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Published on: November 26, 2011
Evidence for phosphorylation-dependent conformational changes in methylesterase CheB
G S Anand1, P N Goudreau, J K Lewis
1Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854, USA.
Protein Science : a Publication of the Protein Society
|June 13, 2000
Summary
Phosphorylation of the CheB response regulator activates its methylesterase activity by inducing conformational changes. These changes reposition regulatory domains, enhancing substrate access and enzyme function.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- The response regulator CheB's methylesterase activity is regulated by phosphorylation.
- The N-terminal regulatory domain has dual roles: inhibitory when unphosphorylated and stimulatory when phosphorylated.
- Structural studies suggest inhibition results from blocked substrate access to the active site.
Purpose of the Study:
- To investigate phosphorylation-dependent conformational changes in CheB.
- To provide evidence supporting a model of CheB activation involving domain repositioning.
Main Methods:
- Comparative analysis of proteolytic cleavage rates by trypsin.
- Examining phosphorylated versus unphosphorylated states of CheB.
- Identifying specific cleavage sites (113, 134, 148) within CheB.
Main Results:
- Observed differences in trypsin cleavage rates between phosphorylated and unphosphorylated CheB.
- Identified three distinct proteolytic cleavage sites.
- One site (113) is in the regulatory domain, and two sites (134, 148) are in the interdomain linker.
Conclusions:
- Results support a mechanism where N-terminal phosphorylation triggers conformational changes.
- These changes propagate within the regulatory domain, leading to domain repositioning.
- Repositioning of N- and C-terminal domains is crucial for stimulating CheB methylesterase activity.
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