Packing selection of Bacillus lentus subtilisin and a site-specific variant.
The crystallization of a variant of Bacillus lentus subtilisin and the native enzyme was achieved using identical conditions. The variant B. lentus was found to grow in two crystal forms, form 1 and form 2, whereas the native B. lentus subtilisin enzyme crystallized in only one, form 1. Form 2 crystals, once obtained, were found to grow much more rapidly than form 1 crystals. The lattice contacts and structural changes giving both crystal forms have been examined. The results show that crystal form 2 has a more complex network of interactions. There is also a small surface conformational change in the form 2 structure relative to the native and variant form 1 crystals and at least two solvent molecules bound to the enzyme in crystal form 1 are displaced in crystal form 2. In addition, a site specific substitution in the variant at position 27 induces a 'short' lattice contact which does not exist in the native B. lentus or the form 2 variant B. lentus. These results suggest that in some circumstances engineered variants could be designed to crystallize more rapidly than the native enzyme.
Department of Research and Development, Genecor International, Inc., South San Francisco, CA 94080, USA.
J L
JL
Dauberman
G
G
Ganshaw
C
C
Simpson
T P
TP
Graycar
S
S
McGinnis
R
R
Bott