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 Thiobacillaus ferrooxidans to pyrite was mediated by aporusticyanin located on the outer surface of the bacterial cell. The mechanism of that adhesion was investigated in more detail. The adhesion of either intact cell or purified aporusticyanin to pyrite was severely inhibited when the mineral was preincubated with ethylenediaminetetraacetic acid, cyanide, or 1,10-phenanthroline. This inhibition was relieved in the presence of sufficient soluble ferrous ions to coordinate the chelator and compete with the pyrite. A His85Ala mutant aporusticyanin bound much less tightly to pyrite than did the wild type apoprotein. Taken together, these observations indicate that binding of the aporusticyanin to solid pyrite is accomplished in part by coordination of the unoccupied copper ligands with iron atoms at the exposed edge of the pyrite crystal lattice.