In-silico prediction of permissive sites of CstH subunit of E. coli CS3 pili for insertion of foreign peptides

Display of peptides on the surface of bacteria have many applications in medicine and biotechnology. Bacterial fimbriae including CS3 pili of E. coli are suitable candidates for expression of foreign epitopes on the surface of bacteria. Permissive sites of this protein، with capability to accept foreign peptides without changes and considerable effects on the structure and function of the protein can be used for expression of foreign peptides. In this study، the permissive sites of the CstH subunit of the CS3 pili were predicted at amino acids 66-67، 100-101 and 109-110 of the mature protein using secondary structure prediction procedures، prediction of disulfide bonds، determination of hydropathy of the protein، alignment of the protein sequence with the sequences in the databases، tertiary structure (modeling) and analysis of the resulted modeles for accessible regions. The results of the in-silico studies were in agreement with the previous laboratory works including display of hexahistidine، cystein reach peptide، ST toxin of enterotoxigenic E. coli and an epitope of Rotavirus NSP4 in this system.