Schell M A
Department of Microbiology, University of Georgia, Athens 30602.
Annu Rev Microbiol. 1993;47:597-626. doi: 10.1146/annurev.mi.47.100193.003121.
The LysR family is composed of > 50 similar-sized, autoregulatory transcriptional regulators (LTTRs) that apparently evolved from a distant ancestor into subfamilies found in diverse prokaryotic genera. In response to different coinducers, LTTRs activate divergent transcription of linked target genes or unlinked regulons encoding extremely diverse functions. Mutational studies and amino acid sequence similarities of LTTRs identify: (a) a DNA-binding domain employing a helix-turn-helix motif (residues 1-65), (b) domains involved in coinducer recognition and/or response (residues 100-173 and 196-206), (c) a domain required for both DNA binding and coinducer response (residues 227-253). DNA footprinting studies suggest that in the absence of coinducer many LTTRs bind to regulated promoters via a 15-bp dyadic sequence with a common structure and position (near -65). Coinducer causes additional interactions of LTTRs with sequences near the -35 RNA polymerase binding site and/or DNA bending that results in transcription activation.
LysR家族由50多个大小相似的自调控转录调节因子（LTTRs）组成，这些调节因子显然是从一个遥远的祖先进化而来，形成了存在于不同原核生物属中的亚家族。响应不同的共诱导物，LTTRs激活相关靶基因或编码极其多样功能的非相关调控子的差异转录。对LTTRs的突变研究和氨基酸序列相似性鉴定出：（a）一个采用螺旋-转角-螺旋基序的DNA结合结构域（第1-65位氨基酸残基），（b）参与共诱导物识别和/或响应的结构域（第100-173位和196-206位氨基酸残基），（c）DNA结合和共诱导物响应所需的结构域（第227-253位氨基酸残基）。DNA足迹研究表明，在没有共诱导物的情况下，许多LTTRs通过具有共同结构和位置（靠近-65）的15bp二元序列与受调控的启动子结合。共诱导物导致LTTRs与-35 RNA聚合酶结合位点附近的序列发生额外相互作用和/或DNA弯曲，从而导致转录激活。
