Kinetics of Reduction of Fe(III) Complexes by Outer Membrane Cytochromes MtrC and OmcA ofShewanella oneidensisMR-1

• DOI: 10.1128/aem.01454-08
• Publication Date: 2008-09-13T00:44:55Z
• Authors: Zheming Wang; Chongxuan Liu; Xuelin Wang; Matthew J. Marshall; John M. Zachara; Kevin M. Rosso; Michel Dupuis; James K. Fredrickson; Steve Heald; Liang Shi
• Keywords: Shewanella oneidensis

ABSTRACT Because of their cell surface locations, the outer membrane c -type cytochromes MtrC and OmcA Shewanella oneidensis MR-1 have been suggested to be terminal reductases for a range redox-reactive metals that form poorly soluble solids or do not readily cross membrane. In this work, we determined kinetics reduction series Fe(III) complexes with citrate, nitrilotriacetic acid (NTA), EDTA by using stopped-flow technique in combination theoretical computation methods. Stopped-flow kinetic data showed reaction proceeded two stages, fast stage was completed less than 1 s, followed second, relatively slower stage. For given complex, electron transfer faster OmcA. cytochrome, order Fe-EDTA > Fe-NTA Fe-citrate. The could modeled parallel second-order bimolecular redox reactions rate constants ranging from 0.872 μM −1 s between complex 0.012 biphasic attributed potential differences among heme groups site heterogeneity within cytochromes. results reorganization energy calculations influenced mostly large energy. demonstrate ligand complexation plays an important role microbial dissimilatory mineral transformation iron, as well other redox-sensitive metal species nature.