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PMID:19435936

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Citation

Koroleva, OA, Calder, G, Pendle, AF, Kim, SH, Lewandowska, D, Simpson, CG, Jones, IM, Brown, JW and Shaw, PJ (2009) Dynamic behavior of Arabidopsis eIF4A-III, putative core protein of exon junction complex: fast relocation to nucleolus and splicing speckles under hypoxia. Plant Cell 21:1592-606

Abstract

Here, we identify the Arabidopsis thaliana ortholog of the mammalian DEAD box helicase, eIF4A-III, the putative anchor protein of exon junction complex (EJC) on mRNA. Arabidopsis eIF4A-III interacts with an ortholog of the core EJC component, ALY/Ref, and colocalizes with other EJC components, such as Mago, Y14, and RNPS1, suggesting a similar function in EJC assembly to animal eIF4A-III. A green fluorescent protein (GFP)-eIF4A-III fusion protein showed localization to several subnuclear domains: to the nucleoplasm during normal growth and to the nucleolus and splicing speckles in response to hypoxia. Treatment with the respiratory inhibitor sodium azide produced an identical response to the hypoxia stress. Treatment with the proteasome inhibitor MG132 led to accumulation of GFP-eIF4A-III mainly in the nucleolus, suggesting that transition of eIF4A-III between subnuclear domains and/or accumulation in nuclear speckles is controlled by proteolysis-labile factors. As revealed by fluorescence recovery after photobleaching analysis, the nucleoplasmic fraction was highly mobile, while the speckles were the least mobile fractions, and the nucleolar fraction had an intermediate mobility. Sequestration of eIF4A-III into nuclear pools with different mobility is likely to reflect the transcriptional and mRNA processing state of the cell.

Links

PubMed PMC2700535 Online version:10.1105/tpc.108.060434

Keywords

Amino Acid Sequence; Arabidopsis/drug effects; Arabidopsis/metabolism; Arabidopsis/ultrastructure; Arabidopsis Proteins/chemistry; Arabidopsis Proteins/genetics; Arabidopsis Proteins/metabolism; Cell Hypoxia; Cell Nucleolus/metabolism; Conserved Sequence; Enzyme Inhibitors/pharmacology; Eukaryotic Initiation Factor-4A/chemistry; Eukaryotic Initiation Factor-4A/genetics; Eukaryotic Initiation Factor-4A/metabolism; Green Fluorescent Proteins/analysis; Leupeptins/pharmacology; Molecular Sequence Data; Protein Transport/drug effects; Recombinant Fusion Proteins/analysis; Sequence Alignment; Sodium Azide/pharmacology; Two-Hybrid System Techniques

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ARATH:RH2

involved_in

GO:0001666: response to hypoxia

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:RH2

located_in

GO:0005654: nucleoplasm

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:RH2

located_in

GO:0005730: nucleolus

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:RH2

located_in

GO:0016607: nuclear speck

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:RH2

part_of

GO:0035145: exon-exon junction complex

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete


See also

References

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