Functional coexistence of twin arsenic resistance systems in Pseudomonas putida KT2440
Functional coexistence of twin arsenic resistance systems in Pseudomonas putida KT2440
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DOI：
10.1111/1462-2920.12464
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发表时间：
2015-01-01
影响因子：
5.1
通讯作者：
de Lorenzo, Victor
中科院分区：
文献类型：
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作者：
David Paez-Espino, A.;Durante-Rodriguez, Gonzalo;de Lorenzo, Victor
土壤细菌PseudomonasputidaKT 2440的基因组具有两个几乎相同的arsRBCH操纵子puridium编码抗无机砷物种。对这种细菌的这些ars簇中的每一个的单染色体和双染色体缺失进行了砷敏感性测试，发现每个操纵子对类金属抗性的贡献不是累加的，因为任何簇都足以赋予细胞高水平的抗性。然而，当温度降低时，与每个ars位点相关的其他相同性状发生了分化。各种突变体在15摄氏度（而不是标准的30摄氏度）下的生长揭示了ars2比ars1对应物对As（III）的抗性高得多。arsB1和arsB2基因以及lacZ融合到Pars1和Pars2启动子的逆转录聚合酶链反应追踪了每个温度下相应基因组转录的差异。因此，如果功能冗余提供了一种在更广泛的物理化学环境下表达的关键活性，则可以选择功能冗余作为稳定状态，而不仅仅是短暂状态。这似乎为在不断变化的情况下茁壮成长的环境细菌的监管问题提供了一个简单的解决方案。
The genome of the soil bacterium Pseudomonas putidaKT2440 bears two virtually identical arsRBCH operons putatively encoding resistance to inorganic arsenic species. Single and double chromosomal deletions in each of these ars clusters of this bacterium were tested for arsenic sensitivity and found that the contribution of each operon to the resistance to the metalloid was not additive, as either cluster sufficed to endow cells with high-level resistance. However, otherwise identical traits linked to each of the ars sites diverged when temperature was decreased. Growth of the various mutants at 15 degrees C (instead of the standard 30 degrees C for P.putida) uncovered that ars2 affords a much higher resistance to As (III) than the ars1 counterpart. Reverse transcription polymerase chain reaction of arsB1 and arsB2 genes as well as lacZ fusions to the Pars1 and Pars2 promoters traced the difference to variations in transcription of the corresponding gene sets at each temperature. Functional redundancy may thus be selected as a stable condition - rather than just as transient state - if it affords one key activity to be expressed under a wider range of physicochemical settings. This seems to provide a straightforward solution to regulatory problems in environmental bacteria that thrive under changing scenarios.