PHOSPHOENZYME FORMATION BY PURIFIED, RECONSTITUTED COPPER ATPASE OF ENTEROCOCCUS-HIRAE

The Enterococcus hirae CopB ATPase serves in the secretion of excess c opper from cells and belongs to the recently discovered, new class of heavy metal transport ATPases. We here report the affinity purificatio n of CopB to near homogeneity and its reconstitution into phospholipid vesicles. In these proteoliposomes, the ATPase formed an acylphosphat e reaction intermediate with the gamma-phosphate of ATP. ATPase activi ty and phosphoenzyme formation were inhibited by vanadate with an Iso of 0.1 mM. Our results suggest that heavy metal and non-heavy metal AT Pases operate by the same underlying mechanism.