FIGURE 5.

FMP iron analysis. A, FMP iron was analyzed as described under “Experimental Procedures.” Panel 1, excision of the gel band corresponding to signal 2 in Fig. 1B; panel 2, second migration on native gel: autoradiogram (left side) and Coomassie Blue staining (right side); panel 3, individual spots revealed by Coomassie Blue staining after SDS-PAGE (left lane): from top to bottom, EF-G factor, aconitase, 30 S ribosomal protein S1, HSP-90, trigger factor, arginosuccinate synthetase, serine hydroxymethyltransferase, aspartate-semialdehyde dehydrogenase. The apparent molecular sizes of standard proteins (right lane) in kDa are indicated. B, distribution of iron in parental cells exposed to agents inhibiting protein translation. Native PAGE analysis of protein extracts was performed as described in Fig. 1. The cells were grown in Tris medium containing the concentrations of MgCl₂ indicated, and ⁵⁹Fe-chrysobactin was supplied at the concentration of 0.125 μm. Nalidixic acid, fusidic acid, and tetracycline were added to bacterial cultures at a concentration of 10 μg, 1.2 mg, and 2.5 μg/ml respectively, 5 min before the addition of 0.5 μm ⁵⁹Fe-chrysobactin.