Open AccessMutations in the Procaspase-3 Dimer Interface Affect the Activity of the Zymogen
Author(s) -
Cristina Pop,
Brett Feeney,
and Ashutosh Tripathy,
A. Clay Clark
Publication year - 2003
Publication title -
biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.43
H-Index - 253
eISSN - 1520-4995
pISSN - 0006-2960
DOI - 10.1021/bi034999p
Subject(s) - affect (linguistics) , zymogen , dimer , chemistry , microbiology and biotechnology , biophysics , biochemistry , communication , biology , enzyme , psychology , organic chemistry
The interface of the procaspase-3 dimer plays a critical role in zymogen maturation. We show that replacement of valine 266, the residue at the center of the procaspase-3 dimer interface, with glutamate resulted in an increase in enzyme activity of approximately 60-fold, representing a pseudoactivation of the procaspase. In contrast, substitution of V266 with histidine abolished the activity of the procaspase-3 as well as that of the mature caspase. While the mutations do not affect the dimeric properties of the procaspase, we show that the V266E mutation may affect the formation of a loop bundle that is important for stabilizing the active site. In contrast, the V266H mutation affects the positioning of loop L3, the loop that forms the bulk of the substrate binding pocket. In some cases, the amino acids affected by the mutations are >20 A from the interface. Overall, the results demonstrate that the integrity of the dimer interface is important for maintaining the proper active site conformation.