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Streptomyces coelicolor M600 BldD ChIP-chip comparison of wild-type with bldD null mutant

ABSTRACT: BldD is a transcriptional regulator essential for morphological development and antibiotic production in Streptomyces coelicolor. Here we identify the BldD regulon by means of chromatin immunoprecipitation. The BldD regulon encompasses ~167 transcriptional units, of which more than 20 are known to play important roles in development and/or secondary metabolism. Strikingly, 42 BldD target genes (~25% of the regulon) encode regulatory proteins, stressing the central, pleiotropic role of BldD. Almost all BldD-binding sites identified by ChIP-chip are present in the promoters of the target genes. An exception is the tRNA gene bldA, where BldD binds within the region encoding the primary transcript, immediately downstream of the position corresponding to the processed, mature 3′-end of the tRNA. We identified a novel BldD target gene (cdgA) that influences differentiation and antibiotic production. cdgA encodes a GGDEF domain protein, implicating c-di-GMP in the regulation of Streptomyces development.

ORGANISM(S): Streptomyces coelicolor

PROVIDER: GSE23401 | GEO | 2010/08/04

SECONDARY ACCESSION(S): PRJNA131303

REPOSITORIES: GEO

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Project description:Background The genomes of Streptomyces coelicolor and Streptomyces lividans bear a considerable degree of orthology. While S. coelicolor is the model streptomycete for studying antibiotic synthesis and differentiation, S. lividans is almost exclusively considered as the preferred host, among actinomycetes, for cloning and expression of exogenous DNA. We used whole genome microarrays as a comparative genomics tool for identifying the subtle yet crucial differences between these two chromosomes. Results We identified five large S. coelicolor genomic islands (≥25 kb) and 18 smaller islets absent in S. lividans chromosome. Many of these regions show anomalous GC bias and codon usage patterns. Six of them are in close vicinity of tRNA genes while nine are flanked with near perfect repeat sequences indicating that these are probable recent evolutionary acquisitions into S. coelicolor. Embedded within these segments are at least four DNA methylases and two probable methyl-sensing restriction endonucleases. Comparison with S. coelicolor transcriptome and proteome data revealed that some of the missing genes are active during the course of growth and differentiation in S. coelicolor. In particular, a pair of methylmalonyl CoA mutase (mcm) genes involved in polyketide precursor biosynthesis, an acyl-CoA dehydrogenase implicated in timing of actinorhodin synthesis and bldB, a developmentally significant regulator whose mutation causes complete abrogation of antibiotic synthesis belong to this category. Conclusion Our findings provide tangible hints for elucidating the genetic basis of important phenotypic differences between these two streptomycetes. Importantly, absence of certain genes in S. lividans identified here could potentially explain the relative ease of DNA transformations or the conditional lack of actinorhodin synthesis in S. lividans. Further genetic studies based on these results will enable one to target specific sequences in the genetically well-characterized S. coelicolor to adapt it for industrial processes. Keywords: Comparative Genomic Hybridization