DNA fragments containing the sequence d(GCGAAAGC) prefer to adopt a base-intercalated (zipper-like) duplex in the crystalline state. To investigate effects of point mutation at the 5th residue on the structure, two crystal structures of d(GCGAGAGC) and d(GCGATAGC) have been determined by X-ray crystallography. In the respective crystals, the two octamers related by a crystallographic two-fold symmetry are aligned in an anti-parallel fashion and associated to each other to form a duplex, suggesting that the base-intercalated duplex is stable even when the 5th residue is mutated with other bases. The sheared G3:A6 pair formation makes the two phosphate backbones closer and facilitates formation of the A-X*-X-A* base-intercalated motif. The three duplexes are assembled around the three-fold axis, and their 3rd and 4th residues are bound to the hexamine cobalt chloride. The central 5th residues are bound to another cation.
X-ray analyses of d(GCGAXAGC) containing G and T at X: the base-intercalated duplex is still stable even in point mutants at the fifth residue.,Kondo J, Umeda S, Fujita K, Sunami T, Takenaka A J Synchrotron Radiat. 2004 Jan 1;11(Pt 1):117-20. Epub 2003 Nov 28. PMID:14646150[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Kondo J, Umeda S, Fujita K, Sunami T, Takenaka A. X-ray analyses of d(GCGAXAGC) containing G and T at X: the base-intercalated duplex is still stable even in point mutants at the fifth residue. J Synchrotron Radiat. 2004 Jan 1;11(Pt 1):117-20. Epub 2003 Nov 28. PMID:14646150
