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Published on: November 26, 2011
How does activation loop phosphorylation modulate catalytic activity in the cAMP-dependent protein kinase: a
Yuhui Cheng1, Yingkai Zhang, J Andrew McCammon
1Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of California at Sand Diego, La Jolla, 92093-0365, USA. ycheng@mccammon.ucsd.edu
Protein Science : a Publication of the Protein Society
|March 9, 2006
Summary
Phosphorylation of Thr 197 in protein kinase A (PKA) is crucial for its catalytic activity. This modification stabilizes the transition state, enhancing phosphoryl transfer and influencing protein dynamics and active site conformation.
Area of Science:
- Biochemistry
- Molecular Biology
- Computational Chemistry
Background:
- Protein phosphorylation is a key regulatory mechanism controlling protein function.
- The catalytic subunit of cAMP-dependent protein kinase (PKA) activity is modulated by phosphorylation at Thr 197.
- Understanding this regulation is vital for comprehending enzyme function.
Purpose of the Study:
- To elucidate the theoretical underpinnings of Thr 197 phosphorylation in PKA.
- To investigate the impact of pThr 197 on catalytic activity and enzyme dynamics.
Main Methods:
- Classical molecular dynamics simulations.
- Ab initio quantum mechanics/molecular mechanics (QM/MM) calculations.
- Comparison of wild-type PKA-Mg(2+) ATP-substrate complex with the dephosphorylated T197A mutant.
Main Results:
- Phosphorylated Thr 197 (pThr 197) stabilizes the transition state of the phosphoryl transfer reaction via electrostatic interactions.
- pThr 197 significantly influences essential protein dynamics within the active site.
- The phosphorylation status at Thr 197 affects the active site conformation.
Conclusions:
- Phosphorylation at Thr 197 is a critical determinant of PKA catalytic efficiency.
- pThr 197 plays a dual role: enhancing catalysis and modulating enzyme dynamics and structure.
- Computational methods provide valuable insights into enzyme regulation by post-translational modifications.
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