FIGURE 3.

Moco binding properties of Arabidopsis MoBP proteins. A, sequence comparison of MoBP C termini. The alignment was generated with ClustalW. Identical residues are shaded in black, and similar residues are shaded in gray. B, Moco binding to MoBP6 and MoBP6 + C terminus (CT) from MoBP3 and MoBP3. For generation of the chimeric protein the last C-terminal 23 amino acids of MoBP3 were fused to MoBP6. 2.5 μm concentrations of each protein were incubated anaerobically with increasing amounts of Moco for 5 min at room temperature. Unbound Moco was removed by gel filtration and the amount of protein-bound Moco subsequently quantified by HPLC FormA analysis (14). Average values were obtained in three duplicate experiments. C, Moco binding to Arabidopsis MoBP wild type proteins and their respective C-terminal-truncated variants. Truncated variants lack the last 27 (MoBP1), 23 (MoBP3), 50 (MoBP4), and 23 (MoBP5) amino acids, respectively. The coincubation reaction contained 2.5 μm concentrations of each protein and 6.4 μm Moco. Proteins and Moco were incubated anaerobically for 5 min at room temperature. Unbound Moco was removed by gel filtration and the amount of protein-bound Moco was subsequently quantified by HPLC FormA analysis (14). Average values were obtained in three duplicate experiments. Error bars, S.E.