Tom Silhavy (Princeton University)
MolBio Seminar Series
Outer Membrane Biogenesis in Gram-Negative Bacteria
The outer membrane (OM) of Gram-negative bacteria functions as a protective barrier. It is unusual because theOM bilayer is asymmetric; the inner leaflet is composed of phospholipids, but the outer leaflet is made of lipopolysaccharide (LPS). Two kinds of proteins are found in theOM. Lipoproteins are inserted into the inner leaflet of theOM by posttranslationally attached lipid moieties. IntegralOM proteins are b-barrel proteins (OMPs). All of the components of theOM are synthesized inside the cell. They must be transported to, and assembled in theOM in the correct orientation to maintain barrier function, and all of this takes place outside the cytoplasm where there is no obvious energy source, such as ATP.
I will present a brief history of how the differences between Gram-positive and Gram-negative bacteria led to the discovery of the outer membrane. Then I will describe how we have used genetic analysis to identify and characterize the cellular components required for LPS and OMP biogenesis. After discussing what is known about these essential cellular processes, I will focus on the genetic approaches we are taking to probe the mechanism by which β-barrel assembly machine folds and inserts OMPs into the OM. My talk will focus on the remarkable insights provided by extragenic suppressors.
Free and open to the university community and the public