Affiliation:
1. Department of Molecular Biosciences, The University of Texas, Austin, Texas, USA
Abstract
ABSTRACT
Vibrio cholerae
is the causative agent of the severe diarrheal disease cholera.
V. cholerae
thrives within the human host, where it replicates to high numbers, but it also persists within the aquatic environments of ocean and brackish water. To survive within these nutritionally diverse environments,
V. cholerae
must encode the necessary tools to acquire the essential nutrient iron in all forms it may encounter. A prior study of systems involved in iron transport in
V. cholerae
revealed the existence of
vciB
, which, while unable to directly transport iron, stimulates the transport of iron through ferrous (Fe
2+
) iron transport systems. We demonstrate here a role for VciB in
V. cholerae
in which VciB stimulates the reduction of Fe
3+
to Fe
2+
, which can be subsequently transported into the cell with the ferrous iron transporter Feo. Iron reduction is independent of functional iron transport but is associated with the electron transport chain. Comparative analysis of VciB orthologs suggests a similar role for other proteins in the VciB family. Our data indicate that VciB is a dimer located in the inner membrane with three transmembrane segments and a large periplasmic loop. Directed mutagenesis of the protein reveals two highly conserved histidine residues required for function. Taken together, our results support a model whereby VciB reduces ferric iron using energy from the electron transport chain.
IMPORTANCE
Vibrio cholerae
is a prolific human pathogen and environmental organism. The acquisition of essential nutrients such as iron is critical for replication, and
V. cholerae
encodes a number of mechanisms to use iron from diverse environments. Here, we describe the
V. cholerae
protein VciB that increases the reduction of oxidized ferric iron (Fe
3+
) to the ferrous form (Fe
2+
), thus promoting iron acquisition through ferrous iron transporters. Analysis of VciB orthologs in
Burkholderia
and
Aeromonas
spp. suggest that they have a similar activity, allowing a functional assignment for this previously uncharacterized protein family. This study builds upon our understanding of proteins known to mediate iron reduction in bacteria.
Funder
HHS | NIH | National Institute of Allergy and Infectious Diseases
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
13 articles.
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