Investigation of factors involved in assembly of the mycolata envelope

Harvard Medical School, Boston MA

Investigators

Abstract

PROJECT SUMMARY Bacteria surround themselves with complex cell structures called cell envelopes to preserve cell integrity, defend against external threats, and to facilitate uptake and metabolism of nutrients essential for bacterial growth and survival within the cell’s environment. Bacteria of the order Corynebacteriales possess unique multilayered envelopes consisting of an arabinogalactan-peptidoglycan cell wall and an outer membrane called the mycomembrane (MM) composed of lipids called mycolic acids. Mycolic acids are a hallmark feature of these bacteria and greatly contribute to the pathogenicity of some corynebacterial, nocardial, and mycobacterial species, such as Corynebacterium diptheriae and Mycobacterium tuberculosis. Much remains to be discovered about the mechanisms involved in the biogenesis and modification of this unique envelope architecture. In particular, it is unclear how these organisms coordinate the synthesis of the different envelope layers during bacterial growth. My preliminary data suggest that TmaT, an enzyme involved in mycolic acid transport to the mycomembrane is regulated by AftD, an arabinosyltransferase that aids in construction of the arabinogalactan layer. These data suggest coordinated regulation of the synthesis of the different cell wall layers. Overall, this work will reveal fundamental mechanisms important for regulation and synthesis of an essential component and attractive drug target of mycobacterial species. The Specific Aims of this F32 application are: Aim 1: Elucidate the role of the TmaT-AftD complex in assembly of the mycolata envelope Aim 2: Characterize new factors required for mycomembrane biogenesis