S-phosphocysteine and phosphohistidine are intermediates in the phosphoenolpyruvate-dependent mannitol transport catalyzed by Escherichia coli EII/sup Mtl/

During a cycle of mannitol transport and phosphorylation, the phosphoryl group originating on P-enolpyruvate is transferred, consecutively, to two sites on the Escherichia coli mannitol-specific carrier (EII/sup Mtl/) before being placed on mannitol. The peptides constituting the two EII/sup Mtl/ phosphorylation sites have been isolated and identified after labeling with [32P]-P-enolpyruvate. The first site is localized in peptide Leu 541-Lys 560. The hydrolysis characteristics of the phosphorylated peptide indicate that a histidine residue is phosphorylated. The second site is located in peptide Ile 380-Met 393, which contains the activity-linked cysteine (384). The hydrolysis characteristics of the phosphopeptide indicate that Cys 384 is the site of phosphorylation