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The Poly-E motif in Titin's PEVK region undergoes pH dependent conformational changes
Dassanayake Mudiyanselage Sudarshi Premawardhana1,2, Fang Zhang1, Jin Xu1
1Chemistry Department, University of Massachusetts Lowell, Lowell, MA, 01854, USA.
Biochemistry and Biophysics Reports
|December 9, 2020
Summary
The PEVK region of the muscle protein titin contributes to elasticity. This study found that poly-glutamic acid (poly-E) motifs within PEVK change structure with pH, unlike PPAK motifs, suggesting a role in muscle recoil.
Area of Science:
- Biophysics
- Molecular Biology
- Muscle Physiology
Background:
- The muscle protein titin is essential for passive muscle elasticity.
- The PEVK region of titin, characterized by proline, glutamate, valine, and lysine, is key to this elasticity.
- The PEVK region's disordered structure and molecular interactions remain incompletely understood.
Purpose of the Study:
- To investigate the structural characteristics of PEVK region motifs under varying pH conditions.
- To elucidate the role of specific sequence motifs in titin's elastic properties.
Main Methods:
- Synthesized two 28-residue peptides representing human titin's PEVK region: PPAK and poly-E motifs.
- Measured structural changes of these peptides across a range of pH values.
Main Results:
- The poly-E peptide exhibited a pH-dependent conformational transition, shifting from an elongated to a collapsed state as pH decreased (midpoint ~pH 5.5).
- The PPAK peptide did not show a similar pH-induced conformational shift.
- These findings indicate distinct structural behaviors between the two PEVK motifs.
Conclusions:
- The poly-E motif's pH sensitivity suggests it may act as a nucleation site for PEVK structure in non-extended muscle states.
- Understanding these motif behaviors is crucial for comprehending titin's contribution to muscle elasticity.
Keywords:
Circular dichroismIntrinsically disordered proteinsPEVKPeptide charge repulsionsSecondary structureTitinMore Related Videos
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