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Title
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Crystallographic identification of an ordered C-terminal domain and a second nucleotide-binding site in RecA: new insights into allostery.
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Authors
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R.Krishna,
G.P.Manjunath,
P.Kumar,
A.Surolia,
N.R.Chandra,
K.Muniyappa,
M.Vijayan.
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Ref.
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Nucleic Acids Res, 2006,
34,
2186-2195.
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PubMed id
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Abstract
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RecA protein is a crucial and central component of the homologous recombination
and DNA repair machinery. Despite numerous studies on the protein, several
issues concerning its action, including the allosteric regulation mechanism have
remained unclear. Here we report, for the first time, a crystal structure of a
complex of Mycobacterium smegmatis RecA (MsRecA) with dATP, which exhibits a
fully ordered C-terminal domain, with a second dATP molecule bound to it. ATP
binding is an essential step for all activities of RecA, since it triggers the
formation of active nucleoprotein filaments. In the crystal filament, dATP at
the first site communicates with a dATP of the second site of an adjacent
subunit, through conserved residues, suggesting a new route for allosteric
regulation. In addition, subtle but definite changes observed in the orientation
of the nucleotide at the first site and in the positions of the segment
preceding loop L2 as well as in the segment 102-105 situated between the 2 nt,
all appear to be concerted and suggestive of a biological role for the second
bound nucleotide.
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