Activation by gene amplification of pitB, encoding a third phosphate transporter of Escherichia coli K-12

Two systems for the uptake of inorganic phosphate (P-i) in Escherichia coli, PitA and Pst, have been described. A revertant of a pitA pstS double mutant that could grow on P-i was isolated. We demonstrate that the expression of a new P-i transporter, PitB, is activated in this strain by a gene amplification event