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Histidines in metallothioneins

Previously characterised metallothioneins from yeast, vertebrates, and other animals coordinate metal ions exclusively through thiolate sulfurs. Up until fairly recently, this was a paradigm of metallothioneins. However, quite a number of metallothioneins do contain histidine residues, which may in principle also coordinate metal ions through their imidazole nitrogens (see: Histidines in metallothioneins (JIB 2008)).

We have currently several metallothioneins under study in our lab in which histidine residues play pivotal roles in modulating the metal-binding properties of these intriguing residues.

  • Bacterial metallothioneins homologous to SmtA contain at least one Cys3His site. The His residue in these appears to be vital for an ordered structure in the C-terminal part of these proteins (see: Role of histidines in bacterial MTs (JBIC 2007))his40_detail.jpg

Picture based on pdb 1jjd (Blindauer et al., PNAS 2001).


Picture based on pdb 2kak (Peroza et al., J. Mol. Biol. 2009)