A team of chaperones play to win in the bacterial periplasm.

Outer membrane protein (OMP) biogenesis is essential to bacterial cell survival and virulence in Gram-negative bacteria. A robust and functionally redundant protein quality control network in the periplasm prevents the formation of toxic aggregates and facilitates proper OMP assembly at the OM. Recent work demonstrates that, despite having overlapping functions, chaperones survival factor A (SurA), seventeen-kilodalton protein (Skp), and FK506 binding protein A (FkpA) and protease chaperone DegP also contribute uniquely to OMP biogenesis. The complex 'teamwork' apparent in OMP biogenesis emerges from individual interactions between periplasmic players and unfolded OMP clients. The survival and virulence of Gram-negative bacteria require proper biogenesis and maintenance of the outer membrane (OM), which is densely packed with β-barrel OM proteins (OMPs). Before reaching the OM, precursor unfolded OMPs (uOMPs) must cross the whole cell envelope. A network of periplasmic chaperones and proteases maintains unfolded but folding-competent conformations of these membrane proteins in the aqueous periplasm while simultaneously preventing off-pathway aggregation. These periplasmic proteins utilize different strategies, including conformational heterogeneity, oligomerization, multivalency, and kinetic partitioning, to perform and regulate their functions. Redundant and unique characteristics of the individual periplasmic players synergize to create a protein quality control team capable responding to changing environmental stresses. [ABSTRACT FROM AUTHOR]