Optimization of a two-plasmid system for the identification of promoters recognized by RNA polymerase containing Staphylococcus aureus alternative sigma factor σB

We optimized a previously established two-plasmid system for the identification of Staphylococcus aureus promoters that are recognized by the alternative transcription factor σB. The method allowed the identification of 18 S. aureusσB-dependent promoters, 12 of which are reported here for the first time to be σB-dependent. S1-nuclease mapping of the respective transcriptional start points revealed that all the promoters contained sequences exhibiting high similarity to the consensus sequence of Bacillus subtilisσB-dependent promoters. The promoters governed expression of genes encoding proteins proposed to be involved in various cellular functions, including the stress response genes and virulence-associated clfA gene for fibrinogen-binding clumping factor. Comparison of the nucleotide sequences upstream of the identified transcription start points identified a σB consensus promoter (GttTaa-N12-15-gGGTAt) that is highly homologous to that of σB of B. subtili

Bioinformatic identification of novel regulatory DNA sequence motifs in Streptomyces coelicolor

BACKGROUND: Streptomyces coelicolor is a bacterium with a vast repertoire of metabolic functions and complex systems of cellular development. Its genome sequence is rich in genes that encode regulatory proteins to control these processes in response to its changing environment. We wished to apply a recently published bioinformatic method for identifying novel regulatory sequence signals to gain new insights into regulation in S. coelicolor. RESULTS: The method involved production of position-specific weight matrices from alignments of over-represented words of DNA sequence. We generated 2497 weight matrices, each representing a candidate regulatory DNA sequence motif. We scanned the genome sequence of S. coelicolor against each of these matrices. A DNA sequence motif represented by one of the matrices was found preferentially in non-coding sequences immediately upstream of genes involved in polysaccharide degradation, including several that encode chitinases. This motif (TGGTCTAGACCA) was also found upstream of genes encoding components of the phosphoenolpyruvate phosphotransfer system (PTS). We hypothesise that this DNA sequence motif represents a regulatory element that is responsive to availability of carbon-sources. Other motifs of potential biological significance were found upstream of genes implicated in secondary metabolism (TTAGGTtAGgCTaACCTAA), sigma factors (TGACN(19)TGAC), DNA replication and repair (ttgtCAGTGN(13)TGGA), nucleotide conversions (CTACgcNCGTAG), and ArsR (TCAGN(12)TCAG). A motif found upstream of genes involved in chromosome replication (TGTCagtgcN(7)Tagg) was similar to a previously described motif found in UV-responsive promoters. CONCLUSIONS: We successfully applied a recently published in silico method to identify conserved sequence motifs in S. coelicolor that may be biologically significant as regulatory elements. Our data are broadly consistent with and further extend data from previously published studies. We invite experimental testing of our hypotheses in vitro and in vivo

The dpsA Gene of Streptomyces coelicolor: Induction of Expression from a Single Promoter in Response to Environmental Stress or during Development

The DpsA protein plays a dual role in Streptomyces coelicolor, both as part of the stress response and contributing to nucleoid condensation during sporulation. Promoter mapping experiments indicated that dpsA is transcribed from a single, sigB-like dependent promoter. Expression studies implicate SigH and SigB as the sigma factors responsible for dpsA expression while the contribution of other SigB-like factors is indirect by means of controlling sigH expression. The promoter is massively induced in response to osmotic stress, in part due to its sensitivity to changes in DNA supercoiling. In addition, we determined that WhiB is required for dpsA expression, particularly during development. Gel retardation experiments revealed direct interaction between apoWhiB and the dpsA promoter region, providing the first evidence for a direct WhiB target in S. coelicolor

Complete Genome Sequence of Streptomyces lavendulae subsp. lavendulae CCM 3239 (Formerly “Streptomyces aureofaciens CCM 3239”), a Producer of the Angucycline-Type Antibiotic Auricin

Busche T, Novakova R, Al'Dilaimi A, et al. Complete Genome Sequence of Streptomyces lavendulae subsp. lavendulae CCM 3239 (Formerly “Streptomyces aureofaciens CCM 3239”), a Producer of the Angucycline-Type Antibiotic Auricin. Genome Announcements. 2018;6(9): e00103-18.Streptomyces lavendulae subsp. lavendulae CCM 3239 produces the angucycline antibiotic auricin and was thought to be the type strain of Streptomyces aureofaciens. We report the complete genome sequence of this strain, which consists of a linear chromosome and the linear plasmid pSA3239, and demonstrate it to be S. lavendulae subsp. lavendulae

Monitoring Protein Secretion in Streptomyces Using Fluorescent Proteins

Fluorescent proteins are a major cell biology tool to analyze protein sub-cellular topology. Here we have applied this technology to study protein secretion in the Gram-positive bacterium Streptomyces lividans TK24, a widely used host for heterologous protein secretion biotechnology. Green and monomeric red fluorescent proteins were fused behind Sec (SPSec) or Tat (SPTat) signal peptides to direct them through the respective export pathway. Significant secretion of fluorescent eGFP and mRFP was observed exclusively through the Tat and Sec pathways, respectively. Plasmid over-expression was compared to a chromosomally integrated spSec-mRFP gene to allow monitoring secretion under high and low level synthesis in various media. Fluorimetric detection of SPSec-mRFP recorded folded states, while immuno-staining detected even non-folded topological intermediates. Secretion of SPSec-mRFP is unexpectedly complex, is regulated independently of cell growth phase and is influenced by the growth regime. At low level synthesis, highly efficient secretion occurs until it is turned off and secretory preforms accumulate. At high level synthesis, the secretory pathway overflows and proteins are driven to folding and subsequent degradation. High-level synthesis of heterologous secretory proteins, whether secretion competent or not, has a drastic effect on the endogenous secretome, depending on their secretion efficiency. These findings lay the foundations of dissecting how protein targeting and secretion are regulated by the interplay between the metabolome, secretion factors and stress responses in the S. lividans model

Minimum Information about a Biosynthetic Gene cluster

A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.Chemistry and Chemical Biolog

Bacterial Regulatory Proteins

The regulation of gene expression in bacteria occurs predominantly at the level of transcription, which is controlled by RNA polymerase [...