Figure 1.

The β-OMP biogenesis pathway in Gram-negative bacteria. (1) Nascent β-OMPs are synthesized in the cytoplasm with an N-terminal signal sequence that routes them through the Sec translocon into the periplasm. (2) Periplasmic chaperones (e.g., SurA, Skp) stabilize the nascent β-OMPs to prevent misfolding or aggregation. Misfolded proteins that cannot be rescued are degraded by DegP to prevent toxicity. (3) The periplasmic chaperones then deliver the nascent β-OMPs to BAM, with SurA being the primary chaperone pathway. (4) BAM then folds and inserts the β-OMPs into the membrane using a mechanism which utilizes a hybrid-barrel intermediate with the barrel domain of BamA. This figure was prepared using BioRender.