Part of the yadCKLM-htrE-yadVN fimbrial operon. Could contribute to adhesion to various surfaces in specific environmental niches. Probably involved in the export and assembly of fimbrial subunits across the outer membrane. Repressed by H-NS. Induced by heat shock. 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 fimbrial export usher family. Incorrect in position 61 onward due to a cloning artifact.