Gram-negative bacteria are surrounded by a secondary membrane of which the outer leaflet is composed of the glycolipid lipopolysaccharide (LPS), which guards against hydrophobic toxins, including many antibiotics. Therefore, LPS synthesis in bacteria ...
Gram-negative bacteria are surrounded by a secondary membrane of which the outer leaflet is composed of the glycolipid lipopolysaccharide (LPS), which guards against hydrophobic toxins, including many antibiotics. Therefore, LPS synthesis in bacteria is an attractive target for antibiotic development. LpxH is a pyrophosphatase involved in LPS synthesis, and previous structures revealed that LpxH has a helical cap that binds its lipid substrates. Here, crystallography and hydrogen-deuterium exchange MS provided evidence for a highly flexible substrate-binding cap in LpxH. Furthermore, molecular dynamics simulations disclosed how the helices of the cap may open to allow substrate entry. The predicted opening mechanism was supported by activity assays of LpxH variants. Finally, we confirmed biochemically that LpxH is inhibited by a previously identified antibacterial compound, determined the potency of this inhibitor, and modeled its binding mode in the LpxH active site. In summary, our work provides evidence that the substrate-binding cap of LpxH is highly dynamic, thus allowing for facile substrate binding and product release between the capping helices. Our results also pave the way for the rational design of more potent LpxH inhibitors.
Organizational Affiliation:
From the Department of Biochemistry, Molecular Biology & Biophysics and.,the Center for Drug Design, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455.,the Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, California 92093, and.,the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Boulder, Colorado 80303.,From the Department of Biochemistry, Molecular Biology & Biophysics and aihar001@umn.edu.,From the Department of Biochemistry, Molecular Biology & Biophysics and bohlx031@umn.edu.,the National Biomedical Computation Resource and.
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