Identification and characterization of hmr19 gene encoding a multidrug resistance efflux protein from Streptomyces hygroscopicus subsp. yingchengensis strain 10-22

• Published in: Acta biochimica et biophysica Sinica 2004-08, Vol.36 (8), p.519-528
• Main Authors: Qin, Lei, Wang, Heng-An, Wu, Zhong-Qin, Zhang, Xiao-Feng, Jin, Mei-Lei, Deng, Zi-Xin, Zhao, Guo-Ping
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacterial Proteins - genetics; Base Sequence; Chromosome Mapping; Cloning, Molecular; DNA, Bacterial - genetics; Drug Resistance, Multiple, Bacterial - genetics; Energy Metabolism; Gene Deletion; Genes, Bacterial; Genes, MDR; Molecular Sequence Data; Phenotype; Sequence Homology, Amino Acid; Streptomyces - drug effects; Streptomyces - genetics; Streptomyces - metabolism; Tetracycline - metabolism
• ISSN: 1672-9145
• DOI: 10.1093/abbs/36.8.519

The hmr19 gene was cloned from Streptomyces hygroscopicus subsp. yingchengensis strain 10-22, a bacterium strain producing agricultural antibiotics. Sequence similarity comparison indicates that hmr19 gene may encode a predicted protein with 14 putative transmembrane alpha-helical spanners, belonging to the drug:H(+) antiporter-2 family of the major facilitator superfamily. The expression of hmr19 in the mycelium of strain 10-22 was detected by Western blotting analysis. Gene replacement technology was employed to construct an hmr19 disruption mutant. The growth inhibition test against different antibiotics indicated that the mutant strain was 5-20 fold more susceptible to tetracycline, vancomycin and mitomycin C than the parental wild type strain. The mutant took up tetracycline much faster and accumulated more antibiotics than the wild type strain 10-22. While with the addition of an energy uncoupler, carbonyl cyanide m-chlorophenylhydrazone, the characteristics of the accumulation of [(3)H]tetracycline in these two strains were almost the same. It was thus concluded that hmr19 encoded a multidrug resistance efflux protein.