Library Construction.
A site directed hlyz library, using the NDT degenerate codon at target sites,was constructed from synthetic oligonucleotides as described in detail elsewhere. The external N-and C-terminal primers included overlap with the EcoRI and XhoI restriction sites in the p416-GAL1-αMF vector.The library was cloned into the p416-GAL1-αMF vector by yeast gap repair homologous recombination in the BJ5464::yEGFP S. cerevisiae strain.The statistics of library coverage were calculated using the GLUE algorithm.