Biology Department, University of York, York YO10 5DD, UK.
Biology Department, University of York, York YO10 5DD, UK; York Biomedical Research Institute (YBRI), University of York, York YO10 5NG, UK.
Cell Rep. 2022 Aug 9;40(6):111183. doi: 10.1016/j.celrep.2022.111183.
Gene transfer agents (GTAs) are small virus-like particles that indiscriminately package and transfer any DNA present in their host cell, with clear implications for bacterial evolution. The first transcriptional regulator that directly controls GTA expression, GafA, was recently discovered, but its mechanism of action has remained elusive. Here, we demonstrate that GafA controls GTA gene expression via direct interaction with the RNA polymerase omega subunit (Rpo-ω) and also positively autoregulates its own expression by an Rpo-ω-independent mechanism. We show that GafA is a modular protein with distinct DNA and protein binding domains. The functional domains we observe in Rhodobacter GafA also correspond to two-gene operons in Hyphomicrobiales pathogens. These data allow us to produce the most complete regulatory model for a GTA and point toward an atypical mechanism for RNA polymerase recruitment and specific transcriptional activation in the Alphaproteobacteria.
基因转移因子（GTAs）是一种小型病毒样颗粒，可随意包装和转移其宿主细胞中存在的任何 DNA，这对细菌进化有明显的影响。最近发现了第一个直接控制 GTA 表达的转录调节因子 GafA，但它的作用机制仍不清楚。在这里，我们证明 GafA 通过与 RNA 聚合酶 ω 亚基（Rpo-ω）的直接相互作用来控制 GTA 基因表达，并且通过一种与 Rpo-ω 无关的机制正向自身调控其自身表达。我们表明 GafA 是一种具有独特 DNA 和蛋白质结合结构域的模块化蛋白质。我们在 Rhodobacter GafA 中观察到的功能结构域也对应于 Hyphomicrobiales 病原体中的两个基因操纵子。这些数据使我们能够为 GTA 生成最完整的调控模型，并指向 Alphaproteobacteria 中 RNA 聚合酶募集和特定转录激活的非典型机制。
