The Interrelationship of Helicase and Nuclease Domains during DNA Translocation by the Molecular Motor EcoR124I

JOURNAL OF MOLECULAR BIOLOGY

卷:384

Article

Sisakova, Eva³  Weiserova, Marie³  Dekker, Cees⁴  Seidel, Ralf¹  Szcezelkun, Mark D.² 

[1] Tech Univ Dresden, Ctr Biotechnol, D-01307 Dresden, Germany

[2] Univ Bristol, Dept Biochem, DNA Prot Interact Unit, Bristol BS8 1TD, Avon, England

[3] Acad Sci Czech Republ, Inst Microbiol, Prague, Czech Republic

[4] Delft Univ Technol, Kavli Inst Nanosci, NL-2628 CJ Delft, Netherlands

关键词: single molecule;    enzyme disorder;    translocase;    helicase;    ATPase;   

DOI  :  10.1016/j.jmb.2008.10.017

来源: Elsevier

【 摘 要 】

The type I restriction-modification enzyme EcoR1241 comprises three subunits with the stoichiometry HsdR(2)/HsdM(2)/HsdS(1). The HsdR subunits are archetypical examples of the fusion between nuclease and helicase domains into a single polypeptide, a linkage that is found in a great many other DNA processing enzymes. To explore the interrelationship between these physically linked domains, we examined the DNA translocation properties of EcoR124I complexes in which the HsdR subunits had been mutated in the RecB-like nuclease motif II or III. We found that nuclease mutations can have multiple effects on DNA translocation despite being distinct from the helicase domain. In addition to reductions in DNA cleavage activity, we also observed decreased translocation and ATPase rates, different enzyme populations with different characteristic translocation rates, a tendency to stall during initiation and altered HsdR turnover dynamics. The significance of these observations to our understanding of domain interactions in molecular machines is discussed. (C) 2008 Elsevier Ltd. All rights reserved.

【 授权许可】

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