• Kumud K Singh

      Articles written in Journal of Biosciences

    • Restriction in the cleavage activity of hammerhead ribozymes ensures ongoing evolution in prebiotic RNA world

      Kumud K Singh Subhendu Ghosh

      More Details Abstract Fulltext PDF

      Self-cleaving infectious RNAs found in many plant viruses and viroids can also cleave intrans and form hammerhead type secondary structure. It has been observed that the cleavage site must contain the triplet GUC. Also, in other cases, the sequence XUY holds good where X = A, C, G, U and Y = A, C, U but not G. The high electronegative nature of guanosine holds the key to its resistance to cleavage which does not allow hybrid formation between the ribozyme and substrate strands. Guanosine resistance to cleavage might have been the starting thrust for the evolution of a translational initiation codon from XUG. A hypothesis is proposed in this regard and its evolutionary consequences are discussed briefly.

  • Journal of Biosciences | News

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