Mittler Michael, Bechthold Andreas, Schulz Georg E
Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstr. 21, D-79104 Freiburg im Breisgau, Germany.
J Mol Biol. 2007 Sep 7;372(1):67-76. doi: 10.1016/j.jmb.2007.06.005. Epub 2007 Jun 9.
The glycosyltransferase UrdGT2 from Streptomyces fradiae catalyzes the formation of a glycosidic C-C bond between a polyketide aglycone and D-olivose. The enyzme was expressed in Escherichia coli, purified and crystallized. Its structure was established by X-ray diffraction at 1.9 A resolution. It is the first structure of a C-glycosyltransferase. UrdGT2 belongs to the structural family GT-B of the glycosyltransferases and is likely to form a C(2)-symmetric dimer in solution. The binding structures of donor and acceptor substrates in five structurally homologous enzymes provided a clear and consistent guide for the substrate-binding structure in UrdGT2. The modeled substrate locations suggest the deeply buried Asp137 as the activator for C-C bond formation and explain the reaction. The putative model can be used to design mutations that change the substrate specificity. Such mutants are of great interest in overcoming the increasing danger of antibiotic resistance.
来自弗氏链霉菌的糖基转移酶UrdGT2催化聚酮苷元与D-橄榄糖之间糖苷C-C键的形成。该酶在大肠杆菌中表达、纯化并结晶。通过分辨率为1.9埃的X射线衍射确定了其结构。这是C-糖基转移酶的首个结构。UrdGT2属于糖基转移酶的GT-B结构家族，在溶液中可能形成C(2)对称二聚体。五种结构同源酶中供体和受体底物的结合结构为UrdGT2中的底物结合结构提供了清晰且一致的指导。模拟的底物位置表明深埋的Asp137是C-C键形成的激活剂并解释了该反应。该推测模型可用于设计改变底物特异性的突变。此类突变体对于克服日益增加的抗生素耐药性危险具有重大意义。
