title: Intermediate subunit of the Gal/GalNAc lectin of Entamoeba histolytica is a member of a gene family containing multiple CXXC sequence motifs.
abstract: Killing by Entamoeba histolytica requires parasite adherence to host galactose- and N-acetyl-D-galactosamine (Gal/GalNAc)-containing cell surface receptors. A 260-kDa heterodimeric E. histolytica Gal/GalNAc lectin composed of heavy (Hgl) and light (Lgl) subunits has been previously described. Here we present the cloning and characterization of Igl, a 150-kDa intermediate subunit of the Gal/GalNAc lectin. Igl, Hgl, and Lgl colocalized on the surface membrane of trophozoites. Two unlinked copies of genes encoding Igl shared 81% amino acid sequence identity (GenBank accession no. AF337950 and AF337951). They encoded cysteine-rich proteins with amino- and carboxy-terminal hydrophobic signal sequences characteristic of glycosylphosphatidylinositol (GPI)-anchored membrane proteins. The igl genes lacked carbohydrate recognition domains but were members of a large family of amebic genes containing CXXC and CXC motifs. These data indicate that Igl is part of the parasite's multimolecular Gal/GalNAc adhesin required for host interaction.
authors.affiliation: Department of Infectious Diseases, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa 259-1193, Japan.
authors.forename: X J
authors.initials: XJ
authors.lastname: Cheng
authors.forename: M A
authors.initials: MA
authors.lastname: Hughes
authors.forename: C D
authors.initials: CD
authors.lastname: Huston
authors.forename: B
authors.initials: B
authors.lastname: Loftus
authors.forename: C A
authors.initials: CA
authors.lastname: Gilchrist
authors.forename: L A
authors.initials: LA
authors.lastname: Lockhart
authors.forename: S
authors.initials: S
authors.lastname: Ghosh
authors.forename: V
authors.initials: V
authors.lastname: Miller-Sims
authors.forename: B J
authors.initials: BJ
authors.lastname: Mann
authors.forename: W A
authors.initials: WA
authors.lastname: Petri
authors.forename: H
authors.initials: H
authors.lastname: Tachibana
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D003545:Cysteine / Q000737:chemistry; D016054:DNA, Protozoan / Q000032:analysis; D004748:Entamoeba histolytica / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D037102:Lectins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; C434499:Igl1 protein, Entamoeba histolytica; C434500:Igl2 protein, Entamoeba histolytica; D037102:Lectins; D015800:Protozoan Proteins; D003545:Cysteine