Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium.
Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium.
EMBO J. 2019 Mar 1;38(5). doi: 10.15252/embj.2018100323. Epub 2019 Jan 11.
The zoonotic pathogen is part of the Rhizobiales, which are alpha-proteobacteria displaying unipolar growth. Here, we show that this bacterium exhibits heterogeneity in its outer membrane composition, with clusters of rough lipopolysaccharide co-localizing with the essential outer membrane porin Omp2b, which is proposed to allow facilitated diffusion of solutes through the porin. We also show that the major outer membrane protein Omp25 and peptidoglycan are incorporated at the new pole and the division site, the expected growth sites. Interestingly, lipopolysaccharide is also inserted at the same growth sites. The absence of long-range diffusion of main components of the outer membrane could explain the apparent immobility of the Omp2b clusters, as well as unipolar and mid-cell localizations of newly incorporated outer membrane proteins and lipopolysaccharide. Unipolar growth and limited mobility of surface structures also suggest that new surface variants could arise in a few generations without the need of diluting pre-existing surface antigens.
人畜共患病原体是根瘤菌目的一部分，根瘤菌目是具有单极生长的α-变形菌。在这里，我们表明，这种细菌在外膜组成上表现出异质性，粗糙型脂多糖簇与必需的外膜孔蛋白 Omp2b 共定位，Omp2b 被认为允许溶质通过孔蛋白进行易化扩散。我们还表明，主要外膜蛋白 Omp25 和肽聚糖被整合到新的极和分裂部位，即预期的生长部位。有趣的是，脂多糖也插入到相同的生长部位。外膜主要成分的长距离扩散的缺失可以解释 Omp2b 簇的明显不流动性，以及新整合的外膜蛋白和脂多糖的单极和中细胞定位。单极生长和表面结构的有限流动性也表明，新的表面变体可以在几代内产生，而不需要稀释预先存在的表面抗原。
