Understanding Magnetite Biomineralisation: The Effect of Short Amino Acid Sequences on the {100} and the {111} Surface

Magnetite (Fe3O4) formation within Magnetospirillum magneticum strain AMB-1 occurs under the influence of the Mms6 protein. It is hypothesised that if key iron binding sites within the C-terminus of the Mms6 protein are substituted for alanine, the protein’s overall iron binding ability is diminished. In this study, an atomistic model of Mms6-driven magnetite formation was developed and the attachment of series amino acid repeats (alanine-alanine, alanine-glutamic acid & glutamic acid-glutamic acid) to the {100} & {111} magnetite surfaces were investigated. Our results suggest the substitution of glutamic acid for alanine residues significantly reduces iron binding affinity of the system, thus confirming the hypothesis. In addition, it is shown that the surface of preferable attachment is the {111} magnetite surface.