FIG. 1.

Structure of the rtxA region, ΔrtxA mutant, and complementing constructs. All constructs are in single copy in the L. pneumophila chromosome except pJDC20, which is present in the low-copy-number (26) plasmid pYUB289 (3, 15). The ΔrtxA mutant carries an in-frame deletion in the rtxA gene, producing a 130-amino-acid protein product, consisting of 6 amino acids from the amino terminus and 124 amino acids from the carboxy terminus. Gene designations are below the arrows on the constructs illustrating the direction of transcription of the genes. Open boxes in AA100 indicate the positions of the 9-amino-acid repeat sequences characteristic of RTX proteins.