Schenkman S, Eichinger D, Pereira M E, Nussenzweig V
Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, São Paulo, Brazil.
Annu Rev Microbiol. 1994;48:499-523. doi: 10.1146/annurev.mi.48.100194.002435.
Sialic acids and sialidases play important roles in cellular interactions and modulate the recognition of pathogenic microbes by mammalian host cells. Protozoan parasites of the genus Trypanosoma express a unique sialic acid-metabolizing enzyme. This enzyme, named trans-sialidase (TS), catalyzes the transfer of sialic acids from host glycoconjugates to acceptor molecules of the parasite plasma membrane. In African trypanosomes, the agents of sleeping sickness, TS is found only in forms developing within the insect vector, and the enzyme sialylates the major surface protein. In Trypanosoma cruzi, the causative agent of Chagas' disease in Central and South America, TS is expressed both in the insect and mammalian forms of the parasite. The T. cruzi enzyme has been biochemically characterized, and the gene encoding the enzyme has been cloned. The enzyme sialylates abundant mucin-like molecules present on the surface of the parasite. Several lines of evidence suggest that TS and sialic acid acceptors on the surface of T. cruzi participate in host-parasite interactions and mediate the initial stages of the trypanosomes' invasion of host cells.
唾液酸和唾液酸酶在细胞相互作用中发挥重要作用，并调节哺乳动物宿主细胞对致病微生物的识别。锥虫属原生动物寄生虫表达一种独特的唾液酸代谢酶。这种酶名为转唾液酸酶（TS），催化唾液酸从宿主糖缀合物转移至寄生虫质膜的受体分子。在非洲锥虫（昏睡病病原体）中，TS仅存在于在昆虫媒介体内发育的形态中，该酶使主要表面蛋白唾液酸化。在中南美恰加斯病的病原体克氏锥虫中，TS在寄生虫的昆虫和哺乳动物形态中均有表达。克氏锥虫的该酶已进行生化特性鉴定，且编码该酶的基因已被克隆。该酶使寄生虫表面存在的大量黏蛋白样分子唾液酸化。多条证据表明，克氏锥虫表面的TS和唾液酸受体参与宿主-寄生虫相互作用，并介导锥虫入侵宿主细胞的初始阶段。
