Part of the ABC transporter complex YkoCDEF that could transport hydroxymethylpyrimidine (HMP) and/or thiamine. Could also transport other HMP-containing products. Probably responsible for the translocation of the substrate across the membrane (Probable). The complex is composed of two ATP-binding proteins (YkoD), two transmembrane proteins (YkoC and YkoE) and a solute-binding protein (YkoF). Belongs to the CbiQ family.