DNAlts

DNAlts refers to alternative DNA structures that deviate from the canonical double helix. While the double helix is the most common and stable form of DNA, under specific conditions such as high concentrations of certain bases, the presence of unusual nucleotides, or specific sequence arrangements, DNA can fold into a variety of non-B-DNA conformations. These include quadruplexes (G-quadruplexes and I-motif), triplexes, hairpins, and Z-DNA, among others.

G-quadruplexes, formed by guanine-rich sequences, consist of stacked G-quartets stabilized by Hoogsteen hydrogen bonds. They have been implicated in regulating gene expression and telomere maintenance. I-motif structures are formed by cytosine-rich sequences and are characterized by intercalated C:C+ pairs. Triplex DNA involves a third strand binding to a duplex, typically in the major groove. Z-DNA is a left-handed helix with a zig-zag backbone, often occurring in GC-rich regions and thought to play a role in transcription and recombination.

The biological relevance of these alternative DNA structures is an active area of research. While historically viewed as transient or rare, increasing evidence suggests that some DNAlts are stable and play functional roles within the cell. Their formation can influence DNA replication, transcription, repair, and recombination processes, and their dysregulation has been linked to various diseases, including cancer. Therapeutic strategies targeting these structures are being explored.