Comparative analyses of Legionella species to identify genetic features of strains causing Legionnaires' disease. Legionella fallonii LLAP-10 strain:ATCC700992

In this study we show that the comparative analyses of 11 Legionella genomes belonging to five species revealed a highly different genome content with >60% of species-specific genes. These comprise a complete prophage in L. micdadei, the first identified in a Legionella genome and the findng that L. fallonii synthesizes cellulose and an active chitin deacetylase. Mobile elements are abundant. Many encode type IV secretion systems for conjugative transfer pointing to their iportance for adaptation. Although the Dot/Icm secretion system is conserved the core set of substrates is small, as only 24 out of >300 described Dot/Icm effector genes are present in all species. New eukaryotic motifs including thaumatin, synaptobrevin or clathrin/coatomer adaptine like domains were identified. Key factors such as proteins involved in oxygen binding, iron storage, host membrane transport and certain Dot/Icm substrates are specific features of disease related strains.