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Kinetic stability as a mechanism for protease longevity.
E L Cunningham1, S S Jaswal, J L Sohl
1Graduate Group in Biophysics, Howard Hughes Medical Institute, Department of Biochemistry, University of California, San Francisco, CA 94143-0448, USA.
Summary
Alpha-lytic protease (alphaLP) achieves stability through kinetics, not thermodynamics, using a pro region to facilitate folding. This results in a metastable, long-lived protease resistant to degradation.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Extracellular serine proteases require stability for function.
- Traditional stability is thermodynamically driven.
- Alpha-lytic protease (alphaLP) exhibits unusual stability.
Purpose of the Study:
- To elucidate the novel stability mechanism of alphaLP.
- To understand the role of the pro region in alphaLP folding and stability.
- To investigate the kinetic stability of alphaLP compared to other proteases.
Main Methods:
- Structural analysis and mutational studies of alphaLP.
- Investigating the interaction between the pro region and the alphaLP C-terminal domain.
- Assessing the proteolytic degradation resistance of alphaLP and homologous proteases.
Main Results:
- AlphaLP stability is kinetically controlled, not thermodynamically.
- The pro region stabilizes the folding transition state and native state of alphaLP.
- AlphaLP exhibits metastability due to a large unfolding barrier and rigidity, enhancing resistance to degradation.
- AlphaLP demonstrates superior survival under proteolytic conditions compared to mammalian proteases.
Conclusions:
- AlphaLP employs a unique kinetic stability mechanism for longevity.
- The pro region is crucial for achieving this metastable state.
- Kinetic stability may be a conserved strategy in bacterial and eukaryotic proteases facing harsh environments.