Thiobacillus ferrooxidans binds specifically to iron atoms at the exposed edge of the pyrite crystal lattice

Previous studies from our laboratories suggested that the specific adhesion of Thiobacillus ferrooxidans to pyrite was mediated by aporusticyanin loca ted on the outer surface of the bacterial cell. The mechanism of that adhes ion was investigated in more detail. The adhesion of either intact cell or purified aporusticyanin to pyrite was severely inhibited when the mineral w as preincubated with ethylenediaminetetraacetic acid, cyanide, or I,10-phen anthroline. This inhibition was relieved in the presence of sufficient solu ble ferrous ions to coordinate the chelator and compete with the pyrite. A His85Ala mutant aporusticyanin bound much less tightly to pyrite than did t he wild type apoprotein. Taken together, these observations indicate that b inding of the aporusticyanin to solid pyrite is accomplished in part by coo rdination of the unoccupied copper ligands with iron atoms at the exposed e dge of the pyrite crystal lattice.