Architecture and Evolution of Blade Assembly in β-propeller Lectins

Lectins with a β-propeller fold bind glycans on the cell surface through multivalent binding sites and appropriate directionality. These proteins are formed by repeats of short domains, raising questions about evolutionary duplication. However, these repeats are difficult to detect in translated genomes and seldom correctly annotated in sequence databases.

To address these issues, the blade signature of the five types of β-propellers using 3D-structural data was defined. With these templates, we predicted 3,887 β-propeller lectins in 1,889 species were predicted. This information was organized in a searchable online database. The data reveal a widespread distribution of β-propeller lectins across species. Prediction also emphasizes multiple architectures and led to the discovery of a β-propeller assembly scenario. This was confirmed by producing and characterizing a predicted protein coded in the genome of Kordia zhangzhouensis. The crystal structure uncovers an intermediate in the evolution of the β-propeller assembly and illustrates the predictive power of well-curated databases.