Template-free prediction of a new monotopic membrane protein fold and assembly by AlphaFold2

AlphaFold2 (AF2) has revolutionized the field of protein structural prediction. Here, we test its ability to predict the tertiary and quaternary structure of a previously undescribed scaffold with new folds and unusual architecture, the monotopic membrane protein caveolin-1 (CAV1). CAV1 assembles into a disc-shaped oligomer composed of 11 symmetrically arranged protomers, each assuming an identical new fold, and contains the largest parallel 5-barrel known to exist in nature. Remarkably, AF2 predicts both the fold of the protomers and the interfaces between them. It also assembles between seven and 15 copies of CAV1 into disc-shaped complexes. However, the predicted multimers are energetically strained, especially the parallel 5-barrel. These findings highlight the ability of AF2 to correctly predict new protein folds and oligomeric assemblies at a granular level while missing some elements of higher-order complexes, thus positing a new direction for the continued development of deep-learning protein structure prediction approaches.

Automated summary

AlphaFold2 (AF2) has demonstrated its ability to accurately predict the folds and interfaces of a previously undescribed protein called caveolin-1 (CAV1), as well as assemble multiple copies of CAV1 into disc-shaped complexes. However, the predicted multimers seem to be energetically strained, particularly the parallel 5-barrel structure. This study highlights the potential of AF2 in predicting new protein folds and oligomeric assemblies, while suggesting the need for further development in predicting higher-order complexes.