Part of an ABC transporter complex involved in the uptake of guanosine (PubMed:21926227). Responsible for the translocation of the substrate across the membrane (Probable). May be a nucleoside transporter of broad specificity but with various affinities for different substrates (PubMed:21926227). The complex is composed of two ATP-binding proteins (NupO), two transmembrane proteins (NupP and NupQ) and a solute-binding protein (NupN). Transcriptionally regulated by CodY. Belongs to the binding-protein-dependent transport system permease family.