Dataset Information

Re-annotation of the Saccharopolyspora erythraea genome using a systems biology approach.

ABSTRACT:

Background

Accurate bacterial genome annotations provide a framework to understanding cellular functions, behavior and pathogenicity and are essential for metabolic engineering. Annotations based only on in silico predictions are inaccurate, particularly for large, high G + C content genomes due to the lack of similarities in gene length and gene organization to model organisms.

Results

Here we describe a 2D systems biology driven re-annotation of the Saccharopolyspora erythraea genome using proteogenomics, a genome-scale metabolic reconstruction, RNA-sequencing and small-RNA-sequencing. We observed transcription of more than 300 intergenic regions, detected 59 peptides in intergenic regions, confirmed 164 open reading frames previously annotated as hypothetical proteins and reassigned function to open reading frames using the genome-scale metabolic reconstruction. Finally, we present a novel way of mapping ribosomal binding sites across the genome by sequencing small RNAs.

Conclusions

The work presented here describes a novel framework for annotation of the Saccharopolyspora erythraea genome. Based on experimental observations, the 2D annotation framework greatly reduces errors that are commonly made when annotating large-high G + C content genomes using computational prediction algorithms.

SUBMITTER: Marcellin E

PROVIDER: S-EPMC4008361 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Publications

Re-annotation of the Saccharopolyspora erythraea genome using a systems biology approach.

Marcellin Esteban E Licona-Cassani Cuauhtemoc C Mercer Tim R TR Palfreyman Robin W RW Nielsen Lars K LK

BMC genomics 20131011

<h4>Background</h4>Accurate bacterial genome annotations provide a framework to understanding cellular functions, behavior and pathogenicity and are essential for metabolic engineering. Annotations based only on in silico predictions are inaccurate, particularly for large, high G + C content genomes due to the lack of similarities in gene length and gene organization to model organisms.<h4>Results</h4>Here we describe a 2D systems biology driven re-annotation of the Saccharopolyspora erythraea g ...[more]

PMID: 24118942

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Project description:BackgroundThe Saccharopolyspora erythraea genome sequence, recently published, presents considerable divergence from those of streptomycetes in gene organization and function, confirming the remarkable potential of S. erythraea for producing many other secondary metabolites in addition to erythromycin. In order to investigate, at whole transcriptome level, how S. erythraea genes are modulated, a DNA microarray was specifically designed and constructed on the S. erythraea strain NRRL 2338 genome sequence, and the expression profiles of 6494 ORFs were monitored during growth in complex liquid medium.ResultsThe transcriptional analysis identified a set of 404 genes, whose transcriptional signals vary during growth and characterize three distinct phases: a rapid growth until 32 h (Phase A); a growth slowdown until 52 h (Phase B); and another rapid growth phase from 56 h to 72 h (Phase C) before the cells enter the stationary phase. A non-parametric statistical method, that identifies chromosomal regions with transcriptional imbalances, determined regional organization of transcription along the chromosome, highlighting differences between core and non-core regions, and strand specific patterns of expression. Microarray data were used to characterize the temporal behaviour of major functional classes and of all the gene clusters for secondary metabolism. The results confirmed that the ery cluster is up-regulated during Phase A and identified six additional clusters (for terpenes and non-ribosomal peptides) that are clearly regulated in later phases.ConclusionThe use of a S. erythraea DNA microarray improved specificity and sensitivity of gene expression analysis, allowing a global and at the same time detailed picture of how S. erythraea genes are modulated. This work underlines the importance of using DNA microarrays, coupled with an exhaustive statistical and bioinformatic analysis of the results, to understand the transcriptional organization of the chromosomes of micro-organisms producing natural products.

Project description:Actinomycetes undergo a dramatic reorganization of metabolic and cellular machinery during a brief period of growth arrest ("metabolic switch") preceding mycelia differentiation and the onset of secondary metabolite biosynthesis. This study explores the role of phosphorylation in coordinating the metabolic switch in the industrial actinomycete Saccharopolyspora erythraea. A total of 109 phosphopeptides from 88 proteins were detected across a 150-h fermentation using open-profile two-dimensional LC-MS proteomics and TiO(2) enrichment. Quantitative analysis of the phosphopeptides and their unphosphorylated cognates was possible for 20 pairs that also displayed constant total protein expression. Enzymes from central carbon metabolism such as putative acetyl-coenzyme A carboxylase, isocitrate lyase, and 2-oxoglutarate dehydrogenase changed dramatically in the degree of phosphorylation during the stationary phase, suggesting metabolic rearrangement for the reutilization of substrates and the production of polyketide precursors. In addition, an enzyme involved in cellular response to environmental stress, trypsin-like serine protease (SACE_6340/NC_009142_6216), decreased in phosphorylation during the growth arrest stage. More important, enzymes related to the regulation of protein synthesis underwent rapid phosphorylation changes during this stage. Whereas the degree of phosphorylation of ribonuclease Rne/Rng (SACE_1406/NC_009142_1388) increased during the metabolic switch, that of two ribosomal proteins, S6 (SACE_7351/NC_009142_7233) and S32 (SACE_6101/NC_009142_5981), dramatically decreased during this stage of the fermentation, supporting the hypothesis that ribosome subpopulations differentially regulate translation before and after the metabolic switch. Overall, we show the great potential of phosphoproteomic studies to explain microbial physiology and specifically provide evidence of dynamic protein phosphorylation events across the developmental cycle of actinomycetes.

Dataset Information

Re-annotation of the Saccharopolyspora erythraea genome using a systems biology approach.

Background

Results

Conclusions

Publications

Re-annotation of the Saccharopolyspora erythraea genome using a systems biology approach.

Similar Datasets

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