A Transcriptional Regulator of a Pristinamycin Resistance Gene in Streptomyces coelicolor

Abstract

Pip is a pristinamycin-induced transcriptional regulator protein detected in many Streptomyces species by its ability to specifically bind sequence motifs within the promoter of a Streptomyces pristinaespiralis multidrug resistance gene (ptr). To investigate the possible role of Pip in regulating multidrug resistance, it was purified from a genetically characterized species, Streptomyces coelicolor, utilizing an affinity matrix of the ptr promoter conjugated to magnetic beads. Reverse genetics identified the corresponding locus and confirmed that it encoded Pip, a protein belonging to the TetR family of procaryotic transcriptional repressors. Pip binding motifs were located upstream of the adjacent gene pep, encoding a major facilitator antiporter homologous to ptr. In vivo analysis of antibiotic susceptibility profiles demonstrated that pep conferred elevated levels of resistance only to pristinamycin I (PI), a streptogramin B antibiotic having clinical importance. Purified recombinant Pip was a dimer (in the presence or absence of PI) and displayed a high affinity for its palindromic binding motifs within the ptr promoter and the upstream region of pep. The Pip/ptr promoter complex was dissociated by PI but not by any of the other nonstreptogramin antibiotics that were described previously as transcriptional inducers. These procaryotic regulatory elements served as the basis for the development of systems allowing repression or induction of cloned genes in mammalian and plant cells in response to streptogramin antibiotics (including pristinamycin, virginiamycin, and Synercid®).

Regulation of Bacterial Drug Export Systems

“…Uncharacterized regulators designated Pip proteins have been proposed to be involved in the regulation of drug transport genes in a range of Streptomyces species (187,188). Isolation of the Pip protein from the genetically well-defined Streptomyces coelicolor indicated that it was a TetR family repressor that regulates the expression of the MFS antiporter Ptr, which confers resistance to the antibiotic pristinamycin I (34).…”

The Bile Response Repressor BreR Regulates Expression of the Vibrio cholerae breAB Efflux System Operon

“…When tetracycline enters the cytoplasm, it binds to TetR, inducing a conformational change that dissociates TetR from the tetA operator, allowing the production of TetA and the active efflux of tetracycline (18,19). This general regulatory mechanism has also been described previously for several members of the TetR family (6,9,12,31,39,47,51). Given that cholate, deoxycholate, and chenodeoxycholate induce breAB and breR expression, we hypothesized that these bile salts may interact with BreR.…”

Ancestral antibiotic resistance in Mycobacterium tuberculosis

“…Antibiotic biosynthetic genes are found in clusters that typically include the corresponding resistance genes to provide selfprotection (10). However, as in other bacteria, genes scattered throughout the genome that may have alternative physiological roles can also confer antibiotic resistance (11). Intuitively, the protective activity of these resistance genes should be a prerequisite for the evolution of antibiotic biosynthetic pathways.…”