A Transcriptional Regulator of a Pristinamycin Resistance Gene in Streptomyces coelicolor

Marc Folcher,Rowan P Morris,Glenn Dale,Khadidja Salah-Bey-Hocini,Patrick H Viollier,Charles J Thompson

doi:10.1074/jbc.m007690200

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(R)).

Highlights

Streptomyces are Gram-positive mycelial soil bacteria that undergo a complex developmental program involving morphological differentiation coordinated with biosynthesis of a vast array of structurally diverse secondary metabolites
pristinamycin-induced DNA binding protein (Pip) activity was detected by gel mobility shifts resulting from Pip binding to the three operator sites in the ptr promoter
Minor amounts of Pip activity eluted in a buffer containing poly(dI-dC)1⁄7poly(dI-dC) (Fig. 1B, lane 3); many proteins were observed by SDS-PAGE in this fraction (Fig. 1A, lane 3)

Summary

Introduction

Streptomyces are Gram-positive mycelial soil bacteria that undergo a complex developmental program involving morphological differentiation coordinated with biosynthesis of a vast array of structurally diverse secondary metabolites. Pip is a pristinamycin-induced transcriptional regulator protein detected in many Streptomyces species by its ability to bind sequence motifs within the promoter of a Streptomyces pristinaespiralis multidrug resistance gene (ptr).

Results

Conclusion