MgtE Homolog FicI Acts as a Secondary Ferrous Iron Importer in Shewanella oneidensis Strain MR-1
Abstract
The transport of metals into and out of cells is necessary for the maintenance of appropriate intracellular concentrations. Metals are needed for incorporation into metalloproteins but become toxic at higher concentrations. Many metal transport proteins have been discovered in bacteria, including the Mg 2+ transporter E (MgtE) family of passive Mg 2+ /Co 2+ cation-selective channels. Low sequence identity exists between members of the MgtE family, indicating that substrate specificity may differ among MgtE transporters. Under anoxic conditions, dissimilatory metal-reducing bacteria, such as Shewanella and Geobacter species, are exposed to high levels of soluble metals, including Fe 2+ and Mn 2+ . Here we characterize SO_3966, which encodes an MgtE homolog in Shewanella oneidensis that we name FicI ( f errous i ron and c obalt i mporter) based on its role in maintaining metal homeostasis. A SO_3966 deletion mutant exhibits enhanced growth over that of the wild type under conditions with high Fe 2+ or Co 2+ concentrations but exhibits wild-type Mg 2+ transport and retention phenotypes. Conversely, deletion of feoB , which encodes an energy-dependent Fe 2+ importer, causes a growth defect under conditions of low Fe 2+ concentrations but not high Fe 2+ concentrations. We propose that FicI represents a secondary, less energy-dependent mechanism for iron uptake by S. oneidensis under high Fe 2+ concentrations.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 15, 2018
- Source ID
- 10.1128/aem.01245-17
Entities
People
- Brittany D. Bennett
- Jeffrey A Gralnick
- Kaitlyn E. Redford
Organizations
- Office of Naval Research