Characterization of EMU, the Arabidopsis homolog of the yeast THO complex member HPR1

Furumizu, Chihiro; Tsukaya, Hirokazu; Komeda, Yoshibumi

doi:10.1261/rna.2265710

Cited by 47 publications

(76 citation statements)

References 73 publications

(86 reference statements)

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“…It has been described that the proteins involved in mRNA decapping, DCP1, DCP2, VCS, and DCP5, as well as the splicing factors STA1, U11/U112-31K, and ERECTA MRNA UNDER-EXPRESSED, play an essential role in Arabidopsis development, their absence being lethal (Lee et al, 2006;Xu et al, 2006;Goeres et al, 2007;Xu and Chua, 2009;Furumizu et al, 2010;Kim et al, 2010). Arabidopsis plants deficient in LSM1 and LSM8 proteins also display quite severe development alterations, but they are viable.…”

Section: Discussionmentioning

confidence: 99%

LSM Proteins Provide Accurate Splicing and Decay of Selected Transcripts to Ensure NormalArabidopsisDevelopment

et al. 2012

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In yeast and animals, SM-like (LSM) proteins typically exist as heptameric complexes and are involved in different aspects of RNA metabolism. Eight LSM proteins, LSM1 to 8, are highly conserved and form two distinct heteroheptameric complexes, LSM1-7 and LSM2-8,that function in mRNA decay and splicing, respectively. A search of the Arabidopsis thaliana genome identifies 11 genes encoding proteins related to the eight conserved LSMs, the genes encoding the putative LSM1, LSM3, and LSM6 proteins being duplicated. Here, we report the molecular and functional characterization of the Arabidopsis LSM gene family. Our results show that the 11 LSM genes are active and encode proteins that are also organized in two different heptameric complexes. The LSM1-7 complex is cytoplasmic and is involved in P-body formation and mRNA decay by promoting decapping. The LSM2-8 complex is nuclear and is required for precursor mRNA splicing through U6 small nuclear RNA stabilization. More importantly, our results also reveal that these complexes are essential for the correct turnover and splicing of selected development-related mRNAs and for the normal development of Arabidopsis. We propose that LSMs play a critical role in Arabidopsis development by ensuring the appropriate development-related gene expression through the regulation of mRNA splicing and decay.

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Section: Discussionmentioning

confidence: 99%

LSM Proteins Provide Accurate Splicing and Decay of Selected Transcripts to Ensure NormalArabidopsisDevelopment

et al. 2012

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“…MEE8 possesses four cysteine residues, which could be involved in PDI2-mediated disulfide bond formation, with residue C96 being a strong candidate for further analysis due to its conservation among several Arabidopsis bHLH proteins. In addition to MEE8, our yeast two-hybrid screen identified two other nuclear interactors of PDI2: HPR1 (At5g09860), a component of the THO/TREX mRNA export complex (Furumizu et al, 2010;Jauvion et al, 2010); and a protein sharing partial homology to the prokaryotic Rho transcription termination factor. PDI2 exited the ER and trafficked through the secretory pathway PDI2 was demonstrated to have a functional 25-residue signal peptide that is co-translationally processed in vitro and inserted into canine microsomal membranes.…”

Section: Discussionmentioning

confidence: 99%

Protein Disulfide Isomerase-2 of Arabidopsis Mediates Protein Folding and Localizes to Both the Secretory Pathway and Nucleus, Where It Interacts with Maternal Effect Embryo Arrest Factor

Cho

Yuen

Kang

et al. 2011

Molecules and Cells

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Protein disulfide isomerase (PDI) is a thiodisulfide oxidoreductase that catalyzes the formation, reduction and rearrangement of disulfide bonds in proteins of eukaryotes. The classical PDI has a signal peptide, two CXXCcontaining thioredoxin catalytic sites (a,a′), two noncatalytic thioredoxin fold domains (b,b′), an acidic domain (c) and a C-terminal endoplasmic reticulum (ER) retention signal. Although PDI resides in the ER where it mediates the folding of nascent polypeptides of the secretory pathway, we recently showed that PDI5 of Arabidopsis thaliana chaperones and inhibits cysteine proteases during trafficking to vacuoles prior to programmed cell death of the endothelium in developing seeds. Here we describe Arabidopsis PDI2, which shares a primary structure similar to that of classical PDI. Recombinant PDI2 is imported into ER-derived microsomes and complements the E. coli protein-folding mutant, dsbA. PDI2 interacted with proteins in both the ER and nucleus, including ER-resident protein folding chaperone, BiP1, and nuclear embryo transcription factor, MEE8. The PDI2-MEE8 interaction was confirmed to occur in vitro and in vivo. Transient expression of PDI2-GFP fusions in mesophyll protoplasts resulted in labeling of the ER, nucleus and vacuole. PDI2 is expressed in multiple tissues, with relatively high expression in seeds and root tips. Immunoelectron microscopy with GFP-and PDI2-specific antisera on transgenic seeds (PDI2-GFP) and wild type roots demonstrated that PDI2 was found in the secretory pathway (ER, Golgi, vacuole, cell wall) and the nuclei. Our results indicate that PDI2 mediates protein folding in the ER and has new functional roles in the nucleus.

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“…Recently it has been reported that ERECTA expression is decreased in an emu mutant (Furumizu et al 2010). EMU encodes a protein homologous to yeast HPR1, a component of the THO complex.…”

Section: Role Of Introns In Erecta Expressionmentioning

confidence: 99%

The presence of multiple introns is essential for ERECTA expression in Arabidopsis

Karve

Liu

Willet

et al. 2011

RNA

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Gene expression in eukaryotes is often enhanced by the presence of introns. Depending on the specific gene, this enhancement can be minor or very large and occurs at both the transcriptional and post-transcriptional levels. The Arabidopsis ERECTA gene contains 27 exons encoding a receptor-like kinase that promotes cell proliferation and inhibits cell differentiation in above-ground plant organs. The expression of ERECTA very strongly depends on the presence of introns. The intronless ERECTA gene does not rescue the phenotype of erecta mutant plants and produces about 500-900 times less protein compared with the identical construct containing introns. This result is somewhat surprising as the region upstream of the ERECTA coding sequence effectively promotes the expression of extraneous genes. Here, we demonstrate that introns are essential for ERECTA mRNA accumulation and, to a lesser extent, for mRNA utilization in translation. Since mRNA produced by intronless ERECTA is degraded at the 39 end, we speculate that introns increase mRNA accumulation through increasing its stability at least in part. No individual intron is absolutely necessary for ERECTA expression, but rather multiple introns in specific locations increase ERECTA expression in an additive manner. The ability of introns to promote ERECTA expression might be linked to the process of splicing and not to a particular intron sequence.

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Characterization of EMU, the Arabidopsis homolog of the yeast THO complex member HPR1

Cited by 47 publications

References 73 publications

LSM Proteins Provide Accurate Splicing and Decay of Selected Transcripts to Ensure NormalArabidopsisDevelopment

LSM Proteins Provide Accurate Splicing and Decay of Selected Transcripts to Ensure NormalArabidopsisDevelopment

Protein Disulfide Isomerase-2 of Arabidopsis Mediates Protein Folding and Localizes to Both the Secretory Pathway and Nucleus, Where It Interacts with Maternal Effect Embryo Arrest Factor

The presence of multiple introns is essential for ERECTA expression in Arabidopsis

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