Aromatic solutes transporter of Bug (Bordetella uptake gene) protein family; contains the type 2 periplasmic binding fold.
Bug27 binds non-carboxylated solute nicotinamide, in contrast to BugD (aspartic acid transporter) and BugE (glutamate transporter) which both bind aliphatic carboxylated ligands. The Bug (Bordetella uptake gene) protein family is a large family of periplasmic solute-binding (PBP) receptors present in a number of bacterial species, but mainly in proteobacteria. Bug proteins are the PBP components of the tripartite carboxylate transporters (TTT). Their expansive expansion in proteobacteria indicates a large functional diversity.