ESCHERICHIA-COLI RECQ PROTEIN IS A DNA HELICASE
ESCHERICHIA-COLI RECQ PROTEIN IS A DNA HELICASE
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DOI：
10.1073/pnas.87.14.5363
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发表时间：
1990-07-01
影响因子：
11.1
通讯作者：
NAKAYAMA, H
中科院分区：
文献类型：
--
作者：
UMEZU, K;NAKAYAMA, K;NAKAYAMA, H
我们将recf重组基因家族中的一员--大肠杆菌RecQ基因构建到高效表达载体中，并对其产物进行纯化，得到近均一的表达产物。纯化的RecQ蛋白具有DNA依赖的ATPase和解旋酶活性。在没有DNA的情况下，没有检测到ATPase活性。作为ATPase辅因子的能力因DNA类型的不同而不同，顺序为：环状单链-GT>线状单链-mchgt。圆形或线性双工。作为一种解旋酶，RecQ蛋白取代了环状或线状噬菌体M13 DNA上71个碱基或143个碱基的单链DNA，解离方向似乎为3‘.fwdarw。相对于推测酶结合到的DNA单链5‘’。此外，该蛋白可以在较高的酶浓度下解开143碱基对钝化的双链DNA。结论：RecQ蛋白是一种未见报道的解旋酶，它可能在重组过程中为链转移反应产生单链尾巴。
The Escherichia coli recQ gene, a member of the RecF recombination gene family, we set in an overexpression plasmid, and its product was purified to near-homogeneity. The purified RecQ protein exhibited a DNA-dependent ATPase and a helicase activity. Without DNA, no ATPase activity was detected. The capacity as ATPase cofactor varied with the type of DNA in the following order: circular single strand > linear single strand .mchgt. circular or linear duplex. As a helicase, RecQ protein displaced an annealed 71-base or 143-base single-stranded fragment from circular or linear phage M13 DNA, and the direction of unwinding seemed to be 3'' .fwdarw. 5'' with respect to the DNA single strand to which the enzyme supposedly bound. Furthermore, the protein could unwind 143-base-pair bluntened duplex DNA at a higher enzyme concentration. It is concluded that RecQ protein is a previously unreported helicase, which might possibly serve to generate single-stranded tails for a strand transfer reaction in the process of recombination.