9-O-Acetylated Sialic Acids have Widespread but Selective Expression: Analysis Using a Chimeric Dual-Function Probe Derived from Influenza C Hemagglutinin-Esterase

• Published in: Proceedings of the National Academy of Sciences - PNAS 1994-08, Vol.91 (16), p.7782-7786
• Main Authors: Klein, A, Krishna, M, Varki, N M, Varki, A
• Format: Article
• Language: English
• Subjects: Adrenal glands; Animals; Cellular biology; Erythrocytes; Esterases - genetics; Esterases - metabolism; Esters; Gammainfluenzavirus - enzymology; Gammainfluenzavirus - genetics; Gangliosides; Glycolipids - chemistry; Glycolipids - isolation & purification; Glycoproteins; Glycoproteins - chemistry; Glycoproteins - isolation & purification; Hemagglutinins, Viral - genetics; Hemagglutinins, Viral - metabolism; Histocytochemistry; Influenza; influenza virus; Influenzavirus C; Molecular Probes; Molecules; Mucins; Proteins; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins - metabolism; Rodents; Sialic Acids - isolation & purification; Tissue Distribution; Viral Fusion Proteins; Viral Proteins - genetics; Viral Proteins - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.91.16.7782

While 9-O-acetylation of sialic acids has been reported in some mammalian tissues, the distribution of this modification on specific cell types and molecules is largely unknown. The influenza C virus hemagglutinin-esterase is a membrane-bound glycoprotein that binds specifically to 9-O-acetylated sialic acids (hemagglutinin activity) and then hydrolyzes the O-acetyl group (receptor-destroying activity). A recombinant soluble form of influenza C virus hemagglutinin-esterase wherein the C-terminal transmembrane and cytoplasmic domains are replaced by the Fc portion of human IgG retains both its recognition and enzymatic functions. The latter activity can selectively remove 9-O-acetyl groups from bound or free sialic acids and, under specific conditions, 7-O-acetyl groups as well. Irreversible inactivation of the esterase unmasks stable recognition activity, giving a molecule that binds specifically to 9-O-acetylated sialic acids. These probes demonstrate widespread but selective expression of 9-O-acetylated sialic acids in certain cell types of rat tissues. Patterns of polarized or gradient expression further demonstrate the regulated nature of this modification. Direct probing of blots and thin-layer plates shows selective expression of 9-O-acetylation on certain glycoproteins and glycolipids in such tissues. Thus, 9-O-acetylation is more widespread than previously thought and occurs on specific molecules and cell types.