Increased influenza A virus sialidase activity with N-acetyl-9-O-acetylneuraminic acid-containing substrates resulting from influenza C virus O-acetylesterase action.
Influenza virus type C (Johannesburg/1/66) was used as a source for the enzyme O-acetylesterase (EC 3.1.1.53) with several natural sialoglycoconjugates as substrates. The resulting products were immediately employed as substrates using influenza virus type A [(Singapore/6/86) (H1N1) or Shanghai/11/87 (H3N2)] as a source for sialidase (neuraminidase, EC 3.2.1.18). A significant increase in the percentage of sialic acid released was found when the O-acetyl group was cleaved by O-acetylesterase activity from certain substrates (bovine submandibular gland mucin, rat serum glycoproteins, human saliva glycoproteins, mouse erythrocyte stroma, chick embryonic brain gangliosides and bovine brain gangliosides). A common feature of all these substrates is that they contain N-acetyl-9-O-acetylneuraminic acid residues. By contrast, no significant increase in the release of sialic acid was detected when certain other substrates could not be de-O-acetylated by the action of influenza C esterase, either because they lacked O-acetylsialic acid (human glycophorin A, alpha 1-acid glycoprotein from human serum, fetuin and porcine submandibular gland mucin) or because the 4-O-acetyl group was scarcely cleaved by the viral O-acetylesterase (equine submandibular gland mucin). The biological significance of these facts is discussed, relative to the infective capacity of influenza C virus.
Muñoz-Barroso
I
I
Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Salamanca, Spain.
García-Sastre
A
A
Villar
E
E
Manuguerra
J C
JC
Hannoun
C
C
Cabezas
J A
JA
D000115:Acetylesterase / Q000378:metabolism*; D009980:Influenza A virus / Q000201:enzymology*; D009982:Gammainfluenzavirus / Q000201:enzymology*; D009439:Neuraminidase / Q000378:metabolism*; D012794:Sialic Acids; D013379:Substrate Specificity
D012794:Sialic Acids; C025676:9-O-acetyl-N-acetylneuraminic acid; D000115:Acetylesterase; D009439:Neuraminidase