Streptomyces coelicolor is a representative of the group of soil-dwelling, filamentous bacteria responsible for producing most natural antibiotics used in human and veterinary medicine. Here we report the 8,667,507 base pair linear chromosome of this organism, containing the largest number of genes so far discovered in a bacterium. The 7,825 predicted genes include more than 20 clusters coding for known or predicted secondary metabolites. The genome contains an unprecedented proportion of regulatory genes, predominantly those likely to be involved in responses to external stimuli and stresses, and many duplicated gene sets that may represent 'tissue-specific' isoforms operating in different phases of colonial development, a unique situation for a bacterium. An ancient synteny was revealed between the central 'core' of the chromosome and the whole chromosome of pathogens Mycobacterium tuberculosis and Corynebacterium diphtheriae. The genome sequence will greatly increase our understanding of microbial life in the soil as well as aiding the generation of new drug candidates by genetic engineering.

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Complete genome sequence of the model actinomycete Streptomyces coelicolor A3(2)

https://www.cell.com/cell/pdf/0092-8674(93)90546-3.pdf

The human mutator gene homolog MSH2 and its association with hereditary nonpolyposis colon cancer.

Modulation of Chemical Composition and Other Parameters of the Cell by Growth Rate

Oxidative stress responses in Escherichia coli and Salmonella typhimurium.

Our intestine is the site of an extraordinarily complex and dynamic environmentally transmitted consortial symbiosis. The molecular foundations of beneficial symbiotic host-bacterial relationships in the gut are being revealed in part from studies of simplified models of this ecosystem, where germ-free mice are colonized with specified members of the microbial community, and in part from comparisons of the genomes of members of the intestinal microbiota. The results emphasize the contributions of symbionts to postnatal gut development and host physiology, as well as the remarkable strategies these microorganisms have evolved to sustain their alliances. These points are illustrated by the human-Bacteroides thetaiotaomicron symbiosis. Interdisciplinary studies of the effects of the intestinal environment on genome structure and function should provide important new insights about how microbes and humans have coevolved mutually beneficial relationships and new perspectives about the foundations of our health.

https://www.pnas.org/content/pnas/100/18/10452.full.pdf

Honor thy symbionts

The rpoA341 (phs) mutation of Escherichia coli results in decreased expression of several positively regulated operons and has been mapped to within or very near the rpoA gene encoding the alpha subunit of RNA polymerase. We have shown that plasmid-directed synthesis of the wild-type alpha subunit can complement the defective phenotypes associated with this mutation consistent with its proposed location within rpoA. This mutation was mapped by marker rescue to within a 182bp region near the 3' end of rpoA and was subsequently transferred to a plasmid by recombination in vivo. DNA sequence analysis revealed that the RpoA341 phenotype was the result of the substitution of lysine 271 by glutamate within the alpha polypeptide. We discuss this result in relation to our current understanding of the functional organization of the alpha subunit.

Escherichia coli rpoA mutation which impairs transcription of positively regulated systems.

RNA polymerase was isolated from two suppressed rpoB amber strains exhibiting relaxed control over RNA synthesis in vivo. In vitro transcription analysis of these mutant holoenzymes carrying defined substitutions at known sites in the beta subunit clearly shows that single amino acid changes in beta render RNA polymerase resistant to ppGpp. This unambiguously demonstrates that RNA polymerase is indeed the target for ppGpp.

Genetic studies on the β subunit of Escherichia coli RNA polymerase. VII: RNA polymerase is a target for ppGpp

We have isolated a set of strains that synthesise 331 potential variants of E. coli DNA-dependent RNA polymerase making use of nonsense suppression of amber mutations in the beta structural gene; rpoB. Translational mapping, together with the effect of known amino acid substitutions, has allowed us to locate sites on the beta polypeptide involved in transcription termination, stringent response and resistance to the antibiotic rifampicin. In general, the C-terminal quarter appears to be less affected by such single amino acid exchanges than the rest of beta. These studies permit for the first time structure-function correlates for the beta subunit of RNA polymerase.

Genetic studies on the β subunit of Escherichia coli RNA polymerase IV: Structure-function correlates

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2883%2980630-9

Robert E. Glass

Papers

Escherichia coli rpoA mutation which impairs transcription of positively regulated systems.

Genetic studies on the β subunit of Escherichia coli RNA polymerase. VII: RNA polymerase is a target for ppGpp

Genetic studies on the β subunit of Escherichia coli RNA polymerase IV: Structure-function correlates

Relaxed mutants of Escherichia coli RNA polymerase.

Involvement of the Escherichia coli RNA polymerase α subunit in transcriptional activation by the bacteriophage lambda CI and CII proteins