Assembly of transmembrane helices of simple polytopic membrane proteins from sequence conservation patterns

Area of Science:

• Structural Biology
• Computational Biology
• Biophysics

Background:

• Transmembrane (TM) helix bundle assembly is crucial for membrane protein function but remains computationally challenging.
• Existing methods struggle with predicting the complex structures of even simple TM helix bundles.

Purpose of the Study:

• To develop a novel computational method for predicting native-like structural models of simple transmembrane helix bundle proteins.
• To leverage sequence conservation patterns for accurate structure prediction.

Main Methods:

• The method analyzes sequence conservation from over 30 homologous sequences to identify patterns.
• It computes conformations for contacting TM helix pairs and generates a library of tertiary folds.
• A scoring system based on sequence conservation and clustering analysis refines the models.

Main Results:

• The method achieved Calpha atom root-mean-square deviation (CA RMSD) of 3-5 Å for known proteins like bacteriorhodopsin.
• In blind predictions for V-type Na(+)-adenosine triphosphatase rotor, the best model showed a 3.4 Å CA RMSD and 55% contact accuracy.
• The model accurately identified the sodium ion binding pocket.

Conclusions:

• The developed computational method is effective for ab initio structure prediction of simple TM helix bundle proteins.
• It provides a reliable approach for modeling membrane proteins with modest numbers of TM helices.
• This tool has potential applications in understanding protein function and designing therapeutics.