Efficient reconstitution of beta-barrel proteins for single-molecule experiments

The outer membrane of Gram-negative bacteria is populated with vital beta-barrel transmembrane proteins, so-called outer-membrane proteins (OMPs). These proteins fold and insert into the outer membrane from the periplasm in absence of any known energy source. Unlike the widely examined process of alpha-helical transmembrane protein folding, the complex steps involved in OMP biogenesis remain obscure. However, in recent years, the development of single-molecule techniques (such as force spectroscopy and single-molecule FRET) has allowed researchers to markedly advance the observation of OMP folding and insertion.