Suchergebnisse

Debido a la importancia que tiene solucionar el bajo rendimiento académico de los estudiantes de medicina, problema constante en la educación superior, y que es una variable multifactorial ampliamente investigada, se propuso el siguiente trabajo de investigación que tuvo objetivo determinar la efectividad de las asesorías académicas para mejorar el aprendizaje de Bioquímica y Biología Molecular en alumnos de la carrera de medicina. Se diseñó un estudio observacional, analítico, prolectivo y longitudinal, en el que se incluyeron un total 64 alumnos de primer semestre que cursaron la materia de Bioquímica y Biología Molecular en la carrera de medicina que decidieron participar en las asesorías de la materia. Como resultado se observó que existió una diferencia estadísticamente significativa entre los promedios comparados antes y después de las asesorías,a favor de la evaluación final en la que se obtuvo una media de 71.52. Se evidenció que se incrementó el total de alumnos que acreditaron y se calculó el Coeficiente de determinación, el cual indicó que el aprendizaje de Bioquímica y Biología Molecular depende en un 53.2 % de las asesorías académicas. Por lo tanto, se puede concluir que las asesorías académicas son efectivas para mejorar el aprendizaje de Bioquímica y Biología Molecular en los estudiantes de medicina.

[EN] Shelf life is an important quality trait for many fruit, including tomatoes. We report that enrichment of anthocyanin, a natural pigment, in tomatoes can significantly extend shelf life. Processes late in ripening are suppressed by anthocyanin accumulation, and susceptibility to Botrytis cinerea, one of the most important postharvest pathogens, is reduced in purple tomato fruit. We show that reduced susceptibility to B. cinerea is dependent specifically on the accumulation of anthocyanins, which alter the spreading of the ROS burst during infection. The increased antioxidant capacity of purple fruit likely slows the processes of overripening. Enhancing the levels of natural antioxidants in tomato provides a novel strategy for extending shelf life by genetic engineering or conventional breeding. ; E.B. and C.M. were supported by the European Union FP6 FLORA project (FOOD-CT-01730), and Y.Z., E.B., and C.M. are supported by the European Union FP7 ATHENA collaborative project (grant agreement 245121). Y.Z. is also supported by a Rotation Studentship from the John Innes Foundation. C.M. and E.B. were supported by the core strategic grant of the Biological and Biotechnological Science Research Council (BBSRC) to the John Innes Centre and are currently supported by the Institute Strategic Program Understanding and Exploiting Plant and Microbial Secondary Metabolism (BB/J004596/1) from the BBSRC. E.B. was supported by a short-term EMBO fellowship for undertaking part of the research reported in this paper. H.-J.S. was supported by grant BB/G042960/1 from the BBSRC and the John Innes Foundation, and A.G. and D.O. are supported by the Fundacion Genoma (Calitom project) and the Spanish Ministry of Science and Education (project BIO2010-15384). This work benefited from the networking activities within the European-funded COST ACTION FA1106 QualityFruit. We thank Andrew Davis for photography. C.M. and J.D.G.J. are Directors of Norfolk Plant Sciences, a company bringing biotechnological improvements in crops to market. ...

[EN] DELLA proteins are the negative regulators of the gibberellin (GA) signaling pathway. GAs have a pervasive effect on plant physiology, influencing processes that span the entire life cycle of the plant. All the information encoded by GAs, either environmental or developmental in origin, is canalized through DELLAs, which modulate the activity of many transcription factors and transcriptional regulators. GAs unlock the signaling pathway by triggering DELLA polyubiquitination and degradation by the 26S proteasome. Recent reports indicate, however, that there are other pathways that trigger DELLA polyubiquitination and degradation independently of GAs. Moreover, results gathered during recent years indicate that other post-translational modifications (PTMs), namely phosphorylation, SUMOylation and glycosylation, modulate DELLA function. The convergence of several PTMs in DELLA therefore highlights the strict regulation to which these proteins are subject. In this review, we summarize these discoveries and discuss DELLA PTMs from an evolutionary perspective and examine the possibilities these and other post-translational regulations offer to improve DELLA-dependent agronomic traits. ; The Spanish Ministry of Science and Innovation (PID2019-109925GB-I00 to D.A.) and the European Union (H2020-MSCA-IF-2016-746396 to A.S.-M.). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). ; Blanco-Touriñán, N.; Serrano-Mislata, A.; Alabadí Diego, D. (2020). Regulation of DELLA proteins by post-translational modifications. Plant and Cell Physiology. 61(11):1891-1901. https://doi.org/10.1093/pcp/pcaa113 ; S ; 1891 ; 1901 ; 61 ; 11

[EN] DELLA proteins are plant specific transcriptional regulators known to interact through their C-terminal GRAS domain with over 150 transcription factors in Arabidopsis thaliana. Besides, DELLAs from vascular plants can interact through the N-terminal domain with the gibberellin receptor encoded by GID1, through which gibberellins promote DELLA degradation. However, this regulation is absent in non-vascular land plants, which lack active gibberellins or a proper GID1 receptor. Current knowledge indicates that DELLAs are important pieces of the signalling machinery of vascular plants, especially angiosperms, but nothing is known about DELLA function during early land plant evolution or if they exist at all in charophytan algae. We have now elucidated the evolutionary origin of DELLA proteins, showing that algal GRAS proteins are monophyletic and evolved independently from those of land plants, which explains why there are no DELLAs outside land plants. DELLA genes have been maintained throughout land plant evolution with only two major duplication events kept among plants. Furthermore, we show that the features needed for DELLA interaction with the receptor were already present in the ancestor of all land plants, and propose that these DELLA N-terminal motifs have been tightly conserved in non-vascular land plants for their function in transcriptional co-activation, which allowed subsequent exaptation for the interaction with the GID1 receptor when vascular plants developed gibberellin synthesis and the corresponding perception module. ; We thank the members of the Hormone Signaling and Plasticity Lab at IBMCP (http://plasticity.ibmcp.csic.es/) for useful discussions and suggestions. Work in our laboratories was supported by grants BFU2016-80621-P of the Spanish Ministry of Economy, Industry and Competitiveness and H2020-MSCA-RISE-2014-644435 of the European Union. J.H.-G. and A.B.-M. hold Fellowships of the Spanish Ministry of Education, Culture and Sport FPU15/01756 and FPU14/01941, respectively. ...

Describe los eventos relacionados con la evolución molecular del VIH-1 en sujetos peruanos TS y NTS infectados de Lima y Callao. Materiales y métodos. Se realizó el análisis molecular del VIH a partir de 93 sujetos infectados, 61 fueron trabajadoras y trabajadores sexuales (TS) y 32 militares no trabajadores sexuales (NTS). Se extrajo el ADN proviral de toda la población, el cual fue sometido a PCR para la amplificación de los genes gag, env, y pol de VIH-1. Los productos fueron purificados, secuenciados y analizados. Los productos de PCR de env fueron analizados mediante ensayo de movilidad de heterodúplex (HMA) y luego clonados y secuenciados en vectores plasmídicos para la identificación de variantes genéticas virales por medio de análisis filogenético. Las secuencias fueron analizadas usando herramientas de bioinformática para la identificación de subtipos genéticos, recombinación, mutaciones en regiones conservadas, mutaciones de resistencia a los antirretrovirales (ARV), hipermutación y tropismo. Para el análisis estadístico de frecuencias, riesgo absoluto (RO) e índice de asociación se usó el programa SPSS versión 21. Se demostró que todas las muestras analizadas fueron subtipo B con evidencia de recombinación entre diferentes subtipos, siendo la forma B/D la más frecuente (28%). Se hallaron dieciocho casos de infecciones mixtas y 66% de virus con tropismo R5. Los virus restantes con tropismo X4 fueron más frecuentes en pacientes con CD4 < 200 células/mL. Asimismo, se hallaron mutaciones no conservadas en la región de MHR, principalmente en TS, incluyendo un caso de hipermutación. También se halló un índice de 24% de resistencia frente a los ARV. Dentro de ello, se encontró evidencia de resistencia primaria (17%) la cual estuvo asociada con el ejercicio del trabajo sexual (p = 0.04) y con la presencia de infecciones mixtas (p = 0.01). Se demuestra que la evolución molecular del VIH sigue trayectorias diferentes entre TS y NTS, siendo la presencia de algunos factores de riesgo como infecciones mixtas y el ejercicio del trabajo sexual determinantes en este proceso. ; Tesis

[EN] Tomato flavour is an important goal for breeders. Volatile organic compounds (VOCs) are major determinants of tomato flavour. Although most tomato varieties for fresh market are F1 hybrids, most studies on the genetic control of flavour-related traits are performed on lines. We quantified 46 VOCs in a panel of 121 small fruited lines and in a test cross panel of 165 hybrids (the previous panel plus 44 elite cherry tomato lines crossed with a common line). High and consistent heritabilities were assessed for most VOCs in the two panels, and 65% of VOC contents were strongly correlated between lines and hybrids. Additivity was observed for most VOCs. We performed genome wide association studies (GWAS) on the two panels separately, along with a third GWAS on the test cross subset carrying only F1 hybrids corresponding to the line panel. We identified 205, 183 and 138 associations, respectively. We identified numerous overlapping associations for VOCs belonging to the same metabolic pathway within each panel; we focused on seven chromosome regions with clusters of associations simultaneously involved in several key VOCs for tomato aroma. The study highlighted the benefit of testcross panels to create tasty F1 hybrid varieties. ; This research was funded by the CIFRE project Qualhytom, grant number 2018/1239, the ANR project TomEpiSet, grant number ANR-16-CE20-0014 and European Union's Horizon 2020 research and innovation programme, HARNESSTOM, grant number No. 101000716. ; Bineau, E.; Rambla Nebot, JL.; Priego-Cubero, S.; Hereil, A.; Bitton, F.; Plissonneau, C.; Granell Richart, A. (2021). Breeding Tomato Hybrids for Flavour: Comparison of GWAS Results Obtained on Lines and F1 Hybrids. Genes. 12(9):1-20. https://doi.org/10.3390/genes12091443 ; S ; 1 ; 20 ; 12 ; 9

Gene homologs of GlnK PII regulators and AmtB-type ammonium transporters are often paired on prokaryotic genomes, suggesting these proteins share an ancient functional relationship. Here, we demonstrate for the first time in Archaea that GlnK associates with AmtB in membrane fractions after ammonium shock, thus, providing a further insight into GlnK-AmtB as an ancient nitrogen sensor pair. For this work, Haloferax mediterranei was advanced for study through the generation of a pyrE2-based counterselection system that was used for targeted gene deletion and expression of Flag-tagged proteins from their native promoters. AmtB1-Flag was detected in membrane fractions of cells grown on nitrate and was found to coimmunoprecipitate with GlnK after ammonium shock. Thus, in analogy to bacteria, the archaeal GlnK PII may block the AmtB1 ammonium transporter under nitrogen-rich conditions. In addition to this regulated protein–protein interaction, the archaeal amtB-glnK gene pairs were found to be highly regulated by nitrogen availability with transcript levels high under conditions of nitrogen limitation and low during nitrogen excess. While transcript levels of glnK-amtB are similarly regulated by nitrogen availability in bacteria, transcriptional regulators of the bacterial glnK promoter including activation by the two-component signal transduction proteins NtrC (GlnG, NRI) and NtrB (GlnL, NRII) and sigma factor σN (σ54) are not conserved in archaea suggesting a novel mechanism of transcriptional control. ; This work was supported by project BIO2008-00082 from the Spanish Ministry of Science and Innovation MICINN awarded to MBP, which includes funding from the European Union ("FEDER"). During this work, L. P.-R. was supported by a fellowship (AP2007-02932) from the Spanish Ministry of Education. This work was also funded by project NIH R01 GM057498 from the National Institute of General Medical Science awarded to J. M.-F. and by project DOE DE-FG02-05ER15650 from the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences (BES) in the U.S. Department of Energy (DOE) awarded to J. M.-F.

[EN] Asymmetric auxin distribution is instrumental for the differential growth that causes organ bending on tropic stimuli and curvatures during plant development. Local differences in auxin concentrations are achieved mainly by polarized cellular distribution of PIN auxin transporters, but whether other mechanisms involving auxin homeostasis are also relevant for the formation of auxin gradients is not clear. Here we show that auxin methylation is required for asymmetric auxin distribution across the hypocotyl, particularly during its response to gravity. We found that loss-of-function mutants in Arabidopsis IAA CARBOXYL METHYLTRANSFERASE1 (IAMT1) prematurely unfold the apical hook, and that their hypocotyls are impaired in gravitropic reorientation. This defect is linked to an auxin-dependent increase in PIN gene expression, leading to an increased polar auxin transport and lack of asymmetric distribution of PIN3 in the iamt1 mutant. Gravitropic reorientation in the iamt1 mutant could be restored with either endodermis-specific expression of IAMT1 or partial inhibition of polar auxin transport, which also results in normal PIN gene expression levels. We propose that IAA methylation is necessary in gravity-sensing cells to restrict polar auxin transport within the range of auxin levels that allow for differential responses. ; We thank Cristina Ferrandiz and the members of the Hormone Signaling and Plasticity Laboratory at Instituto de Biologia Molecular y Celular de Plantas for discussions and critical reading of the manuscript, and Malcolm Bennett for providing seeds of the reporter lines. Work in the authors' laboratories has been funded by grants from the Spanish Ministry of Economy and Competitiveness (BIO2013-43184-P, to D.A. and M.A.B., and BFU2014-55575-R, to S.P.), the German Research Foundation (EXC-1028-CEPLAS, EXC-294-BIOSS and GSC 4-SGBM, to M.D.Z.), the European Union (H2020-MSCA-RISE-2014-644435, to M.A.B. and D.A.), and the European Research Council (Project ERC-2011-StG-20101109-PSDP, to J.F.). ...

[EN] A biocomputing strategy implemented in hybrid nanocarriers for controlled cargo delivery is described. The nanodevice consists of enzyme-functionalized Janus Au-mesoporous silica nanoparticles, which behave as an electronic demultiplexer (DEMUX). The nanocarrier is capable of reading molecular information from the environment (lactose) and selecting one of two possible outputs (galactose production or 4-methylumbellilferone release and activation) depending on the presence of an addressing input NAD(+). ; The authors wish to thank the Spanish Government (projects RTI2018-100910-B-C41 (MCUI/AEI/FEDER, UE), CTQ2017-87954-P), the Generalitat Valenciana (PROMETEO 2018/024), the Comunidad de Madrid (IND2017/BMD-7642) and CIBER-BBN (NANOCOMMUNITY project) for support. ; De Luis-Fernández, B.; García-Fernández, A.; Llopis-Lorente, A.; Villalonga, R.; Sancenón Galarza, F.; Martínez-Máñez, R. (2020). A 1-to-2 demultiplexer hybrid nanocarrier for cargo delivery and activation. Chemical Communications. 56(69):9974-9977. https://doi.org/10.1039/d0cc03803b ; S ; 9974 ; 9977 ; 56 ; 69 ; Soto, F., & Chrostowski, R. (2018). Frontiers of Medical Micro/Nanorobotics: in vivo Applications and Commercialization Perspectives Toward Clinical Uses. Frontiers in Bioengineering and Biotechnology, 6. doi:10.3389/fbioe.2018.00170 ; Zhang, X., Chen, L., Lim, K. H., Gonuguntla, S., Lim, K. W., Pranantyo, D., … Soh, S. (2019). The Pathway to Intelligence: Using Stimuli‐Responsive Materials as Building Blocks for Constructing Smart and Functional Systems. Advanced Materials, 31(11), 1804540. doi:10.1002/adma.201804540 ; Mailloux, S., & Katz, E. (2014). Biocomputing, Biosensing and Bioactuation Based on Enzyme Biocatalyzed Reactions. Biocatalysis, 1(1). doi:10.2478/boca-2014-0002 ; Katz, E. (2018). Boolean Logic Gates Realized with Enzyme‐catalyzed Reactions – Unusual Look at Usual Chemical Reactions. ChemPhysChem, 20(1), 9-22. doi:10.1002/cphc.201800900 ; Erbas-Cakmak, S., Kolemen, S., Sedgwick, A. C., Gunnlaugsson, T., James, T. ...

[EN] A naphthalimide-based two-photon probe (AHGa) for the detection of cell senescence is designed. The probe contains a naphthalimide core, an L-histidine methyl ester linker, and an acetylated galactose bonded to one of the aromatic nitrogen atoms of the L-histidine through a hydrolyzable N-glycosidic bond. Probe AHGa is transformed into AH in senescent cells resulting in an enhanced fluorescent emission intensity. In vivo detection of senescence is validated in mice bearing tumor xenografts treated with senescence-inducing chemotherapy. ; The authors thank the financial support from the Spanish Government (Projects MAT2015-64139-C4-1-R) and the Generalitat Valenciana (Project PROMETEOII/2014/047). B.L-T. is grateful to the Spanish Ministry of Economy for her PhD grant. I.G. thanks the Generalitat Valenciana for her PhD grant. A.B. thanks the Spanish Government for the financial support "Juan de la Cierva-Incorporacion". M.R. is grateful to "La Caixa" foundation for his PhD scholarship. Work in the M.S. group was funded by the CNIO and by grants from Spanish Ministry of Economy, the European Regional Development Fund (SAF project) the European Research Council (ERC Advanced Grant), and the Botin Foundation and Banco Santander (Santander Universities Global Division). D.M.-E. was funded by a "Ramon y Cajal" Programme Senior Grant and the "RETOS" National Programme for Research (MINECO), Cancer Research UK, and the CRUK Cambridge Centre Early Detection Programme. ; Lozano-Torres, B.; Galiana, I.; Rovira, M.; Garrido-García, EM.; Chaib, S.; Bernardos Bau, A.; Muñoz-Espín, D. (2017). An OFF-ON Two-Photon Fluorescent Probe for Tracking Cell Senescence in Vivo. Journal of the American Chemical Society. 139(26):8808-8811. https://doi.org/10.1021/jacs.7b04985 ; S ; 8808 ; 8811 ; 139 ; 26

[EN] Mesoporous silica nanoparticles capped with acetylcholinesterase, through boronic ester linkages, selectively release an entrapped cargo in the presence of acetylcholine. ; The authors acknowledge financial support from the Spanish Government (MAT2015-64139-C4-1-R, MAT2015-64139-C4-4-R and AGL2015-70235-C2-2-R) and the Generalitat Valenciana (PROMETEO2018/024). T. Godoy-Reyes is grateful to Generalitat Valenciana for her Santiago Grisollía fellowship. A. García-Fernández is grateful to the Spanish Government for her FPU fellowship ; Godoy-Reyes, TM.; Llopis-Lorente, A.; García-Fernández, A.; Gaviña, P.; Costero, AM.; Martínez-Máñez, R.; Sancenón Galarza, F. (2019). Acetylcholine-responsive cargo release using acetylcholinesterase-capped nanomaterials. Chemical Communications. 55(41):5785-5788. https://doi.org/10.1039/c9cc02602a ; S ; 5785 ; 5788 ; 55 ; 41 ; McCorry, L. K. (2007). Physiology of the Autonomic Nervous System. American Journal of Pharmaceutical Education, 71(4), 78. doi:10.5688/aj710478 ; W. M. Haschek , C. G.Rousseaux and M. A.Wallig , Nervous System , in Fundamentals of Toxicologic Pathology , 2nd edn, Academic Press CY , San Diego , 2010 , p. 377 ; Klinkenberg, I., Sambeth, A., & Blokland, A. (2011). Acetylcholine and attention. Behavioural Brain Research, 221(2), 430-442. doi:10.1016/j.bbr.2010.11.033 ; Hasselmo, M. E. (2006). The role of acetylcholine in learning and memory. Current Opinion in Neurobiology, 16(6), 710-715. doi:10.1016/j.conb.2006.09.002 ; An, M. C., Lin, W., Yang, J., Dominguez, B., Padgett, D., Sugiura, Y., … Lee, K.-F. (2010). Acetylcholine negatively regulates development of the neuromuscular junction through distinct cellular mechanisms. Proceedings of the National Academy of Sciences, 107(23), 10702-10707. doi:10.1073/pnas.1004956107 ; Ehrenstein, G., Galdzicki, Z., & Lange, G. D. (1997). The choline-leakage hypothesis for the loss of acetylcholine in Alzheimer's disease. Biophysical Journal, 73(3), 1276-1280. doi:10.1016/s0006-3495(97)78160-8 ; Fambrough, D. ...

[EN] The thickening of plant organs is supported by secondary growth, a process by which new vascular tissues (xylem and phloem) are produced. Xylem is composed of several cell types, including xylary fibers, parenchyma and vessel elements. In Arabidopsis, it has been shown that fibers are promoted by the class-I KNOX gene KNAT1 and the plant hormones gibberellins, and are repressed by a small set of receptor-like kinases; however, we lack a mechanistic framework to integrate their relative contributions. Here, we show that DELLAs, negative elements of the gibberellin signaling pathway, physically interact with KNAT1 and impair its binding to KNAT1-binding sites. Our analysis also indicates that at least 37% of the transcriptome mobilized by KNAT1 is potentially dependent on this interaction, and includes genes involved in secondary cell wall modifications and phenylpropanoid biosynthesis. Moreover, the promotion by constitutive overexpression of KNAT1 of fiber formation and the expression of genes required for fiber differentiation were still reverted by DELLA accumulation, in agreement with post-translational regulation of KNAT1 by DELLA proteins. These results suggest that gibberellins enhance fiber development by promoting KNAT1 activity. ; This work was funded by the Ministerio de Ciencia y Tecnologia (BFU2016-80621-P, BIO2016-71933-P and BIO2016-79147-R to M.A.B., D.A. and J.A., respectively). A.F-B. and N.B-T. were recipients of a Ministerio de Economia y Competitividad FPI Fellowships (BES-2011-045689 and BES-2014-068868, respectively), and A.S.-M. and M.A.B. acknowledge funding from the European Union (H2020-MSCA-IF-2016-746396). J.A. is supported by a Ramon y Cajal contract from the Ministerio de Economia y Competitividad (RYC-2014-15752). ; Felipo-Benavent, A.; Urbez Lagunas, C.; Blanco-Touriñán, N.; Serrano Mislata, A.; Baumberger, N.; Achard, P.; Agustí, J. (2018). Regulation of xylem fiber differentiation by gibberellins through DELLA-KNAT1 interaction. Development. 145(23). ...

[EN] Amblyseius swirskii is a predatory mite widely used for the control of very important pest species, such as whiteflies and thrips, in organic farming and conventional agriculture. However, this species cannot establish on tomato crops, probably due to the toxic effects of plant trichomes and their exudates. We evaluated tomato plants for effects on: a) A. swirskii preference mediated by plant volatiles, b) A. swirskii development, predation capacity and reproductive performance, c) the dispersal and survival of mites as affected by stem trichomes, and d) mite survival as a function of secondary metabolites secreted by tomato trichomes. The results showed that A. swirskii mites which gained experience foraging on tomato plants, tend to avoid them. The survival of A. swirskii eggs and juveniles on tomato leaves was not different from that on sweet pepper. However, adult survival was significantly lower when tested on whole plants. This was ostensibly due to the impact of trichomes and their secondary metabolites that are abundant on the stems and which negatively impacted mite dispersal on the plant. Among the secondary metabolites detected in tomato trichomes, the strongest negative effects were associated with acyl sugars. Acyl sugars were highly toxic to the mites and also, physically accumulated on their bodies after walking on tomato stems. Altogether, our results reveal why A. swirskii is not an efficient biocontrol agent on tomato crops. ; This work was funded by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 641456. JGC was supported by the Spanish Ministry of Economy and Competitiveness, Ramon y Cajal Program (RYC-2013-13834). JLR was supported by the Spanish Ministry of Economy and Competitiveness through a "Juan de la Cierva-Formacion" grant (FJCI-2016-28601). Mass spectrometric determinations were carried out at Servei Central d'Instrumentacio Cientifica (SCIC) from Universitat Jaume I. ; Paspati, A.; Rambla Nebot, JL.; ...

[EN] Copper is an essential element in plants. When scarce, copper is acquired from extracellular environment or remobilized from intracellular sites, through members of the high affinity copper transporters family COPT located at the plasma membrane and internal membrane, respectively. Here, we show that COPT3 is an intracellular copper transporter, located at a compartment of the secretory pathway, that is mainly expressed in pollen grains and vascular bundles. Contrary to the COPT1 plasma membrane member, the expression of the internal COPT3 membrane transporter was higher at 12 h than at 0 h of a neutral photoperiod day under copper deficiency. The screening of a library of conditionally overexpressed transcription factors implicated members of the TCP family in the COPT3 differential temporal expression pattern. Particularly, in vitro, TCP16 was found to bind to the COPT3 promoter and down-regulated its expression. Accordingly, TCP16 was mainly expressed at 0 h under copper deficiency and induced at 12 h by copper excess. Moreover, TCP16 overexpression resulted in increased sensitivity to copper deficiency, whereas the tcp16 mutant was sensitive to copper excess. Both copper content and the expression of particular copper status markers were altered in plants with modified levels of TCP16. Consistent with TCP16 affecting pollen development, the lack of COPT3 function led to altered pollen morphology. Furthermore, analysis of copt3 and COPT3 overexpressing plants revealed that COPT3 function exerted a negative effect on TCP16 expression. Taken together, these results suggest a differential daily regulation of copper uptake depending on the external and internal copper pools, in which TCP16 inhibits copper remobilization at dawn through repression of intracellular transporters. ; This work has been supported by grants BIO2017-87828-C2-1-P (LP) and the TRANSPLANTA Consortium (CSD2007-00057) from the Spanish Ministry of Economy and Competitiveness, and by FEDER funds from the European Union. NA-C and AC-S were ...

To obtain insights into archaeal nitrogen signaling and haloadaptation of the nitrogen/carbon/energy-signaling protein PII, we determined crystal structures of recombinantly produced GlnK2 from the extreme halophilic archaeon Haloferax mediterranei, complexed with AMP or with the PII effectors ADP or ATP, at respective resolutions of 1.49 Å, 1.45 Å, and 2.60 Å. A unique trait of these structures was a three-tongued crown protruding from the trimer body convex side, formed by an 11-residue, N-terminal, highly acidic extension that is absent from structurally studied PII proteins. This extension substantially contributed to the very low pI value, which is a haloadaptive trait of H. mediterranei GlnK2, and participated in hexamer-forming contacts in one crystal. Similar acidic N-extensions are shown here to be common among PII proteins from halophilic organisms. Additional haloadaptive traits prominently represented in H. mediterranei GlnK2 are a very high ratio of small residues to large hydrophobic aliphatic residues, and the highest ratio of polar to nonpolar exposed surface for any structurally characterized PII protein. The presence of a dense hydration layer in the region between the three T-loops might also be a haloadaptation. Other unique findings revealed by the GlnK2 structure that might have functional relevance are: the adoption by its T-loop of a three-turn α-helical conformation, perhaps related to the ability of GlnK2 to directly interact with glutamine synthetase; and the firm binding of AMP, confirmed by biochemical binding studies with ATP, ADP, and AMP, raising the possibility that AMP could be an important PII effector, at least in archaea. ; This work was supported by grants from the Spanish government (BFU2011-30407 and BIO2008_00082, to V. Rubio and M. J. Bonete, respectively) and from the Valencian government (Prometeo 2009/51 to V. Rubio). C. Palanca is a JAE-Predoc fellow of the CSIC and, during this work, L. Pedro-Roig was a FPU fellow of the Spanish Ministry of Education. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under BioStruct-X (grant agreement No. 283570).