| 1. |
- Camilleri, C., et al.
(author)
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The Arabidopsis TONNEAU2 gene encodes a putative novel protein phosphatase 2A regulatory subunit essential for the control of the cortical cytoskeleton
- 2002
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In: Plant Cell. - 1040-4651 .- 1532-298X. ; 14:4, s. 833-845
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Journal article (peer-reviewed)abstract
- In Arabidopsis ton2 mutants, abnormalities of the cortical microtubular cytoskeleton, such as disorganization of the interphase microtubule array and lack of the preprophase band before mitosis, markedly affect cell shape and arrangement as well as overall plant morphology. We present the molecular isolation of the TON2 gene, which is highly conserved in higher plants and has a vertebrate homolog of unknown function. It encodes a protein similar in its C-terminal part to B" regulatory subunits of type 2A protein phosphatases (PP2As). We show that the TON2 protein interacts with an Arabidopsis type A subunit of PP2A in the yeast two-hybrid system and thus likely defines a novel subclass of PP2A subunits that are possibly involved in the control of cytoskeletal structures in plants., ISSN = 1040-4651, DOI = 10.1105/tpc.010402, url = ://WOS:000175350100008, year = 2002, type = Journal Article
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| 2. |
- Ahlfors, Reetta, et al.
(author)
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Arabidopsis RADICAL-INDUCED CELL DEATH1 belongs to the WWE protein-protein interaction domain protein family and modulates abscisic acid, ethylene, and methyl jasmonate responses.
- 2004
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In: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 16:7, s. 1925-37
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Journal article (peer-reviewed)abstract
- Experiments with several Arabidopsis thaliana mutants have revealed a web of interactions between hormonal signaling. Here, we show that the Arabidopsis mutant radical-induced cell death1 (rcd1), although hypersensitive to apoplastic superoxide and ozone, is more resistant to chloroplastic superoxide formation, exhibits reduced sensitivity to abscisic acid, ethylene, and methyl jasmonate, and has altered expression of several hormonally regulated genes. Furthermore, rcd1 has higher stomatal conductance than the wild type. The rcd1-1 mutation was mapped to the gene At1g32230 where it disrupts an intron splice site resulting in a truncated protein. RCD1 belongs to the (ADP-ribosyl)transferase domain–containing subfamily of the WWE protein–protein interaction domain protein family. The results suggest that RCD1 could act as an integrative node in hormonal signaling and in the regulation of several stress-responsive genes.
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| 3. |
- Andersson, Jenny, et al.
(author)
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Antisense inhibition of the photosynthetic antenna proteins CP29 and CP26 : implications for the mechanism of protective energy dissipation
- 2001
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In: The Plant Cell. - : American Society of Plant Biologists. - 1040-4651 .- 1532-298X. ; 13:5, s. 1193-1204
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Journal article (peer-reviewed)abstract
- The specific roles of the chlorophyll a/b binding proteins CP29 and CP26 in light harvesting and energy dissipation within the photosynthetic apparatus have been investigated. Arabidopsis was transformed with antisense constructs against the genes encoding the CP29 or CP26 apoprotein, which gave rise to several transgenic lines with remarkably low amounts of the antisense target proteins. The decrease in the level of CP24 protein in the CP29 antisense lines indicates a physical interaction between these complexes. Analysis of chlorophyll fluorescence showed that removal of the proteins affected photosystem II function, probably as a result of changes in the organization of the light-harvesting antenna. However, whole plant measurements showed that overall photosynthetic rates were similar to those in the wild type. Both antisense lines were capable of the qE type of nonphotochemical fluorescence quenching, although there were minor changes in the capacity for quenching and in its induction kinetics. High-light-induced violaxanthin deepoxidation to zeaxanthin was not affected, although the pool size of these pigments was decreased slightly. We conclude that CP29 and CP26 are unlikely to be sites for nonphotochemical quenching.
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| 4. |
- Bharti, K, et al.
(author)
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Tomato heat stress transcription factor HsfB1 represents a novel type of general transcription coactivator with a histone-like motif interacting with the plant CREB binding protein ortholog HAC1
- 2004
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In: The Plant cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 16:6, s. 1521-1535
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Journal article (peer-reviewed)abstract
- In contrast with the class A heat stress transcription factors (HSFs) of plants, a considerable number of HSFs assigned to classes B and C have no evident function as transcription activators on their own. However, in the following article, we provide evidence that tomato (Lycopersicon peruvianum) HsfB1 represents a novel type of coactivator cooperating with class A HSFs (e.g., with tomato HsfA1). Provided the appropriate promoter architecture, the two HSFs assemble into an enhanceosome-like complex, resulting in strong synergistic activation of reporter gene expression. Moreover, HsfB1 also cooperates in a similar manner with other activators, for example, with the ASF1/2 enhancer binding proteins of the 35S promoter of Cauliflower mosaic virus or with yet unidentified activators controlling housekeeping gene expression. By these effects, HsfB1 may help to maintain and/or restore expression of certain viral or housekeeping genes during ongoing heat stress. The coactivator function of HsfB1 depends on a histone-like motif in its C-terminal domain with an indispensable Lys residue in the center (GRGKMMK). This motif is required for recruitment of the plant CREB binding protein (CBP) ortholog HAC1. HsfA1, HsfB1, and HAC1/CBP form ternary complexes in vitro and in vivo with markedly enhanced efficiency in promoter recognition and transcription activation in plant and mammalian (COS7) cells. Using small interfering RNA–mediated knock down of HAC1 expression in Arabidopsis thaliana mesophyll protoplasts, the crucial role for the coactivator function of HsfB1 was confirmed.
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| 5. |
- Bourquin, V., et al.
(author)
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Xyloglucan endotransglycosylases have a function during the formation of secondary cell walls of vascular tissues
- 2002
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In: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 14:12, s. 3073-3088
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Journal article (peer-reviewed)abstract
- Xyloglucan transglycosylases (XETs) have been implicated in many aspects of cell wall biosynthesis, but their function in vascular tissues, in general, and in the formation of secondary walls, in particular, is less well understood. Using an in situ XET activity assay in poplar stems, we have demonstrated XET activity in xylem and phloem fibers at the stage of secondary wall formation. Immunolocalization of fucosylated xylogucan with CCRC-M1 antibodies showed that levels of this species increased at the border between the primary and secondary wall layers at the time of secondary wall deposition. Furthermore, one of the most abundant XET isoforms in secondary vascular tissues (PttXET16A) was cloned and immunolocalized to fibers at the stage of secondary wall formation. Together, these data strongly suggest that XET has a previously unreported role in restructuring primary walls at the time when secondary wall layers are deposited, probably creating and reinforcing the connections between the primary and secondary wall layers. We also observed that xylogucan is incorporated at a high level in the inner layer of nacreous walls of mature sieve tube elements.
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| 6. |
- Butenko, Melinka A., et al.
(author)
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Inflorescence deficient in abscission controls floral organ abscission in Arabidopsis and identifies a novel family of putative Ligands in Plants
- 2003
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In: The Plant Cell. - : American Society of Plant Biologists. - 1040-4651 .- 1532-298X. ; 15:10, s. 2296-2307
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Journal article (peer-reviewed)abstract
- Abscission is an active process that enables plants to shed unwanted organs. Because the purpose of the flower is to facilitate pollination, it often is abscised after fertilization. We have identified an Arabidopsis ethylene-sensitive mutant, inflorescence deficient in abscission (ida), in which floral organs remain attached to the plant body after the shedding of mature seeds, even though a floral abscission zone develops. The IDA gene, positioned in the genomic DNA flanking the single T-DNA present in the ida line, was identified by complementation. The gene encodes a small protein with an N-terminal signal peptide, suggesting that the IDA protein is the ligand of an unknown receptor involved in the developmental control of floral abscission. We have identified Arabidopsis genes, and cDNAs from a variety of plant species, that encode similar proteins, which are distinct from known ligands. IDA and the IDA-like proteins may represent a new class of ligands in plants
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| 7. |
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| 8. |
- Ivanov, Konstantin I, et al.
(author)
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Phosphorylation of the potyvirus capsid protein by protein kinase CK2 and its relevance for virus infection.
- 2003
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In: Plant Cell. - 1040-4651. ; 15:9, s. 2124-39
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Journal article (peer-reviewed)abstract
- We reported previously that the capsid protein (CP) of Potato virus A (PVA) is phosphorylated both in virus-infected plants and in vitro. In this study, an enzyme that phosphorylates PVA CP was identified as the protein kinase CK2. The alpha-catalytic subunit of CK2 (CK2alpha) was purified from tobacco and characterized using in-gel kinase assays and liquid chromatography-tandem mass spectrometry. The tobacco CK2alpha gene was cloned and expressed in bacterial cells. Specific antibodies were raised against the recombinant enzyme and used to demonstrate the colocalization of PVA CP and CK2alpha in infected tobacco protoplasts. A major site of CK2 phosphorylation in PVA CP was identified by a combination of mass spectrometric analysis, radioactive phosphopeptide sequencing, and mutagenesis as Thr-242 within a CK2 consensus sequence. Amino acid substitutions that affect the CK2 consensus sequence in CP were introduced into a full-length infectious cDNA clone of PVA tagged with green fluorescent protein. Analysis of the mutant viruses showed that they were defective in cell-to-cell and long-distance movement. Using in vitro assays, we demonstrated that CK2 phosphorylation inhibited the binding of PVA CP to RNA, suggesting a molecular mechanism of CK2 action. These results suggest that the phosphorylation of PVA CP by CK2 plays an important regulatory role in virus infection.
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| 9. |
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| 10. |
- Lindahl, Marika, et al.
(author)
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The thylakoid FtsH protease plays a role in the light-induced turnover of the photosystem II D1 protein
- 2000
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In: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 12:3, s. 419-431
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Journal article (peer-reviewed)abstract
- The photosystem II reaction center D1 protein is known to turn over frequently. This protein is prone to irreversible damage caused by reactive oxygen species that are formed in the light, the damaged, nonfunctional D1 protein is degraded and replaced by a new copy. However, the proteases responsible for D1 protein degradation remain unknown. In this study, we investigate the possible role of the FtsH protease, an ATP-dependent zinc metalloprotease, during this process. The primary light-induced cleavage product of the D1 protein, a 23-kD fragment, was found to be degraded in isolated thylakoids in the dark during a process dependent on ATP hydrolysis and divalent metal ions, suggesting the involvement of FtsH. Purified FtsH degraded the 23-kD D1 fragment present in isolated photosystem II core complexes, as well as that in thylakoid membranes depleted of endogenous FtsH. In this study, we definitively identify the chloroplast protease acting on the D1 protein during its light-induced turnover. Unlike previously identified membrane-bound substrates for FtsH in bacteria and mitochondria, the 23-kD D1 fragment represents a novel class of FtsH substrate - functionally assembled proteins that have undergone irreversible photooxidative damage and cleavage.
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