Screening and identification of the polypeptides specifically binding to the adhesion protein of Myco-plasma genitalium

Abstract

Objective To screen and identify the polypeptides specifically binding to the adhesion protein of Mycoplasma genitalium(MgPa) by using the Ph.D.-12™ phage display peptide library for further understanding the biological function and the possible pathogenic mechanism of the MgPa. Methods The Ph.D.-12™ phage display peptide library was used for 3 rounds of biopanning with the purified recombinant MgPa (rMgPa) as the given target. The phages were collected for amplification after biopanning. The single strand DNA of phage clones were extracted and purified by using the sodium iodide method for further sequencing. ELISA, competitive binding assay and dot immunobinding assay were performed to analyze the specific binding of positive phages to rMgPa. Results A significant enrichment of phages was achieved after 3 rounds of biopanning. Eleven different phage exogenous sequences (P1-P11) were detected among the 38 phages randomly selected from the agar. Two core sequences were deduced according to the repeating times of amino acids among the 11 polypeptide sequences, which were V-H-W-D-F-R-Q-W-W-Q-P-S and D-W-S-S-W-V-H/Y-R-D-P-Q-T/S. Ten out of the 11 representative phages (P1-P10) specifically combined with the rMgPa. Conclusion Two polypeptides specifically binding to rMgPa were successfully screened out, which provided the tool for further investigation on the biological function of MgPa and the pathogenic mechanism of Mycoplasma genitalium. Key words: Mycoplasma genitalium; Adhesin protein; Ph.D.-12™ Phage Display Peptide Library; Specific binding polypeptides