A structural comparison of lipopolysaccharide biosynthesis loci of Legionella pneumophila serogroup 1 strains

Abstract

BackgroundThe lipopolysaccharide (LPS) is the major immuno-dominant antigen of all Legionella species including L. pneumophila. Its diversity is the basis for the classification of L. pneumophila into serogroups and monoclonal subgroups and is thought to be involved in strain specific virulence. The understanding of the genetic basis of the LPS-antigen is incomplete. Thus, we analyzed the genetic locus involved in LPS-biosynthesis of L. pneumophila serogroup 1 (Sg1) strains with the focus on strain specific gene composition.ResultsThe LPS-biosynthesis loci of 14 L. pneumophila Sg1 strains comprise two distinct regions: A 15 kb region containing LPS-biosynthesis genes that can be found in all L. pneumophila strains and a Sg1-specific 18 kb region. The 15 kb region is highly conserved among Sg1 strains as reflected by high homologies of single ORFs and by a consistent ORF arrangement. In contrast, the Sg1 specific 18 kb region is variable and partially disrupted by phage related genes. We propose that the region spanning from ORF 6 to ORF 11 of the Sg1-specific region is likely involved in late LPS-modification. Due to the high variability of this small region and various combinations of single ORFs within this region a strain specific LPS-structure could be synthesized including modifications of legionaminic acid derivates.ConclusionsOur data clearly demonstrate that the gene structure of the LPS-biosynthesis locus of L. pneumophila Sg1 strains show significant interstrain variability. These data can be used for further functional analysis of the LPS synthesis to understand pathogenesis and reactivity with monoclonal antibodies. Moreover, variable but strain specific regions can serve as basis for the development of novel genotyping assays.

Legionella pneumophila strain associated with the first evidence of person-to-person transmission of Legionnaires’ disease: a unique mosaic genetic backbone

“…In order to investigate the genetic basis determining the serogroup type of the strain PtVFX/2014 (serogroup 1), we analyzed the nucleotide sequences of two genes ( wzt and wzm ) belonging to the lipopolysaccaride (LPS) cluster of L. pneumophila 39 , since these loci were found to be good genetic markers for discriminating L. pneumophila serogroups 34 35 . In this regard, phylogenetic reconstructions over individual gene alignments were performed through MEGA5 by using the neighbor-joining method with bootstrapping (1000 replicates) and the Kimura-2-parameter for distance estimates.…”

Complete Genome Sequences of the Historical Legionella pneumophila Strains OLDA and Pontiac

“…Genome analyses with Geneious version 9 (10) revealed that the previously described ~30-kb unstable genetic element (11) was absent from strain OLDA, but a pP36-like element (12) is maintained. A deletion of the lag-1 O-acetyltransferase also corroborates its monoclonal antibody-2 (mAb2 = mAb3/1) negative phenotype (13, 14). Strain OLDA is sequence type 1 (ST1) (15) and highly similar (≥98.5%) to the ST1 L. pneumophila reference strain Paris (NC_006368) (16).…”

Population analysis ofLegionella pneumophilareveals the basis of resistance to complement-mediated killing

“…Mapping to the L. pneumophila Philadelphia 1 reference genome (Accession number: AE017354) revealed that 39% (n=673) of the k-mers aligned to a region of the genome spanning between loci lpg0748 and lpg0781 representing an 18 kb cluster of genes involved in LPS biosynthesis and modification ( Fig. 2) (Petzold et al, 2013). A total of 22 genes in this cluster each had at least one significantly enriched k-mer that mapped to it: lpg0751, lpg0752, lpg0755, lpg0758, lpg0759, lpg0760, lpg0761, lpg0762, lpg0766, lpg0767, lpg0768, lpg0769, lpg0771, lpg0772, lpg0773, lpg0774, lpg0775, lpg0777 (lag-1), lpg0778, lpg0779, lpg0780 and lpg0781 (Fig.…”