首页> 外文期刊>Applied and Environmental Microbiology >CatM Regulation of the benABCDE Operon: Functional Divergence of Two LysR-Type Paralogs in Acinetobacter baylyi ADP1
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CatM Regulation of the benABCDE Operon: Functional Divergence of Two LysR-Type Paralogs in Acinetobacter baylyi ADP1

机译:benABCDE操纵子的CatM调节:巴氏不动杆菌ADP1中两个LysR型旁系同源物的功能差异

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Two LysR-type transcriptional regulators, BenM and CatM, control benzoate consumption by the soil bacterium Acinetobacter baylyi ADP1. These homologs play overlapping roles in the expression of multiple genes. This study focuses on the benABCDE operon, which initiates benzoate catabolism. At this locus, BenM and CatM each activate transcription in response to the catabolite cis,cis-muconate. BenM, but not CatM, additionally responds to benzoate as an effector. Regulation by CatM alone is insufficient for growth on benzoate as the sole carbon source. However, three point mutations independently increased CatM-activated benA transcription and enabled growth on benzoate without BenM. Two mutations generate variants with one amino acid change in the 303-residue CatM, CatM(V158M) and CatM(R156H). These substitutions affected regulation of benA differently than that of catB, another CatM-regulated gene involved in benzoate catabolism. In relation to CatM, CatM(V158M) increased cis,cis-muconate-dependent transcription of benA but decreased that of catB. CatM(R156H) increased effector-independent expression of catB compared to CatM. In contrast, cis,cis-muconate was required with CatM(R156H) to activate unusually high benA expression. Thus, induction by cis,cis-muconate depends on both the sequence of CatM and the promoter. A point mutation at position ?40 of the benA promoter enhanced CatM-activated gene expression and altered regulation by CatM(R156H). BenM and CatM bound to the same locations on ben region DNA. The frequency with which spontaneous mutations allow CatM to substitute for BenM might predict that one regulator would be sufficient for controlling benzoate consumption. This prediction is discussed in light of current and previous studies of the BenM-CatM regulon.
机译:两个LysR型转录调节剂BenM和CatM控制土壤细菌Baylyi Alytobacter ADP1对苯甲酸酯的消耗。这些同源物在多个基因的表达中起重叠作用。这项研究的重点是启动苯甲酸酯分解代谢的beABCDE操纵子。在这个基因座,BenM和CatM分别响应于分解代谢物顺式,顺式-粘康酸酯来激活转录。 BenM,但不是CatM,另外还响应苯甲酸酯作为效应子。仅CatM的监管不足以使苯甲酸作为唯一的碳源生长。但是,三个点的突变独立地增加了CatM激活的benA转录,并使其在不含BenM的苯甲酸酯上生长。在303个残基的CatM,CatM(V158M)和CatM(R156H)中,两个突变产生具有一个氨基酸变化的变体。这些取代对benA的调节作用与对catB的调节作用不同,catB是另一种受苯甲酸分解代谢的CatM调节基因。关于CatM,CatM(V158M)增加了beA的顺,顺-粘液依赖性转录,但降低了catB的转录。与CatM相比,CatM(R156H)增加了catB的效应子独立表达。相比之下,CatM(R156H)需要顺式,顺式-粘康酸酯才能激活异常高的benA表达。因此,顺式,顺式-粘康酸酯的诱导取决于CatM的序列和启动子。 benA启动子第40位的点突变增强了CatM激活的基因表达,并改变了CatM(R156H)的调节作用。 BenM和CatM结合到ben区域DNA的相同位置。自发突变允许CatM替代BenM的频率可能预示着一种调节剂足以控制苯甲酸酯的消耗。根据BenM-CatM regulon的当前和以前的研究讨论了这一预测。

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