Insertion Mutagenesis of the Ferric Pyoverdine Receptor FpvA of Pseudomonas aeruginosa: Identification of Permissive Sites and a Region Important for Ligand Binding

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

在fpvA基因内部插入一段18氨基酸编码序列后，鉴定出位于残基Y350、A402、R451、R521及R558处的允许插入位点，该结果与这些残基位于该蛋白质膜外环区域的特性相符。尽管在Y350与A402位点的插入会损害铁-假单胞菌素（ferric pyoverdine）的结合与摄取能力，但在R451、R521及R558位点的插入并未对受体功能造成不利影响。该区域（即Y350与A402所在的位点区域）可能参与配体结合位点的构成，或与该位点存在相互作用。