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Millisecond time scale conformational flexibility in a hyperthermophile protein at ambient temperature
G Hernandez1, F E Jenney, M W Adams
1Bioscience, Group BS-1, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Summary
Hyperthermophile proteins like rubredoxin are highly thermostable but still flexible. This study reveals rapid conformational opening, challenging the idea that rigidity causes thermal stability in extremophiles.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Dynamics
Background:
- Hyperthermophile proteins exhibit remarkable thermal stability.
- Rubredoxin from Pyrococcus furiosus is the most thermostable protein known.
- The prevailing hypothesis links hyperthermostability to increased conformational rigidity.
Purpose of the Study:
- To investigate the conformational dynamics of Pyrococcus furiosus rubredoxin.
- To determine if protein flexibility contradicts the rigidity hypothesis for hyperthermostability.
Main Methods:
- Utilized hydrogen exchange experiments to probe protein dynamics.
- Analyzed EX(2) exchange kinetics and activation energy values.
- Focused on amide positions and solvent accessibility at 28 degrees C.
Main Results:
- Demonstrated rapid conformational opening (millisecond time frame or faster) for all amide positions.
- Observed exchange activation energies similar to unstructured peptides for protected amides.
- Indicated sufficient flexibility for solvent and catalyst access with minimal structural disruption.
Conclusions:
- The conformational flexibility of Pyrococcus furiosus rubredoxin is significant.
- These findings challenge the hypothesis that enhanced conformational rigidity underlies hyperthermophile protein stability.
- Protein dynamics play a crucial role in the function of thermostable proteins.