Project description:Study of the role of the FLV/DOT4 protein in post-transcriptional regulation of chloroplast gene expression. DOT4 is a pentatricopeptide repeat protein targeted to the chloroplast which regulates the editing of the rpoC1 transcript
Project description:Study of the role of the FLV/DOT4 protein in post-transcriptional regulation of chloroplast gene expression. DOT4 is a pentatricopeptide repeat protein targeted to the chloroplast which regulates the editing of the rpoC1 transcript The editing level of rpoC1 varies from one tissue to the other and because the main macroscopic phenotype of the flv/dot4 mutant are white leaf margins. We compared the leaf border to the leaf center of wild-type Col0 plants but also the leaf borders of col0 and flv/dot4 knock out mutants by sequencing total RNA depleted from rRNA to get a global view of gene expression (including post-transcrional modifications) of the 3 plant genomes: nucleus, chloroplast and mitochondria. mRNA seq on wild-type Col and FLV mutants knock out.
Project description:Sensorimotor dysfunction following incomplete spinal cord injury (SCI) is often characterized by paralysis, spasticity and pain. Previously, we showed that intrathecal (i.t.) administration of the albumin-oleic acid (A-OA) complex in rats with SCI produced partial improvement of these symptoms and that oral 2-hydroxyoleic acid (HOA), a non-hydrolyzable OA analogue), was efficacious in the modulation and treatment of nociception and pain-related anxiety, respectively. Here we observed that intrathecal treatment with the complex albumin-HOA (A-HOA) every 3 days following T9 spinal contusion injury promoted significant recovery in locomotor function and marked an inhibition of TA noxious reflex activity (i.e., nociception) in Wistar rats. To investigate the mechanism of action of A-HOA, microarray analysis was carried out in the spinal cord lesion area. Representative genes involved in pain and neuroregeneration were selected to validate the changes observed in the microarray analysis by quantitative real-time RT-PCR. Comparison of the expression between healthy rats, SCI rats, and SCI treated with A-HOA rats revealed relevant changes in the expression of genes associated with neuronal morphogenesis and growth, neuronal survival, pain and inflammation. Thus, treatment with A-HOA not only induced a significant overexpression of growth and differentiation factor 10 (GDF10), tenascin C (TNC), aspirin (ASPN) and sushi-repeat-containing X-linked 2 (SRPX2), but also a significant reduction in the expression of prostaglandin E synthase (PTGES) and phospholipases A1 and A2 (PLA1/2). Currently, SCI has very important unmet clinical needs. A-HOA proved to downregulate genes involved in inflammation and upregulate genes involved in neuron growth, which balanced the important body response to medular lesion and allowed recovery from paralysis and pain.
Project description:Plastid Encoded RNA Polymerase (PEP) is a bacterial type multisubunit RNA polymerase responsible for the bulk of transcription in chloroplasts. It contains four core subunits, which are orthologs of their cyanobacterial counterparts. In Arabidopsis thaliana PEP associates with 12 PEP-associated proteins (PAPs), which serve as peripheral subunits of the RNA polymerase. The exact contributions of PAPs to PEP function remain poorly understood. We show that a peripheral subunit of PEP, PAP1 (pTAC3), binds the same genomic loci as RpoB, a core subunit of PEP. PAP1 (pTAC3) and another peripheral PEP subunit, PAP7 (pTAC14), are required for RpoB binding to DNA. RpoB and another core PEP subunit, RpoC1, are expressed in pap1 (ptac3) and pap7 (ptac14) mutants. We propose that the peripheral subunits of PEP are required for the recruitment of core PEP subunits to DNA. pTAC3, binds the same genomic loci as RpoB, a core subunit of PEP. PAP1 pTAC3 and another peripheral PEP subunit, PAP7
Project description:RNA polymerases (RNAPs) transcribe DNA into RNA and are found in all living organisms with several degrees of complexity from single polypeptide chain to multimeric enzymes. In chloroplast of angiosperms, two RNAPs are involved in plastid gene transcription: the nuclear-encoded RNA polymerase (NEP) and the plastid-encoded RNA polymerase (PEP). The PEP is a prokaryotic-type multimeric RNAP found in different states depending on light stimuli and cell identity. One of these active states requires the assembly of nuclear-encoded proteins named PEP-Associated Proteins (PAPs) with the catalytic core, triggering the timely transcription of photosynthesis-associated plastid genes in cells acquiring their photosynthetic apparatus. A purification procedure was used to enrich native PEP from Sinapis alba chloroplasts. Crosslinking coupled to mass spectrometry provided initial structural information about the relative position of PEP subunits within the complex.
Project description:RNA polymerases (RNAPs) transcribe DNA into RNA and are found in all living organisms with several degrees of complexity from single polypeptide chain to multimeric enzymes. In chloroplast of angiosperms, two RNAPs are involved in plastid gene transcription: the nuclear-encoded RNA polymerase (NEP) and the plastid-encoded RNA polymerase (PEP). The PEP is a prokaryotic-type multimeric RNAP found in different states depending on light stimuli and cell identity. One of these active states requires the assembly of nuclear-encoded proteins named PEP-Associated Proteins (PAPs) with the catalytic core, triggering the timely transcription of photosynthesis-associated plastid genes in cells acquiring their photosynthetic apparatus. A purification procedure was used to enrich native PEP from Sinapis alba chloroplasts. Mass spectrometry-based proteomic analysis of the obtained fraction identified the expected subunits, i.e. the core components and the PAPs as the most abundant proteins.
Project description:Chloroplasts are organelles responsible for photosynthesis. They originated form a procaryotic ancestor in the process of endosymbiosis and contain their own genomes. The chloroplast genome is packaged into a chromatin-like structure known as the nucleoid. The internal arrangement of the nucleoid, molecular mechanisms of DNA packaging and connection of the nucleoid structure to gene expression remain poorly understood. We show that Arabidopsis thaliana chloroplast nucleoids have a unique organization driven by DNA binding to the thylakoid membranes. Membrane association of specific DNA regions is correlated with high levels of transcription, high protein occupancy and reduced DNA accessibility. Genes with low levels of transcription are further away from the membranes, have lower protein occupancy and higher DNA accessibility. Gene-specific disruption of transcription in sigma factor mutants causes a corresponding reduction in membrane association, indicating that RNA polymerase activity causes DNA tethering to the membranes. We propose that transcription organizes the chloroplast nucleoid into a transcriptionally active membrane-associated core and a less active Periphery.