WhiB7, an Fe-S-dependent Transcription Factor That Activates Species-specific Repertoires of Drug Resistance Determinants in Actinobacteria

摘要: WhiB-like (Wbl) proteins are well known for their diverse roles in actinobacterial morphogenesis, cell division, virulence, primary and secondary metabolism, intrinsic antibiotic resistance. Gene disruption experiments showed that three different Actinobacteria (Mycobacterium smegmatis, Streptomyces lividans, Rhodococcus jostii) each exhibited a whiB7-dependent resistance profile. Heterologous expression of whiB7 genes these profiles reflected the host's repertoire endogenous genes. Transcriptional activation two regulon, tap (a multidrug transporter) erm(37) ribosomal methyltransferase), required interaction WhiB7 with promoters. Furthermore, heterologous isolated from Mycobacterium species demonstrated divergencies drug specificity homologous structural contribute to variation WhiB7-dependent has specific tryptophan/glycine-rich region four conserved cysteine residues; it also peptide sequence (AT-hook) at its C terminus binds AT-rich DNA motifs upstream promoters activates. Targeted mutagenesis were provide vivo. Anaerobically purified S. lividans was dimeric contained 2.1 ± 0.3 2.2 mol iron sulfur, respectively, per protomer (consistent presence 2Fe-2S cluster). However, properties dimer's absorption spectrum most consistent an oxygen-labile 4Fe-4S cluster, suggesting 50% occupancy. These data first insights into iron-sulfur clusters as they exist vivo, major unresolved issue studies Wbl proteins.