Thioredoxin can influence gene expression by affecting gyrase activity

Li, K.

doi:10.1093/nar/gkh794

Cited by 17 publications

(23 citation statements)

References 65 publications

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“…Because the loss of RHL1 function leads to a phenotype as severe as that of topo VI mutants, it is clear that RHL1 plays an essential role in the plant topo VI complex. In some organisms, topos are thought to be part of a large protein complex, and some proteins and͞or protein complexes may modulate topo activities (37)(38)(39). In addition to the work on Barren in Drosophila (38), this study provides direct genetic evidence that an additional component in the topo complex plays a vital role to modify its function.…”

Section: Hyp7 Is Essential For Successive Endocycles Beyond 8cmentioning

confidence: 76%

RHL1 is an essential component of the plant DNA topoisomerase VI complex and is required for ploidy-dependent cell growth

Sugimoto‐Shirasu

Roberts

Stacey

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

106

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How cells achieve their final sizes is a pervasive biological question. One strategy to increase cell size is for the cell to amplify its chromosomal DNA content through endoreduplication cycles. Although endoreduplication is widespread in eukaryotes, we know very little about its molecular mechanisms. Successful progression of the endoreduplication cycle in Arabidopsis requires a plant homologue of archaeal DNA topoisomerase (topo) VI. To further understand how DNA is endoreduplicated and how this process is regulated, we isolated a dwarf Arabidopsis mutant, hyp7 (hypocotyl 7), in which various large cell types that in the wild type normally endoreduplicate multiple times complete only the first two rounds of endoreduplication and stall at 8C. HYP7 encodes the RHL1 (ROOT HAIRLESS 1) protein, and sequence analysis reveals that RHL1 has similarity to the C-terminal domain of mammalian DNA topo II␣, another type II topo that shares little sequence homology with topo VI. RHL1 shows DNA binding activity in vitro, and we present both genetic and in vivo evidence that RHL1 forms a multiprotein complex with plant topo VI. We propose that RHL1 plays an essential role in the topo VI complex to modulate its function and that the two distantly related topos, topo II and topo VI, have evolved a common domain that extends their function. Our data suggest that plant topo II and topo VI play distinct but overlapping roles during the mitotic cell cycle and endoreduplication cycle.endoreduplication ͉ hypocotyl ͉ root hairless T he control of cell size is a highly regulated process with inputs from genetic, hormonal, and environmental cues. Yeast and mammalian cells usually only double their size during their development; therefore, a key question in their size control is how proliferating cells coordinate cell growth and cell division to maintain size homeostasis. Yeast and many mammalian cells have a cell size checkpoint mechanism in which cells divide only when they reach a critical size (1), whereas some mammalian cells may control their size through extracellular signals (2). Although plant cells also double their cell size during proliferation, they commonly undergo an additional, massive (sometimes Ͼ1,000-fold), postmitotic cell enlargement. Such a large increase in volume is driven by a combination of production of new cytoplasmic mass and cell expansion (driven by water uptake and vacuolar growth), but little is known about the underlying mechanisms involved. Recent genetic evidence strongly supports the classical ''karyoplasmic ratio'' theory that one mechanism to increase cell size is by increasing the ploidy level within a cell, for example through endoreduplication, defined as the amplification of chromosomal DNA without corresponding cell division (3). Several mutants and transgenic plants that have aberrant levels of endoreduplication have been isolated and have led to the identification of key regulators of the endoreduplication cycle or endocycle (3-7). How these regulators control downstream events, however, rem...

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Section: Hyp7 Is Essential For Successive Endocycles Beyond 8cmentioning

confidence: 76%

RHL1 is an essential component of the plant DNA topoisomerase VI complex and is required for ploidy-dependent cell growth

Sugimoto‐Shirasu

Roberts

Stacey

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

106

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“…More recently, TRX was also shown to be involved in the oxygen-dependent regulation of photosynthesis genes encoded by the puf operon in Rhodobacter sphaeroides (Pasternak et al, 1999). Reduced TRX-A of R. sphaeroides interacts with DNA gyrase in a thiol-independent manner and alters its DNA supercoiling activity, thereby affecting gene expression (Li et al, 2004). Available evidence suggests that PGE is also under redox control in higher plants (Pfannschmidt and Liere, 2005).…”

Section: Discussionmentioning

confidence: 99%

Plastidial Thioredoxin z Interacts with Two Fructokinase-Like Proteins in a Thiol-Dependent Manner: Evidence for an Essential Role in Chloroplast Development in Arabidopsis and Nicotiana benthamiana

et al. 2010

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Here, we characterize a plastidial thioredoxin (TRX) isoform from Arabidopsis thaliana that defines a previously unknown branch of plastidial TRXs lying between x-and y-type TRXs and thus was named TRX z. An Arabidopsis knockout mutant of TRX z had a severe albino phenotype and was inhibited in chloroplast development. Quantitative real-time RT-PCR analysis of the mutant suggested that the expressions of genes that depend on a plastid-encoded RNA polymerase (PEP) were specifically decreased. Similar results were obtained upon virus-induced gene silencing (VIGS) of the TRX z ortholog in Nicotiana benthamiana. We found that two fructokinase-like proteins (FLN1 and FLN2), members of the pfkB-carbohydrate kinase family, were potential TRX z target proteins and identified conserved Cys residues mediating the FLN-TRX z interaction. VIGS in N. benthamiana and inducible RNA interference in Arabidopsis of FLNs also led to a repression of PEPdependent gene transcription. Remarkably, recombinant FLNs displayed no detectable sugar-phosphorylating activity, and amino acid substitutions within the predicted active site imply that the FLNs have acquired a new function, which might be regulatory rather than metabolic. We were able to show that the FLN2 redox state changes in vivo during light/dark transitions and that this change is mediated by TRX z. Taken together, our data strongly suggest an important role for TRX z and both FLNs in the regulation of PEP-dependent transcription in chloroplasts.

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“…In Rhodobacter sphaeroides, expression of genes from the puf operon is controlled by thioredoxin (Pasternak et al, 1999). Furthermore, redox signals via thioredoxin are able to influence gene expression by affecting gyrase activity (Li et al, 2004). Thus, the association of these components to the TAC might ensure its regulation in response to various signals.…”

Section: Discussionmentioning

confidence: 99%

pTAC2, -6, and -12 Are Components of the Transcriptionally Active Plastid Chromosome That Are Required for Plastid Gene Expression

et al. 2005

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Transcription in plastids is mediated by a plastid-encoded multimeric (PEP) and a nuclear-encoded single-subunit RNA polymerase (NEP) and a still unknown number of nuclear-encoded factors. By combining gel filtration and affinity chromatography purification steps, we isolated transcriptionally active chromosomes from Arabidopsis thaliana and mustard (Sinapis alba) chloroplasts and identified 35 components by electrospray ionization ion trap tandem mass spectrometry. Eighteen components, called plastid transcriptionally active chromosome proteins (pTACs), have not yet been described. T-DNA insertions in three corresponding genes, ptac2, -6, and -12, are lethal without exogenous carbon sources. Expression patterns of the plastid-encoded genes in the corresponding knockout lines resemble those of Drpo mutants. For instance, expression of plastid genes with PEP promoters is downregulated, while expression of genes with NEP promoters is either not affected or upregulated in the mutants. All three components might also be involved in posttranscriptional processes, such as RNA processing and/or mRNA stability. Thus, pTAC2, -6, and -12 are clearly involved in plastid gene expression.

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Thioredoxin can influence gene expression by affecting gyrase activity

Cited by 17 publications

References 65 publications

RHL1 is an essential component of the plant DNA topoisomerase VI complex and is required for ploidy-dependent cell growth

RHL1 is an essential component of the plant DNA topoisomerase VI complex and is required for ploidy-dependent cell growth

Plastidial Thioredoxin z Interacts with Two Fructokinase-Like Proteins in a Thiol-Dependent Manner: Evidence for an Essential Role in Chloroplast Development in Arabidopsis and Nicotiana benthamiana

pTAC2, -6, and -12 Are Components of the Transcriptionally Active Plastid Chromosome That Are Required for Plastid Gene Expression

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