Genetic Evidence for a Link Between Glycolysis and DNA Replication

BACKGROUND: A challenging goal in biology is to understand how the principal cellular functions are integrated so that cells achieve viability and optimal fitness in a wide range of nutritional conditions. METHODOLOGY/PRINCIPAL FINDINGS: We report here a tight link between glycolysis and DNA synthesis. The link, discovered during an analysis of suppressors of thermosensitive replication mutants in bacterium Bacillus subtilis, is very strong as some metabolic alterations fully restore viability to replication mutants in which a lethal arrest of DNA synthesis otherwise occurs at a high, restrictive, temperature. Full restoration of viability by such alterations was limited to cells with mutations in three elongation factors (the lagging strand DnaE polymerase, the primase and the helicase) out of a large set of thermosensitive mutants affected in most of the replication proteins. Restoration of viability resulted, at least in part, from maintenance of replication protein activity at high temperature. Physiological studies suggested that this restoration depended on the activity of the three-carbon part of the glycolysis/gluconeogenesis pathway and occurred in both glycolytic and gluconeogenic regimens. Restoration took place abruptly over a narrow range of expression of genes in the three-carbon part of glycolysis. However, the absolute value of this range varied greatly with the allele in question. Finally, restoration of cell viability did not appear to be the result of a decrease in growth rate or an induction of major stress responses. CONCLUSIONS/SIGNIFICANCE: Our findings provide the first evidence for a genetic system that connects DNA chain elongation to glycolysis. Its role may be to modulate some aspect of DNA synthesis in response to the energy provided by the environment and the underlying mechanism is discussed. It is proposed that related systems are ubiquitous

A Deubiquitylating Complex Required for Neosynthesis of a Yeast Mitochondrial ATP Synthase Subunit

The ubiquitin system is known to be involved in maintaining the integrity of mitochondria, but little is known about the role of deubiquitylating (DUB) enzymes in such functions. Budding yeast cells deleted for UBP13 and its close homolog UBP9 displayed a high incidence of petite colonies and slow respiratory growth at 37°C. Both Ubp9 and Ubp13 interacted directly with Duf1 (DUB-associated factor 1), a WD40 motif-containing protein. Duf1 activates the DUB activity of recombinant Ubp9 and Ubp13 in vitro and deletion of DUF1 resulted in the same respiratory phenotype as the deletion of both UBP9 and UBP13. We show that the mitochondrial defects of these mutants resulted from a strong decrease at 37°C in the de novo biosynthesis of Atp9, a membrane-bound component of ATP synthase encoded by mitochondrial DNA. The defect appears at the level of ATP9 mRNA translation, while its maturation remained unchanged in the mutants. This study describes a new role of the ubiquitin system in mitochondrial biogenesis

Identification d'un complexe de déubiquitylation impliqué dans le fonctionnement mitochondrial

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

On Nonparametric Conditional Quantile Estimation for Non-stationary Random

International audienceA kernel conditional quantile estimate of a real-valued non-stationary spatial process is proposed for a prediction goal at a non-observed location of the underlying process. The originality is based on the ability to take into account some local spatial dependency. Large sample properties based on almost complete and $L^q$-consistencies of the estimator are established. A numerical study is given in order to illustrate the performance of our methodology

Asymptotic properties of nonparametric quantile estimation with spatial dependency

International audienc

Δ<i>ubp9</i> Δ<i>ubp13</i>, Δ<i>duf1</i> and Δ<i>ubp9</i>Δ<i>ubp13</i>Δ<i>duf1</i> cells display defective respiration.

<p>Cells grown on galactose at 37°C to the exponential phase, were diluted in potassium buffer pH 7.2 and placed for a few hours at 37°C. Respiratory growth was then measured on entire cells, after the addition of 0.2% galactose, over a period of 7 min, with a Clark-Type electrode, as previously described <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038071#pone.0038071-Blaiseau1" target="_blank">[51]</a>.</p

Respiratory growth of yeast <i>ubp</i> mutants.

<p>Dilution series of wild-type BY4741 (WT) and Δ<i>ubpx</i> strains were grown on media containing fermentable (glucose) or respiratory (lactate) substrates, at 30°C, for 3 and 5 days, respectively. Similar results were obtained with ethanol and glycerol as respiratory substrates.</p

Genotypes and sources of yeast strains.

<p>Δ<i>ubpn</i> refers to a collection of strains, each with the deletion of a single <i>UBP</i> gene (1≤ n ≤16).</p

Δ<i>ubp9</i> Δ<i>ubp13</i> and Δ<i>duf1</i> mutants have a similar respiratory phenotype, which is not aggravated by the deletion of <i>UBP16</i>.

<p>Dilution series of wild-type BY4741 (WT), Δ<i>ubp9</i>, Δ<i>ubp13,</i> Δ<i>ubp16,</i> Δ<i>ubp9</i> Δ<i>ubp13</i>, Δ<i>duf1,</i> Δ<i>ubp9</i> Δ<i>ubp13</i> Δ<i>ubp16</i> and Δ<i>ubp9</i> Δ<i>ubp13</i> Δ<i>duf1</i> strains were grown on medium containing fermentable (glucose) or respiratory (lactate) substrates for 5 days at 30°C and 37°C.</p