Part of the ABC transporter complex XacGHIJK involved in the uptake of xylose and arabinose. The complex is composed of two ATP-binding proteins (XacJ and XacK), two transmembrane proteins (XacH and XacI) and a solute-binding protein (XacG). Transcriptionally up-regulated by both L-arabinose and D-xylose via the pentose-specific regulator XacR. Deletion mutant shows decreased growth rate on arabinose or xylose. It cannot grow on low concentrations of arabinose or xylose. Belongs to the bacterial solute-binding protein 1 family.