Evidence for direct interactions between the mercuric ion transporter (MerT) and mercuric reductase (MerA) from the Tn501 mer operon

• Published in: Biometals 2008-04, Vol.21 (2), p.107-116
• Main Authors: Schue, Mathieu, Glendinning, Kerry J, Hobman, Jon L, Brown, Nigel L
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biophysics; Cation Transport Proteins - chemistry; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; DNA Transposable Elements; Enzymes; Escherichia coli - genetics; Escherichia coli - metabolism; Ion transport; Ions; Mercuric ion reductase; Mercuric ion transport; Mercury; Mercury - chemistry; Mercury - metabolism; Operon; Oxidoreductases - chemistry; Oxidoreductases - genetics; Oxidoreductases - metabolism; Protein Structure, Tertiary; protein-protein interactions; Proteins; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Two-Hybrid System Techniques
• ISSN: 0966-0844; 1572-8773
• DOI: 10.1007/s10534-007-9097-4

Mercuric ion resistance in bacteria requires transport of mercuric ions (Hg²⁺) into the cytoplasmic compartment where they are reduced to the less toxic metallic mercury (Hg⁰) by mercuric reductase (MR). The long-established model for the resistance mechanism predicts interactions between the inner membrane mercuric ion transporter, MerT, and the N-terminal domain of cytoplasmic MR, but attempts to demonstrate this interaction have thus far been unsuccessful. A recently developed bacterial two-hybrid protein interaction detection system was used to show that the N-terminal region of MR interacts with the cytoplasmic face of MerT. We also show that the cysteine residues on the cytoplasmic face of the MerT protein are required for maximal mercuric ion transport but not for the interaction with mercuric reductase.