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The CorA Mg2+ transporter is a homotetramer
Mary Ann Warren1, Lisa M Kucharski, Alexander Veenstra
1Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-4965, USA.
Journal of Bacteriology
|July 3, 2004
Summary
CorA, a magnesium transporter in bacteria and archaea, functions as a homotetramer. Structural analysis reveals transmembrane segments of individual monomers are closely associated within the membrane pore.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- CorA is the primary magnesium (Mg2+) transporter in Bacteria and Archaea.
- Its C-terminal domain features three transmembrane segments, suggesting oligomeric structure.
Purpose of the Study:
- To elucidate the oligomeric state of the CorA transporter.
- To investigate the structural organization of CorA within the cell membrane.
Main Methods:
- Site-directed mutagenesis to introduce cysteine residues at specific locations.
- Chemical cross-linking using formaldehyde and carbon disulfide.
- Oxidation studies to induce disulfide bond formation.
- Purification and structural analysis of soluble domains.
- Mutagenesis of intramembrane residues to cysteine.
Main Results:
- Cysteine substitutions and cross-linking experiments indicated CorA forms a tetramer.
- Analysis of periplasmic domains also supported a tetrameric structure.
- Mutagenesis of intramembrane residues revealed close proximity between TM segments of adjacent monomers.
Conclusions:
- CorA functions as a homotetramer in both Bacteria and Archaea.
- The transmembrane segments of individual CorA monomers are closely associated, forming the Mg2+ transport pore.