The Hammerhead Ribozyme: Structure, Catalysis, and Gene Regulation - Progress in Molecular Biology and Translational Science - page 4

2. THE MINIMAL SEQUENCE
The minimal hammerhead ribozyme ( Fig. 1.1 A and B) consists of a
core region of 15 conserved (mostly invariant) nucleotides flanked by three
helical stems. In 2003, it finally became clear that optimal activity required
the presence of a tertiary interaction between stem(s) I and II. Although there
Figure 1.1 The minimal and full-length hammerhead ribozymes. (A) A schematic rep-
resentation of the secondary structure of the minimal hammerhead ribozyme. (B) The
crystal structure of a corresponding minimal hammerhead ribozyme. The longer strand
is the enzyme and the shorter strand is the substrate. (C) A schematic representation of
the full-length hammerhead ribozyme emphasizing the presence of a tertiary contact
between stem(s) I and II. (D) The crystal structure of a corresponding full-length ham-
merhead ribozyme. Again, the longer strand is the enzyme and the shorter strand is the
substrate.