TOP: A ribbon-diagram of the TEM-52b-lactamase crystal structure. Arrows show positions of the three mutations that contribute to antibiotic resistance.
BOTTOM: X-axis shows the locations of all the mutations predicted by
directed evolution, as well as those found in nature. Y-axis shows the
three methods of directed evolution—DNA analogs, gene shuffling,
mutator strain—and the natural mutants of b-lactamase
that have been identified. Of the eleven mutations predicted by directed
evolution, eight (arrows) have been found in nature.
Courtesy Ray Stevens and Mike Hanson