Pharmaceutical Risk and the Quality of Life

Quality-of-life research is briefly described and said to be in its infancy. However, the authors observe that such studies may, e.g., make it possible to better match patients and therapies. They also predict that, as scientific difficulties are overcome, the pharmaceutical industry will become more active in planning, implementing and evaluating such research

The Targeting of the atToc159 Preprotein Receptor to the Chloroplast Outer Membrane is Mediated by its GTPase Domain and is Regulated by GTP

The multimeric translocon at the outer envelope membrane of chloroplasts (Toc) initiates the recognition and import of nuclear-encoded preproteins into chloroplasts. Two Toc GTPases, Toc159 and Toc33/34, mediate preprotein recognition and regulate preprotein translocation. Although these two proteins account for the requirement of GTP hydrolysis for import, the functional significance of GTP binding and hydrolysis by either GTPase has not been defined. A recent study indicates that Toc159 is equally distributed between a soluble cytoplasmic form and a membrane-inserted form, raising the possibility that it might cycle between the cytoplasm and chloroplast as a soluble preprotein receptor. In the present study, we examined the mechanism of targeting and insertion of the Arabidopsis thaliana orthologue of Toc159, atToc159, to chloroplasts. Targeting of atToc159 to the outer envelope membrane is strictly dependent only on guanine nucleotides. Although GTP is not required for initial binding, the productive insertion and assembly of atToc159 into the Toc complex requires its intrinsic GTPase activity. Targeting is mediated by direct binding between the GTPase domain of atToc159 and the homologous GTPase domain of atToc33, the Arabidopsis Toc33/34 orthologue. Our findings demonstrate a role for the coordinate action of the Toc GTPases in assembly of the functional Toc complex at the chloroplast outer envelope membrane

The targeting of the atToc159 preprotein receptor to the chloroplast outer membrane is mediated by its GTPase domain and is regulated by GTP

The multimeric translocon at the outer envelope membrane of chloroplasts (Toc) initiates the recognition and import of nuclear-encoded preproteins into chloroplasts. Two Toc GTPases, Toc159 and Toc33/34, mediate preprotein recognition and regulate preprotein translocation. Although these two proteins account for the requirement of GTP hydrolysis for import, the functional significance of GTP binding and hydrolysis by either GTPase has not been defined. A recent study indicates that Toc159 is equally distributed between a soluble cytoplasmic form and a membrane-inserted form, raising the possibility that it might cycle between the cytoplasm and chloroplast as a soluble preprotein receptor. In the present study, we examined the mechanism of targeting and insertion of the Arabidopsis thaliana orthologue of Toc159, atToc159, to chloroplasts. Targeting of atToc159 to the outer envelope membrane is strictly dependent only on guanine nucleotides. Although GTP is not required for initial binding, the productive insertion and assembly of atToc159 into the Toc complex requires its intrinsic GTPase activity. Targeting is mediated by direct binding between the GTPase domain of atToc159 and the homologous GTPase domain of atToc33, the Arabidopsis Toc33/34 orthologue. Our findings demonstrate a role for the coordinate action of the Toc GTPases in assembly of the functional Toc complex at the chloroplast outer envelope membrane

Essential Role of the G-Domain in Targeting of the Protein Import Receptor atToc159 to the Chloroplast Outer Membrane

Two homologous GTP-bindin proteins, atToc33 and atToc159, control access of cytosolic precursor proteins to the chloroplast, at Toc33 is a constitutive outer chloroplast membrane protein, whereas the precusor receptor atToc159 may be able to switch between a soluble and an integral membrane form. By transient expression of GFP fusion proteins, mutant analysis, and biochemical experimentation, we demonstrate that the GTP-binding domain regulates the targeting of cytosolic atToc159 to the chloroplast and mediates the switch between cytosolic and integral membrane forms. Mutant atToc159, unable to bind GTP, does not reinstate a green phenotype in an albino mutant (ppi2) lacking endogenous atToc159, remaining trapped in the cytosol. Thus, the function of atToc159 in chloroplast biogenesis is dependent on an intrinsic GTP-regulated swtich that controls localization of the receptor to the chloroplast envelope

New challenges to improve organic bread wheat production in Europe

The total organic area in the EU-27 had an annual average growth rate of nearly 15% from 1998 to 2006 with winter wheat being the most important cereal crop. Wheat yield in organic farming is around 30% to 70% of yield of conventional farming but higher premia for organic wheat may to some extent compensate for this. Bread wheat is grown in a variety of crop rotations and farming systems and four basic organic crop production systems have been defined. Nitrogen deficiency and weed infestation are considered to be the most serious threat in organic wheat production. Organic wheat producers will have to fulfil the technological needs of bakers although the requirements differ widely from small artisan bakers to large enterprises handling the organic bread processing. To maintain and expand organic wheat production, there is a need to control weed population, manage nitrogen nutrition and maintain crop diversity in the cropping system. In order to obtain a share in the premium price of organic wheat products, farmers may involve in further processing and marketing

AGTEC-Org Agronomy Handbook of Methods

A common handbook was conceived in the CORE Organic AGTEC-Org project in order to give some elements of field trial monitoring

Targeting of an abundant cytosolic form of the protein import receptor at Toc159 to the outer chloroplast membrane

Chloroplast biogenesis requires the large-scale import of cytosolically synthesized precursor proteins. A trimeric translocon (Toc complex) containing two homologous GTP-binding proteins (atToc33 and atToc159) and a channel protein (atToc75) facilitates protein translocation across the outer envelope membrane. The mechanisms governing function and assembly of the Toc complex are not yet understood. This study demonstrates that atToc159 and its pea orthologue exist in an abundant, previously unrecognized soluble form, and partition between cytosol-containing soluble fractions and the chloroplast outer membrane. We show that soluble atToc159 binds directly to the cytosolic domain of atToc33 in a homotypic interaction, contributing to the integration of atToc159 into the chloroplast outer membrane. The data suggest that the function of the Toc complex involves switching of atToc159 between a soluble and an integral membrane form

Differential phosphorylation of the N - terminal extension regulates phytochrome B signaling

Viczián, András. Institute of Plant Biology. Biological Research Centre. Szeged, Hungary.Ádám, Éva. Institute of Plant Biology. Biological Research Centre. Szeged, Hungary.Staudt, Anne Marie. University of Freiburg. Institute of Biology II. Freiburg, Germany.Lambert, Dorothee. University of Freiburg. Institute of Biology II. Freiburg, Germany.Klement, Eva. Biological Research Centre. Laboratory of Proteomics Research. Szeged, Hungary.Romero Montepaone, Sofia. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Hiltbrunner, Andreas. University of Freiburg. Institute of Biology II. Freiburg, Germany.Casal, Jorge José. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.1635–1650Phytochrome B (phyB) is an excellent light quality and quantity sensor that can detect subtle changes in the light environment. The relative amounts of the biologically active photoreceptor (phyB Pfr) are determined by the light conditions and light independent thermal relaxation of Pfr into the inactive phyB Pr, termed thermal reversion. Little is known about the regulation of thermal reversion and how it affects plants’ light sensitivity. In this study we identified several serine/threonine residues on the N-terminal extension (NTE) of Arabidopsis thaliana phyB that are differentially phosphorylated in response to light and temperature, and examined transgenic plants expressing nonphosphorylatable and phosphomimic phyB mutants. The NTE of phyB is essential for thermal stability of the Pfr form, and phosphorylation of S86 particularly enhances the thermal reversion rate of the phyB Pfr–Pr heterodimer in vivo. We demonstrate that S86 phosphorylation is especially critical for phyB signaling compared with phosphorylation of the more N terminal residues. Interestingly, S86 phosphorylation is reduced in light, paralleled by a progressive Pfr stabilization under prolonged irradiation. By investigating other phytochromes (phyD and phyE) we provide evidence that acceleration of thermal reversion by phosphorylation represents a general mechanism for attenuating phytochrome signaling

Extrachloroplastic PP7L functions in chloroplast development and abiotic stress tolerance

Chloroplast biogenesis is indispensable for proper plant development and environmental acclimation. In a screen for mutants affected in photosynthesis, we identified the protein phosphatase7-like (pp7l) mutant, which displayed delayed chloroplast development in cotyledons and young leaves. PP7L, PP7, and PP7-long constitute a subfamily of phosphoprotein phosphatases. PP7 is thought to transduce a blue-light signal perceived by crys and phy a that induces expression of SIGMA FACTOR5 (SIG5). We observed that, like PP7, PP7L was predominantly localized to the nucleus in Arabidopsis (Arabidopsis thaliana), and the pp7l phenotype was similar to that of the sig6 mutant. However, SIG6 expression was unaltered in pp7l mutants. Instead, loss of PP7L compromised translation and ribosomal RNA (rRNA) maturation in chloroplasts, pointing to a distinct mechanism influencing chloroplast development. Promoters of genes deregulated in pp7l-1 were enriched in PHYTOCHROME-INTERACTING FACTOR (PIF)-binding motifs and the transcriptome of pp7l-1 resembled those of pif and CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1) signalosome complex (csn) mutants. However, pif and csn mutants, as well as cop1, cryptochromes (cry)1 cry2, and phytochromes (phy)A phyB mutants, do not share the pp7l photosynthesis phenotype. PhyB protein levels were elevated in pp7l mutants, but phyB overexpression plants did not resemble pp7l. These results indicate that PP7L operates through a different pathway and that the control of greening and photosystem biogenesis can be separated. The lack of PP7L increased susceptibility to salt and high-light stress, whereas PP7L overexpression conferred resistance to highlight stress. Strikingly, PP7L was specifically recruited to Brassicales for the regulation of chloroplast development. This study adds another player involved in chloroplast biogenesis