Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of E. coli cells during cell death programmed by a restriction-modification system

ABSTRACT: Genetically programmed deaths play important roles in the biology of unicellular prokaryotic cells. Some gene complexes force their maintenance on the host bacterial cells by killing cells that have lost them. This form of programmed death called post-segregational killing or genetic addiction is brought about by several Type II restriction-modification gene complexes, through restriction attack on the undermethylated chromosome, and underlie their behavior as selfish mobile elements. To learn the genetic steps to death, we examined how carriage and loss of PaeR7I restriction-modification gene complex affect host Escherichia coli cells through transcriptome and experimental analyses. The PaeR7I complex was on a temperature-sensitive plasmid so that the killing was induced by a temperature shift. We used microarrays to detail the global program of gene expression underlying cell death process mediated by PaeR7I restriction-modification system in E. coli. Experiment Overall Design: Post-segregational cell killing was induced by blocking replication of a temperature sensitive plasmid carrying PaeR7I RM gene complex by shifting up the cultivation temperature. At 30℃, the permissive temperature for the plasmid replication, growth as monitored by OD660, of MG1655/pTN9 (r+m+) was indistinguishable from those of MG1655/pTN11 (r-m+) and MG1655/pHSG415 (vector). Cell death was observed at least 4 h after the temperature shift only in MG1655/pTN9 (r+m+) as in the previous works; the increase in viable cell counts stopped and resulted in decrease of cell viability. To analyze global gene expression when cells went to death, we performed transcriptome analysis 0 h, 1h, 1 h 50 min, and 3h after the temperature shift. We used Affimetrix E. coli antisense genome array. Experiments were performed independently twice.

ORGANISM(S): Escherichia coli

SUBMITTER: Yoko Asakura

PROVIDER: E-GEOD-7326 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

From damaged genome to cell surface: transcriptome changes during bacterial cell death triggered by loss of a restriction-modification gene complex.

Asakura Yoko Y Kobayashi Ichizo I

Nucleic acids research 20090320 9

Genetically programmed cell deaths play important roles in unicellular prokaryotes. In postsegregational killing, loss of a gene complex from a cell leads to its descendants' deaths. With type II restriction-modification gene complexes, such death is triggered by restriction endonuclease's attacks on under-methylated chromosomes. Here, we examined how the Escherichia coli transcriptome changes after loss of PaeR7I gene complex. At earlier time points, activation of SOS genes and sigma(E)-regulon ...[more]

PMID: 19304752

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Project description:Escherichia coli O157 presents a number of specific problems in terms of food safety and public health. It has been found that E. coli O157 is more resistant to a number of the stresses encountered during food production such as heat, pH and osmotic shock. This greater resistance is thought to contribute to the low infectious dose of E. coli O157 (<100 organisms). Moreover, E. coli O157 is associated with debilitating conditions such as haemorrhagic colitis and haemoytic uraemic syndrome, particularly in children and the elderly. We have been studying the stress responses of E. coli O157:H7 (Sakai) and comparing with a commensal strain of E. coli K-12, MG1655. We found that E. coli O157 (Sakai) is more sensitive to oxidative stress than MG1655. A microarray study of these strains treated with sub-lethal concentrations (0.5mg/ml) of menadione revealed big differences in their responses. In E. coli O157 (Sakai), 540 genes responded significantly to the treatment compared to 121 genes in MG1655. One surprising finding from the microarray data was the observation that many iron-transport genes were up-regulated in E. coli O157 (Sakai) whereas relatively few were induced in MG1655 despite the fact that the bacteria were grown in a medium containing ample iron. We speculated that the induction of iron transport genes in an iron-rich medium might have contributed to the enhanced killing of E. coli O157 (Sakai) through triggering of a Fenton reaction. We speculated that the difference in sensitivity to oxidative stress might be due to differences in the intracellular iron content of E. coli O157 and MG1655. We found that E. coli O157 contains ~50% more iron than MG1655 and believe that during oxidative stress, this iron is released by damaged proteins. The greater levels of free iron in E. coli O157 will trigger a greater Fenton reaction that can damage the ferric uptake regulator (Fur), resulting in unregulated iron transport. In MG1655, the lower iron content results in a smaller Fenton reaction, enabling the cellular protection systems to limit damage and protect Fur.

Dataset Information

Transcription profiling of E. coli cells during cell death programmed by a restriction-modification system

Publications

From damaged genome to cell surface: transcriptome changes during bacterial cell death triggered by loss of a restriction-modification gene complex.

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