Members of this protein family contain multiple copies of the beta-propeller-forming Kelch repeat. All are full-length homologs to YjhT of Escherichia coli, which has been identified as a mutarotase for sialic acid. This protein improves bacterial ability to obtain host sialic acid, and thus serves as a virulence factor. Some bacteria carry what appears to be a cyclically permuted homolog of this protein.