180 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature