ATP-binding cassette domain of the phosphate transport system
Phosphate uptake is of fundamental importance in the cell physiology of bacteria because phosphate is required as a nutrient. The Pst system of E. coli comprises four distinct subunits encoded by the pstS, pstA, pstB, and pstC genes. The PstS protein is a phosphate-binding protein located in the periplasmic space. PstA and PstC are hydrophobic and they form the transmembrane portion of the Pst system. PstB is the catalytic subunit, which couples the energy of ATP hydrolysis to the import of phosphate across cellular membranes through the Pst system, often referred as ABC-protein. PstB belongs to one of the largest superfamilies of proteins characterized by a highly conserved adenosine triphosphate (ATP) binding cassette (ABC), which is also a nucleotide binding domain (NBD).
Jiyao W et al.(2023). "The conserved domain database in 2023.",