FIG 1.

The PTS^Ntr components in different bacteria. The operon organization of genes encoding the PTS^Ntr components NPr (A) and EI^Ntr (B) in various bacteria is shown. Homologous genes are shown with the same color; open reading frames that have no homologues in the other regions presented are represented by white arrows. rpoN encodes the nitrogen sigma factor, yhbH encodes a ribosome binding protein, ptsN encodes EIIA^Ntr, ptsK encodes NPr kinase/phosphorylase, ptsO encodes NPr, ptsI encodes an EI-like protein, rppH encodes RNA pyrophosphohydrolase, ptsP encodes EI^Ntr, lgt encodes diacylglyceryl transferase, and thyA encodes thymidylate synthetase. Bcep, Burkholderia cepacia; Bjap, Bradyrhizobium japonicum; Xcam, Xanthomonas campestris; Ecol, Escherichia coli; Abau, Acinetobacter baumannii; Cbur, Coxiella burnetii; Lpne, L. pneumophila; Loak, Legionella oakridgensis; Lhac, Legionella hackeliae; Llan, Legionella lansingensis; Lmic, L. micdadei; and Lgee, Legionella geestiana. The ptsO operon organization found in L. pneumophila is the same in 21 other Legionella species (Fig. 2). (C) Schematic representation of the PTS^Ntr phosphorylation cascade. Phosphoryl groups are sequentially transferred on histidine residues from PEP to EI^Ntr, NPr, and subsequently to EII^Ntr. Phosphorylation of NPr by HPrK/P on serine is also indicated.