Unknown,Transcriptomics,Genomics,Proteomics

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Phenotype and expression profile of S. erythraea rifampicin-resistant (rif) mutants affected in erythromycin production

ABSTRACT: In this study we have used the rifampicin selection as a tool to genetically improve the erythromycin producer Saccharopolyspora erythraea. Two rifampicin-resistant (rif) mutants, rif1 and rif6, have been characterized in more detail. With respect to the parental strain NRRL2338, rif1 (harboring the missense S444F) exhibited higher respiratory performance and final erythromycin yields; in contrast, rif6 (harboring the missense Q426R) was slow-growing, developmental-defective and severely impaired in erythromycin production. The results of genome-wide analysis of expression profiles using DNA micro-arrays demonstrated that these mutations deeply changed the transcriptional profile of S. erythraea with marked regional distribution. Keywords: mutants versus wild type comparison in a time course experiment Total of 12 Samples

ORGANISM(S): Saccharopolyspora erythraea

SUBMITTER: Giorgio Corti

PROVIDER: E-GEOD-12017 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Phenotypes and gene expression profiles of Saccharopolyspora erythraea rifampicin-resistant (rif) mutants affected in erythromycin production.

Carata Elisabetta E Peano Clelia C Tredici Salvatore M SM Ferrari Francesco F Talà Adelfia A Corti Giorgio G Bicciato Silvio S De Bellis Gianluca G Alifano Pietro P

Microbial cell factories 20090330

<h4>Background</h4>There is evidence from previous works that bacterial secondary metabolism may be stimulated by genetic manipulation of RNA polymerase (RNAP). In this study we have used rifampicin selection as a strategy to genetically improve the erythromycin producer Saccharopolyspora erythraea.<h4>Results</h4>Spontaneous rifampicin-resistant (rif) mutants were isolated from the parental strain NRRL2338 and two rif mutations mapping within rpoB, S444F and Q426R, were characterized. With resp ...[more]

PMID: 19331655

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Project description:Information about molecular mechanisms underlying improvement of antibiotic-producing microorganisms with traditional mutation and screening approach is largely missing. This information is essential to develop rational approaches to strain improvement. In this study by using comparative genomic analysis we have identified all genetic changes that have occurred during development of an erythromycin overproducer, which was obtained by the traditional mutate-and-screen method. Compared with parental Saccharopolyspora erythraea NRRL 2338, a total of 117 deletion, 78 insertion and 12 transposition sites were found across the genome of the overproducer. Among them, 71 insertion/deletion sites mapped within coding sequences (CDSs) generating frame-shift mutations. Moreover, single nucleotide variations affecting a total of 144 CDSs were identified between the two genomes. Overall, variations affect a total of 227 proteins in the genome of the overproducer. The analysis of metabolic pathways demonstrated that a considerable number of mutations affect genes coding for key enzymes involved in central carbon and nitrogen metabolism, and biosynthesis of secondary metabolites, redirecting common precursors toward erythromycin biosynthesis. Interestingly, several mutations inactivate genes coding for proteins that play fundamental roles in basic transcription and translation machineries including the transcription anti-termination factor NusB and the transcription elongation factor Efp. These mutations, along with those affecting genes coding for pleiotropic or pathway-specific regulators, may affect global expression profile. Consistent transcriptomic data were obtained from a comparative analysis between NRRL 2338 and the erythromycin overproducer gene expression profiling performed with DNA microarray. Genomic data also indicated that the mutate-and-screen process might have been accelerated by mutations in DNA repair genes. Our findings, largely unanticipated, reveal new targets suitable for rationale improvement of antibiotic-producing strains. According to a rough estimate, actinomycetes, which are among the most abundant bacteria in soil, produce over 70% of naturally occurring antibiotics and other biologically active substances including anti-tumour agents and immunosuppressants. However, these microorganisms must often be genetically improved for higher production before they can be used in the industry. Strain improvement has traditionally relied on multiple rounds of random mutagenesis and screening. This method is essentially empirical, and notably time-consuming and expansive. Currently, the availability of molecular genetics tools and useful information about the biosynthetic pathways and genetic control for most of biologically active substances has opened the way for improving strains by rational engineering. These rational strain improvement strategies benefit of the support of genomic and post-genomic technologies. In this study by using comparative genomic analysis we have identified all genetic changes that have occurred during development of an erythromycin overproducer, which was obtained by the traditional mutate-and-screen method. Our findings, largely unanticipated, reveal new molecular targets suitable for rationale improvement of antibiotic-producing strains by recombinant technologies, and support the evidence that combining classical and recombinant strain improvement with a solid fermentation development program is the best way to improve production of biologically active substances. Erythromycin over-producing Strain at various time points

Dataset Information

Phenotype and expression profile of S. erythraea rifampicin-resistant (rif) mutants affected in erythromycin production

Publications

Phenotypes and gene expression profiles of Saccharopolyspora erythraea rifampicin-resistant (rif) mutants affected in erythromycin production.

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