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| {{STRUCTURE_1jb8| PDB=1jb8 | SCENE= }} | | {{STRUCTURE_1jb8| PDB=1jb8 | SCENE= }} |
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| '''The Crystal Structure of an RNA/DNA Hybrid Reveals Novel Intermolecular Intercalation'''
| | ===The Crystal Structure of an RNA/DNA Hybrid Reveals Novel Intermolecular Intercalation=== |
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| ==Overview==
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| An intermolecular intercalation of base pairs was found at the CA step in the I222 crystal structure of the RNA.DNA hybrid, r(CAAAGAAAAG).d(CTTTTCTTTG), which contains two-thirds of the polypurine tract sequence of HIV-1 with a substitution of cytosine for the initial adenine. This sequence crystallized in both P212121 and I222 space groups, with an rms difference of only 0.63 A between residues 3 to 18 of the two forms. P212121 and I222 helices are both A-like, but intercalation occurs only in the I222 crystal form. The present structure shows bases stacked in parallel rather than perpendicular as in intercalated DNA (I-DNA). The base intercalation is also different from zipper-like meshing of bases seen in the center of the crystal structure of d(GCGAAAGCT), which does not have Watson-Crick base pairing. The base-step intercalation seen here is reminiscent of domain swapping in proteins; therefore, we call this phenomenon "base-pair swapping." It involves a highly mobile CA step and seems to be sequence-specific and electrostatically stable without disrupting Watson-Crick interactions. It also exhibits a large rise concurrent with unwinding of the helix (low twist). We present a base-pair swapping dimer in nucleic acids.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12872000}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12872000 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12872000}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Rna/dna hybrid]] | | [[Category: Rna/dna hybrid]] |
| [[Category: Rna/dna polypurine tract]] | | [[Category: Rna/dna polypurine tract]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 21:00:29 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 19:57:27 2008'' |