Department of Genetics, Institute of Molecular and Cell Biology, Tartu University and Estonian Biocentre, 23 Riia Street, 51010 Tartu, Estonia.
Mol Microbiol. 2011 Oct;82(2):265-8. doi: 10.1111/j.1365-2958.2011.07824.x. Epub 2011 Sep 14.
Evolution of catabolic pathways for the degradation of synthetic nitroaromatic compounds is currently ongoing process because these compounds have been in nature only for a short time. Bacteria isolated from contaminated areas contain pathways for the degradation of nitroaromatic compounds at different stages of progression. Therefore, the emergence of pathways for the degradation of such chemicals provides a good opportunity to investigate evolutionary processes leading to the emergence of new metabolic routes and their regulatory systems. In Burkholderia sp. strain DNT the regulatory gene encoding the LysR-type transcriptional regulator DntR is placed divergently of the dinitrotoluene (DNT) dioxygenase genes. This regulator still recognizes salicylate, an effector of its NagR-like ancestor but not DNT. In this issue of Molecular Microbiology, de las Heras et al. demonstrate that the DntR does not respond to any metabolic intermediates of the DNT catabolic pathway. The results of this study suggest that the catabolic pathway for the degradation of DNT has reached to an early stage of evolution when novel specificities of the catabolic enzymes have already acquired but the cognate regulatory system is still missing. This research addresses some fundamental questions about bottlenecks to be solved during evolution of new catabolic operons.
目前，用于降解合成硝基芳香族化合物的分解代谢途径正在不断进化，因为这些化合物在自然界中存在的时间还很短。从污染地区分离出的细菌含有不同阶段进展的硝基芳香族化合物降解途径。因此，降解这些化学物质的途径的出现为研究导致新代谢途径及其调控系统出现的进化过程提供了很好的机会。在伯克霍尔德氏菌属菌株 DNT 中，编码 LysR 型转录调节因子 DntR 的调节基因与二硝基甲苯（DNT）双加氧酶基因呈反向排列。这种调节剂仍然识别水杨酸，它是其 NagR 样祖先的效应物，但不是 DNT。在本期《分子微生物学》中，de las Heras 等人证明 DntR 不会对 DNT 分解代谢途径的任何代谢中间产物做出反应。这项研究的结果表明，DNT 降解的分解代谢途径已经进化到早期阶段，此时已经获得了新型特定的分解代谢酶，但仍缺乏同源调节系统。这项研究解决了新的分解代谢操纵子进化过程中需要解决的一些基本问题。
