Involvement of Aromatic Amino Acids in Phenylmercury Transport by MerT Protein

概要

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To investigate the role of aromatic amino acids of MerT protein in phenylmercury transport, two merT variants (pMRTm1P and pMRTm2P) with specific site-directed mutations were constructed and examined their effects on C_6H_5Hg^+-transport. Substitution of Phe-36 and Trp-40 residues located on the periplasmic loop of MerT in turn with Ala and Val, respectively, did not affect the Hg^<2+>-uptake, but caused a significant reduction in the C_6H_5Hg^+-uptake by bacterial cells with intact merT gene. Introduction of specific mutations changing Phe-108, 114, 115 to Ala, and Tyr-110, 116 to Ser in the C-terminal region of the third transmembrane of MerT also caused large reduction in the uptake of C_6H_5Hg^+, but had no effect on the Hg^<2+>uptake. In addition, both mutations caused a significant reduction in the hypersensitivity to C_6H_5Hg^+, but without affecting the Hg^<2+>-hypersensitive phenotype. Together these results suggest that the aromatic amino acids of MerT protein may play an important role in the transport of C_6H_5Hg^+ across the cell membrane.
公益社団法人日本薬学会の論文
2006-08-01