Consecutive A X T pairs can adopt a left-handed DNA structure.

Abstract

The capacity of six sequences with different numbers and orientations of APT pairs flanked by alternating C'G pairs to adopt left-handed structures was evaluated in recombinant plasmids. A series of synthetic oligodeoxynucleotides were cloned into the BamHI site of pRW790, a small plasmid (=%2 kilobases) prepared especially for conformational studies of this type. Supercoil relaxation studies by twodimensional gel electrophoresis on topoisomers of each plasmid revealed the energetics and structures of the left-handed helices. Also, the presence of supercoil-induced altered DNA conformations within the inserts of topoisomer populations of the plasmids was detected by reaction with S1 nuclease followed by restriction mapping of the cleavage sites. We conclude that consecutive TEA base pairs, whether alternating (TATA) or contiguous (TTTT), can adopt a left-handed conformation (presumably Z) when flanked by reasonably short runs of alternating (C-G). (n = 3-5).Thus, these results substantially broaden the range of DNA sequences that can adopt left-handed Z conformations.

The association between microsatellite polymorphisms in intron II of the human Toll-like receptor 2 gene and tuberculosis among Koreans

“…[45][46][47] However, the functional impact of nucleotide repeats in terms of length on the promoter activity is still debated. Longer (GT)n repeats in the promoter of heme oxygenase-1 gene were associated with lower promoter activity.…”

Sequence discrimination of the Zα domain of human ADAR1 during B–Z transition of DNA duplexes

“…The AÁT base pairs partially distort the overall Z-DNA structure by disrupting the hydration spine [16]. The ability of DNA duplexes to undergo the B-Z transition can be ordered as follows: (i) d(CG) repeat (which undergoes the transition most readily), (ii) d(TG/AC) repeat, (iii) d(GGGC) repeat, and (iv) d(TATA) repeat [19,20]. Recently, a structural study revealed that Za ADAR1 binds to the Z-conformation of both non-CG-repeat DNA duplexes and a d(CGCGCG) 2 duplex similarly, suggesting that Za ADAR1 recognizes Z-DNA through a common structural feature rather than by a specific sequence or structural alternations [21].…”

Modulation of Apolipoprotein D and Apolipoprotein E mRNA Expression by Growth Arrest and Identification of Key Elements in the Promoter

“…Because these characteristics correspond to established criteria for Z-DNA formation (55)(56)(57)(58)(59)(60)(61), it is probable that the APP element in the apoD promoter can form Z-DNA. Z-DNA conformations and APP sequences have been associated with both activation (62)(63)(64)(65) and repression (66 -70) of gene expression in mammalian cells.…”