Structural Insights into Antibodies Specific for Bacterial Lipopolysaccharide Core and Development of Protein Electron Crystallography Techniques




Gomery, Kathryn

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Lipopolysaccharide (LPS), one of the main components of Gram-negative bacterial cell walls, is a potent endotoxin. Structures of the unique protective monoclonal antibody (mAb) WN1 222-5 in complex with Escherichia coli R2 and R4 LPS core regions show that recognition occurs in a manner similar to the innate immune receptor Toll-like receptor 4 (TLR4). Inner core LPS is shown to exist in a conserved epitope with multiple intramolecular interactions that allows the conserved epitope to bind strongly to mAb WN1 222-5. The structure of mAb FDP4, directed against truncated E. coli J-5 LPS, shows a deep pocket combining site specific for a terminal epitope that does not allow room for wild type (wt) LPS. Research into these anti-LPS binding mAbs opens up new avenues for potential septic shock therapy. The explosion of new techniques and bright x-ray sources in the 80’s and 90’s led to rapid advancement of protein x-ray crystallography; however, structure determination on some of the most important problems is now stalled due to the general inability to grow crystals of sufficient size. Recent advances in electron microscopy (EM) technology has led to improved beam characteristics, which has allowed the initiation of research to develop EM as a viable alternative to x-ray crystallography. In this research, method development using standard equipment to explore potential avenues for analysing three-dimensional protein crystals via EM has been explored.



Antibodies, Lipopolysaccharide, Structural Biology, Electron Crystallography, Carbohydrates, Septic Shock