Báo cáo khoa học: A kinetic approach to the dependence of dissimilatory metal reduction by Shewanella oneidensis MR-1 on the outer membrane cytochromes c OmcA and OmcB

A Kinetic Approach to the Dependence of Dissimilatory Metal Reduction by Shewanella Oneidensis MR-1 on the Outer Membrane Cytochromes c OmcA and OmcB

Authors: Jimmy Borloo, Bjorn Vergauwen, Lina De Smet, Ann Brigé, Bart Motte, Bart Devreese, and Jozef Van Beeumen

Field: Laboratory for Protein Biochemistry and Protein Engineering, Ghent University, Belgium

Document Content: This research investigates the role of outer membrane cytochromes c, OmcA and OmcB, in the dissimilatory metal reduction capabilities of the Gram-negative bacterium Shewanella oneidensis MR-1. The study constructs and analyzes mutants lacking OmcA, OmcB, or both, to understand their specific contributions to the reduction of various metals, including Fe(III), V(V), Se(VI), and U(VI). Results indicate that both OmcA and OmcB are essential for Fe(III) reduction, with OmcB being the primary reductase. Furthermore, OmcA and OmcB function as the sole terminal Fe(III) reductases in S. oneidensis MR-1. The research also explores the inhibitory effects of vanadate on these cytochromes and suggests that other proteins may be involved in Se(VI) and U(VI) respiration.

Detailed Contents:

• Keywords: kinetic enzyme parameters; metal reduction; outer membrane cytochromes c OmcA and OmcB; Shewanella oneidensis MR-1; terminal reductases
• Correspondence details
• Abstract
• Growth analyses of anaerobically metal-respiring omcA, omcB and omcA omcB MR-1R mutants relative to their MR-1R parent
• Decaheme cytochrome c quantification of anaerobically Fe(III)-respiring omcA¯, omcB and omcA omcB MR-1R mutants relative to their MR-1R parent
• Figure 1: Anaerobic liquid growth experiments
• Figure 2: Heme quantifications reveal unaltered protein production profiles
• Figure 3: Kinetic characterization of OmcA- and OmcB-dependent Fe(III)-nitrilotriacetic acid reduction
• Table 1: Enzymatic properties of OmcA- and OmcB-dependent Fe(III)-nitrilotriacetic acid reduction
• Figure 4: Competition assays of OmcA- and OmcB-dependent Fe(III)-nitrilotriacetic acid reduction with other metals
• Figure 5: Analysis of the modes of inhibition of OmcA- and OmcB-dependent Fe(III) reduction by V(V)
• Discussion
• Experimental procedures
• Acknowledgements
• References