The donor subsite of trehalose-6-phosphate synthase -: Binary complexes with UDP-glucose and UDP-2-deoxy-2-fluoro-glucose at 2 Å resolution
The donor subsite of trehalose-6-phosphate synthase -: Binary complexes with UDP-glucose and UDP-2-deoxy-2-fluoro-glucose at 2 Å resolution
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DOI：
10.1074/jbc.m307643200
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发表时间：
2004-01-16
影响因子：
4.8
通讯作者：
Davies, GJ
中科院分区：
文献类型：
--
作者：
Gibson, RP;Tarling, CA;Davies, GJ
海藻糖是一种不寻常的非还原性二糖，具有多种生物学作用，从食品储存到细胞保护，免受环境应力，如干燥，压力，热休克，极冷和氧自由基。它也是分枝杆菌细胞壁糖脂的组成部分。海藻糖的主要酶促途径首先涉及葡萄糖从UDP-葡萄糖供体转移至葡萄糖-6-磷酸以形成α，α-1，1海藻糖-6-磷酸。该反应中两个糖苷键的构型同时形成，由糖基转移酶海藻糖-6-磷酸合酶（OtsA）催化，其作用是保留UDP-糖供体的异头构型。基于氨基酸序列相似性将活化的糖依赖性糖基转移酶分类为约70个不同的家族，将OtsA置于糖基转移酶家族20中（参见afmb.cnrs-mrs.fr/CAZY/）。最近的2.4埃结构的大肠杆菌OtsA揭示了一个双结构域的酶与催化发生在双β/α/β结构域的界面。在这里，我们提出了2.0埃结构的E。coliOtsA与UDP-Glc或不可转移的类似物UDP-2-脱氧-2-氟葡萄糖复合。这两种复合物揭示了供体亚位点的相互作用，证实了与糖原磷酸化酶的强烈相似性，并揭示了与先前报道的UDP和葡萄糖6-磷酸复合物的实质性构象差异。两个结构域的相对取向和N-末端环（残基9 - 22）的实质性（高达10埃）移动表征了本文报道的二元UDP-糖复合物的更开放的"松弛"构象。
Trehalose is an unusual non-reducing disaccharide that plays a variety of biological roles, from food storage to cellular protection from environmental stresses such as desiccation, pressure, heat-shock, extreme cold, and oxygen radicals. It is also an integral component of the cell-wall glycolipids of mycobacteria. The primary enzymatic route to trehalose first involves the transfer of glucose from a UDP-glucose donor to glucose-6-phosphate to form alpha,alpha-1,1 trehalose-6-phosphate. This reaction, in which the configurations of two glycosidic bonds are set simultaneously, is catalyzed by the glycosyltransferase trehalose-6-phosphate synthase ( OtsA), which acts with retention of the anomeric configuration of the UDP-sugar donor. The classification of activated sugar-dependent glycosyltransferases into approximately 70 distinct families based upon amino acid sequence similarities places OtsA in glycosyltransferase family 20 (see afmb.cnrs-mrs.fr/CAZY/). The recent 2.4 Angstrom structure of Escherichia coli OtsA revealed a two-domain enzyme with catalysis occurring at the interface of the twin beta/alpha/beta domains. Here we present the 2.0 Angstrom structures of the E. coli OtsA in complex with either UDP-Glc or the non-transferable analogue UDP-2-deoxy-2-fluoroglucose. Both complexes unveil the donor subsite interactions, confirming a strong similarity to glycogen phosphorylases, and reveal substantial conformational differences to the previously reported complex with UDP and glucose 6-phosphate. Both the relative orientation of the two domains and substantial ( up to 10 Angstrom) movements of an N-terminal loop ( residues 9 - 22) characterize the more open "relaxed" conformation of the binary UDP-sugar complexes reported here.