Expression, characterization and structure determination of an active site mutant (Glu202-Gln) of mini-stromelysin-1.Steele, D.L., El-Kabbani, O., Dunten, P., Windsor, L.J., Kammlott, R.U., Crowther, R.L., Michoud, C., Engler, J.A., Birktoft, J.J.
(2000) Protein Eng 13: 397-405
- PubMed: 10877850
- DOI: https://doi.org/10.1093/protein/13.6.397
- Primary Citation of Related Structures:
- PubMed Abstract:
Human stromelysin-1 is a member of the matrix metalloproteinase (MMP) family of enzymes. The active site glutamic acid of the MMPs is conserved throughout the family and plays a pivotal role in the catalytic mechanism. The structural and functional consequences of a glutamate to glutamine substitution in the active site of stromelysin-1 were investigated in this study. In contrast to the wild-type enzyme, the glutamine-substituted mutant was not active in a zymogram assay where gelatin was the substrate, was not activated by organomercurials and showed no activity against a peptide substrate. The glutamine-substituted mutant did, however, bind to TIMP-1, the tissue inhibitor of metalloproteinases, after cleavage of the propeptide with trypsin. A second construct containing the glutamine substitution but lacking the propeptide was also inactive in the proteolysis assays and capable of TIMP-1 binding. X-ray structures of the wild-type and mutant proteins complexed with the propeptide-based inhibitor Ro-26-2812 were solved and in both structures the inhibitor binds in an orientation the reverse of that of the propeptide in the pro-form of the enzyme. The inhibitor makes no specific interactions with the active site glutamate and a comparison of the wild-type and mutant structures revealed no major structural changes resulting from the glutamate to glutamine substitution.
Department of Biochemistry and Molecular Genetics, Oral Cancer Research Center and Research Center in Oral Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.