title: The interaction of N-glycans in Fcγ receptor I α-chain with Escherichia coli K1 outer membrane protein A for entry into macrophages: experimental and computational analysis.
abstract: Neonatal meningitis, caused by Escherichia coli K1, is a serious central nervous system disease. We have established that macrophages serve as permissive niches for E. coli K1 to multiply in the host and for attaining a threshold level of bacterial load, which is a prerequisite for the onset of the disease. Here, we demonstrate experimentally that three N-glycans in FcγRIa interact with OmpA of E. coli K1 for binding to and entering the macrophages. Adoptive transfer of FcγRIa(-/-) bone marrow-derived macrophages transfected with FcγRIa into FcγRIa(-/-) newborn mice renders them susceptible to E. coli K1-induced meningitis. In contrast, mice that received bone marrow-derived macrophages transfected with FcγRIa in which N-glycosylation sites 1, 4, and 5 are mutated to alanines exhibit resistance to E. coli K1 infection. Our molecular dynamics and simulation studies predict that N-glycan 5 exhibits strong binding at the barrel site of OmpA formed by loops 3 and 4, whereas N-glycans 1 and 4 interact with loops 1, 3, and 4 of OmpA at tip regions. Molecular modeling data also suggest no role for the IgG binding site in the invasion process. In agreement, experimental mutations in IgG binding site had no effect on the E. coli K1 entry into macrophages in vitro or on the onset of meningitis in newborn mice. Together, this integration of experimental and computational studies reveals how the N-glycans in FcγRIa interact with the OmpA of E. coli K1 for inducing the disease pathogenesis.
authors.affiliation: From the Division of Infectious Diseases and the Department of Pediatrics and.
authors.forename: Subramanian
authors.initials: S
authors.lastname: Krishnan
authors.affiliation: the Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, and.
authors.forename: Fan
authors.initials: F
authors.lastname: Liu
authors.affiliation: the Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, and the Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048.
authors.forename: Ravinder
authors.initials: R
authors.lastname: Abrol
authors.affiliation: From the Division of Infectious Diseases and the Department of Pediatrics and.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Hodges
authors.affiliation: the Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, and wag@wag.caltech.edu.
authors.forename: William A
authors.initials: WA
authors.lastname: Goddard
authors.affiliation: From the Division of Infectious Diseases and the Department of Pediatrics and the Department of Surgery, Children's Hospital Los Angeles, University of Southern California, Los Angeles, California 90027, pnemani@chla.usc.edu.
authors.forename: Nemani V
authors.initials: NV
authors.lastname: Prasadarao
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000831:Animals, Newborn; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002460:Cell Line; D004926:Escherichia coli / Q000378:metabolism*; D006031:Glycosylation; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology*; D020814:Meningitis, Escherichia coli / Q000235:genetics / Q000382:microbiology*; D051379:Mice; D008958:Models, Molecular; D009154:Mutation; D011134:Polysaccharides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017452:Receptors, IgG / Q000737:chemistry*; D014162:Transfection
chemical_list: D001425:Bacterial Outer Membrane Proteins; C485701:Fcgr1 protein, mouse; D011134:Polysaccharides; D017452:Receptors, IgG; C078167:OMPA outer membrane proteins
keywords: Computer Modeling; Escherichia coli (E. coli); Fc-gamma Receptor; Infectious Disease; Macrophage; Meningitis; N-Glycans; Outer Membrane Protein A