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Molecular characterization and transcriptional analysis of a multidrug resistance gene cloned from the pristinamycin‐producing organism, Streptomyces pristinaespiralis
Author(s) -
Blanc Veronique,
SalahBey Khadidja,
Folcher Marc,
Thompson Charles J.
Publication year - 1995
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1995.mmi_17050989.x
Subject(s) - biology , gene , streptomyces , genetics , open reading frame , microbiology and biotechnology , peptide sequence , bacteria
A multidrug resistance gene ( mdr ) has been cloned from Streptomyces pristinaespiralis , a producer of two antibiotics having synergistic activities together known as pristinamycin. This gene, ptr , provides resistance not only to two structurally dissimilar compounds (pristinamycin I, PI; pristinamycin II, PII) and the natural pristinamycin mixture but also to rifampicin. Mutagenesis and subcloning of ptr localized it to a 2 kb region which was sequenced and analysed. It contained an open reading frame of 1506 bp which encoded a putative membrane protein with 14 hydrophobic domains, and showed sequence similarity to a superfamily of bacterial proteins that employ transmembrane electrochemical gradients to catalyse active efflux of various antibiotics and toxic compounds. Ptr was most similar to a subfamily which included other mdr genes and antibiotic transport genes associated with antibiotic biosynthetic gene clusters in actinomycetes. In vitro coupled transcription‐translation experiments were used to identify the ptr gene product. Analysis of the upstream region did not reveal a divergently transcribed repressor gene, as is the case for several related resistance determinants involved in antibiotic transport, suggesting that ptr is regulated by a different mechanism. Transcriptional analyses of this gene, carried out in both S. pristinaespiralis and Streptomyces lividans , indicated the same transcriptional start point and predicted −10 and −35 hexamers which were somewhat similar to Streptomyces vegetative‐type promoters.