Identification of chondroitin sulfate glucuronyltransferase as chondroitin synthase-3 involved in chondroitin polymerization - Chondroitin polymerization is achieved by multiple enzyme complexes consisting of chondroitin synthase family members
Identification of chondroitin sulfate glucuronyltransferase as chondroitin synthase-3 involved in chondroitin polymerization - Chondroitin polymerization is achieved by multiple enzyme complexes consisting of chondroitin synthase family members
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DOI：
10.1074/jbc.m707549200
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发表时间：
2008-04-25
影响因子：
4.8
通讯作者：
Kitagawa, Hiroshi
中科院分区：
文献类型：
--
作者：
Izumikawa, Tomomi;Koike, Toshiyasu;Kitagawa, Hiroshi
最近，我们证明了软骨素聚合是由人软骨素合成酶-1(ChSy-1)、ChSy-2(软骨素硫酸盐合成酶3，CSS3)和软骨素聚合因子(ChPF)的任意两个组合实现的。尽管另一个ChSy家族成员，称为硫酸软骨素葡萄糖醛酸基转移酶(CSGlcA-T)已被鉴定，但它在软骨素聚合中的作用尚不清楚，因为它只具有葡萄糖醛酸基转移酶II的活性，负责延长硫酸软骨素(CS)链。在此，我们报道了CSGlcA-T通过与ChSy-1、ChSy-2(CSS3)或ChPF相互作用，对含有截短连接区四糖的α-血栓调节蛋白表现出聚合活性，并且不同组合中共表达的蛋白形成的软骨素的链长不同。此外，在不同组合中共表达的ChSy家族成员对两种合成的受体底物--GlcUAβ1-3Galβ1-O-萘乙醇和GlcUAβ1-3Galβ1-O-C2H4NH-苄氧羰基表现出截然不同但重叠的受体底物特异性，这两种底物都与糖胺多糖-蛋白质连接区四糖共享二糖序列。此外，CSGlcA-T的过表达增加了HeLa细胞中CS的数量，而CSGlcA-T的RNA干扰导致细胞中CS的数量减少。此外，对CSGlcA-T突变体的分析表明，CSGlcA-T的糖基转移酶活性在软骨素聚合过程中起着重要作用。总之，这些结果表明，软骨素聚合是由ChSy-1、ChSy-2、CSGlcA-T和ChPF的多个组合实现的，并且每个组合在CS的生物合成中可能发挥着独特的作用。基于这些结果，我们将CSGlcA-T软骨素合酶-3(ChSy-3)重新命名为CSGlcA-T软骨素合酶-3。
Recently, we demonstrated that chondroitin polymerization is achieved by any two combinations of human chondroitin synthase-1 (ChSy-1), ChSy-2 (chondroitin sulfate synthase 3, CSS3), and chondroitin-polymerizing factor (ChPF). Although an additional ChSy family member, called chondroitin sulfate glucuronyltransferase (CSGlcA-T), has been identified, its involvement in chondroitin polymerization remains unclear because it possesses only glucuronyltransferase II activity responsible for the elongation of chondroitin sulfate (CS) chains. Herein, we report that CSGlcA-T exhibits polymerization activity on alpha-thrombomodulin bearing the truncated linkage region tetrasaccharide through its interaction with ChSy-1, ChSy-2 (CSS3), or ChPF, and the chain length of chondroitin formed by the co-expressed proteins in various combinations is different. In addition, ChSy family members co-expressed in various combinations exhibited distinct but overlapping acceptor substrate specificities toward the two synthetic acceptor substrates, GlcUA beta 1-3Gal beta 1-O-naphthalenemethanol and GlcUA beta 1-3Gal beta 1-O-C2H4NH-benzyloxycarbonyl, both of which share the disaccharide sequence with the glycosaminoglycan-protein linkage region tetrasaccharide. Moreover, overexpression of CSGlcA-T increased the amount of CS in HeLa cells, whereas the RNA interference of CSGlcA-T resulted in a reduction of the amount of CS in the cells. Furthermore, the analysis using the CSGlcA-T mutant that lacks any glycosyltransferase activity but interacts with other ChSy family members showed that the glycosyltransferase activity of CSGlcA-T plays an important role in chondroitin polymerization. Overall, these results suggest that chondroitin polymerization is achieved by multiple combinations of ChSy-1, ChSy-2, CSGlcA-T, and ChPF and that each combination may play a unique role in the biosynthesis of CS. Based on these results, we renamed CSGlcA-T chondroitin synthase-3 (ChSy-3).