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YoeB toxin is activated during thermal stress.

Janssen BD, Garza-Sánchez F, Hayes CS - Microbiologyopen (2015)

Bottom Line: Moreover, heat-activated YoeB does not induce growth arrest nor does it suppress global protein synthesis.In fact, E. coli cells proliferate more rapidly at elevated temperatures and instantaneously accelerate their growth rate in response to acute heat shock.We propose that heat-activated YoeB may serve a quality control function, facilitating the recycling of stalled translation complexes through ribosome rescue pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California.

No MeSH data available.


Related in: MedlinePlus

Lon and YoeB are required for temperature-induced A-site mRNA cleavage. (A) flag-(m)ybeL-PP transcripts were expressed in the indicated genetic backgrounds at 37°C and 42°C and analyzed by northern hybridization. (B) flag-(m)ybeL-PP transcripts were expressed in cells that lack six characterized toxin-antitoxin modules (Δtox(6)) at 37°C and 42°C, and compared to background that retain these toxin-antitoxin genes (tox+). (C) flag-(m)ybeL-PP transcripts were expressed in ssrA−Δrnb cells that carry deletions in the indicated toxin–antitoxin genes. Growth at 42°C induces truncated mRNA in all cells except those deleted for yefM-yoeB. The migration positions of stop codon truncated messages are indicated by control transcripts prepared by in vitro transcription. The horizontal arrows indicate an additional truncated transcript that is produced during growth at 42°C.
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fig02: Lon and YoeB are required for temperature-induced A-site mRNA cleavage. (A) flag-(m)ybeL-PP transcripts were expressed in the indicated genetic backgrounds at 37°C and 42°C and analyzed by northern hybridization. (B) flag-(m)ybeL-PP transcripts were expressed in cells that lack six characterized toxin-antitoxin modules (Δtox(6)) at 37°C and 42°C, and compared to background that retain these toxin-antitoxin genes (tox+). (C) flag-(m)ybeL-PP transcripts were expressed in ssrA−Δrnb cells that carry deletions in the indicated toxin–antitoxin genes. Growth at 42°C induces truncated mRNA in all cells except those deleted for yefM-yoeB. The migration positions of stop codon truncated messages are indicated by control transcripts prepared by in vitro transcription. The horizontal arrows indicate an additional truncated transcript that is produced during growth at 42°C.

Mentions: Some type II TA modules encode ribosome-dependent RNases that cleave A-site codons (Pedersen et al. 2003; Prysak et al. 2009; Feng et al. 2013). Toxins are typically activated through Lon protease-mediated degradation of antitoxins (Gerdes and Maisonneuve 2012; Brzozowska and Zielenkiewicz 2013); therefore we examined flag-(m)ybeL-PP transcript processing in Δlon cells. We observed less truncated mRNA in Δlon compared to lon+ backgrounds even at 37°C (Fig.2A, lanes 2 and 4), indicating that Lon influences A-site cleavage during translational pauses. But more importantly, we failed to detect heat-induced mRNase activity in Δlon mutants (Fig.2A, lanes 7 and 9). The latter result suggests that a toxin is responsible for heat-induced mRNase activity, which led us to test an E. coli strain that lacks multiple TA genes. The E. coli Δtox(6) strain lacks six validated TA systems encoded by the relBE, mazEF, yefM-yoeB, dinJ-yafQ, chpBIK and yhaV genes. As reported previously (Garza-Sánchez et al. 2009), flag-(m)ybeL-PP transcripts still undergo A-site cleavage in the ssrA−Δtox(6) background at 37°C (Fig.2B, lanes 2 and 4). However, ssrA−Δtox(6) Δrnb cells did not exhibit heat-induced mRNase activity (Fig.2B, lanes 7 and 9), strongly suggesting that one (or more) of the deleted toxins is responsible for activity. Further analysis of ssrA−Δrnb strains carrying individual TA gene deletions revealed that ΔyefM-yoeB mutants lack the heat-induced activity (Fig.2C).


YoeB toxin is activated during thermal stress.

Janssen BD, Garza-Sánchez F, Hayes CS - Microbiologyopen (2015)

Lon and YoeB are required for temperature-induced A-site mRNA cleavage. (A) flag-(m)ybeL-PP transcripts were expressed in the indicated genetic backgrounds at 37°C and 42°C and analyzed by northern hybridization. (B) flag-(m)ybeL-PP transcripts were expressed in cells that lack six characterized toxin-antitoxin modules (Δtox(6)) at 37°C and 42°C, and compared to background that retain these toxin-antitoxin genes (tox+). (C) flag-(m)ybeL-PP transcripts were expressed in ssrA−Δrnb cells that carry deletions in the indicated toxin–antitoxin genes. Growth at 42°C induces truncated mRNA in all cells except those deleted for yefM-yoeB. The migration positions of stop codon truncated messages are indicated by control transcripts prepared by in vitro transcription. The horizontal arrows indicate an additional truncated transcript that is produced during growth at 42°C.
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Related In: Results  -  Collection

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fig02: Lon and YoeB are required for temperature-induced A-site mRNA cleavage. (A) flag-(m)ybeL-PP transcripts were expressed in the indicated genetic backgrounds at 37°C and 42°C and analyzed by northern hybridization. (B) flag-(m)ybeL-PP transcripts were expressed in cells that lack six characterized toxin-antitoxin modules (Δtox(6)) at 37°C and 42°C, and compared to background that retain these toxin-antitoxin genes (tox+). (C) flag-(m)ybeL-PP transcripts were expressed in ssrA−Δrnb cells that carry deletions in the indicated toxin–antitoxin genes. Growth at 42°C induces truncated mRNA in all cells except those deleted for yefM-yoeB. The migration positions of stop codon truncated messages are indicated by control transcripts prepared by in vitro transcription. The horizontal arrows indicate an additional truncated transcript that is produced during growth at 42°C.
Mentions: Some type II TA modules encode ribosome-dependent RNases that cleave A-site codons (Pedersen et al. 2003; Prysak et al. 2009; Feng et al. 2013). Toxins are typically activated through Lon protease-mediated degradation of antitoxins (Gerdes and Maisonneuve 2012; Brzozowska and Zielenkiewicz 2013); therefore we examined flag-(m)ybeL-PP transcript processing in Δlon cells. We observed less truncated mRNA in Δlon compared to lon+ backgrounds even at 37°C (Fig.2A, lanes 2 and 4), indicating that Lon influences A-site cleavage during translational pauses. But more importantly, we failed to detect heat-induced mRNase activity in Δlon mutants (Fig.2A, lanes 7 and 9). The latter result suggests that a toxin is responsible for heat-induced mRNase activity, which led us to test an E. coli strain that lacks multiple TA genes. The E. coli Δtox(6) strain lacks six validated TA systems encoded by the relBE, mazEF, yefM-yoeB, dinJ-yafQ, chpBIK and yhaV genes. As reported previously (Garza-Sánchez et al. 2009), flag-(m)ybeL-PP transcripts still undergo A-site cleavage in the ssrA−Δtox(6) background at 37°C (Fig.2B, lanes 2 and 4). However, ssrA−Δtox(6) Δrnb cells did not exhibit heat-induced mRNase activity (Fig.2B, lanes 7 and 9), strongly suggesting that one (or more) of the deleted toxins is responsible for activity. Further analysis of ssrA−Δrnb strains carrying individual TA gene deletions revealed that ΔyefM-yoeB mutants lack the heat-induced activity (Fig.2C).

Bottom Line: Moreover, heat-activated YoeB does not induce growth arrest nor does it suppress global protein synthesis.In fact, E. coli cells proliferate more rapidly at elevated temperatures and instantaneously accelerate their growth rate in response to acute heat shock.We propose that heat-activated YoeB may serve a quality control function, facilitating the recycling of stalled translation complexes through ribosome rescue pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California.

No MeSH data available.


Related in: MedlinePlus