Crystal structure of chondroitinase B from Flavobacterium heparinum and its complex with a disaccharide product at 1.7 Å resolution
Crystal structure of chondroitinase B from Flavobacterium heparinum and its complex with a disaccharide product at 1.7 Å resolution
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DOI：
10.1006/jmbi.1999.3292
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发表时间：
1999-12-17
影响因子：
5.6
通讯作者：
Cygler, M
中科院分区：
文献类型：
--
作者：
Huang, WJ;Matte, A;Cygler, M
糖胺聚糖（GAG）是酸性杂多糖家族，包括诸如硫酸软骨素、硫酸皮肤素、肝素和硫酸角质素的分子。GAG内的O-糖苷键的裂解可以通过水解酶以及裂解酶完成，产生二糖和寡糖产物。我们已经确定了软骨素酶B的晶体结构，一种来自肝素黄杆菌的糖胺聚糖裂解酶，以及它与硫酸皮肤素二糖产物的复合物，两者都在1.7埃分辨率下。软骨素酶B采用右手平行β-螺旋折叠，最初在果胶酸裂解酶中发现，随后在几种多糖裂解酶和水解酶中发现。软骨素酶B和假单胞菌属的甘露糖醛酸裂解酶之间的序列同源性表明该蛋白质也采用β-螺旋折叠。二糖产物的结合发生在由从β-螺旋表面延伸的环形成的带正电荷的裂缝内。已经鉴定了负责识别二糖的氨基酸残基以及潜在的催化残基。两个精氨酸残基，Arg 318和Arg 364，被发现与连接到O-4的N-乙酰半乳糖胺的硫酸基团相互作用。硫酸皮肤素的裂解可能发生在二糖的还原端，Glu 333可能作为一般碱。(C)北京：科学出版社.
Glycosaminoglycans (GAGs) are a family of acidic heteropolysaccharides, including such molecules as chondroitin sulfate, dermatan sulfate, heparin and keratan sulfate. Cleavage of the O-glycosidic bond within GAGs can be accomplished by hydrolases as well as lyases, yielding disaccharide and oligosaccharide products. We have determined the crystal structure of chondroitinase B, a glycosaminoglycan lyase from Flavobacterium heparinum, as well as its complex with a dermatan sulfate disaccharide product, both at 1.7 Angstrom resolution. Chondroitinase B adopts the right-handed parallel beta-helix fold, found originally in pectate lyase and subsequently in several polysaccharide lyases and hydrolases. Sequence homology between chondroitinase B and a mannuronate lyase from Pseudomonas sp. suggests this protein also adopts the beta-helix fold. Binding of the disaccharide product occurs within a positively charged cleft formed by loops extending from the surface of the beta-helix. Amino acid residues responsible for recognition of the disaccharide, as well as potential catalytic residues, have been identified. Two arginine residues, Arg318 and Arg364, are found to interact with the sulfate group attached to O-4 of N-acetylgalactosamine. Cleavage of dermatan sulfate likely occurs at the reducing end of the disaccharide, with Glu333 possibly acting as the general base. (C) 1999 Academic Press.