title: Structurally distinct requirements for binding of P-selectin glycoprotein ligand-1 and sialyl Lewis x to Anaplasma phagocytophilum and P-selectin.
abstract: Colonization of neutrophils by the bacterium Anaplasma phagocytophilum causes the disease human granulocytic ehrlichiosis. The pathogen also infects mice, its natural host. Like binding of P-selectin, binding of A. phagocytophilum to human neutrophils requires expression of P-selectin glycoprotein ligand-1 (PSGL-1) and alpha1-3-fucosyltransferases that construct the glycan determinant sialyl Lewis x (sLex). Binding of A. phagocytophilum to murine neutrophils, however, requires expression of alpha1-3-fucosyltransferases but not PSGL-1. To further characterize the molecular features that A. phagocytophilum recognizes, we measured bacterial binding to microspheres bearing specific glycoconjugates or to cells expressing human PSGL-1 and particular glycosyltransferases. Like P-selectin, A. phagocytophilum bound to purified human PSGL-1 and to glycopeptides modeled after the N terminus of human PSGL-1 that presented sLex on an O-glycan. Unlike P-selectin, A. phagocytophilum bound to glycopeptides that contained sLex but lacked tyrosine sulfation or a specific core-2 orientation of sLex on the O-glycan. A. phagocytophilum bound only to glycopeptides that contained a short amino acid sequence found in the N-terminal region of human but not murine PSGL-1. Unlike P-selectin, A. phagocytophilum bound to cells expressing PSGL-1 in cooperation with sLex on both N-and O-glycans. Moreover, bacteria bound to microspheres coupled independently with glycopeptide lacking sLex and with sLex lacking peptide. These results demonstrate that, unlike P-selectin, A. phagocytophilum binds cooperatively to a nonsulfated N-terminal peptide in human PSGL-1 and to sLex expressed on PSGL-1 or other glycoproteins. Distinct bacterial adhesins may mediate these cooperative interactions.
authors.affiliation: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Yago
authors.forename: Anne
authors.initials: A
authors.lastname: Leppänen
authors.forename: Jason A
authors.initials: JA
authors.lastname: Carlyon
authors.forename: Mustafa
authors.initials: M
authors.lastname: Akkoyunlu
authors.forename: Sougata
authors.initials: S
authors.lastname: Karmakar
authors.forename: Erol
authors.initials: E
authors.lastname: Fikrig
authors.forename: Richard D
authors.initials: RD
authors.lastname: Cummings
authors.forename: Rodger P
authors.initials: RP
authors.lastname: McEver
mesh_terms: D018829:Adhesins, Bacterial / Q000502:physiology; D000595:Amino Acid Sequence; D041081:Anaplasma phagocytophilum / Q000502:physiology*; D000818:Animals; D001422:Bacterial Adhesion; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D008863:Microspheres; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism*; D019007:P-Selectin / Q000378:metabolism*; D000080506:Sialyl Lewis X Antigen; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D019007:P-Selectin; C084882:P-selectin ligand protein; D000080506:Sialyl Lewis X Antigen; D014443:Tyrosine