Adenine-Thymine-rich duplex DNA (AT-rich DNA)

Adenine-Thymine-rich (AT-rich) duplex DNA refers to double-stranded DNA segments with a high proportion of A-T base pairs, which possess distinct structural and electrostatic properties compared to GC-rich regions (Zimmer & Wähnert, 1986). These sequences are frequently located in critical regulatory areas such as promoters (e.g., TATA boxes), origins of replication, and scaffold/matrix attachment regions (S/MARs), where they influence gene expression and chromosomal architecture (Nelson et al., 1987). The minor groove of AT-rich DNA is narrower and more electronegative, providing a unique binding pocket for small molecule ligands known as minor groove binders (MGBs) (Dervan, 2001). By binding to these regions, drugs can physically block the access of transcription factors and enzymes like polymerases, thereby inhibiting DNA replication and transcription. This mechanism is exploited in the development of antimicrobial, antiparasitic, and anticancer agents, such as Pentamidine and Diminazene (Wilson et al., 2008). For instance, minor groove binders can displace essential proteins from the DNA, leading to cell cycle arrest or apoptosis in rapidly dividing cells. In the context of infectious diseases, these agents often target the AT-rich kinetoplast DNA of parasites like Trypanosoma. However, achieving sufficient sequence specificity to avoid broad genotoxicity remains a significant therapeutic challenge in drug design. Despite these challenges, AT-rich DNA remains a foundational target for understanding DNA-ligand interactions and developing site-specific genomic tools.

Other names

AT-rich sequencesAT-rich regionsMinor groove of AT-rich DNAPoly(dA-dT) sequencesA-tracts

Minor groove binding that displaces transcription factors and inhibits DNA-dependent enzymes such as RNA polymerase and DNA polymerase (Zimmer & Wähnert, 1986; Dervan, 2001).