The structural complexities of bacteria are becoming increasingly apparent. Gram-negative bacteria can be divided into several subcellular compartments. There are two aqueous compartments called the cytoplasm and the periplasm. The cytoplasm is enclosed by a phospholipid bilayer called the inner membrane (IM), which is itself surrounded by an asymmetric bilayer called the outer membrane (OM). The periplasm lies in the space between the IM and OM, and is home to the peptidoglycan cell wall (CW). Present throughout these compartments are proteins with diverse and important biological functions. Some of these proteins are membrane-embedded and allow the transfer of molecules between compartments. Others are soluble enzymes involved in metabolic reactions. Much work has been devoted toward understanding how each of these compartments is formed and maintained. This review focuses on a particular aspect of OM biogenesis, namely the assembly of integral outer membrane proteins (OMPs).
Making a beta-barrel: assembly of outer membrane proteins in Gram-negative bacteria. Curr Opin Microbiol. 03 Jan 2012
The outer membrane (OM) of Gram-negative bacteria is an essential organelle that serves as a selective permeability barrier by keeping toxic compounds out of the cell while allowing vital nutrients in. How the OM and its constituent lipid and protein components are assembled remains an area of active research. In this review, we describe our current understanding of how outer membrane proteins (OMPs) are delivered to and then assembled in the OM of the model Gram-negative organism Escherichia coli.