PNNL

Abstract

The x-ray crystal structure of Shewanella oneidensis OmcA, an extracellular decaheme cytochrome involved in mineral reduction, was solved to a resolution of 2.7 Å. The four OmcA molecules in the asymmetric unit were arranged so the distance between heme-5 on adjacent OmcA monomers was less than 1 nm, indicative of a transient OmcA dimer capable of intermolecular electron transfer. A previously identified hematite binding motif was identified near heme 10, forming a hydroxylated surface that would bring a heme-10 electron egress site to ~ 1 nm of mineral surface.