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A model for transmembrane helix with a cis-proline in the middle
1Molecular Biophysics Unit, Indian Institute of Science, Banglaore, India.
FEBS Letters
|October 23, 1995
Summary
Integral membrane proteins (IMPs) may utilize proline cis-trans isomerization for function. Molecular dynamics simulations reveal that a cis-proline residue can maintain an almost straight alpha-helix structure in IMPs.
Area of Science:
- Biochemistry
- Structural Biology
- Computational Biology
Background:
- Proline residues, particularly in their cis conformation, are found in transmembrane helices of integral membrane proteins (IMPs).
- Cis-trans isomerization of proline is hypothesized to play a role in the function and folding of IMPs.
Purpose of the Study:
- To investigate the structural consequences of incorporating a cis-proline residue into an ideal alpha-helix.
- To explore how integral membrane proteins might accommodate cis-proline and its potential role in function/folding.
Main Methods:
- A molecular dynamics (MD) simulation was performed on a model peptide sequence containing a cis-proline residue within an alpha-helical structure.
- Analysis of the conformational changes adopted by the peptide during the MD simulation.
Main Results:
- The simulation demonstrated that residues near the cis-proline could adopt alternative conformations.
- This allowed the peptide to maintain an overall almost straight alpha-helical structure, despite the presence of cis-proline.
Conclusions:
- Integral membrane proteins can accommodate cis-proline residues within their transmembrane helices without significant disruption of helical structure.
- The observed structural flexibility suggests a plausible mechanism for the involvement of cis-trans isomerization in IMP folding and function.