Structure of d(TGCGCG)·d(CGCGCA) in two crystal forms: effect of sequence and crystal packing in Z-­DNA

✍ Scribed by Thiyagarajan, S. ;Rajan, S. S. ;Gautham, N.

• Book ID: 104478117
• Publisher: International Union of Crystallography
• Year: 2005
• Tongue: English
• Weight: 594 KB
• Volume: 61
• Category: Article
• ISSN: 0907-4449
• DOI: 10.1107/s0907444905016781

✦ Synopsis

The sequence d(TGCGCG).d(CGCGCA) crystallized in two crystal forms, orthorhombic and hexagonal, in the presence of cobalt hexammine chloride, a known inducer of the left-handed Z-form of DNA. The crystal structures have been solved and refined at 1.71 A resolution in space group P2(1)2(1)2(1) and 2.0 A resolution in space group P6(5). The orthorhombic structure contains one Z-DNA hexamer duplex, while the hexagonal structure contains two hexamer duplexes in the structure. Of the latter, one is situated on a crystallographic sixfold screw axis, leading to disorder. This paper reports the effects of sequence and crystal packing on the structure of Z-type DNA. The structures lend additional support to the authors' earlier conclusion that a stretch of four C.G base pairs is sufficient to nucleate and define the regular model of the left-handed helix based on the structure of d(CGCGCG)2.