Cell surface proteins in archaeal and bacterial genomes comprising “LVIVD”, “RIVW” and “LGxL” tandem sequence repeats are predicted to fold as β-propeller

Proteins that share even low sequence homologies are known to adopt similar folds. The β-propeller structural motif is one such example. Identifying sequences that adopt a β-propeller fold is useful to annotate protein structure and function. Often, tandem sequence repeats provide the necessary signal for identifying β-propellers in proteins. In our recent analysis to identify cell surface proteins in archaeal and bacterial genomes, we identified some proteins that contain novel tandem repeats “LVIVD”, “RIVW” and “LGxL”. In this work, based on protein fold predictions and three-dimensional comparative modeling methods, we predicted that these repeat types fold as β-propeller. Further, the evolutionary trace analysis of all proteins constituting amino acid sequence repeats in β-propellers suggest that the novel repeats have diverged from a common ancestor.