Intermediates revealed in the kinetic mechanism for DNA unwinding by a monomeric helicase

被引：40

作者：

Eoff, RL ^{[1
]}

Raney, KD ^{[1
]}

机构：

[1] Univ Arkansas Med Sci, Dept Biochem & Mol Biol, Little Rock, AR 72205 USA

来源：

NATURE STRUCTURAL & MOLECULAR BIOLOGY | 2006年 / 13卷 / 03期

关键词：

D O I：

10.1038/nsmb1055

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Helicases unwind dsDNA during replication, repair and recombination in an ATP-dependent reaction. The mechanism for helicase activity can be studied using oligonucleotide substrates to measure formation of single-stranded ( ss) DNA from double-stranded ( ds) DNA. This assay provides an 'all-or-nothing' readout because partially unwound intermediates are not detected. We have determined conditions under which an intermediate in the reaction cycle of Dda helicase can be detected by trapping a partially unwound substrate. The appearance of this intermediate supports a model in which each ssDNA product interacts with the helicase after unwinding has occurred. Kinetic analysis indicates that the intermediate appears during a slow step in the reaction cycle that is flanked by faster steps for unwinding. These observations demonstrate a complex mechanism containing nonuniform steps for a monomeric helicase. The potential biological significance of such a mechanism is discussed.

引用

页码：242 / 249

页数：8

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