Not part of a putrescine export system (PubMed:27803167). Very similar to a S.typhimurium protein implicated in antimicrobial peptide resistance, but the SapBCDF operon in E.coli is implicated in putrescine export (PubMed:27803167). No change in extracellular putrescine levels. Belongs to the bacterial solute-binding protein 5 family.