Institute of Medical Microbiology and Hygiene, Faculty of Medicine 'Carl Gustav Carus', University of Technology Dresden, Fetscherstraße 74, Dresden D-01307, Germany.
BMC Microbiol. 2013 Sep 4;13:198. doi: 10.1186/1471-2180-13-198.
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.
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.
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.
脂多糖（LPS）是所有军团菌属物种（包括嗜肺军团菌）的主要免疫显性抗原。其多样性是嗜肺军团菌血清群和单克隆亚群分类的基础，被认为与菌株特异性毒力有关。对 LPS 抗原的遗传基础的了解并不完整。因此，我们分析了血清群 1（Sg1）嗜肺军团菌菌株 LPS 生物合成的遗传基因座，重点关注菌株特异性基因组成。
14 株嗜肺军团菌 Sg1 菌株的 LPS 生物合成基因座包含两个不同的区域：一个包含所有嗜肺军团菌菌株都存在的 LPS 生物合成基因的 15kb 区域和一个 Sg1 特异性的 18kb 区域。15kb 区域在 Sg1 菌株中高度保守，单个 ORF 的高同源性和一致的 ORF 排列反映了这一点。相比之下，Sg1 特异性的 18kb 区域是可变的，部分被噬菌体相关基因破坏。我们提出，Sg1 特异性区域中从 ORF6 到 ORF11 的区域可能参与晚期 LPS 修饰。由于该小区域的高度变异性以及该区域内单个 ORF 的各种组合，可以合成具有军团菌酸衍生物修饰的菌株特异性 LPS 结构。
我们的数据清楚地表明，嗜肺军团菌 Sg1 菌株的 LPS 生物合成基因座的基因结构显示出显著的菌株间变异性。这些数据可用于进一步分析 LPS 合成的功能，以了解发病机制和与单克隆抗体的反应性。此外，可变但具有菌株特异性的区域可以作为新型基因分型检测的基础。
