Teitzel Gail M, Geddie Ashley, De Long Susan K, Kirisits Mary Jo, Whiteley Marvin, Parsek Matthew R
Department of Civil and Environmental Engineering, Northwestern University, Evanston, Illinois 60208, USA.
J Bacteriol. 2006 Oct;188(20):7242-56. doi: 10.1128/JB.00837-06.
Transcriptional profiles of Pseudomonas aeruginosa exposed to two separate copper stress conditions were determined. Actively growing bacteria subjected to a pulse of elevated copper for a short period of time was defined as a "copper-shocked" culture. Conversely, copper-adapted populations were defined as cells actively growing in the presence of elevated copper. Expression of 405 genes changed in the copper-shocked culture, compared to 331 genes for the copper-adapted cultures. Not surprisingly, there were genes identified in common to both conditions. For example, both stress conditions resulted in up-regulation of genes encoding several active transport functions. However, there were some interesting differences between the two types of stress. Only copper-adapted cells significantly altered expression of passive transport functions, down-regulating expression of several porins belonging to the OprD family. Copper shock produced expression profiles suggestive of an oxidative stress response, probably due to the participation of copper in Fenton-like chemistry. Copper-adapted populations did not show such a response. Transcriptional profiles also indicated that iron acquisition is fine-tuned in the presence of copper. Several genes induced under iron-limiting conditions, such as the siderophore pyoverdine, were up-regulated in copper-adapted populations. Interesting exceptions were the genes involved in the production of the siderophore pyochelin, which were down-regulated. Analysis of the copper sensitivity of select mutant strains confirmed the array data. These studies suggest that two resistance nodulation division efflux systems, a P-type ATPase, and a two-component regulator were particularly important for copper tolerance in P. aeruginosa.
测定了铜绿假单胞菌在两种不同铜胁迫条件下的转录谱。将短期受到铜浓度升高脉冲作用的活跃生长细菌定义为“铜冲击”培养物。相反，铜适应群体定义为在铜浓度升高情况下活跃生长的细胞。与铜适应培养物中的331个基因相比，“铜冲击”培养物中有405个基因的表达发生了变化。不出所料，两种条件下都鉴定出了一些共同的基因。例如，两种胁迫条件都导致编码几种主动运输功能的基因上调。然而，两种胁迫类型之间存在一些有趣的差异。只有铜适应细胞显著改变了被动运输功能的表达，下调了属于OprD家族的几种孔蛋白的表达。铜冲击产生的表达谱表明存在氧化应激反应，这可能是由于铜参与了类芬顿化学反应。铜适应群体没有表现出这种反应。转录谱还表明，在有铜存在的情况下，铁的获取得到了精细调节。在铁限制条件下诱导的几个基因，如铁载体绿脓菌素，在铜适应群体中上调。有趣的例外是参与铁载体焦铜素产生的基因，这些基因被下调。对选定突变株的铜敏感性分析证实了阵列数据。这些研究表明，两个耐药结节分裂外排系统、一个P型ATP酶和一个双组分调节因子对铜绿假单胞菌的耐铜性尤为重要。
