Crystal structure of a DNA polymerase sliding clamp from a Gram-positive bacterium
Crystal structure of a DNA polymerase sliding clamp from a Gram-positive bacterium
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DOI：
10.1186/1472-6807-6-2
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发表时间：
2006-01-10
影响因子：
--
通讯作者：
Kuriyan, J
中科院分区：
文献类型：
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作者：
Argiriadi, MA;Goedken, ER;Kuriyan, J
背景：滑动DNA夹是DNA有效复制所需的持续合成因子。DNA聚合酶通过与环绕DNA的滑动夹相互作用保持与核酸模板的接近，从而将聚合酶连接到DNA底物。虽然革兰氏阴性菌（E. coli）、真核生物、古生菌和T4类噬菌体的DNA聚合酶Ⅲ全酶的二聚体β亚基的晶体结构，以及G+菌的滑动钳结构的研究尚未见报道。来自这种革兰氏阳性生物的滑动夹形成环状二聚体组装体，其在总体结构上与来自革兰氏阴性细菌、噬菌体T4、真核生物和古细菌的滑动夹的结构相似。二聚体具有类似于90埃×类似于70埃×类似于25埃的总体尺寸，具有足够大以容纳双链体DNA的中心室。与其他组件的圆形形状相比，S。结论：S.化脓性大肠杆菌和E.大肠杆菌中只有23%的相同性，使得S.在没有直接实验信息的情况下，化脓性肉芽肿很难夹紧。我们的S.化脓性链球菌β亚基完成了来自滑动夹的所有主要序列分组的夹结构目录。更椭圆而不是圆形结构的S。化脓性链球菌钳位意味着环绕DNA的拓扑性质，而不是精确的几何形状，是该蛋白质家族最保守的方面。
Background: Sliding DNA clamps are processivity factors that are required for efficient DNA replication. DNA polymerases maintain proximity to nucleic acid templates by interacting with sliding clamps that encircle DNA and thereby link the polymerase enzyme to the DNA substrate. Although the structures of sliding clamps from Gram-negative bacteria (E. coli), eukaryotes, archaea, and T4-like bacteriophages are well-known, the structure of a sliding clamp from Gram-positive bacteria has not been reported previously.Results: We have determined the crystal structure of the dimeric beta subunit of the DNA polymerase III holoenzyme of Streptococcus pyogenes. The sliding clamp from this Gram-positive organism forms a ring-shaped dimeric assembly that is similar in overall structure to that of the sliding clamps from Gram-negative bacteria, bacteriophage T4, eukaryotes and archaea. The dimer has overall dimensions of similar to 90 angstrom x similar to 70 angstrom x similar to 25 angstrom with a central chamber that is large enough to accommodate duplex DNA. In comparison to the circular shape of other assemblies, the S. pyogenes clamp adopts a more elliptical structure.Conclusion: The sequences of sliding clamps from S. pyogenes and E. coli are only 23% identical, making the generation of structural models for the S. pyogenes clamp difficult in the absence of direct experimental information. Our structure of the S. pyogenes beta subunit completes the catalog of clamp structures from all the major sequence grouping of sliding clamps. The more elliptical rather than circular structure of the S. pyogenes clamp implies that the topological nature of encircling DNA, rather than a precise geometric shape, is the most conserved aspect for this family of proteins.