title: A sialylated glycan microarray reveals novel interactions of modified sialic acids with proteins and viruses.
abstract: Many glycan-binding proteins in animals and pathogens recognize sialic acid or its modified forms, but their molecular recognition is poorly understood. Here we describe studies on sialic acid recognition using a novel sialylated glycan microarray containing modified sialic acids presented on different glycan backbones. Glycans terminating in β-linked galactose at the non-reducing end and with an alkylamine-containing fluorophore at the reducing end were sialylated by a one-pot three-enzyme system to generate α2-3- and α2-6-linked sialyl glycans with 16 modified sialic acids. The resulting 77 sialyl glycans were purified and quantified, characterized by mass spectrometry, covalently printed on activated slides, and interrogated with a number of key sialic acid-binding proteins and viruses. Sialic acid recognition by the sialic acid-binding lectins Sambucus nigra agglutinin and Maackia amurensis lectin-I, which are routinely used for detecting α2-6- and α2-3-linked sialic acids, are affected by sialic acid modifications, and both lectins bind glycans terminating with 2-keto-3-deoxy-D-glycero-D-galactonononic acid (Kdn) and Kdn derivatives stronger than the derivatives of more common N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). Three human parainfluenza viruses bind to glycans terminating with Neu5Ac or Neu5Gc and some of their derivatives but not to Kdn and its derivatives. Influenza A virus also does not bind glycans terminating in Kdn or Kdn derivatives. An especially novel aspect of human influenza A virus binding is its ability to equivalently recognize glycans terminated with either α2-6-linked Neu5Ac9Lt or α2-6-linked Neu5Ac. Our results demonstrate the utility of this sialylated glycan microarray to investigate the biological importance of modified sialic acids in protein-glycan interactions.
authors.affiliation: Department of Biochemistry and the Glycomics Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Xuezheng
authors.initials: X
authors.lastname: Song
authors.forename: Hai
authors.initials: H
authors.lastname: Yu
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Lasanajak
authors.forename: Mary M
authors.initials: MM
authors.lastname: Tappert
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Air
authors.forename: Vinod K
authors.initials: VK
authors.lastname: Tiwari
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Cao
authors.forename: Harshal A
authors.initials: HA
authors.lastname: Chokhawala
authors.forename: Haojie
authors.initials: H
authors.lastname: Zheng
authors.forename: Richard D
authors.initials: RD
authors.lastname: Cummings
authors.forename: David F
authors.initials: DF
authors.lastname: Smith
mesh_terms: D001665:Binding Sites; D006801:Humans; D009980:Influenza A virus; D037102:Lectins / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D040081:Protein Array Analysis; D011506:Proteins / Q000378:metabolism*; D018108:Respirovirus; D012794:Sialic Acids / Q000737:chemistry / Q000378:metabolism*; D014780:Viruses / Q000378:metabolism*
chemical_list: D037102:Lectins; D011134:Polysaccharides; D011506:Proteins; D012794:Sialic Acids