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.
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September 2003
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Research Article|
September 15 2003
Malleable conformation of the elastic PEVK segment of titin: non-co-operative interconversion of polyproline II helix, β-turn and unordered structures
Kan MA;
Kan MA
Muscle Proteomics and Nanotechnology Section, Laboratory of Muscle Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, U.S.A.
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Kuan WANG
Kuan WANG
1
Muscle Proteomics and Nanotechnology Section, Laboratory of Muscle Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, U.S.A.
1To whom correspondence should be addressed (e-mail wangk@exchange.nih.gov).
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Publisher: Portland Press Ltd
Received:
May 13 2003
Revision Received:
June 10 2003
Accepted:
June 20 2003
Accepted Manuscript online:
June 20 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2003
The Biochemical Society, London © 2003
Biochem J (2003) 374 (3): 687–695.
Article history
Received:
May 13 2003
Revision Received:
June 10 2003
Accepted:
June 20 2003
Accepted Manuscript online:
June 20 2003
Citation
Kan MA, Kuan WANG; Malleable conformation of the elastic PEVK segment of titin: non-co-operative interconversion of polyproline II helix, β-turn and unordered structures. Biochem J 15 September 2003; 374 (3): 687–695. doi: https://doi.org/10.1042/bj20030702
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