MOLECULAR-STRUCTURE OF THE G-A BASE PAIR IN DNA AND ITS IMPLICATIONS FOR THE MECHANISM OF TRANSVERSION MUTATIONS
MOLECULAR-STRUCTURE OF THE G-A BASE PAIR IN DNA AND ITS IMPLICATIONS FOR THE MECHANISM OF TRANSVERSION MUTATIONS
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DOI：
10.1073/pnas.83.8.2402
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发表时间：
1986-04-01
影响因子：
11.1
通讯作者：
KENNARD, O
中科院分区：
文献类型：
--
作者：
BROWN, T;HUNTER, WN;KENNARD, O
合成的脱氧十二聚体d（C-G-C-G-A-A-T-T-A-G-C-G）用X-射线衍射法分析，结构精确到R = 0.17和2.5-Δ G的残余误差。分辨率（2 σ）数据），其中83个水分子定位。该序列结晶为B-DNA螺旋的一整圈，并含有2个嘌呤-嘌呤（G. A）碱基对和10个沃森-克里克碱基对。分析结果表明，腺嘌呤相对于糖部分是顺式取向的，而鸟嘌呤通常是反式取向的。两种碱基的氮原子都与2.84埃的鸟嘌呤的N-1形成氢键。从腺嘌呤的N-7和腺嘌呤的N-6在2.74埃。鸟嘌呤的O-6。C-1.cntdot. . cntdot. . cntdot. C-1 ″分离为10.7埃。接近于标准沃森-克里克碱基对。嘌呤的掺入。十二聚体中两步的嘌呤碱基对双螺旋的局部或整体构象几乎没有扰动。结构特征与G. cntdot. T摆动对和标准G. C对提示了两种类型碱基对错配的差异酶修复的基本原理。
The synthetic deoxydodecamer d(C-G-C-G-A-A-T-T-A-G-C-G) was analyzed by x-ray diffraction methods, and the structure was refined to a residual error of R = 0.17 and 2.5-.ANG. resolution (2 .sigma. data) with 83 water molecules located. The sequence crystallizes as a full turn of a B-DNA helix and contains 2 purine-purine (G .cntdot. A) base pairs and 10 Watson-Crick base pairs. The analysis shows conclusively that adenine is in the syn orientation with respect to the sugar moietay whereas guanine adopts the usual trans orientation. Nitrogen atoms of both bases are involved in hydrogen bonding with the N-1 of guanine of 2.84 .ANG. from the N-7 of adneine and the N-6 of adenine within 2.74 .ANG. of the O-6 of guanine. The C-1 .cntdot. .cntdot. .cntdot. C-1'' separation is 10.7 .ANG. close to that for standard Watson-Crick base pairs. The incorporation of the purine .cntdot. purine base pairs at two steps in the dodecamer causes little perturbation of either the local or the global conformation of the double helix. Comparison of the structural features with those of the G .cntdot. T wobble pair and standard G .cntdot. C pair suggests a rationale for the differential enzymatic repair of the two types of base-pair mismatches.