Reilman Ewoud, Mars Ruben A T, van Dijl Jan Maarten, Denham Emma L
Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. box 30001, 9700 RB Groningen, the Netherlands.
Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. box 30001, 9700 RB Groningen, the Netherlands
Nucleic Acids Res. 2014 Oct;42(18):11393-407. doi: 10.1093/nar/gku832. Epub 2014 Sep 12.
Expression of particular drug transporters in response to antibiotic pressure is a critical element in the development of bacterial multidrug resistance, and represents a serious concern for human health. To obtain a better understanding of underlying regulatory mechanisms, we have dissected the transcriptional activation of the ATP-binding cassette (ABC) transporter BmrC/BmrD of the Gram-positive model bacterium Bacillus subtilis. By using promoter-GFP fusions and live cell array technology, we demonstrate a temporally controlled transcriptional activation of the bmrCD genes in response to antibiotics that target protein synthesis. Intriguingly, bmrCD expression only occurs during the late-exponential and stationary growth stages, irrespective of the timing of the antibiotic challenge. We show that this is due to tight transcriptional control by the transition state regulator AbrB. Moreover, our results show that the bmrCD genes are co-transcribed with bmrB (yheJ), a small open reading frame immediately upstream of bmrC that harbors three alternative stem-loop structures. These stem-loops are apparently crucial for antibiotic-induced bmrCD transcription. Importantly, the antibiotic-induced bmrCD expression requires translation of bmrB, which implies that BmrB serves as a regulatory leader peptide. Altogether, we demonstrate for the first time that a ribosome-mediated transcriptional attenuation mechanism can control the expression of a multidrug ABC transporter.
特定药物转运蛋白在抗生素压力下的表达是细菌多药耐药性发展的关键因素，对人类健康构成严重威胁。为了更好地理解其潜在调控机制，我们剖析了革兰氏阳性模式细菌枯草芽孢杆菌中ATP结合盒（ABC）转运蛋白BmrC/BmrD的转录激活过程。通过使用启动子-GFP融合和活细胞阵列技术，我们证明了bmrCD基因在针对蛋白质合成的抗生素作用下呈现出时间控制的转录激活。有趣的是，bmrCD的表达仅在指数生长后期和稳定期出现，与抗生素挑战的时间无关。我们发现这是由于过渡态调节因子AbrB的严格转录控制所致。此外，我们的结果表明bmrCD基因与bmrB（yheJ）共转录，bmrB是bmrC上游紧邻的一个小开放阅读框，含有三个可变的茎环结构。这些茎环显然对抗生素诱导的bmrCD转录至关重要。重要的是，抗生素诱导的bmrCD表达需要bmrB的翻译，这意味着BmrB作为一种调控前导肽。总之，我们首次证明核糖体介导的转录衰减机制可以控制多药ABC转运蛋白的表达。
