一种在噬菌体T4感染的大肠杆菌细胞中诱导产生的DNA解旋酶。

A DNA-unwinding enzyme induced in bacteriophage-T4-infected Escherichia coli cells.

作者信息

Krell H, Dürwald H, Hoffmann-Berling H

出版信息

Eur J Biochem. 1979 Jan 15;93(2):387-95. doi: 10.1111/j.1432-1033.1979.tb12835.x.

DOI:10.1111/j.1432-1033.1979.tb12835.x

Abstract

A single-stranded DNA-dependent ATP gamma-phosphohydrolase of Mr 56000 induced after infection of Escherichia coli cells with bacteriophage T4, probably the ATPase dependent on gene dda of the phage, was isolated. Studies on the enzyme show that in the presence of ATP and M2+ ions it is capable of dissociating partially double-stranded fd bacteriophage DNA into the single strands and that some 3000 enzyme copies are required to unwind the 6400-nucleotides-long DNA. Unwinding is inhibited by reducing the length of the single-stranded portion of DNA to two nucleotides. In addition it can be inhibited by sulfhydryl reagents which block the ATPase or by trapping free enzyme molecules in the assay system. The results suggest that unwinding is initiated near the single-stranded portion of the DNA and is driven by the ATPase. It further appears that the enzyme unwinds by adsorbing to the DNA. Affinity of the enzyme for double-standed DNA is not detectable by DNA binding assay.

摘要

一种分子量为56000的单链DNA依赖性ATPγ-磷酸水解酶在大肠杆菌细胞被噬菌体T4感染后被诱导产生，它可能是依赖噬菌体dda基因的ATP酶，已被分离出来。对该酶的研究表明，在ATP和M2+离子存在的情况下，它能够将部分双链fd噬菌体DNA解离成单链，并且大约需要3000个酶分子才能解开6400个核苷酸长的DNA。当将DNA单链部分的长度减少到两个核苷酸时，解旋作用受到抑制。此外，它还可以被阻断ATP酶的巯基试剂或通过在测定系统中捕获游离酶分子而受到抑制。结果表明，解旋作用在DNA的单链部分附近启动，并由ATP酶驱动。进一步看来，该酶通过吸附到DNA上进行解旋。通过DNA结合测定法无法检测到该酶对双链DNA的亲和力。