Institute for Microbiology, Center for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany.
Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany.
Microbiologyopen. 2021 Oct;10(5):e1234. doi: 10.1002/mbo3.1234.
Streptococcus suis, an emerging zoonotic pathogen, causes invasive diseases in pigs, including sepsis, meningitis, endocarditis, pneumonia, and arthritis. Importantly, similar pathologies are reported in human S. suis infections. In previous work, the locus SSU0375 of S. suis strain P1.7 had been identified as a conditionally essential gene by intrathecal experimental infection of pigs with a transposon library of S. suis. This study aimed to identify the function of the corresponding gene product. Bioinformatics analysis and homology modeling revealed sequence and structural homologies with the Streptococcus pneumoniae mid-cell-anchored protein Z (MapZ) that is involved in cell division in different bacterial species. Indeed, depletion of this locus in S. suis strain 10 revealed a growth defect as compared to the wild type. Electron microscopy analysis of the corresponding mutant demonstrated morphological growth defects as compared to the wild-type strain, including an irregular cell shape and size as well as mispositioned division septa. Light microscopy and subsequent quantitative image analysis confirmed these morphological alterations. In the genetic rescue strain, the wild-type phenotype was completely restored. In summary, we proposed that SSU0375 or the corresponding locus in strain 10 encode for a S. suis MapZ homolog that guides septum positioning as evidenced for other members of the Streptococci family.
猪链球菌，一种新兴的人畜共患病病原体，可引起猪的侵袭性疾病，包括败血症、脑膜炎、心内膜炎、肺炎和关节炎。重要的是，人类 S. suis 感染也有类似的病理变化。在之前的工作中，猪链球菌 P1.7 菌株的 SSU0375 基因座已被确定为条件必需基因，通过对猪进行 S. suis 转座子文库的鞘内实验感染得到证实。本研究旨在确定相应基因产物的功能。生物信息学分析和同源建模显示与肺炎链球菌中参与不同细菌细胞分裂的中隔锚定蛋白 Z (MapZ)具有序列和结构同源性。事实上，与野生型相比，10 号猪链球菌菌株中该基因座的缺失导致生长缺陷。与野生型菌株相比，相应突变体的电子显微镜分析显示出形态生长缺陷，包括不规则的细胞形状和大小以及错位的分裂隔膜。明场显微镜和随后的定量图像分析证实了这些形态变化。在遗传修复菌株中，野生型表型完全恢复。总之，我们提出 SSU0375 或 10 号菌株中的相应基因座编码猪链球菌 MapZ 同源物，该同源物指导隔膜定位，这与其他链球菌家族成员的情况一致。
