Cd(2+)-induced aggregation of Escherichia coli pyrophosphatase.
We report here that Escherichia coli pyrophosphatase aggregates in the presence of millimolar Cd(2+). This highly cooperative process was specific to both the metal ion and the protein and could be reversed fully by decreasing the Cd(2+) concentration. Aggregation was enhanced by Mg(2+), the natural cofactor of pyrophosphatase, and Mn(2+). Mutations at the intersubunit metal-binding site had no effect, whereas mutation at Glu139, which is part of the peripheral metal-binding site found in pyrophosphatase crystals near the contact region between two enzyme molecules, suppressed aggregation. These findings indicate that aggregation is affected by Cd(2+) binding to the peripheral metal-binding site, probably by strengthening intermolecular Trp149-Trp149' stacking interactions.
Zimenkov
Yury V
YV
A. N. Belozersky Institute of Physico-Chemical Biology and School of Chemistry, Moscow State University, Moscow, Russia.
Salminen
Anu
A
Efimova
Irina S
IS
Lahti
Reijo
R
Baykov
Alexander A
AA
D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D011755:Pyrophosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D029968:Escherichia coli Proteins; D002104:Cadmium; D008345:Manganese; D011755:Pyrophosphatases; D008274:Magnesium