Probing outer membrane biogenesis

The outer membrane (OM) of Gram-negative bacteria is a complex organelle composed of phospholipids, glycolipids and proteins that acts as a barrier to harmful compounds such as antibiotics. Studies of OM biosynthesis using OM-deficient mutants have provided unclear results, as OM-deficient mutants generally have nonspecific permeability defects. In the 22 April issue of Cell, Ruiz et al. describe 'chemical conditionality' screens to identify mutant E. coli strains that confer enhanced resistance to antibiotics. A paper in the same issue by Wu et al. describes the identification of a multiprotein complex that is required for biosynthesis of OM -barrel proteins in E. coli.