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Recently, post-transcriptional regulation of mRNA mediated by N6-methyladenosine (m6A) has been found to have profound effects on transcriptome regulation during plant responses to various abiotic stresses. However, whether this RNA modification can affect an oxidative stress response in plants has not been studied. To assess the role of m6A modifications during copper-induced oxidative stress responses, m6A-IP-seq was performed in Arabidopsis seedlings exposed to high levels of copper sulfate. This analysis revealed large-scale shifts in this modification on the transcripts most relevant for oxidative stress. This altered epitranscriptomic mark is known to influence transcript abundance and translation; therefore we scrutinized these possibilities. We found an increased abundance of copper-enriched m6A-containing transcripts. Similarly, we also found increased ribosome occupancy of copper-enriched m6A-containing transcripts, specifically those encoding proteins involved with stress responses relevant to oxidative stressors. Furthermore, the significance of the m6A epitranscriptome on plant oxidative stress tolerance was uncovered by assessing germination and seedling development of the mta (N6-methyladenosine RNA methyltransferase A mutant complemented with ABI3:MTA) mutant exposed to high copper treatment. These analyses suggested hypersensitivity of the mta mutant compared to the wild-type plants in response to copper-induced oxidative stress. Overall, our findings suggest an important role for m6A in the oxidative stress response of Arabidopsis.
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Contribution of YjbIH to virulence factor expression and host colonization in Staphylococcus aureus
To persist within the host and cause disease, Staphylococcus aureus relies on its ability to precisely fine-tune virulence factor expression in response to rapidly-changing environments. During an unbiased transposon mutant screen, we observed that disruption of the two-gene operon, yjbIH , resulted in decreased pigmentation and aureolysin activity relative to the wild-type strain. Further analyses revealed that YjbH, a predicted thioredoxin-like oxidoreductase, is mostly responsible for the observed yjbIH mutant phenotypes, though a minor role exists for the putative truncated hemoglobin YjbI. These differences were due to significantly decreased expression of crtOPQMN and aur . Previous studies found that YjbH targets the disulfide- and oxidative-stress responsive regulator Spx for degradation by ClpXP. The absence of yjbH or yjbI resulted in altered sensitivities to nitrosative and oxidative stress and iron deprivation. Additionally, aconitase activity was altered in the yjbH and yjbI mutant strains. Decreased pigmentation and Aur activity in the yjbH mutant was found to be Spx-dependent. Lastly, we used a murine sepsis model to determine the effect of the yjbIH deletion on pathogenesis and found that the mutant was better able to colonize the kidneys and spleens during an acute infection than the wild-type strain. These studies identify changes in pigmentation and protease activity in response to YjbIH and are the first to show a role for these proteins during infection.
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- Award ID(s):
- 1750624
- PAR ID:
- 10093136
- Date Published:
- Journal Name:
- Infection and Immunity
- ISSN:
- 0019-9567
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1128/IAI.00155-19
