Identification and Characterization of a Sialidase Released by the Salivary Gland of the Hematophagous Insect Triatoma infestans

• Published in: The Journal of biological chemistry Vol. 273; no. 38; pp. 24575 - 24582
• Main Authors: Amino, Rogerio, Porto, Rafael Marques, Chammas, Roger, Egami, Mizue Imoto, Schenkman, Sergio
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.09.1998; American Society for Biochemistry and Molecular Biology
• Subjects: 2-DEOXY-2,3-DEHYDRO-N-ACETYLNEURAMINIC ACID; AMINO SUGARS; Animals; ANTIGENS; Bacteria - enzymology; BLOOD GROUPS; Chagas Disease - transmission; Chromatography, Gel; Chromatography, Ion Exchange; Eating; Electrophoresis, Polyacrylamide Gel; ENZYME INHIBITORS; ENZYMIC ACTIVITY; FEEDING HABITS; GLYCOSIDASES; HEMATOPHAGY; HEPES; HEPES - pharmacology; Insect Bites and Stings; Kinetics; L-Selectin - metabolism; MOLECULAR WEIGHT; Neuraminidase - isolation & purification; Neuraminidase - metabolism; P-Selectin - metabolism; PURIFICATION; Recombinant Fusion Proteins - metabolism; Reduviidae; SALIVA; SALIVARY GLANDS; Salivary Glands - enzymology; SIALIC ACIDS; SIALYL LEWIS ANTIGENS; Substrate Specificity; Triatoma - enzymology; TRIATOMA INFESTANS; Trypanosoma - enzymology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.273.38.24575

Sialidases (EC 3.2.1.18) are commonly found in viruses, bacteria, fungi, protozoa, and vertebrates, but not in invertebrates. We have previously reported the presence of a new sialidase activity in the gut of exclusively hematophagous insects of the Triatoma genus, which transmit Chagas' disease (Amino, R., Acosta, A., Morita, O. M., Chioccola, V. L. P., and Schenkman, S. (1995) Glycobiology 5, 625–631). Here we show that this sialidase is present in the salivary gland of Triatoma infestans, and it is released with the saliva during the insect bite. The sialidase was purified to homogeneity (>5000 times) to a specific activity of more than 20 units/mg. It elutes from a gel filtration column with a volume corresponding to the size of 33 kDa, and it migrates as a single 26-kDa band in SDS-polyacrylamide gel electrophoresis, which is unusually smaller when compared with other known sialidases. T. infestanssialidase hydrolyzes preferentially α2→3-linked sialic acids at pH 4–8, with maximal activity between pH 5.5 and 6.5, which is compatible with the optimal pH of secreted sialidases. The sialidase is competitively inhibited by 2-deoxy-2,3-dehydro-N-acetyl-neuraminic acid (Ki = 0.075 mm) and differently from many sialidases, with exception of Salmonella typhimuriumsialidase, it is inhibited competitively by HEPES (Ki = 15 mm). The fact that T. infestans sialidase is released with the saliva and can hydrolyze sialyl-LewisX blood groups, which are the ligands for selectins, suggests that it might have a role in the blood feeding.