Recombinant bacterial lipocalin blc and uses thereof

The present inventors have solved the crystal structure of an Escherichia coli bacterial lipocalin polypeptide, which depicts a monomeric protein. Previous crystal structures have been reported, but these appear to be inaccurate, as they predicted, e.g., a dimeric protein. The crystal structure of a bacterial lipocalin provided by the present invention leads to numerous uses. For example, the present invention provides for the design, construction and use of recombinant libraries of diversified bacterial lipocalins resulting from a bacterial lipocalin polypeptide “backbone”.