Insertion mutagenesis of the ferric pyoverdine receptor FpvA of Pseudomonas aeruginosa: Identification of permissive sites and a region important forligand binding

Insertion of an 18-amino-acid-encoding sequence within the fpvA gene identi fied permissive sites at residues Y350, A402, R451, R521, and R558, consist ent with these residues occurring in extramembranous loop regions of the pr otein. Insertions at R451, R521, and R558 did not adversely affect receptor function, although insertions at Y350 and A402 compromised ferric pyoverdi ne binding and uptake. The latter region likely contributes to or interacts with the ligand-binding site.