División de Biología Molecular. IPICYT. Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, #2055, Col. Lomas 4ª sección. San Luis Potosí, San Luis Potosí 78216, Mexico.
J Med Microbiol. 2024 Oct;73(10). doi: 10.1099/jmm.0.001905.
. Adherence is a major virulence trait in that, in many strains, depends on the (epithelial adhesin) genes, which confer the ability to adhere to epithelial and endothelial cells of the host. The genes are generally found at subtelomeric regions, which makes them subject to subtelomeric silencing. In , subtelomeric silencing depends on different protein complexes, such as silent information regulator and yKu complexes, and other proteins, such as Repressor/activator protein 1 (Rap1) and Abf1. At the locus, which encodes the main adhesin Epa1, we previously found at least two -acting elements, the protosilencer Sil2126 and the negative element, that contribute to the propagation of silencing from the telomere to the subtelomeric region.. Abf1 binds to the regulatory regions of and other regions at the telomere E-R, thereby negatively regulating transcription.. To determine whether Abf1 and Rap1 silencing proteins bind to previously identified acting elements on the right telomere of chromosome E (E-R subtelomeric region), resulting in negative regulation of transcription and infer Abf1 and Rap1 recognition sites in .. We used chromatin immunoprecipitation (ChIP) followed by quantitative PCR to determine the binding sites for Abf1 and Rap1 in the intergenic regions between and and and , and mutants were used to determine the silencing level of the promoter region.. We found that Abf1 predominantly binds to the promoter region, leading to negative regulation of expression. Furthermore, the mutant , which lacks the last 43 amino acids at its C-terminal end and is defective for subtelomeric silencing, exhibits hyperadherence to epithelial cells compared to the parental strain, suggesting that is derepressed. We also determined the motif-binding sequences for Abf1 and Rap1 in using data from the ChIP assays.. Together these data indicate that Abf1 negatively regulates expression, leading to decreased adhesion of to epithelial cells.
. 黏附性是 的一个主要毒力特征，在许多菌株中，它依赖于 （上皮黏附素）基因，这些基因赋予了与宿主上皮细胞和内皮细胞黏附的能力。 基因通常位于着丝粒末端区域，这使得它们受到着丝粒末端沉默的影响。 在 中，着丝粒末端沉默依赖于不同的蛋白质复合物，如沉默信息调节因子和 yKu 复合物，以及其他蛋白质，如 Repressor/activator protein 1 (Rap1) 和 Abf1。在 基因座，它编码主要黏附素 Epa1，我们之前发现了至少两个 作用元件，原沉默子 Sil2126 和负性元件，它们有助于沉默从端粒传播到着丝粒末端区域。. Abf1 结合到 和其他位于端粒 E-R 的调节区域，从而负调控 转录。. 为了确定 Abf1 和 Rap1 沉默蛋白是否结合到染色体 E 的右端粒上先前鉴定的作用元件（E-R 着丝粒末端区域），从而导致 转录的负调控，并推断 Abf1 和 Rap1 在 中的识别位点。. 我们使用染色质免疫沉淀（ChIP）和定量 PCR 来确定 Abf1 和 Rap1 在 基因和 基因之间的基因间区域以及 基因和 基因之间的结合位点，并且使用突变体来确定 启动子区域的沉默水平。. 我们发现 Abf1 主要结合到 启动子区域，导致 表达的负调控。此外，缺失其 C 末端最后 43 个氨基酸且对着丝粒末端沉默有缺陷的突变体 与亲本菌株相比，对上皮细胞的黏附性显著增强，表明 被去阻遏。我们还使用 ChIP 实验的数据确定了 Abf1 和 Rap1 在 中的结合序列。. 这些数据表明，Abf1 负调控 表达，导致 对上皮细胞的黏附性降低。
