title: Anaplasma marginale Outer Membrane Protein A Is an Adhesin That Recognizes Sialylated and Fucosylated Glycans and Functionally Depends on an Essential Binding Domain.
abstract: Anaplasma marginalecauses bovine anaplasmosis, a debilitating and potentially fatal tick-borne infection of cattle. BecauseA. marginaleis an obligate intracellular organism, its adhesins that mediate entry into host cells are essential for survival. Here, we demonstrate thatA. marginaleouter membrane protein A (AmOmpA; AM854) contributes to the invasion of mammalian and tick host cells. AmOmpA exhibits predicted structural homology to OmpA ofA. phagocytophilum(ApOmpA), an adhesin that uses key lysine and glycine residues to interact with α2,3-sialylated and α1,3-fucosylated glycan receptors, including 6-sulfo-sialyl Lewis x (6-sulfo-sLex). Antisera against AmOmpA or its predicted binding domain inhibitsA. marginaleinfection of host cells. Residues G55 and K58 are contributory, and K59 is essential for recombinant AmOmpA to bind to host cells. Enzymatic removal of α2,3-sialic acid and α1,3-fucose residues from host cell surfaces makes them less supportive of AmOmpA binding. AmOmpA is both an adhesin and an invasin, as coating inert beads with it confers adhesiveness and invasiveness. Recombinant forms of AmOmpA and ApOmpA competitively antagonizeA. marginaleinfection of host cells, but a monoclonal antibody against 6-sulfo-sLexfails to inhibit AmOmpA adhesion andA. marginaleinfection. Thus, the two OmpA proteins bind related but structurally distinct receptors. This study provides a detailed understanding of AmOmpA function, identifies its essential residues that can be targeted by blocking antibody to reduce infection, and determines that it binds to one or more α2,3-sialylated and α1,3-fucosylated glycan receptors that are unique from those targeted by ApOmpA.
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Kathryn S
authors.initials: KS
authors.lastname: Hebert
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: David
authors.initials: D
authors.lastname: Seidman
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Aminat T
authors.initials: AT
authors.lastname: Oki
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Jerilyn
authors.initials: J
authors.lastname: Izac
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Sarvani
authors.initials: S
authors.lastname: Emani
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Lee D
authors.initials: LD
authors.lastname: Oliver
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Miller
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Brittney K
authors.initials: BK
authors.lastname: Tegels
authors.affiliation: Research Complex for Medical Frontiers, Aichi Medical University, Yazako, Nagakute, Japan.
authors.forename: Reiji
authors.initials: R
authors.lastname: Kannagi
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Marconi
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA jason.carlyon@vcuhealth.org.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Carlyon
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000378:metabolism*; D020816:Amino Acid Motifs; D000596:Amino Acids; D042322:Anaplasma marginale / Q000502:physiology*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D005643:Fucose / Q000378:metabolism; D007106:Immune Sera / Q000276:immunology; D008958:Models, Molecular; D008968:Molecular Conformation; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs
chemical_list: D018829:Adhesins, Bacterial; D000596:Amino Acids; D001425:Bacterial Outer Membrane Proteins; D007106:Immune Sera; D011134:Polysaccharides; C078167:OMPA outer membrane proteins; D005643:Fucose; D019158:N-Acetylneuraminic Acid
keywords: Anaplasma; Ehrlichia; Lewis antigen; Lewis x; adhesin; bacterial invasion; intracellular bacteria; obligate intracellular bacteria; rickettsia; tick-borne pathogens