Search results for " Biosynthesis"

Transcriptional and translational study of the Drosophila subobscura hsp83 gene in normal and heat-shock conditions

1993

In this paper we report a transcriptional and translational study of the hsp83 gene of Drosophila subobscura. This gene is located at the 18C region of the J chromosome. A monoclonal antibody raised against hsp83 was used for the immunological detection of this protein by Western blotting throughout the development of D. subobscura in control and heat-shock conditions. Our results indicate that puff 18C is not only heat-shock inducible but is also expressed during normal development and its level of expression increases at the end of the prepupa period. We detected hsp83 at normal temperatures, in particular developmental stages with the exception of the larval and the beginning of prepupa…

Translational adaptation to heat stress is mediated by RNA 5‐methylcytosine in Caenorhabditis elegans

2021

Abstract Methylation of carbon‐5 of cytosines (m5C) is a post‐transcriptional nucleotide modification of RNA found in all kingdoms of life. While individual m5C‐methyltransferases have been studied, the impact of the global cytosine‐5 methylome on development, homeostasis and stress remains unknown. Here, using Caenorhabditis elegans, we generated the first organism devoid of m5C in RNA, demonstrating that this modification is non‐essential. Using this genetic tool, we determine the localisation and enzymatic specificity of m5C sites in the RNome in vivo. We find that NSUN‐4 acts as a dual rRNA and tRNA methyltransferase in C. elegans mitochondria. In agreement with leucine and proline bein…

AICA-ribosiduria due to ATIC deficiency: Delineation of the phenotype with three novel cases, and long-term update on the first case.

2020

5-Amino-4-imidazolecarboxamide-ribosiduria (AICA)-ribosiduria is an exceedingly rare autosomal recessive condition resulting from the disruption of the bifunctional purine biosynthesis protein PURH (ATIC), which catalyzes the last two steps of de novo purine synthesis. It is characterized biochemically by the accumulation of AICA-riboside in urine. AICA-ribosiduria had been reported in only one individual, 15 years ago. In this article, we report three novel cases of AICA-ribosiduria from two independent families, with two novel pathogenic variants in ATIC. We also provide a clinical update on the first patient. Based on the phenotypic features shared by these four patients, we define AICA-…

Nouvelles perspectives concernant la structure et la fonction du domaine carboxyl terminal de Hfq

2015

Accumulating evidence indicates that RNA metabolism components assemble into supramolecular cellular structures to mediate functional compartmentalization within the cytoplasmic membrane of the bacterial cell. This cellular compartmentalization could play important roles in the processes of RNA degradation and maturation. These components include Hfq, the RNA chaperone protein, which is involved in the post-transcriptional control of protein synthesis mainly by the virtue of its interactions with several small regulatory ncRNAs (sRNA). The Escherichia coli Hfq is structurally organized into two domains. An N-terminal domain that folds as strongly bent β-sheets within individual protomers to…

Structure and function of the vacuolar Ccc1/VIT1 family of iron transporters and its regulation in fungi

2020

Iron is an essential micronutrient for most living beings since it participates as a redox active cofactor in many biological processes including cellular respiration, lipid biosynthesis, DNA replication and repair, and ribosome biogenesis and recycling. However, when present in excess, iron can participate in Fenton reactions and generate reactive oxygen species that damage cells at the level of proteins, lipids and nucleic acids. Organisms have developed different molecular strategies to protect themselves against the harmful effects of high concentrations of iron. In the case of fungi and plants, detoxification mainly occurs by importing cytosolic iron into the vacuole through the Ccc1/V…

Polymorphism of mytilin B mRNA is not traslated into mature peptide

2008

Diversity of mRNAs from mytilin B, one of the five mytilins identified in the Mediterranean mussel, Mytilus galloprovincialis, has been investigated from circulating hemocytes. One mussel expressed simultaneously two to ten different mytilin B mRNAs as observed in denaturing gradient gel electrophoresis (DGGE), defining 10 individual DGGE patterns (named A to J) within the mussels from Messina, Sicily (Italy). Three patterns accounted for 79% of the individuals whereas other patterns were found in only 2-7% of the 57 analyzed mussels. Base mutations were observed at specific locations, mainly within COOH-terminus and 3'UTR, leading to 36 nucleotide sequence variants and 21 different coding …

A genome-wide transcriptional study reveals that iron deficiency inhibits the yeast TORC1 pathway

2019

Iron is an essential micronutrient that participates as a cofactor in a broad range of metabolic processes including mitochondrial respiration, DNA replication, protein translation and lipid biosynthesis. Adaptation to iron deficiency requires the global reorganization of cellular metabolism directed to optimize iron utilization. The budding yeast Saccharomyces cerevisiae has been widely used to characterize the responses of eukaryotic microorganisms to iron depletion. In this report, we used a genomic approach to investigate the contribution of transcription rates to the modulation of mRNA levels during adaptation of yeast cells to iron starvation. We reveal that a decrease in the activity…

Techniques for Biosynthesis

2015

Shuttling of the autoantigen La between nucleus and cell surface after uv irradiation of human keratinocytes.

1990

During the past years we have established that the nuclear autoantigen La shuttles between the nucleus and the cytoplasm in tumor cells after inhibition of transcription or virus infection. We reinvestigated this shuttling using primary human keratinocytes from both healthy donors and patients with xeroderma pigmentosum. Ultraviolet irradiation resulted in both an inhibition of transcription and a translocation of La protein from the nucleus to the cytoplasm. After a prolonged inhibition of transcription La protein relocated into the nucleus and assembled with nuclear storage regions. The uv-induced shuttling included a translocation to the cell surface, where La protein colocalized with ep…

Discovery of novel pathways of microbial arginine biosynthesis

2012

The amino acid L-arginine is an essential component of all living organisms. Its importance resides in the variety of functions that arginine itself, along with some intermediary metabolites involved in its de novo synthesis in the cell. In many prokaryotes, fungi, and plants the de novo biosynthesis of arginine proceeds from glutamate in eight enzymatic steps (Figure 2). The first committed step of this pathway is the N-acetylation of glutamate. Acetylation of the early precursors of arginine distinguishes them from the analogous intermediates in the biosynthesis of proline. Although each and every step of the pathway is essential for its completion, transcarbamylation of ornithine to prod…