Molecular characterization of nucleocytosolic O-GlcNAc transferases of Giardia lamblia and Cryptosporidium parvum
Molecular characterization of nucleocytosolic O-GlcNAc transferases of Giardia lamblia and Cryptosporidium parvum
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DOI：
10.1093/glycob/cwn107
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发表时间：
2009-04-01
期刊：
影响因子：
4.3
通讯作者：
Samuelson, John
中科院分区：
文献类型：
--
作者：
Banerjee, Sulagna;Robbins, Phillips W.;Samuelson, John
O-连接N-乙酰葡糖胺转移酶（OGT）催化单个GlcNAc转移到核质蛋白的Ser或Thr。OGT活性可能与激酶的活性竞争，参与动物和植物中的信号传导，并且OGT活性的异常与2型糖尿病相关。在这里，我们表明，预测具有特征性的三肽重复序列和纺锤结构域的酶的ogt基因存在于一些原生生物（贾第虫、隐孢子虫、弓形虫和网囊藻）中，但在大多数被检查的原生生物中不存在（例如，疟原虫属、锥虫属、内阿米巴属和毛滴虫属）。类似地，ogt基因存在于一些真菌中，但在许多其他真菌中不存在，这表明次生损失是ogt基因进化的重要贡献者。贾第虫和隐孢子虫的核胞质提取物显示OGT活性，并且重组贾第虫和隐孢子虫OGT分别在酵母和细菌中具有活性。这些结果表明核胞质蛋白的O-GlcNAc修饰在简单真核生物中也具有功能的可能性。
O-Linked N-acetylglucosaminyltransferase (OGT) catalyzes the transfer of a single GlcNAc to the Ser or Thr of nucleocytoplasmic proteins. OGT activity, which may compete with that of kinases, is involved in signaling in animals and plants, and abnormalities in OGT activities have been associated with type 2 diabetes. Here, we show that ogt genes that predict enzymes with characteristic tetratricopeptide repeats and a spindly domain are present in some protists (Giardia, Cryptosporidium, Toxoplasma, and Dictyostelium) but are absent from the majority of protists examined (e.g., Plasmodium, Trypanosoma, Entamoeba, and Trichomonas). Similarly, ogt genes are present in some fungi but are absent from numerous other fungi, suggesting that secondary loss is an important contributor to the evolution of ogt genes. Nucleocytosolic extracts of Giardia and Cryptosporidium show OGT activity, and recombinant Giardia and Cryptosporidium OGTs are active in yeast and bacteria, respectively. These results suggest the possibility that O-GlcNAc modification of nucleocytosolic proteins also has function(s) in simple eukaryotes.