| Type: | Domain | Name: | PapD-like |
| Description: | The PapD-like superfamily of periplasmic chaperones directs the assembly of over 30 diverse adhesive surface organelles that mediate the attachment of many different pathogenic bacteria to host tissues, a critical early step in the development of disease. PapD, the prototypical chaperone, is necessary for the assembly of P pili. P pili contain the adhesin PapG, which mediates the attachment of uropathogenic Escherichia colito Gal(alpha) Gal receptors present on kidney cells and are critical for the initiation of pyelonephritis. The PapD-like chaperones consist of two Ig-like domains oriented toward each other, forming L-shaped molecules. In the chaperone-subunit complex, the G1beta strand of the chaperone completes an atypical Ig fold in the subunit by occupying the groove and running parallel to the subunit C-terminal F strand. This donor strand complementation interaction simultaneously stabilises pilus subunits and caps their interactive surfaces, preventing their premature oligomerisation in the periplasm. During pilus biogenesis, the highly conserved N-terminal extension of one subunit has been proposed to displace the chaperone G1beta strand from its neighbouring subunit in a mechanism termed donor strand exchange [].This entry represents the immunoglobulin (Ig)-like beta-sandwich domain found in PapD, as well as in other periplasmic chaperone proteins that include FimC and SfaE from E. coli, and Caf1m from Yersinia pestis[]. In addition, major sperm proteins (MSP) and other related sperm proteins (such as WR4 and SSP-19) contain an Ig-like domain with a similar structural fold to PapD [, ]. Major sperm proteins are central components in molecular interactions underlying sperm motility, with many isoforms existing in Caenorhabditis elegans. | Short Name: | PapD-like |
