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Title
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Structure of HinP1I endonuclease reveals a striking similarity to the monomeric restriction enzyme MspI.
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Authors
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Z.Yang,
J.R.Horton,
R.Maunus,
G.G.Wilson,
R.J.Roberts,
X.Cheng.
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Ref.
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Nucleic Acids Res, 2005,
33,
1892-1901.
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PubMed id
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Abstract
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HinP1I, a type II restriction endonuclease, recognizes and cleaves a palindromic
tetranucleotide sequence (G/CGC) in double-stranded DNA, producing 2 nt 5'
overhanging ends. Here, we report the structure of HinP1I crystallized as one
protein monomer in the crystallographic asymmetric unit. HinP1I displays an
elongated shape, with a conserved catalytic core domain containing an
active-site motif of SDX18QXK and a putative DNA-binding domain. Without
significant sequence homology, HinP1I displays striking structural similarity to
MspI, an endonuclease that cleaves a similar palindromic DNA sequence (C/CGG)
and binds to that sequence crystallographically as a monomer. Almost all the
structural elements of MspI can be matched in HinP1I, including both the DNA
recognition and catalytic elements. Examining the protein-protein interactions
in the crystal lattice, HinP1I could be dimerized through two helices located on
the opposite side of the protein to the active site, generating a molecule with
two active sites and two DNA-binding surfaces opposite one another on the outer
surfaces of the dimer. A possible functional link between this unusual
dimerization mode and the tetrameric restriction enzymes is discussed.
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