| 1. |
- Gamm, Magdalena, et al.
(författare)
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Increased sucrose levels mediate selective mRNA translation in Arabidopsis
- 2014
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Protein synthesis is a highly energy demanding process and is regulated according to cellular energy levels. Light and sugar availability affect mRNA translation in plant cells but the specific roles of these factors remain unclear. In this study, sucrose was applied to Arabidopsis seedlings kept in the light or in the dark, in order to distinguish sucrose and light effects on transcription and translation. These were studied using microarray analysis of steady-state mRNA and mRNA bound to translating ribosomes. Results: Steady-state mRNA levels were affected differently by sucrose in the light and in the dark but general translation increased to a similar extent in both conditions. For a majority of the transcripts changes of the transcript levels were followed by changes in polysomal mRNA levels. However, for 243 mRNAs, a change in polysomal occupancy (defined as polysomal levels related to steady-state levels of the mRNA) was observed after sucrose treatment in the light, but not in the dark condition. Many of these mRNAs are annotated as encoding ribosomal proteins, supporting specific translational regulation of this group of transcripts. Unexpectedly, the numbers of ribosomes bound to each mRNA decreased for mRNAs with increased polysomal occupancy. Conclusions: Our results suggest that sucrose regulate translation of these 243 mRNAs specifically in the light, through a novel regulatory mechanism. Our data shows that increased polysomal occupancy is not necessarily leading to more ribosomes per transcript, suggesting a mechanism of translational induction not solely dependent on increased translation initiation rates.
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| 2. |
- Jiang, Rays H. Y., et al.
(författare)
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Distinctive Expansion of Potential Virulence Genes in the Genome of the Oomycete Fish Pathogen Saprolegnia parasitica
- 2013
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 9:6, s. e1003272-
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Tidskriftsartikel (refereegranskat)abstract
- Oomycetes in the class Saprolegniomycetidae of the Eukaryotic kingdom Stramenopila have evolved as severe pathogens of amphibians, crustaceans, fish and insects, resulting in major losses in aquaculture and damage to aquatic ecosystems. We have sequenced the 63 Mb genome of the fresh water fish pathogen, Saprolegnia parasitica. Approximately 1/3 of the assembled genome exhibits loss of heterozygosity, indicating an efficient mechanism for revealing new variation. Comparison of S. parasitica with plant pathogenic oomycetes suggests that during evolution the host cellular environment has driven distinct patterns of gene expansion and loss in the genomes of plant and animal pathogens. S. parasitica possesses one of the largest repertoires of proteases (270) among eukaryotes that are deployed in waves at different points during infection as determined from RNA-Seq data. In contrast, despite being capable of living saprotrophically, parasitism has led to loss of inorganic nitrogen and sulfur assimilation pathways, strikingly similar to losses in obligate plant pathogenic oomycetes and fungi. The large gene families that are hallmarks of plant pathogenic oomycetes such as Phytophthora appear to be lacking in S. parasitica, including those encoding RXLR effectors, Crinkler's, and Necrosis Inducing-Like Proteins (NLP). S. parasitica also has a very large kinome of 543 kinases, 10% of which is induced upon infection. Moreover, S. parasitica encodes several genes typical of animals or animal-pathogens and lacking from other oomycetes, including disintegrins and galactose-binding lectins, whose expression and evolutionary origins implicate horizontal gene transfer in the evolution of animal pathogenesis in S. parasitica.
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| 3. |
- Nijenhuis, Wilco, et al.
(författare)
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A TPR domain-containing N-terminal module of MPS1 is required for its kinetochore localization by Aurora B
- 2013
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 201:2, s. 217-231
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Tidskriftsartikel (refereegranskat)abstract
- The mitotic checkpoint ensures correct chromosome segregation by delaying cell cycle progression until all kinetochores have attached to the mitotic spindle. In this paper, we show that the mitotic checkpoint kinase MPS1 contains an N-terminal localization module, organized in an N-terminal extension (NTE) and a tetratricopeptide repeat (TPR) domain, for which we have determined the crystal structure. Although the module was necessary for kinetochore localization of MPS1 and essential for the mitotic checkpoint, the predominant kinetochore binding activity resided within the NTE. MPS1 localization further required HEC1 and Aurora B activity. We show that MPS1 localization to kinetochores depended on the calponin homology domain of HEC1 but not on Aurora B-dependent phosphorylation of the HEC1 tail. Rather, the TPR domain was the critical mediator of Aurora B control over MPS1 localization, as its deletion rendered MPS1 localization insensitive to Aurora B inhibition. These data are consistent with a model in which Aurora B activity relieves a TPR-dependent inhibitory constraint on MPS1 localization.
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| 4. |
- Resjö, Svante, et al.
(författare)
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Quantitative Label-Free Phosphoproteomics of Six Different Life Stages of the Late Blight Pathogen Phytophthora infestans Reveals Abundant Phosphorylation of Members of the CRN Effector Family
- 2014
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 13:4, s. 1848-1859
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Tidskriftsartikel (refereegranskat)abstract
- The oomycete Phytophthora infestans is the causal agent of late blight in potato and tomato. Since the underlying processes that govern pathogenicity and development in P. infestans are largely unknown, we have performed a large-scale phosphoproteomics study of six different P. infestans life stages. We have obtained quantitative data for 2922 phosphopeptides and compared their abundance. Life-stages-pecific phosphopeptides include ATP-binding cassette transporters and a kinase that only occurs in appressoria. In an extended data set, we identified 2179 phosphorylation sites and deduced 22 phosphomotifs. Several of the phosphomotifs matched consensus sequences of kinases that occur in P. infestans but not Arabidopsis. In addition, we detected tyrosine phosphopeptides that are potential targets of kinases resembling mammalian tyrosine kinases. Among the phosphorylated proteins are members of the RXLR and Crinkler effector families. The latter are phosphorylated in several life stages and at multiple positions, in sites that are conserved between different members of the Crinkler family. This indicates that proteins in the Crinkler family have functions beyond their putative role as (necrosis-inducing) effectors. This phosphoproteomics data will be instrumental for studies on oomycetes and host oomycete interactions. The data sets have been deposited to ProteomeXchange (identifier PXD000433).
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| 5. |
- Suijkerbuijk, Saskia J E, et al.
(författare)
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The vertebrate mitotic checkpoint protein BUBR1 is an unusual pseudokinase
- 2012
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Ingår i: Developmental Cell. - Cambridge, United States : Cell Press. - 1534-5807 .- 1878-1551. ; 22:6, s. 1321-1329
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Tidskriftsartikel (refereegranskat)abstract
- Chromosomal stability is safeguarded by a mitotic checkpoint, of which BUB1 and Mad3/BUBR1 are core components. These paralogs have similar, but not identical, domain organization. We show that Mad3/BUBR1 and BUB1 paralogous pairs arose by nine independent gene duplications throughout evolution, followed by parallel subfunctionalization in which preservation of the ancestral, amino-terminal KEN box or kinase domain was mutually exclusive. In one exception, vertebrate BUBR1-defined by the KEN box-preserved the kinase domain but allowed nonconserved degeneration of catalytic motifs. Although BUBR1 evolved to a typical pseudokinase in some vertebrates, it retained the catalytic triad in humans. However, we show that putative catalysis by human BUBR1 is dispensable for error-free chromosome segregation. Instead, residues that interact with ATP in conventional kinases are essential for conformational stability in BUBR1. We propose that parallel evolution of BUBR1 orthologs rendered its kinase function dispensable in vertebrates, producing an unusual, triad-containing pseudokinase.
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| 6. |
- Wind, Julia J., et al.
(författare)
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ABI4 : versatile activator and repressor
- 2013
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385 .- 1878-4372. ; 18:3, s. 125-132
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Tidskriftsartikel (refereegranskat)abstract
- The ABSCISIC ACID INSENSITIVE4 (ABI4) gene was discovered to be an abscisic acid (ABA) signaling responsive transcription factor active during seed germination. The evolutionary history of the ABI4 gene supports its role as an ABA signaling intermediate in land plants. Investigating the ABI4 protein-cis element interaction supports the proposal that ABI4 binding to its known CE1 cis-element competes with transcription factor binding to the overlapping G-Box element. Recent publications report on ABI4 as a regulatory factor in diverse processes. In developing seedlings, ABI4 mediates sugar signaling, lipid breakdown, and plastid-to-nucleus signaling. Moreover, ABI4 is a regulator of rosette growth, redox signaling, cell wall metabolism and the effect of nitrate on lateral root development.
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