PMID:28346704

Citation	'Bobik, K, McCray, TN, Ernest, B, Fernandez, JC, Howell, KA, Lane, T, Staton, M and Burch-Smith, TM (2017) The chloroplast RNA helicase ISE2 is required for multiple chloroplast RNA processing steps in Arabidopsis thaliana. Plant J. '
Abstract	INCREASED SIZE EXCLUSION LIMIT2 (ISE2) is a chloroplast-localized RNA helicase that is indispensable for proper plant development. Chloroplasts in leaves with reduced ISE2 expression have previously been shown to exhibit reduced thylakoid contents and increased stromal volume, indicative of defective development. It has recently been reported that ISE2 is required for the splicing of group II introns from chloroplast transcripts. The current study extends these findings, and presents evidence for ISE2's role in multiple aspects of chloroplast RNA processing beyond group II intron splicing. Loss of ISE2 from Arabidopsis thaliana leaves resulted in defects in C-to-U RNA editing, altered accumulation of chloroplast transcripts and chloroplast-encoded proteins, and defective processing of chloroplast ribosomal RNAs. Potential ISE2 substrates were identified by RNA immunoprecipitation followed by next-generation sequencing (RIP-seq), and the diversity of RNA species identified supports ISE2's involvement in multiple aspects of chloroplast RNA metabolism. Comprehensive phylogenetic analyses revealed that ISE2 is a non-canonical Ski2-like RNA helicase that represents a separate sub-clade unique to green photosynthetic organisms, consistent with its function as an essential protein. Thus ISE2's evolutionary conservation may be explained by its numerous roles in regulating chloroplast gene expression. This article is protected by copyright. All rights reserved.
Links	PubMed Online version:10.1111/tpj.13550
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARATH:ISE2		GO:0016554: cytidine to uridine editing	ECO:0000315:		P		ISE2 in A. thaliana. Figure 2. Loss of ISE2 compromises C-to-U RNA editing at specific sites. 6 sites known to undergo C-to-U editing are monitored, with a marked decrease in editing in cells with silenced ISE2.	complete CACAO 12408
ARATH:ISE2		GO:0000373: Group II intron splicing	ECO:0000315:		P		ISE2 in A. thaliana. Figure 4. ISE2 is required for splicing of a group II intron in ycf3 transcripts. Verified using qPCR and gel electrophoresis showing an increase in the unspliced variant of the intron.	complete CACAO 12409
ARATH:ISE2		GO:1901259: chloroplast rRNA processing	ECO:0000315:		P		ISE2 in A. thaliana. Figure 5. Loss of ISE2 leads to defects in rRNA processing. With silenced ISE2, aberrant forms of rRNA are visualized with gel electrophoresis when compared to overexpressed ISE2 and control cells.	complete CACAO 12410

References

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