Identification of macrolide antibiotic-binding human_p8 protein

Clarithromycin is a macrolide antibiotic that is widely used in clinical medicine. Macrolide antibiotics such as clarithromycin specifically bind to the 50S subunit of the bacterial ribosome thereby interfering with protein biosynthesis. A selected peptide sequence from our former study, composed of 19 amino acids, which was isolated from a phage display library because of its ability to bind clarithromycin, displayed significant similarity to a portion of the human_p8 protein. The recombinant p8 protein binds to biotinylated-clarithromycin immobilized on a streptavidin-coated sensor chip and the dissociation constant was determined. The binding of recombinant p8 protein to double-stranded DNA was inhibited by biotinylated-clarithromycin, clarithromycin, erythromycin and azithromycin in gel mobility shift assay. Dechlorogriseofulvin, obtained from a natural product screening, also inhibited human p8 protein binding to DNA. This study illustrates the general utility of the phage display method in detecting protein-ligand interactions.