Plasmids and Genetic Diversity of L pneumophila

Genome comparison of strains Paris, Lens, and Philadelphia 1 identified a conserved backbone of 2500 genes and about 300 strain-specific genes representing 9-11% of the genome (Fig. 15.4). The strain-specific complement of each of these three strains contains several transcriptional regulators, some GGDEF/EAL regulators (Table 15.4), which represent a very prominent family of regulators in L.pneumophila, different ankyrin proteins (Table 15.3), and several restriction modification systems. Many of the strain-specific genes are of as yet unknown function. However, this specific gene complement may allow adaptations to different environments. In addition to the high genetic diversity present in the L. pneu-mophila chromosomes, strain-specific plasmids were also identified in strains

Plasmid Family

Fig. 15.4 Core genome and unique gene complement of L. pneumophila strains Paris, Lens, and Philadelphia. Orthologous genes were defined by reciprocal best-match FASTA comparisons. The threshold was set to a minimum of 80% sequence identities and a ratio of the length of 0.75 to 1.33. * indicates that plasmid genes were not considered in the calculation.

Fig. 15.4 Core genome and unique gene complement of L. pneumophila strains Paris, Lens, and Philadelphia. Orthologous genes were defined by reciprocal best-match FASTA comparisons. The threshold was set to a minimum of 80% sequence identities and a ratio of the length of 0.75 to 1.33. * indicates that plasmid genes were not considered in the calculation.

Tab. 15.4 GGDEF/EAL regulator family and its distribution in the three sequenced genomes.

Paris

Gene name Lens

Philadelphia

Domains

TMa helices

lpp0029

lpl0030

lpg0029

3 PAS, GGDEF, EAL

0 0

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