WhiA is a highly unusual transcriptional regulator related to family of eukaryotic homing endonucleases. required for sporulation in the filamentous bacterium Streptomyces, but homologues unknown function are also found throughout Gram-positive bacteria. To better understand role Streptomyces development and its as transcription factor, we identified regulon through combination chromatin immunoprecipitation-sequencing (ChIP-seq) microarray profiling, exploiting new model organism genus,...

WhiB is the founding member of a family proteins (the WhiB-like [Wbl] family) that carry [4Fe-4S] iron-sulfur cluster and play key roles in diverse aspects biology actinomycetes, including pathogenesis, antibiotic resistance, control development. In Streptomyces, essential for process developmentally controlled cell division leads to sporulation. The biochemical function Wbl has been controversial; here, we set out determine unambiguously if functions as transcription factor using chromatin...

The orphan, atypical response regulators BldM and WhiI each play critical roles in Streptomyces differentiation. is required for the formation of aerial hyphae, differentiation these reproductive structures into mature spores. To gain insight function, we defined genome-wide regulon using ChIP-Seq transcriptional profiling. target genes clustered two groups based on their whi gene dependency. Expression Group I depended bldM but was independent all genes, biochemical experiments showed that...

Streptomyces are our primary source of antibiotics, produced concomitantly with the transition from vegetative growth to sporulation in a complex developmental life cycle. We previously showed that signaling molecule c-di-GMP binds BldD, master repressor, control initiation development. Here we demonstrate also intervenes later development differentiation reproductive hyphae into spores by arming novel anti-σ (RsiG) bind and sequester sporulation-specific σ factor (σWhiG). present structure...

Streptomycetes are filamentous bacteria that differentiate by producing spore-bearing reproductive structures called aerial hyphae. The transition from vegetative to growth is controlled the bld (bald) loci, and mutations in genes prevent formation of hyphae, either blocking entry into development (typically activators) or inducing precocious sporulation mycelium repressors). One genes, bldC, encodes a 68-residue DNA-binding protein related domain MerR-family transcription factors. Recent...

Abstract Streptomycetes are notable for their complex life cycle and production of most clinically important antibiotics. A key factor that controls entry into development the onset antibiotic is 68-residue protein, BldC. BldC a putative DNA-binding protein related to MerR regulators, but lacks coiled-coil dimerization effector-binding domains characteristic classical proteins. Hence, molecular function has been unclear. Here we show indeed regulon includes other developmental regulators....

Summary The extracytoplasmic function (ECF) σ factor, E , is a key regulator of the cell envelope stress response in Streptomyces coelicolor . Although its role maintaining wall integrity has been known for over decade, comprehensive analysis genes under control not undertaken. Here, using combination chromatin immunoprecipitation‐sequencing (ChIP‐seq), microarray transcriptional profiling and bioinformatic analysis, we attempt to define regulon. Approximately half identified encode proteins...

Bacterial cell division is driven by the polymerization of GTPase FtsZ into a contractile structure, so-called Z-ring. This essential process involves proteins that modulate dynamics and hence overall Z-ring architecture. Actinobacteria like Streptomyces Mycobacterium lack known key FtsZ-regulators. Here we report identification SepH, conserved actinobacterial protein directly regulates dynamics. We show SepH crucially involved in venezuelae it binds via helix-turn-helix motif, stimulating...

Studies of transcriptional initiation in different bacterial clades reveal diverse molecular mechanisms regulating this first step gene expression. The WhiA and WhiB factors are both required to express cell division genes Actinobacteria essential notable pathogens such as Mycobacterium tuberculosis . WhiA/B regulons binding sites have been elucidated Streptomyces venezuelae ( Sven ), where they coordinate activate sporulation septation. However, how these cooperate at the level is not...

The bacterial activator protein NorR binds to enhancer-like elements, upstream of the promoter site, and activates σ54-dependent transcription genes that encode nitric oxide detoxifying enzymes (NorVW), in response NO stress. Unique norVW Escherichia coli is presence three enhancer sites associated with a binding site for σ54-RNA polymerase. Here we show all are required NorR-dependent catalysis open complex formation by σ54-RNAP holoenzyme (Eσ54). We demonstrate this essentially due need...

Filamentous actinobacteria such as Streptomyces undergo two distinct modes of cell division, leading to partitioning growing hyphae into multicellular compartments via cross-walls, and septation release unicellular spores. Specific determinants for cross-wall formation the importance hyphal compartmentalization development are largely unknown. Here we show that SepX, an actinobacterial-specific protein, is crucial both division in venezuelae. Importantly, find sepX-deficient mutants grow...

Bacterial enhancer binding proteins (bEBPs) are specialized transcriptional activators that assemble as hexameric rings in their active forms and utilize ATP hydrolysis to remodel the conformation of RNA polymerase containing alternative sigma factor σ(54). Transcriptional activation by NorR bEBP is controlled a regulatory GAF domain represses ATPase activity central AAA+ absence nitric oxide. Here, we investigate mechanism interdomain repression characterizing substitutions bypass domain....

BldD-(c-di-GMP) sits on top of the regulatory network that controls differentiation in Streptomyces, repressing a large regulon developmental genes when bacteria are growing vegetatively. In this way, BldD functions as an inhibitor blocks initiation sporulation. Here, we report identification and characterisation BldO, additional repressor acts to sustain vegetative growth prevent entry into However, unlike pleiotropic regulator BldD, show BldO dedicated single key target gene, whiB,...

Summary σ 54 ‐dependent transcription controls a wide range of stress‐related genes in bacteria and is tightly regulated. In contrast to 70 , the ‐ RNA polymerase holoenzyme forms stable closed complex at promoter site that rarely isomerises into transcriptionally competent open complexes. The conversion complexes requires ATPase activity activator proteins bind remotely upstream transcriptional start site. These activators belong large AAA protein family majority them consist an N ‐terminal...

The bacterial protein WhiD belongs to the Wbl family of iron-sulfur [Fe-S] proteins present only in actinomycetes. In Streptomyces coelicolor, it is required for late stages sporulation, but precisely how functions unknown. Here, we report results from vitro and vivo experiments with venezuelae (SvWhiD), which differs S. coelicolor (ScWhiD) at C terminus. We observed that, like ScWhiD other proteins, SvWhiD binds a [4Fe-4S] cluster that moderately sensitive O2 highly nitric oxide (NO)....

Streptomyces are filamentous bacteria with a complex developmental life cycle characterized by the formation of spore-forming aerial hyphae. Transcription chaplin and rodlin genes, which essential for hyphae production, is directed extracytoplasmic function (ECF) σ factor BldN, in turn controlled an anti-σ factor, RsbN. RsbN shows no sequence similarity to known factors binds inhibits BldN unknown manner. Here we describe 2.23 Å structure RsbN-BldN complex. The that harbors σ2 σ4 domains...

DNA damage triggers a widely conserved stress response in bacteria called the SOS response, which involves two key regulators, activator RecA and transcriptional repressor LexA. Despite wide conservation of number genes controlled by LexA varies considerably between different organisms. The filamentous soil-dwelling genus Streptomyces contain homologs, but their roles have not been systematically studied. Here, we demonstrate that are required for survival venezuelae during DNA-damaging...

Abstract Extracytoplasmic function (ECF) sigma factors are key transcriptional regulators that prokaryotes have evolved to respond environmental challenges. Streptomyces tsukubaensis harbours 42 ECFs reprogram stress-responsive gene expression. Among them, SigG1 features a minimal conserved ECF σ 2 –σ 4 architecture and an additional C-terminal extension encodes SnoaL_2 domain, which is characteristic for of group ECF56. Although proteins with such domain organisation widely found among...