Part of the ABC transporter complex MolBCA involved in molybdate import (PubMed:22078568, PubMed:24722984). Functions as a low-affinity molybdate transporter (PubMed:24722984). Binds to both molybdate and tungstate, but not to sulfate or phosphate (PubMed:22078568). The MolBCA complex shows a decrease in affinity in the presence of increasing concentrations of substrate and nucleotide. The complex is composed of two ATP-binding proteins (MolC), two transmembrane proteins (MolB) and a solute-binding protein (MolA). Nucleotide binding is coupled to a conformational shift at the periplasmic gate. This shift is akin to unlocking a swinging door: allowing just enough space for molybdate to slip into the cell. The lower cytoplasmic gate, identified as gate I, remains open throughout the MolBC-A mechanism, and cytoplasmic gate II closes in the presence of nucleotide. Belongs to the bacterial solute-binding protein 8 family.