Comparative Structural Biology of Eubacterial and Archaeal Oligosaccharyltransferases
Comparative Structural Biology of Eubacterial and Archaeal Oligosaccharyltransferases
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DOI：
10.1074/jbc.m109.081752
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发表时间：
2010-02-12
影响因子：
4.8
通讯作者：
Kohda, Daisuke
中科院分区：
文献类型：
--
作者：
Maita, Nobuo;Nyirenda, James;Kohda, Daisuke
寡糖基转移酶（OST）催化寡糖从脂质供体转移到新生多肽链中的天冬酰胺残基。在细菌空肠弯曲杆菌中，单亚基膜蛋白PglB催化N-糖基化。我们报告的2.8埃分辨率的晶体结构的C-末端球状结构域的PglB和它的比较与以前确定的结构从古菌Pyrococcus AglB。这两个远亲的寡糖基转移酶共享出乎意料的结构相似性，超出了序列比较的预期。推定的催化位点的共同架构揭示了一个新的催化基序PglB。定点突变分析证实了该基序对催化功能的贡献。细菌PglB和古细菌AglB与真核生物STT 3一起构成OST沿着催化亚基的蛋白质家族。STT 3/PglB/AglB蛋白家族的结构辅助多序列比对揭示了三种类型的OST催化中心。这种新的分类将提供一个有用的框架，了解真核生物，古细菌和细菌的OST酶的酶学性质。
Oligosaccharyltransferase (OST) catalyzes the transfer of an oligosaccharide from a lipid donor to an asparagine residue in nascent polypeptide chains. In the bacterium Campylobacter jejuni, a single-subunit membrane protein, PglB, catalyzes N-glycosylation. We report the 2.8 angstrom resolution crystal structure of the C-terminal globular domain of PglB and its comparison with the previously determined structure from the archaeon Pyrococcus AglB. The two distantly related oligosaccharyltransferases share unexpected structural similarity beyond that expected from the sequence comparison. The common architecture of the putative catalytic sites revealed a new catalytic motif in PglB. Site-directed mutagenesis analyses confirmed the contribution of this motif to the catalytic function. Bacterial PglB and archaeal AglB constitute a protein family of the catalytic subunit of OST along with STT3 from eukaryotes. A structure-aided multiple sequence alignment of the STT3/PglB/AglB protein family revealed three types of OST catalytic centers. This novel classification will provide a useful framework for understanding the enzymatic properties of the OST enzymes from Eukarya, Archaea, and Bacteria.