Part of the yfcOPQRSUV fimbrial operon. Could contribute to adhesion to various surfaces in specific environmental niches. Increases adhesion to eukaryotic T24 bladder epithelial cells in the absence of fim genes. Expression is negatively regulated by H-NS and subjected to cAMP receptor protein (CRP)-mediated catabolite repression. Deletion of the operon under classical laboratory conditions does not result in any major effect on E.coli capacity to form biofilms compared with the wild-type strain. The operon is cryptic under classical laboratory conditions, but is functional when constitutively expressed. Belongs to the periplasmic pilus chaperone family.