Ligand Binding in the Conserved Interhelical Loop of CorA, a Magnesium Transporter from Mycobacterium tuberculosis*

AUTOR(ES)

Hu, Jian

FONTE

American Society for Biochemistry and Molecular Biology

RESUMO

CorA is a constitutively expressed magnesium transporter in many bacteria. The crystal structures of Thermotoga maritima CorA provide an excellent structural framework for continuing studies. Here, the ligand binding properties of the conserved interhelical loop, the only portion of the protein exposed to the periplasmic space, are characterized by solution nuclear magnetic resonance spectroscopy. Through titration experiments performed on the isolated transmembrane domain of Mycobacterium tuberculosis CorA, it was found that two CorA substrates (Mg2+ and Co2+) and the CorA-specific inhibitor (Co(III) hexamine chloride) bind in the loop at the same binding site. This site includes the glutamic acid residue from the conserved “MPEL” motif. The relatively large dissociation constants indicate that such interactions are weak but not atypical for channels. The present data support the hypothesis that the negatively charged loop could act as an electrostatic ring, increasing local substrate concentrations before transport across the membrane.

Documentos Relacionados

• Magnesium transport in Salmonella typhimurium: 28Mg2+ transport by the CorA, MgtA, and MgtB systems.
• The CorA Mg2+ Transporter Is a Homotetramer
• The CorA Mg2+ Transporter Does Not Transport Fe2+
• Functional Similarity between Archaeal and Bacterial CorA Magnesium Transporters
• Magnesium Uptake by CorA Is Essential for Viability of the Gastric Pathogen Helicobacter pylori