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The Determination of Protease Specificity in Mouse Tissue Extracts by MALDI-TOF Mass Spectrometry: Manipulating PH to Cause Specificity Changes
Published on: May 25, 2018
Structural and kinetic determinants of protease substrates
John C Timmer1, Wenhong Zhu, Cristina Pop
1Apoptosis and Cell Death Research Program at the Burnham Institute for Medical Research, La Jolla, California, USA.
Nature Structural & Molecular Biology
|September 22, 2009
Summary
Protease activity, including caspase-3 and glutamyl endopeptidase (GluC), can occur in alpha-helices, not just unstructured loops. This study defines a kinetic threshold for protease signaling events.
Area of Science:
- Proteomics
- Enzymology
- Molecular Biology
Background:
- Understanding protease specificity is crucial for deciphering cellular signaling pathways.
- Proteases are key regulators of biological processes, but their substrate recognition mechanisms are not fully understood.
- Distinguishing legitimate signaling substrates from non-substrates is a fundamental challenge.
Purpose of the Study:
- To investigate the structural determinants and kinetic properties of protease cleavage sites.
- To identify substrates of caspase-3 and glutamyl endopeptidase (GluC) in Escherichia coli.
- To define the kinetic threshold for protease-mediated signaling events.
Main Methods:
- N-terminal proteomics was employed to identify protease cleavage sites in the E. coli proteome.
- Biochemical and kinetic characterization of protease-substrate interactions.
- Engineering of E. coli substrates to determine catalytic rates and kinetic thresholds.
Main Results:
- Both caspase-3 and GluC were found to cleave alpha-helices as frequently as unstructured loops, challenging existing dogma.
- E. coli caspase-3 substrates exhibited significantly lower catalytic rates compared to natural substrates, suggesting coevolution.
- A kinetic threshold was defined by engineering an E. coli substrate, providing a benchmark for signaling events.
Conclusions:
- Protease cleavage is not restricted to unstructured loops and can occur within alpha-helical structures.
- Protease and substrate coevolution plays a significant role in substrate recognition and catalytic efficiency.
- This study provides novel insights into protease-substrate relationships and validation strategies for large-scale approaches.
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