CRYSTAL-STRUCTURE OF DNA PHOTOLYASE FROM ESCHERICHIA-COLI
CRYSTAL-STRUCTURE OF DNA PHOTOLYASE FROM ESCHERICHIA-COLI
复制标题
DOI：
10.1126/science.7604260
复制
发表时间：
1995-06-30
期刊：
影响因子：
56.9
通讯作者：
DEISENHOFER, J
中科院分区：
文献类型：
--
作者：
PARK, HW;KIM, ST;DEISENHOFER, J
光裂合酶通过分裂主要UV光产物顺式，顺式-环丁烷嘧啶二聚体（Pyr >$（$），而不是Pyr）的环丁烷环来修复对DNA的紫外（UV）损伤。该反应由蓝光引发，并通过远程能量转移，单电子转移和自由基机制的酶催化进行。给出了大肠杆菌DNA光裂合酶的三维晶体结构，并将原子模型在2.3埃分辨率下修正到R值为0.172。471个氨基酸的多肽链折叠成类似于二核苷酸结合结构域的氨基末端α/β结构域和羧基末端螺旋结构域; 72个残基的环连接结构域。捕光辅助因子5，10-亚甲基四氢叶酸聚谷氨酸盐（MTHF）结合在两个结构域之间的裂缝中。从MTHF到催化辅因子黄素腺嘌呤二核苷酸（FAD）的能量转移发生在16.8埃的距离上。FAD在螺旋结构域中心的两个螺旋簇之间采用U形构象，并且可通过该结构域表面中的孔进入。孔洞的尺寸和极性与Pyr >$（$）over bar Pyr二核苷酸的尺寸和极性相匹配，这表明Pyr >$（$）over bar Pyr“翻转”出螺旋以适应这个孔洞，并且黄素和Pyr >$（$）over bar Pyr之间的电子转移发生在货车德瓦尔斯接触距离上。
Photolyase repairs ultraviolet (UV) damage to DNA by splitting the cyclobutane ring of the major UV photoproduct, the cis,syn-cyclobutane pyrimidine dimer (Pyr >$($) over bar Pyr). The reaction is initiated by blue light and proceeds through long-range energy transfer, single electron transfer, and enzyme catalysis by a radical mechanism. The three-dimensional crystallographic structure of DNA photolyase from Escherichia coli is presented and the atomic model was refined to an R value of 0.172 at 2.3 Angstrom resolution. The polypeptide chain of 471 amino acids is folded into an amino-terminal alpha/beta domain resembling dinucleotide binding domains and a carboxyl-terminal helical domain; a loop of 72 residues connects the domains. The light-harvesting cofactor 5,10-methenyltetrahydrofolylpolyglutamate (MTHF) binds in a cleft between the two domains. Energy transfer from MTHF to the catalytic cofactor flavin adenine dinucleotide (FAD) occurs over a distance of 16.8 Angstrom. The FAD adopts a U-shaped conformation between two helix clusters in the center of the helical domain and is accessible through a hole in the surface of this domain. Dimensions and polarity of the hole match those of a Pyr >$($) over bar Pyr dinucleotide, suggesting that the Pyr >$($) over bar Pyr ''flips out'' of the helix to fit into this hole, and that electron transfer between the flavin and the Pyr >$($) over bar Pyr occurs over van der Waals contact distance.