Abstract
Among root membrane proteins of tomato we found a metal binding protein and cloned its cDNA, LeGlp1. Two Cys residues at N-terminus may coordinate to metal ions. In this report, we constructed pBI121 vectors that express LeGlp1 mutants with the Cys residues mutated to Ser. LeGlp1 mutants were isolated from the leaves of transgenic tobacco and examined its metal binding by the affinity to Ni(II) column.
LeGlp1 mutant was synthesized as well as the native LeGlp1 but with rather unstable structure than the native one. Any of the mutants that lost one of the two Cys residues could not bind to the Ni(II) column indicating that the Cys is involved in the metal binding. Green-fluorescence protein fused with the N-terminal extension of LeGlp1 was localized at the Casparian band, which suggests the role of LeGlp1 in the uptake of metal ions.
