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Open Access Research article

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

Markus Petzold12, Alexander Thürmer1, Susan Menzel1, Johan W Mouton2, Klaus Heuner3 and Christian Lück1*

Author Affiliations

1 Institute of Medical Microbiology and Hygiene, Faculty of Medicine ‘Carl Gustav Carus’, University of Technology Dresden, Fetscherstraße 74, Dresden D-01307, Germany

2 Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, PO Box 9101, Nijmegen, Netherlands

3 Cellular Interactions of Bacterial Pathogens, Centre for Biological Security, Division 2 (ZBS2), Robert Koch-Institute, Nordufer 20, Berlin D-13353, Germany

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BMC Microbiology 2013, 13:198  doi:10.1186/1471-2180-13-198

Published: 4 September 2013

Abstract

Background

The 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.

Results

The 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.

Conclusions

Our 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.

Keywords:
Legionella pneumophila; Lipopolysaccharide; Locus organization; Monoclonal antibody typing