Figure 3.

Positions of DH1-1A amino acid substitutions within the PI-SceI crystal structure. (A) A ribbon diagram of the PI-SceI structure (colored purple) was generated using SPOCK (52) from coordinates deposited in the RCSB Protein Data Bank (entry 1DFA). The side chains of PI-SceI residues that are substituted in the DH1-1A protein are colored red and are labeled. The endonucleolytic active site is located at the base of the two conserved LAGLIDADG α-helices, which are colored green. (B) The same diagram as in (A) but rotated 180° about the y-axis. Not shown are the side chains for Ile132 and Ile276, which are situated in disordered regions of the crystal structure.