Gene duplication facilitates the evolution of biological complexity, as one copy of a gene retains its original function while a duplicate copy can acquire mutations that would otherwise diminish fitness. Duplication has played a particularly important role in the evolution of regulatory networks by permitting novel regulatory interactions and responses to stimuli. The diverse MarR family of transcription factors (MFTFs) illustrate this concept, ranging from highly specific repressors of single operons to pleiotropic global regulators controlling hundreds of genes. MFTFs are often genetically and functionally linked to antimicrobial efflux systems. However, the SlyA MFTF lineage in the Enterobacteriaceae plays little or no role in regulating efflux but rather functions as transcriptional counter-silencers, which alleviate xenogeneic silencing of horizontally acquired genes and facilitate bacterial evolution by horizontal gene transfer. This review will explore recent advances in our understanding of MFTF traits that have contributed to their functional evolution.

中文翻译：

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MarR家族转录因子在调控网络中作为反沉默子的演变。

基因复制促进了生物复杂性的进化，因为一个基因的一个副本保留了其原始功能，而一个副本则可以获取否则会降低适应性的突变。通过允许新颖的调节相互作用和对刺激的反应，复制在调节网络的进化中发挥了特别重要的作用。多样的MarR转录因子家族（MFTF）阐明了这一概念，从单个操纵子的高度特异性阻遏物到控制数百个基因的多效性全局调节剂。MFTF通常在遗传和功能上与抗菌外排系统相关。但是，肠杆菌科中的SlyA MFTF谱系在调节外排中几乎没有或没有任何作用，但起着转录反沉默子的作用，减轻水平获取基因的异种沉默，并通过水平基因转移促进细菌进化。这篇综述将探讨我们对MFTF特征的最新进展，这些特征有助于其功能进化。