This superfamily represents the thioester domain found near the N-terminus of a variety of bacterial surface proteins and pili. This domain contains an unusual covalent ester bond between a conserved cysteine and glutamine residue PMID:20729215. Thioester-containing domains are unexpectedly prevalent in Gram-positive bacteria, including many clinically relevant pathogens. This suggests that thioester domains may target distinct receptors and have a widespread but currently unappreciated role in mediating pathogen adhesion to hosts PMID:26032562.

The domain is also involved in bacterial-encoded covalent binding as a new molecular principle in host-microbe interactions. Thioesters in bacterial adhesins act like 'chemical harpoons', which microbes can use to irreversibly attach themselves to molecules within their host's tissues PMID:26032562

INTERPRO:IPR013552, PFAM:PF08341,DOI:10.7554/eLife.06638,DOI:10.1074/jbc.M110.149385,DOI:10.1074/jbc.M113.523761