Department of Molecular Medicine, University of South Florida, Tampa, Florida, USA.
Infect Immun. 2024 Jun 11;92(6):e0009024. doi: 10.1128/iai.00090-24. Epub 2024 May 3.
of , the Lyme disease pathogen, encodes a hypothetical protein of unknown function. In this study, we showed that BB0616 was not surface-exposed or associated with the membrane through localization analyses using proteinase K digestion and cell partitioning assays. The expression of was influenced by a reduced pH but not by growth phases, elevated temperatures, or carbon sources during cultivation. A transcriptional start site for was identified by using 5' rapid amplification of cDNA ends, which led to the identification of a functional promoter in the 5' regulatory region upstream of . By analyzing a -deficient mutant and its isogenic complemented counterparts, we found that the infectivity potential of the mutant was significantly attenuated. The inactivation of displayed no effect on borrelial growth in the medium or resistance to oxidative stress, but the mutant was significantly more susceptible to osmotic stress. In addition, the production of global virulence regulators such as BosR and RpoS as well as virulence-associated outer surface lipoproteins OspC and DbpA was reduced in the mutant. These phenotypes were fully restored when gene mutation was complemented with a wild-type copy of . Based on these findings, we concluded that the hypothetical protein BB0616 is required for the optimal infectivity of , potentially by impacting virulence gene expression as well as survival of the spirochete under stressful conditions.
伯氏疏螺旋体的一种假定蛋白，编码一种未知功能的假定蛋白。在本研究中，我们通过蛋白酶 K 消化和细胞分区分析等定位分析表明，BB0616 既不暴露于表面，也不与膜相关。在培养过程中，表达受到 pH 值降低的影响，但不受生长阶段、高温或碳源的影响。通过使用 5' 快速扩增 cDNA 末端鉴定到 的转录起始位点，这导致在 的上游 5' 调控区鉴定到一个功能性启动子。通过分析一个 - 缺陷突变体及其同源互补对照，我们发现突变体的感染力显著减弱。失活 对培养基中的伯氏疏螺旋体生长或对氧化应激的抗性没有影响，但突变体对渗透压应激更敏感。此外，突变体中全局毒力调节剂如 BosR 和 RpoS 以及与毒力相关的外表面脂蛋白 OspC 和 DbpA 的产生减少。当用野生型拷贝基因突变互补时，这些表型完全得到恢复。基于这些发现，我们得出结论，假定蛋白 BB0616 是 最佳感染力所必需的，可能通过影响 毒力基因表达以及螺旋体在应激条件下的存活。
