2qs6 | pdb_00002qs6

Structure of a Hoogsteen antiparallel duplex with extra-helical thymines

spinqualitylabelsall models 2qs6, resolution 3.08Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2qs6 is a 14 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Publication Abstract from PubMed We present the crystal structure of the DNA duplex formed by d(ATATATCT). The crystals contain seven stacked antiparallel duplexes in the asymmetric unit with A.T Hoogsteen base pairs. The terminal CT sequences bend over so that the thymines enter the minor groove and form a hydrogen bond with thymine 2 of the complementary strand in the Hoogsteen duplex. Cytosines occupy extra-helical positions; they contribute to the crystal lattice through various kinds of interactions, including a unique CAA triplet. The presence of thymine in the minor groove apparently contributes to the stability of the DNA duplex in the Hoogsteen conformation. These observations open the way toward finding under what conditions the Hoogsteen duplex may be stabilized in vivo. The present crystal structure also confirms the tendency of A.T-rich oligonucleotides to crystallize as long helical stacks of duplexes. Stabilization by extra-helical thymines of a DNA duplex with Hoogsteen base pairs.,Pous J, Urpi L, Subirana JA, Gouyette C, Navaza J, Campos JL J Am Chem Soc. 2008 May 28;130(21):6755-60. Epub 2008 May 1. PMID:18447354 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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