Design of a functionally equivalent nonglycosylated analog of the glycopeptide antibiotic formaecin I

Various nonglycosylated analogs were designed in order to explore the role of glycosylation in formaecin I, an antibacterial glycopeptide of insect origin. The functional behavior of a designed nonglycosylated analog (P⁷,endo P^8a,ΔT¹¹)formaecin I was found to be similar to that of native glycosylated peptide. Both the peptides showed similar antibacterial activities against Escherichia coli and Salmonella strains. The designed nonglycosylated analog (P⁷,endo P^8a,ΔT¹¹)formaecin I has low binding affinity to LPS identical to that of native glycopeptide, formaecin I. Both the peptides have similar killing kinetics and are nontoxic to erythrocytes. Formaecin I and designed nonglycosylated (P⁷,endo P^8a,ΔT¹¹)formaecin I have no definite conformational features associated with them. The glycosylated residue of threonine in formaecin I and proline residues in designed peptide [(P⁷,endo P^8a,ΔT¹¹)formaecin I], possibly help in stabilizing the correct conformation that facilitates presentation of the peptide to its receptor. It is evident that a functionally equivalent nonglycosylated analog of native glycosylated antibacterial peptide can be designed by strategically modifying the sequence.