Unexpected interactions of the cyanobacterial metallothionein SmtA with uranium

Abstract

Metallothioneins may protect against the chemical toxicity of uranium; thus, we have studied interactions between the cyanobacterial metallothionein SmtA and uranyl. While no uranyl complexes formed with fully or partially demetalated SmtA, its folded, fully zinc-metalated form bound uranyl even in the presence of large excesses of highly competitive carbonate. 1H NMR signals for methylene groups of three surface-exposed carboxylate side-chains were selectively broadened in presence of uranyl, suggesting their involvement in complex formation