2-Acylamido analogues of N-acetylglucosamine prime formation of chitin oligosaccharides by yeast chitin synthase 2.
2-Acylamido analogues of N-acetylglucosamine prime formation of chitin oligosaccharides by yeast chitin synthase 2.
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酵母壳蛋白合酶2的N-乙酰葡萄糖素寡糖的N-乙酰葡萄糖素形成的2-酰胺类似物2。
DOI：
10.1074/jbc.m114.550749
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发表时间：
2014-05-02
期刊：
影响因子：
--
通讯作者：
Orlean P
中科院分区：
文献类型：
--
作者：
Gyore J;Parameswar AR;Hebbard CF;Oh Y;Bi E;Demchenko AV;Price NP;Orlean P
背景：几丁质合酶受N - 乙酰葡糖胺（GlcNAc）刺激。
结果：GlcNAc以及GlcNAc的2 - 酰氨基类似物刺激酵母几丁质合酶形成几丁质寡糖，并且GlcNAc被转移至2 - 酰氨基类似物上。
结论：几丁质合酶将GlcNAc类似物用作引物，每次转移一个GlcNAc。
意义：这些结果为多糖合酶机制提供了新的见解，并为合成新型修饰多糖提供了思路。
几丁质是由β1,4 - 连接的N - 乙酰葡糖胺（GlcNAc）残基组成的同聚物，是真菌细胞壁和节肢动物外骨骼的关键成分。几丁质合酶在通常由游离GlcNAc刺激的反应中将GlcNAc从UDP - GlcNAc转移至预先存在的几丁质链上。通过使用表达单一几丁质合酶Chs2的酵母菌株，检测几丁质寡糖（COs）和不溶性几丁质的形成，并将GlcNAc替换为GlcNAc的2 - 酰氨基类似物来探究GlcNAc的作用。几丁质合酶孵育过程中，COs的合成强烈依赖于GlcNAc的存在，并且N,N′ - 二乙酰壳二糖（GlcNAc₂）是主要的反应产物。GlcNAc₂以及N - 丙酰基 - 、N - 丁酰基 - 和N - 羟乙酰基葡糖胺也刺激COs和不溶性几丁质的形成。对在GlcNAc的2 - 酰氨基类似物存在下形成的COs进行的MALDI分析表明，它们包含一个GlcNAc类似物以及一个或多个额外的GlcNAc残基。这些结果表明，Chs2可以使用某些GlcNAc的2 - 酰氨基类似物，可能还有游离的GlcNAc和GlcNAc₂，作为UDP - GlcNAc依赖的糖基转移反应中的GlcNAc受体。此外，修饰二糖的形成表明几丁质合酶能够转移单个GlcNAc残基。
Background: Chitin synthases are stimulated by N-acetylglucosamine (GlcNAc). Results: GlcNAc and 2-acylamido analogues of GlcNAc stimulate formation of chitin oligosaccharides by yeast chitin synthase, and GlcNAc is transferred to the 2-acylamido analogues. Conclusion: Chitin synthases use GlcNAc analogues as primers and transfer one GlcNAc at a time. Significance: Results are new insights into polysaccharide synthase mechanism and suggest ways of synthesizing novel modified polysaccharides. Chitin, a homopolymer of β1,4-linked N-acetylglucosamine (GlcNAc) residues, is a key component of the cell walls of fungi and the exoskeletons of arthropods. Chitin synthases transfer GlcNAc from UDP-GlcNAc to preexisting chitin chains in reactions that are typically stimulated by free GlcNAc. The effect of GlcNAc was probed by using a yeast strain expressing a single chitin synthase, Chs2, by examining formation of chitin oligosaccharides (COs) and insoluble chitin, and by replacing GlcNAc with 2-acylamido analogues of GlcNAc. Synthesis of COs was strongly dependent on inclusion of GlcNAc in chitin synthase incubations, and N,N′-diacetylchitobiose (GlcNAc2) was the major reaction product. Formation of both COs and insoluble chitin was also stimulated by GlcNAc2 and by N-propanoyl-, N-butanoyl-, and N-glycolylglucosamine. MALDI analyses of the COs made in the presence of 2-acylamido analogues of GlcNAc showed they that contained a single GlcNAc analogue and one or more additional GlcNAc residues. These results indicate that Chs2 can use certain 2-acylamido analogues of GlcNAc, and likely free GlcNAc and GlcNAc2 as well, as GlcNAc acceptors in a UDP-GlcNAc-dependent glycosyltransfer reaction. Further, formation of modified disaccharides indicates that CSs can transfer single GlcNAc residues.