Download MendeleyCharacterization of Lys-698 to met substitution in human plasminogen catalytic domain
Terzyan, S., Wakeham, N., Zhai, P., Rodgers, K., Zhang, X.C.(2004) Proteins 56: 277-284
- PubMed: 15211511
- DOI: https://doi.org/10.1002/prot.20070
- Primary Citation of Related Structures:
1RJX - PubMed Abstract:
Streptokinase (SK) is a human plasminogen (Pg) activator secreted by streptococci. The activation mechanism of SK differs from that of physiological Pg activators in that SK is not a protease and cannot proteolytically activate Pg. Instead, it forms a tight complex with Pg that proteolytically activates other Pg molecules. The residue Lys-698 of human Pg was hypothesized to participate in triggering activation in the SK-Pg complex. Here, we report a study of the Lys-698 to Met substitution in the catalytic domain of Pg (microPg) containing the proteolytic activation-resistant background (R561A). While it remains competent in forming a complex with SK, maintaining a comparable equilibration dissociation constant (K(D)), the recombinant protein shows a nearly 60-fold reduction in amidolytic activity relative to its R561A background when mixed with native SK. A 2.3 A crystal structure of this mutant microPg confirmed the correct folding of this recombinant protein. Combined with other biochemical data, these results support the premise that Lys-698 of human Pg plays a functional role in the so-called N-terminal insertion activation mechanism by SK.
Organizational Affiliation:
Crystallography Research Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, Oklahoma 73104, USA.
