Nucleotide sequence, regulation and functional analysis of the papC gene required for cell surface localization of Pap pili of uropathogenic Escherichia coli

The papC gene of uropathogenic Escherichia coli is required for the formation of digalactoside-binding Pap pili. papC forms part of an operon wherein the regulatory gene papB, the major pilin gene papA, a minor pilin-like gene papH, and papC are co-transcribed. Furthermore, the extent of PapC synthesis was found to affect the number of pili expressed on the cell surface. The DNA sequence of the papC gene is presented and its deduced amino acid sequence is compared to that of the FaeD protein encoded by the K88 pili gene cluster. The PapC protein was localized to the E. coli outer membrane where it may form a trans-membrane channel through which pilin subunits are surface localized.