Fundación Instituto Leloir

About: Fundación Instituto Leloir is a facility organization based out in Buenos Aires, Argentina. It is known for research contribution in the topics: Dentate gyrus & Neurogenesis. The organization has 702 authors who have published 1052 publications receiving 39299 citations.

Growing with the wind. Ribosomal protein hydroxylation and cell growth.

Abstract: In this Extra View we comment on our recent work on Sudestada1 (Sud1), a Drosophila 2-oxoglutarate (2OG)-dependent dioxygenase that belongs to the Ribosomal Oxygenase (ROX) subfamily. Sud1 is required for normal growth in Drosophila, and is conserved in yeast and mammals. We reported that Sud1 hydroxylates the ribosomal protein S23 (RPS23), and that its loss of function restricts growth and provokes activation of the unfolded protein response, apoptosis and autophagy. In this Extra View we speculate on the role that RPS23 hydroxylation might play in stop codon recognition and on the possible link between Sud1 loss-of-function and activation of the Unfolded Protein Response, Stress Granules formation and growth impairment.

Structural and functional characterization of a cold-adapted stand-alone TPM domain reveals a relationship between dynamics and phosphatase activity.

Abstract: The TPM domain constitutes a family of recently characterized protein domains that are present in most living organisms. Although some progress has been made in understanding the cellular role of TPM-containing proteins, the relationship between structure and function it is not clear yet. We have recently solved the solution and crystal structure of one TPM domain (BA42) from the Antarctic bacterium Bizionia argentinensis. In this work we demonstrate that BA42 has phosphoric-monoester hydrolase activity. The activity of BA42 is strictly dependent on the binding of divalent metals and retains nearly 70% of the maximum at 4° C, a typical characteristic of cold adapted enzymes. From HSQC, 15N relaxation measurements and molecular dynamics studies we determine that the flexibility of the crossing loops was associated to the protein activity. Thermal unfolding experiments showed that the local increment in flexibility of Mg2+-bound BA42, when compared with Ca2+-bound BA42, is associated to a decrease in global protein stability. Finally, through mutagenesis experiments we unambiguously demonstrate that the region comprising the metal binding site participates in the catalytic mechanism. The results shown here contribute to the understanding of the relationship between structure and function of this newly family of TPM domains providing important cues on the regulatory role of Mg2+ and Ca2+ and the molecular mechanism underlying enzyme activity at low temperatures. This article is protected by copyright. All rights reserved.

Ethylene signaling increases reactive oxygen species accumulation to drive root hair initiation in Arabidopsis thaliana

Abstract: Root hair initiation is a highly regulated aspect of root development. The plant hormone, ethylene, and its precursor, 1-amino-cyclopropane-1-carboxylic acid (ACC), induce formation and elongation of root hairs. We asked whether elevated ethylene induced root hair formation by increasing reactive oxygen species (ROS) synthesis in hair cells. Using confocal microscopy paired with redox biosensors and dyes, we demonstrated that treatments that elevate ethylene levels led to increased ROS accumulation in hair cells prior to root hair formation. In two ethylene-insensitive mutants, etr1-3 and ein3/eil1, there was no increase in root hair number or ROS accumulation. Conversely, etr1-7, a constitutive ethylene signaling receptor mutant, has increased root hair formation and ROS accumulation similar to ethylene-treated wild type seedlings. The rhd2-6 mutant, with a defect in the gene encoding a ROS synthesizing Respiratory Burst Oxidase Homolog C (RBOHC), showed impaired ethylene-dependent ROS synthesis and root hair formation and decreased RBOH enzyme activity compared to Col-0. To identify additional proteins that drive ROS induced root hair formation, we examined a time course root transcriptomic dataset examining Col-0 grown in the presence of ACC and identified PRX44 and other positively regulated transcripts that encode class III peroxidases (PRXs). The prx44-2 mutant has decreased root hair initiation and ROS accumulation when treated with ACC compared to Col-0 and pPRX44::GFP fluorescence is increased in response to ACC treatment. Together, these results support a model in which ethylene increases ROS accumulation through RBOHC and PRX44 to drive root hair formation. SIGNIFICANCE STATEMENTRoot hairs are essential for water and nutrient acquisition and anchorage in soil. The hormone ethylene increases both root hair initiation and elongation. Short-term treatment with ethylene and its precursor, ACC, increased reactive oxygen species (ROS) accumulation in trichoblast cells prior to root hair initiation. Ethylene signaling through the ETR1 receptor and transcription factors, EIN3/EIL1, increased ROS and root hair initiation. Genetic and biochemical approaches identified ROS producing enzymes that are regulated by ethylene signaling and required for root hair initiation. Ethylene signaling increased activity of RBOHC and elevated transcript abundance of a class III peroxidase, PRX44, to drive root hair initiation. Our findings demonstrate that ethylene-induced root hair initiation is dependent on changes in ROS homeostasis.