Identification of glycoproteins targeted by Trypanosoma cruzi trans-sialidase, a virulence factor that disturbs lymphocyte glycosylation.
Identification of glycoproteins targeted by Trypanosoma cruzi trans-sialidase, a virulence factor that disturbs lymphocyte glycosylation.
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克氏锥虫转唾液酸酶（一种干扰淋巴细胞糖基化的毒力因子）靶向的糖蛋白的鉴定。
DOI：
10.1093/glycob/cwq037
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发表时间：
2010
期刊：
影响因子：
4.3
通讯作者：
Campetella,Oscar
中科院分区：
文献类型：
--
作者：
Muia,RominaP;Yu,Hai;Prescher,JenniferA;Hellman,Ulf;Chen,Xi;Bertozzi,CarolynR;Campetella,Oscar
克氏锥虫是美洲锥虫病或恰加斯病的病原体，它通过表达表面锚定的转唾液酸酶来绕过唾液酸从头合成的缺陷。这种酶将唾液酸残基从宿主的唾液酸糖缀合物转移到寄生虫的半乳糖基糖缀合物。除了在受感染哺乳动物体内的寄生虫持久性/复制中发挥关键作用之外，转唾液酸酶还被释放到血流中，并通过改变免疫细胞的唾液酸化来诱导宿主免疫系统的改变。了解这些事件的一个主要障碍是难以在细胞表面天然存在的所有唾液酸中识别转移的唾液酸。在这里，我们报告使用叠氮基修饰的非天然唾液酸来识别那些在转唾液酸酶催化反应中充当唾液酸残基的细胞表面受体的分子，这些分子随后可能参与诱导的免疫改变。在活的寄生虫中，我们很容易观察到叠氮基唾液酸转移到表面粘蛋白。当评估小鼠胸腺细胞和脾细胞作为叠氮糖的受体时，揭示了有效标记的糖蛋白的复杂模式。在两个白细胞群体中，标记的主要蛋白质被鉴定为不同的 CD45 亚型。细胞结构的破坏增加了叠氮基唾液酸标记蛋白的数量和分子量分布。尽管如此，CD45 仍然是主要受体。质谱分析使我们能够识别其他受体，主要是整合素。本文报道的研究结果为理解 T 期间转唾液酸酶诱导的免疫系统异常提供了分子基础。克鲁兹感染。
Trypanosoma cruzi, the agent of the American trypanosomiasis or Chagas disease, bypasses its lack of de novo synthesis of sialic acids by expressing a surface-anchoredtrans-sialidase. This enzyme transfers sialic acid residues from the host's sialylglycoconjugates to the parasite's galactosylglycoconjugates. In addition to carrying out a pivotal role in parasite persistence/replication within the infected mammal, thetrans-sialidase is shed into the bloodstream and induces alterations in the host immune system by modifying the sialylation of the immune cells. A major obstacle to understand these events is the difficulty to identify the transferred sialic acid among all those naturally occurring on the cell surface. Here, we report the use of azido-modified unnatural sialic acid to identify those molecules that act as cell surface acceptors of the sialyl residue in thetrans-sialidase-catalyzed reaction, which might then be involved in the immune alterations induced. In living parasites, we readily observed the transfer of azido-sialic acid to surface mucins. When evaluating mouse thymocytes and splenocytes as acceptors of the azido-sugar, a complex pattern of efficiently tagged glycoproteins was revealed. In both leukocyte populations, the main proteins labeled were identified as different CD45 isoforms. Disruption of the cell architecture increased the number and the molecular weight distribution of azido-sialic acid tagged proteins. Nevertheless, CD45 remained to be the main acceptor. Mass spectrometry assays allowed us to identify other acceptors, mainly integrins. The findings reported here provide a molecular basis to understand the abnormalities induced in the immune system by thetrans-sialidase duringT. cruziinfection.