When purified without the use of ionic detergents, both OmpA and OprF proteins contained nearly 20% alpha-helical structures, which disappeared completely upon the addition of sodium dodecyl sulfate. This result suggests that the proteins fold in a similar manner, with an N-terminal, membrane-spanning beta-barrel domain and a C-terminal, globular, periplasmic domain.

In the postgenomic era, a major challenge remains, elucidating the thermodynamic forces governing receptor-ligand specificity and promiscuity. We report a straightforward approach for mapping side-chain contributions to binding for the multipartner interactions characteristic of the human proteome. Double barrel shotgun scanning dissects binding to two or more targets through combinatorial muta...

Autotransporters (ATs) are the largest group of proteins secreted by Gram-negative bacteria and include many virulence factors from human pathogens. ATs are synthesized as large precursors with a C-terminal domain that is inserted in the outer membrane (OM) and is essential for the translocation of an N-terminal passenger domain to the extracellular milieu. Several mechanisms have been proposed...

Biogenesis of mitochondrial β-barrel proteins requires two preprotein translocases, the general translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). TOM and SAM form a supercomplex that promotes transfer of β-barrel precursors. The SAM core complex contains the channel protein Sam50, which cooperates with Sam35 in precursor recognition, and the peripheral membra...

The outer membrane of Gram-negative bacteria is replete with a host of β-barrel outer membrane proteins (OMPs). Despite serving a variety of essential functions, including immune response evasion, the exact mechanism of OMP folding and membrane insertion remains largely unclear. The β-barrel assembly machinery complex is required for OMP biogenesis. Crystal structures and molecular dynamics (MD...

Most proteins adopt an approximate structural symmetry. However, they have no symmetry detectable in their sequences and it is unclear for most of these proteins whether their structural symmetry originates from duplication. As one of the six popular folds (super-folds) possessing an approximate structural symmetry, the triosephosphate isomerase barrel (TIM-barrel) domain has been widely studie...

BamA is the main component of the β-barrel assembly machinery (BAM) that folds and inserts outer membrane proteins in Gram-negative bacteria. Crystal structures have suggested that this process involves conformational changes in the transmembrane β-barrel of BamA that allow for lateral opening, as well as large overall rearrangements of its periplasmic POTRA domains. Here, we identify local dyn...

Protein S is a calcium-binding protein comprising two Greek key beta-barrel domains. We have used NMR and optical spectroscopies to show that, in the absence of calcium, the N-terminal domain of protein S forms two equilibrium folding intermediates that are in slow exchange. The intermediates arise from differential calcium-dependent folding of subdomains which are not contiguous along the poly...

The folding mechanism of outer membrane proteins (OMPs) of Gram-negative bacteria into lipid bilayers has been studied using OmpA of E. coli and FomA of F. nucleatum as examples. Both, OmpA and FomA are soluble in unfolded form in urea and insert and fold into phospholipid bilayers upon strong dilution of the denaturant urea. OmpA is a structural protein and forms a small ion channel, composed ...