解码生命 守护健康

Abstract: The plasmid-encoded colistin resistance gene (mcr-1) has recently been reported in various Gram-negative species. However, the expression profile of mcr-1 remains unknown. Here, we investigated the expression of mcr-1 in various plasmids and bacteria. The mcr-1 expression levels in pMCR1_IncX4 varied from 1.81 × 10–5 to 1.05 × 10–4 (pmol per μg total RNA) in the two K. pneumoniae strains SZ03 and SZ04 (ST25) and the two E. coli strains SZ01 and CDA6 (ST2448 and ST167, respectively). The mcr-1 expression levels of pMCR1_IncI2 in E. coli SZ02 (ST2085) and E. coli BJ13 (ST457) were 5.27 × 10–5 and 2.58 × 10–5, respectively. In addition, the expression of chromosomal mcr-1 in ST156 E. coli BJ10 was 5.49×10–5. Interestingly, after 4μg/ml colistin treatment, mcr-1 in pMCR1_IncX4 increased 2- and 4-fold at 20 and 120 mins, respectively, in all pMCR1_IncX4-harboring strains, except for ST2448 E. coli, which had a lower expression after 20 mins that restored to baseline levels after 120 mins. In contrast, mcr-1 expression of pMCR1_IncI2 in the two E. coli strains (SZ02, BJ13) and the chromosomal mcr-1 in E. coli (BJ10) remained at baseline levels after 20 and 120 mins. In the same genetic background host strain E. coli E600, mcr-1 expression of pMCR1_IncX4 and pMCR1_IncI2 were similar and were decreased after colistin treatment for 20 min. However, mcr-1 in pMCR1_IncX4 was up-regulated after colistin treatment for 120 min, while mcr-1 in pMCR1_IncI2 was down-regulated compared to the untreated control. Our results suggested that mcr-1 has distinct expression profiles on different plasmids, bacterial hosts, and after antibiotic treatment.

中文摘要：最近在各种革兰氏阴性菌种中报道了质粒编码的粘菌素抗性基因（mcr-1）。然而，mcr-1的表达谱仍然是未知的。在这里，我们调查了mcr-1在各种质粒和细菌中的表达。在两种肺炎克雷伯菌菌株SZ03和SZ04（ST25）和两种大肠杆菌菌株SZ01和SZ03中，mCR-1的表达水平在1.81×10-5〜1.05×10-4（pmol /μg总RNA） CDA6（分别是ST2448和ST167）。 pMCR1_IncI2在大肠杆菌SZ02（ST2085）和大肠杆菌BJ13（ST457）中的mcr-1表达水平分别为5.27×10-5和2.58×10-5。另外，ST156大肠杆菌BJ10中染色体mcr-1的表达为5.49×10-5。有趣的是，在4μg/ ml粘菌素处理后，在所有携带pMCR1_IncX4的菌株中，在pMCR1_IncX4中的mcr-1分别在20和120分钟增加2和4倍，除了ST2448大肠杆菌（其在20分钟在120分钟后恢复到基线水平。相比之下，两个大肠杆菌菌株（SZ02，BJ13）中的pMCR1_IncI2和大肠杆菌（BJ10）中的染色体mcr-1的mcr-1表达在20和120分钟后保持在基线水平。在相同的遗传背景宿主菌株大肠杆菌E600中，pMCR1_IncX4和pMCR1_IncI2的mcr-1表达相似，并且在粘菌素处理20分钟后降低。然而，与未处理的对照相比，在粘蛋白处理120分钟后，pMCR1_IncX4中的mcr-1上调，而pMCR1_IncI2中的mcr-1下调。我们的研究结果表明，mcr-1在不同的质粒，细菌宿主和抗生素处理后具有不同的表达谱。

DOI: 10.18632/oncotarget.22538