Abstract

Diderm bacteria, such as Gram-negative bacteria and mycobacteria, contain two lipid bilayers in their cellular envelopes – an inner membrane (IM) comprising mostly of phospholipids (PLs), and an outer membrane (OM) that additionally contains unique glycolipids (lipopolysaccharides (LPS) in Gram-negative bacteria and mycolic acids in mycobacteria). The OM is essential for growth in these organisms. Furthermore, the OM serves as an effective permeability barrier that in part allows Gram-negative bacteria and mycobacteria to survive in harsh environments, and renders them intrinsically resistant to many antibiotics. Despite the importance of the OMs in these bacteria, the processes that assemble these bilayers, in particular lipid transport, are not well understood. In this seminar, I will describe our work in understanding and characterizing lipid trafficking pathways in Escherichia coli and Mycobacterium smegmatis, and discuss how these systems function in maintaining lipid homeostasis in the OMs of these organisms.