Legionella pneumophilamacrophage infectivity potentiator protein appendage domains modulate protein dynamics and inhibitor binding

Abstract

AbstractMacrophage infectivity potentiator (MIP) proteins are widespread in human pathogens includingLegionella pneumophila, the causative agent of Legionnaires’ disease and protozoans such asTrypanosoma cruzi. All MIP proteins contain a FKBP (FK506 binding protein)-like prolyl-cis/trans- isomerase domain that hence presents an attractive drug target. Some MIPs such as theLegionella pneumophilaprotein (LpMIP) have additional appendage domains of mostly unknown function. In full- length, homodimericLpMIP, the N-terminal dimerization domain is linked to the FKBP-like domain via a long, free-standing stalk helix. Combining X-ray crystallography, NMR and EPR spectroscopy and SAXS, we elucidated the importance of the stalk helix for protein dynamics and inhibitor binding to the FKBP-like domain and bidirectional crosstalk between the different protein regions. The first comparison of a microbial MIP and a human FKBP in complex with the same synthetic inhibitor was made possible by high-resolution structures ofLpMIP with a [4.3.1]-aza-bicyclic sulfonamide and provides a basis for designing pathogen-selective inhibitors. Through stereospecific methylation, the affinity of inhibitors toL. pneumophilaandT. cruziMIP was greatly improved. The resulting X-ray inhibitor-complex structures ofLpMIP andTcMIP at 1.49 and 1.34 Å, respectively, provide a starting point for developing potent inhibitors against MIPs from multiple pathogenic microorganisms.