Communication between subunits critical to DNA binding by hexameric helicase of bacteriophage T7

Seung Joo Lee, Udi Qimron, Charles C. Richardson

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The DNA helicase encoded by bacteriophage T7 consists of six identical subunits that form a ring through which the DNA passes. Binding of ssDNA is a prior step to translocation and unwinding of DNA by the helicase. Arg-493 is located at a conserved structural motif within the interior cavity of the helicase and plays an important role in DNA binding. Replacement of Arg-493 with lysine or histidine reduces the ability of the helicase to bind DNA, hydrolyze dTTP, and unwind dsDNA. In contrast, replacement of Arg-493 with glutamine abolishes these activities, suggesting that positive charge at the position is essential. Based on the crystallographic structure of the helicase, Asp-468 is in the range to form a hydrogen bonding with Arg-493 on the adjacent subunit. In vivo complementation results indicate that an interaction between Asp-468 and Arg-493 is critical for a functional helicase and those residues can be swapped without losing the helicase activity. This study suggests that hydrogen bonding between Arg-493 and Asp-468 from adjacent subunits is critical for DNA binding ability of the T7 hexameric helicase.

Original languageEnglish
Pages (from-to)8908-8913
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number26
StatePublished - 1 Jul 2008
Externally publishedYes


FundersFunder number
National Institute of General Medical SciencesR01GM054397


    • DNA replication
    • Hydrogen bonding
    • Residue swappping
    • Subunit interaction


    Dive into the research topics of 'Communication between subunits critical to DNA binding by hexameric helicase of bacteriophage T7'. Together they form a unique fingerprint.

    Cite this