Putative auto-transporter adhesin, head GIN domain
This bacterial family of proteins shows structural similarity to other pectin lyase families. Although structures from this family align with acetyl-transferases, there is no conservation of catalytic residues found. It is likely that the function is one of cell-adhesion. In Structure 3jx8, it is interesting to note that the sequence of contains several well defined sequence repeats, centred around GSG motifs defining the tight beta turn between the two sheets of the super-helix; there are 8 such repeats in the C-terminal half of the protein, which could be grouped into 4 repeats of two. It seems likely that this family belongs to the superfamily of trimeric auto-transporter adhesins (TAAs), which are important virulence factors in Gram-negative pathogens. In the case of Parabacteroides distasonis, which is a component of the normal distal human gut microbiota, TAA-like complexes probably modulate adherence to the host (information derived from TOPSAN).