The transcriptional apparatus of chloroplasts

lgloi, G.L.; Kössel, Hans

doi:10.1080/07352689209382326

Cited by 144 publications

(88 citation statements)

References 175 publications

(124 reference statements)

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“…Chloroplasts of higher plants possess at least two RNA polymerases with different biochemical properties and phylogenetic origins: a plastid-encoded multimeric RNA polymerase (PEP), which resembles eubacterial RNA polymerases, and a nucleus-encoded phage-type RNA polymerase (NEP) (Hu and Bogorad, 1990;Igloi and Kö ssel, 1992;Lerbs-Mache, 1993;Pfannschmidt and Link, 1994;Liere and Maliga, 1999). In addition to PEP, the existence of NEP has already been suggested from studies with the parasite Epifagus virginiana, which lacks the plastid rpoBC operon (Morden et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

“…The TAC is membrane attached and consists of several multimeric protein complexes. In in vitro assays, the TAC can transcribe endogenously bound DNA, while the transcriptional activity of sRNAP requires the addition of DNA (Igloi and Kö ssel, 1992;. TAC fractions have been isolated by gel filtration from different organisms (Briat et al, 1979;Rushlow and Hallick, 1982;Reiss and Link, 1985).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…Most preparations were done by either sucrose density gradient centrifugation (Nemoto et al 1988;Cannon et al 1997) or by gel filtration of extracts prepared from plastid membranes treated with detergents (Hallick et al 1976;Krause and Krupinska 2000). The DNA containing fraction prepared by gel filtration was called TAC, because it has been used initially to determine the activity and composition of the transcriptional apparatus (see reviews of Gruissem and Tonkyn 1993;Igloi and Kössel 1992;Sakai et al 2004, and references therein). The TAC fraction is prepared from plastid membranes by release of the nucleoids with detergents and by subsequent purification involving sepharose gel filtration and other steps (Krause and Krupinska 2000;Pfalz et al 2006).…”

Section: Analysis Of the Protein Composition Of Plastid Nucleoidsmentioning

confidence: 99%

New insights into plastid nucleoid structure and functionality

Krupinska¹,

Melonek²,

Krause

2012

Planta

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Investigations over many decades have revealed that nucleoids of higher plant plastids are highly dynamic with regard to their number, their structural organization and protein composition. Membrane attachment and environmental cues seem to determine the activity and functionality of the nucleoids and point to a highly regulated structure-function relationship. The heterogeneous composition and the many functions that are seemingly associated with the plastid nucleoids could be related to the high number of chromosomes per plastid. Recent proteomic studies have brought novel nucleoidassociated proteins into the spotlight and indicated that plastid nucleoids are an evolutionary hybrid possessing prokaryotic nucleoid features and eukaryotic (nuclear) chromatin components, several of which are dually targeted to the nucleus and chloroplasts. Future studies need to unravel if and how plastid-nucleus communication depends on nucleoid structure and plastid gene expression.

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“…The core of the E. coli-like plastid-encoded RNA polymerase (PEP), which initiates transcription from sequences resembling E. coli s 70 -type promoters, consists of two a-subunits, and the b-, b'-, and b''-subunits encoded by the plastid genes rpoA, rpoB, rpoC1, and rpoC2, respectively (Igloi and Kössel, 1992). In C. reinhardtii, the rpoB and rpoC1 genes are further split in two parts (Fong and Surzycki, 1992;Maul et al, 2002).…”

Section: Loss Of Chloroplast Gene Transcription and Translation Affecmentioning

confidence: 99%

Repression of Essential Chloroplast Genes Reveals New Signaling Pathways and Regulatory Feedback Loops inChlamydomonas

et al. 2013

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Although reverse genetics has been used to elucidate the function of numerous chloroplast proteins, the characterization of essential plastid genes and their role in chloroplast biogenesis and cell survival has not yet been achieved. Therefore, we developed a robust repressible chloroplast gene expression system in the unicellular alga Chlamydomonas reinhardtii based mainly on a vitamin-repressible riboswitch, and we used this system to study the role of two essential chloroplast genes: ribosomal protein S12 (rps12), encoding a plastid ribosomal protein, and rpoA, encoding the a-subunit of chloroplast bacterial-like RNA polymerase. Repression of either of these two genes leads to the arrest of cell growth, and it induces a response that involves changes in expression of nuclear genes implicated in chloroplast biogenesis, protein turnover, and stress. This response also leads to the overaccumulation of several plastid transcripts and reveals the existence of multiple negative regulatory feedback loops in the chloroplast gene circuitry.

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The transcriptional apparatus of chloroplasts

Cited by 144 publications

References 175 publications

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

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

New insights into plastid nucleoid structure and functionality

Repression of Essential Chloroplast Genes Reveals New Signaling Pathways and Regulatory Feedback Loops inChlamydomonas

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