Additionally, we need to do the same with James Watson and Francis Crick’s canonical right-handed double-stranded (ds) B-DNA structure and histone interactions and expand our view on DNA structure to include non-B-DNA conformations, such as the alternative left-handed DNA (ds-Z-DNA), tightly bent DNA, and looped DNA. Additionally, other unusual nucleic acids, such as multistranded DNAs (e.g., triplex DNA, G-quadruplex DNA, and i-motif DNA molecules), need to be considered when discussing chemical modifications of histones. These noncanonical DNA structures play important roles in regulating transcriptional gene expression but are usually left out of the molecular biological conversation. Researchers need to place an emphasis on the relationship between chemical modifications of histones and not just canonical B-DNA but also alternative and multistranded DNA structures. Adding these noncanonical DNA-based structural factors will further expand our knowledge on how the histone code works, adding another layer to its complexity beyond just chemical modifications of proteins, canonical B-DNA, and epigenetics.
July 14, 2022