Lipopolysaccharide translocation across the Gram-negative inner membrane; development and exploitation of reagents and knowledge to guide early stage

点击翻译按钮获取中文摘要

Lipopolysaccharide (LPS) is a key component of the highly protective cell surface of Gram-negative pathogens. LPS is produced and displayed on the cell surface by the actions of a series of enzymes and a multi-protein transport system termed the Lpt complex. Bacterial survival is compromised if LPS production is curtailed and genetic studies reveal that many of the genes encoding proteins involved in LPS production/transport are essential. A high level of research activity has concentrated on characterisation of the cytosolic biosynthetic enzymes and the proteins that involve transfer from periplasm to cell surface, at the outer membrane. Our plan is to focus on the missing area, and to characterise those proteins involved in the transfer of components across the inner membrane. The three key proteins to be investigated are MsbA, LptF and LptG. MsbA is an ATPase driven flippase, which acts in conjunction with thepotentially heterodimeric LptF-LptG pair. It is an ATP-binding cassette transporter and the fold is known. However, for LptF-G there is are no known orthologous structures. The LptF and LptG proteins typically share about 20% sequence identity and secondary structure predictions suggest a common fold, predicted to comprise 6 transmembrane helices, is present. These two proteins may form homo or heterodimers, a feature we aim to clarify at the onset of the project.