Co2+ Selectivity of Thermotoga maritima CorA and Its Inability to Regulate Mg2+ Homeostasis Present a New Class of CorA Proteins

CorA is a family of divalent cation transporters ubiquitously present in bacteria and archaea. Although CorA can transport both Mg2+ and Co2+ almost equally well, its main role has been suggested to be that of primary Mg2+ transporter of prokaryotes and hence the regulator of Mg2+ homeostasis. The r...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of biological chemistry 2011-05, Vol.286 (18), p.16525-16532
Main Authors: Xia, Yu, Lundbäck, Anna-Karin, Sahaf, Newsha, Nordlund, Gustav, Brzezinski, Peter, Eshaghi, Said
Format: Article
Language:English
Subjects:
Bacterial Metabolism
Cation Transport Proteins - genetics
Cation Transport Proteins - metabolism
Cobalt - metabolism
Homeostasis - physiology
Ion Channels
Magnesium - metabolism
Membrane Function
Membrane Proteins
Membrane Trafficking
Metals
Microbiology
Thermotoga maritima - genetics
Thermotoga maritima - metabolism
Transporter
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:CorA is a family of divalent cation transporters ubiquitously present in bacteria and archaea. Although CorA can transport both Mg2+ and Co2+ almost equally well, its main role has been suggested to be that of primary Mg2+ transporter of prokaryotes and hence the regulator of Mg2+ homeostasis. The reason is that the affinity of CorA for Co2+ is relatively low and thus considered non-physiological. Here, we show that Thermotoga maritima CorA (TmCorA) is incapable of regulating the Mg2+ homeostasis and therefore cannot be the primary Mg2+ transporter of T. maritima. Further, our in vivo experiments confirm that TmCorA is a highly selective Co2+ transporter, as it selects Co2+ over Mg2+ at >100 times lower concentrations. In addition, we present data that show TmCorA to be extremely thermostable in the presence of Co2+. Mg2+ could not stabilize the protein to the same extent, even at high concentrations. We also show that addition of Co2+, but not Mg2+, specifically induces structural changes to the protein. Altogether, these data show that TmCorA has the role of being the transporter of Co2+ but not Mg2+. The physiological relevance and requirements of Co2+ in T. maritima is discussed and highlighted. We suggest that CorA may have different roles in different organisms. Such functional diversity is presumably a reflection of minor, but important structural differences within the CorA family that regulate the gating, substrate selection, and transport.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M111.222166