Part:BBa_K3970002

The BS module，which is the lexO is the diversification and characterization of the LexA-binding motifs. We find it in an paper. The previously characterized LexA binding motif has a consensus sequence of a 16 bp palindrome, CTGTATATATATACAG. Yeast contains a number of genes regulated by the LexA repressor. These genes, as well as the previously used modified GAL1 promoter with 8 LexA BS, contain a spectrum of sequence modifications deviating from the consensus LexA binding site .Based on the native LexA binding sites present in the regulatory region of the lexA gene and in the ColEI operator, the author designed versions of the LexA BS with minor sequence modifications and tested their binding affinity to purified sTF16 in the electrophoretic mobility shift assay (EMSA) . The sTF16 used was composed of a LexA DNA binding domain, the Herpes simplex virus transactivation domain (VP16) and a 6×His-tag. The results indicate that all four versions of the BSs bind similarly to the LexA-DNA-binding domain in vitro and therefore can also be expected to perform similarly within a synthetic output promoter in vivo.

Reference: Synthetic Transcription Amplifier System for Orthogonal Control of Gene Expression in Saccharomyces cerevisiae;PLOS ONE | DOI:10.1371/journal.pone.0148320