Molecular cloning and functional characterization of an ATP-binding cassette transporter OtrC from <it>Streptomyces rimosus</it>

• Main Authors: Yu Lan, Yan Xiangyun, Wang Long, Chu Ju, Zhuang Yingping, Zhang Siliang, Guo Meijin
• Format: Article
• Language: English
• Published: BMC 2012-08-01
• Series: BMC Biotechnology
• Subjects: <it>Streptomyces rimosus</it>; OtrC; ATP-binding cassette transporter; ATP hydrolysis; Multidrug resistance
• Online Access: http://www.biomedcentral.com/1472-6750/12/52

<p>Abstract</p> <p>Background</p> <p>The <it>otrC</it> gene of <it>Streptomyces rimosus</it> was previously annotated as an oxytetracycline (OTC) resistance protein. However, the amino acid sequence analysis of OtrC shows that it is a putative ATP-binding cassette (ABC) transporter with multidrug resistance function. To our knowledge, none of the ABC transporters in <it>S. rimosus</it> have yet been characterized. In this study, we aimed to characterize the multidrug exporter function of OtrC and evaluate its relevancy to OTC production.</p> <p>Results</p> <p>In order to investigate OtrC’s function, <it>otrC</it> is cloned and expressed in <it>E. coli</it> The exporter function of OtrC was identified by ATPase activity determination and ethidium bromide efflux assays. Also, the susceptibilities of OtrC-overexpressing cells to several structurally unrelated drugs were compared with those of OtrC-non-expressing cells by minimal inhibitory concentration (MIC) assays, indicating that OtrC functions as a drug exporter with a broad range of drug specificities. The OTC production was enhanced by 1.6-fold in M4018 (<it>P</it> = 0.000877) and 1.4-fold in SR16 (<it>P</it> = 0.00973) duplication mutants, while it decreased to 80% in disruption mutants (<it>P</it> = 0.0182 and 0.0124 in M4018 and SR16, respectively).</p> <p>Conclusions</p> <p>The results suggest that OtrC is an ABC transporter with multidrug resistance function, and plays an important role in self-protection by drug efflux mechanisms. This is the first report of such a protein in <it>S. rimosus</it>, and <it>otrC</it> could be a valuable target for genetic manipulation to improve the production of industrial antibiotics.</p>