Yang Grace Li, Annika Breidenstein, Ronnie P-A Berntsson, Peter J Christie
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引用次数: 0
摘要
移动遗传因子(MGE)在细菌间的共轭传播是通过在移动遗传因子的转移起源(oriT)序列上组装松弛体开始的。弛豫体组装的一个关键步骤是将催化弛豫酶招募到 oriT 内的 DNA 链特异性切割位点上,但这一步骤尚未明确。在这里,我们通过 AlphaFold 建模、亲和力牵引和体内定点光交联等方法证明,TraK Ribbon-Helix-Helix DNA 结合蛋白通过一种动态的相互作用将 TraI 招募到 oriT 上,在这种相互作用中,TraI 的 C 端非结构域(TraICTD)缠绕在 TraK 的 C 端四聚体结构域上。在弛豫体组装时,构象变化会破坏这种接触,TraICTD 会自我结合,这是弛豫酶催化功能或底物与转移通道结合的先决条件。这些发现描述了模型 MGE 共轭传播所需的关键早期处理反应。
Conjugative transfer of the IncN plasmid pKM101 is mediated by dynamic interactions between the TraK accessory factor and TraI relaxase.
Conjugative dissemination of mobile genetic elements (MGEs) among bacteria is initiated by assembly of the relaxosome at the MGE's origin-of-transfer (oriT) sequence. A critical but poorly defined step of relaxosome assembly involves recruitment of the catalytic relaxase to its DNA strand-specific nicking site within oriT. Here, we present evidence by AlphaFold modeling, affinity pulldowns, and in vivo site-directed photocrosslinking that the TraK Ribbon-Helix-Helix DNA-binding protein recruits TraI to oriT through a dynamic interaction in which TraI's C-terminal unstructured domain (TraICTD) wraps around TraK's C-proximal tetramerization domain. Upon relaxosome assembly, conformational changes disrupt this contact, and TraICTD instead self-associates as a prerequisite for relaxase catalytic functions or substrate engagement with the transfer channel. These findings delineate key early-stage processing reactions required for conjugative dissemination of a model MGE.
期刊介绍:
FEBS Letters is one of the world''s leading journals in molecular biology and is renowned both for its quality of content and speed of production. Bringing together the most important developments in the molecular biosciences, FEBS Letters provides an international forum for Minireviews, Research Letters and Hypotheses that merit urgent publication.