Nasizadeh S, Thiman L, Persson L
Department of Experimental Medical Science, Lund University, Lund, Sweden.
Amino Acids. 2008 Apr;34(3):421-8. doi: 10.1007/s00726-007-0552-x. Epub 2007 May 21.
Ornithine decarboxylase (ODC) has a very fast turnover in mammalian cells, but is a stable enzyme in T. brucei and other trypanosmatid parasites like Leishmania donovani. However, Crithidia fasciculata, which is a phylogenetically closely related trypanosomatid to L. donovani, has an ODC with a rapid turnover. Interestingly, C. fasciculata ODC, but not L. donovani ODC, is rapidly degraded also in mammalian systems. In order to obtain information on what sequences are important for the rapid degradation of C. fasciculata ODC, we produced a variety of C. fasciculata/L. donovani ODC hybrid proteins and characterized their turnover using two different mammalian expression systems. The results obtained indicate that C. fasciculata ODC contains several sequence elements essential for the rapid turnover of the protein and that these regions are mainly located in the central part of the enzyme.
鸟氨酸脱羧酶（ODC）在哺乳动物细胞中的更新速度非常快，但在布氏锥虫以及其他锥虫寄生虫（如杜氏利什曼原虫）中却是一种稳定的酶。然而，作为与杜氏利什曼原虫在系统发育上密切相关的锥虫，纤细无鞭毛体的ODC更新速度很快。有趣的是，纤细无鞭毛体的ODC在哺乳动物系统中也会迅速降解，而杜氏利什曼原虫的ODC则不会。为了获得有关哪些序列对纤细无鞭毛体ODC的快速降解很重要的信息，我们制备了多种纤细无鞭毛体/杜氏利什曼原虫ODC杂交蛋白，并使用两种不同的哺乳动物表达系统对它们的更新情况进行了表征。所得结果表明，纤细无鞭毛体ODC含有几个对该蛋白质快速更新至关重要的序列元件，并且这些区域主要位于酶的中央部分。
