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DNA binding to RecD: role of the 1B domain in SF1B helicase activity
Author(s) -
Saikrishnan Kayarat,
Griffiths Stuart P,
Cook Nicola,
Court Robert,
Wigley Dale B
Publication year - 2008
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2008.144
Subject(s) - biology , helicase , genetics , dna , computational biology , gene , rna
The molecular mechanism of superfamily 1Bα helicases remains unclear. We present here the crystal structure of the RecD2 helicase from Deinococcus radiodurans at 2.2‐Å resolution. The structure reveals the folds of the 1B and 2B domains of RecD that were poorly ordered in the structure of the Escherichia coli RecBCD enzyme complex reported previously. The 2B domain adopts an SH3 fold which, although common in eukaryotes, is extremely rare in bacterial systems. In addition, the D. radioduran s RecD2 structure has aided us in deciphering lower resolution (3.6 Å) electron density maps for the E. coli RecBCD enzyme in complex with a long DNA substrate that interacts with the RecD subunit. Taken together, these structures indicated an important role for the 1B domain of RecD, a β‐hairpin that extends from the surface of the 1A domain and interacts with the DNA substrate. On the basis of these structural data, we designed a mutant RecD2 helicase that lacks this pin. The ‘pin‐less’ mutant protein is a fully active ssDNA‐dependent ATPase but totally lacks helicase activity.