Part of the ABC transporter complex PotFGHI involved in putrescine uptake (PubMed:8416922, PubMed:23719730). Responsible for the translocation of the substrate across the membrane (Probable). Imports putrescine for maintenance of the optimal concentration of polyamines necessary for cell growth in the presence of glucose (PubMed:23719730). Transport is feedback inhibited by intracellular polyamines. The complex is composed of two ATP-binding proteins (PotG), two transmembrane proteins (PotH and PotI) and a solute-binding protein (PotF). Belongs to the binding-protein-dependent transport system permease family. CysTW subfamily.