Fazzino Lisa, Tilly Kit, Dulebohn Daniel P, Rosa Patricia A
Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.
Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
Infect Immun. 2015 Dec;83(12):4800-10. doi: 10.1128/IAI.00925-15. Epub 2015 Oct 5.
Borrelia burgdorferi, a causative agent of Lyme borreliosis, is a zoonotic pathogen that survives in nutrient-limited environments within a tick, prior to transmission to its mammalian host. Survival under these prolonged nutrient-limited conditions is thought to be similar to survival during stationary phase, which is characterized by growth cessation and decreased protein production. Multiple ribosome-associated proteins are implicated in stationary-phase survival of Escherichia coli. These proteins include hibernation-promoting factor (HPF), which dimerizes ribosomes and prevents translation of mRNA. Bioinformatic analyses indicate that B. burgdorferi harbors an hpf homolog, the bb0449 gene. BB0449 protein secondary structure modeling also predicted HPF-like structure and function. However, BB0449 protein was not localized in the ribosome-associated protein fraction of in vitro-grown B. burgdorferi. In wild-type B. burgdorferi, bb0449 transcript and BB0449 protein levels are low during various growth phases. These results are inconsistent with patterns of synthesis of HPF-like proteins in other bacterial species. In addition, two independently derived bb0449 mutants successfully completed the mouse-tick infectious cycle, indicating that bb0449 is not required for prolonged survival in the nutrient-limited environment in the unfed tick or any other stage of infection by B. burgdorferi. We suggest either that BB0449 is associated with ribosomes under specific conditions not yet identified or that BB0449 of B. burgdorferi has a function other than ribosome conformation modulation.
伯氏疏螺旋体是莱姆病的病原体，是一种人畜共患病原体，在传播给哺乳动物宿主之前，它能在蜱虫体内营养有限的环境中存活。在这些长期营养有限的条件下存活被认为类似于稳定期的存活，其特征是生长停止和蛋白质产量下降。多种核糖体相关蛋白与大肠杆菌的稳定期存活有关。这些蛋白质包括促进休眠因子（HPF），它使核糖体二聚化并阻止mRNA的翻译。生物信息学分析表明，伯氏疏螺旋体含有一个hpf同源物，即bb0449基因。BB0449蛋白二级结构建模也预测了类似HPF的结构和功能。然而，BB0449蛋白并未定位于体外培养的伯氏疏螺旋体的核糖体相关蛋白组分中。在野生型伯氏疏螺旋体中，bb0449转录本和BB0449蛋白水平在不同生长阶段都很低。这些结果与其他细菌物种中类似HPF蛋白的合成模式不一致。此外，两个独立衍生的bb0449突变体成功完成了小鼠-蜱虫感染周期，表明在未进食的蜱虫体内营养有限的环境中或伯氏疏螺旋体感染的任何其他阶段，延长存活不需要bb0449。我们认为，要么BB0449在尚未确定的特定条件下与核糖体相关，要么伯氏疏螺旋体的BB0449具有除核糖体构象调节之外的其他功能。
