FIG. 1.

KapK interacts in vitro with NirA and NplA. Glutathione-agarose columns containing GST-NirA, GST-NplA, or GST were loaded with [³⁵S]methionine-labeled KapK (input), which was prepared in a coupled in vitro transcription-translation system. Columns were washed (see Materials and Methods for details), and fractions were eluted using 5 mM reduced glutathione. The autoradiographs show KapK coeluted with fractions containing GST-NirA (NirA-KapK, left panel) or GST-NplA (NplA-KapK, right panel) fusion proteins. Columns containing only GST did not show KapK in the eluted fractions. KapK showed the expected mass of ∼125 kDa, as determined with a molecular mass marker (not shown). Below the autoradiographs GST and GST fusion proteins of the same elution fractions are visualized by using SDS-PAGE and Coomassie blue staining.