Condition-specific RNA editing in the coral symbiont Symbiodinium microadriaticum.

Yi Jin Liew,Yong Li,Christian R Voolstra,Manuel Aranda,Sebastian Baumgarten,Vivian G Cheung

doi:10.1371/journal.pgen.1006619

Yi Jin Liew, Yong Li + Show 4 more

Open Access

https://doi.org/10.1371/journal.pgen.1006619

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Abstract

RNA editing is a rare post-transcriptional event that provides cells with an additional level of gene expression regulation. It has been implicated in various processes including adaptation, viral defence and RNA interference; however, its potential role as a mechanism in acclimatization has just recently been recognised. Here, we show that RNA editing occurs in 1.6% of all nuclear-encoded genes of Symbiodinium microadriaticum, a dinoflagellate symbiont of reef-building corals. All base-substitution edit types were present, and statistically significant motifs were associated with three edit types. Strikingly, a subset of genes exhibited condition-specific editing patterns in response to different stressors that resulted in significant increases of non-synonymous changes. We posit that this previously unrecognised mechanism extends this organism’s capability to respond to stress beyond what is encoded by the genome. This in turn may provide further acclimatization capacity to these organisms, and by extension, their coral hosts.

Highlights

RNA editing is a collection of co- or post-transcriptional processes that produce RNA sequences that differ from their DNA templates
We identified nuclear-encoded genes undergoing RNA editing in S. microadriaticum, a dinoflagellate symbiont of reef-building corals
When subjected to several common environmental stressors, the editing frequencies of some genes shifted in a consistent pattern that was specific to the applied stress

Summary

Introduction

RNA editing is a collection of co- or post-transcriptional processes that produce RNA sequences that differ from their DNA templates (excluding mRNA splicing, capping and polyadenylation) These processes provide organisms with an additional layer of post-transcriptional control, and typically manifest as the production of tissue-specific protein isoforms [1], play a role in caste determination [2], or to adapt to a new environment [3]. Studies in human monocytes show specific induction of C-to-U edits in the human SDHB gene in response to hypoxic conditions [4]; in Drosophila, A-to-I edit frequencies have been shown to respond to heat stress [5] For the latter, the changes were tightly linked to transcriptional silencing of the sole RNA editing enzyme encoded in the genome.

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