Abstract
To understand the structural basis of molecular elasticity and protein interaction of the elastic PEVK (Pro-Glu-Val-Lys) segment of the giant muscle protein titin, we carried out a detailed analysis of a representative PEVK module and a 16-module PEVK protein under various environmental conditions. Three conformational states, polyproline II (PPII) helix, β-turn and unordered coil were identified by CD and NMR. These motifs interconvert without long-range co-operativity. As a general trend, the relative content of PPII increases with lower temperature and higher polarity, β-turn increases with lower temperature and lower polarity, and unordered coil increases with higher temperature and higher polarity. NMR studies demonstrate that trans-proline residues are the predominant form at room temperature (22°C), with little trans-to-cis isomerization below 35°C. Ionic strength affects salt bridges between charged side chains, but not the backbone conformation. We conclude that titin PEVK conformation is malleable and responds to subtle environmental changes without co-operativity. This gradual conformational transition may represent a regulatory mechanism for fine-tuning protein interactions and elasticity.
Original language | English |
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Pages (from-to) | 687-695 |
Number of pages | 9 |
Journal | Biochemical Journal |
Volume | 374 |
Issue number | 3 |
DOIs | |
Publication status | Published - Sept 15 2003 |
Externally published | Yes |
Keywords
- Circular dichroism (CD)
- Elastic protein
- Nuclear magnetic resonance (NMR)
- Polyproline II helix-coil (PhC) motif
- Titin
- Trans-to-cis-proline isomerization
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology