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Plakophilin 1 (PKP1), a member of the p120ctn subfamily of the armadillo (ARM)-repeat-containing proteins, is an important structural component of cell–cell adhesion scaffolds although it can also be ubiquitously found in the cytoplasm and the nucleus. RYBP (RING 1A and YY1 binding protein) is a multifunctional intrinsically disordered protein (IDP) best described as a transcriptional regulator. Both proteins are involved in the development and metastasis of several types of tumors. We studied the binding of the armadillo domain of PKP1 (ARM-PKP1) with RYBP by using in cellulo methods, namely immunofluorescence (IF) and proximity ligation assay (PLA), and in vitro biophysical techniques, namely fluorescence, far-ultraviolet (far-UV) circular dichroism (CD), and isothermal titration calorimetry (ITC). We also characterized the binding of the two proteins by using in silico experiments. Our results showed that there was binding in tumor and non-tumoral cell lines. Binding in vitro between the two proteins was also monitored and found to occur with a dissociation constant in the low micromolar range (~10 μM). Finally, in silico experiments provided additional information on the possible structure of the binding complex, especially on the binding ARM-PKP1 hot-spot. Our findings suggest that RYBP might be a rescuer of the high expression of PKP1 in tumors, where it could decrease the epithelial–mesenchymal transition in some cancer cells.

Los biofertilizantes preparados con extractos de microalgas, son una alternativa sostenible en el mejoramiento, producción y protección de los cultivos agrícolas, siendo uno de los campos por explorar y más prometedores de la biotecnología y bioingeniería. Las microalgas son microrganismos multifuncionales que, poseen eficiencia fotosintética, capacidad de suministrar nitrógeno en formas disponibles para las plantas además, potencian el desarrollo de los cultivos por medio de reguladores de crecimiento o fitohormonas (auxinas, giberelinas y citoquinas) y a altos niveles de macro y micronutrientes, indispensables para las plantas. Estos microorganismos fotosintéticos necesitan condiciones estándar para su rápido crecimiento que se asemejan a las de las plantas: luz, temperatura (18-28ºC), pH (6-9) y nutrientes que pueden provenir de distintas fuentes tanto orgánicas (biol, compost, gallinaza) como inorgánicas (agroquímicos). Además, pueden ser cultivadas para su producción a gran escala en sistemas abiertos a la atmósfera y cerrados cumpliendo condiciones controladas, como en el caso de los fotobiorreactores. En la presente revisión se comparan los diferentes tipos biofertilizantes, cultivos de microalgas y su producción a gran escala, se presenta una perspectiva de la situación actual de los biofertilizantes en el mundo y un análisis de los principales retos a vencer como: el costo de producción, selección y optimización de técnicas de aislamiento de cepas, diseño de biorreactores, etc.

PADI4 is a peptidyl-arginine deiminase (PADI) involved in the conversion of arginine to citrulline. PADI4 is present in macrophages, monocytes, granulocytes, and several cancer cells. It is the only PADI family member observed within both the nucleus and the cytoplasm. PADI4 has a predicted nuclear localization sequence (NLS) comprising residues Pro56 to Ser83, to allow for nuclear translocation. Recent predictors also suggest that the region Arg495 to Ile526 is a possible NLS. To understand how PADI4 is involved in cancer, we studied the ability of intact PADI4 to bind importin α3 (Impα3), a nuclear transport factor that plays tumor-promoting roles in several cancers, and its truncated species (ΔImpα3) without the importin-binding domain (IBB), by using fluorescence, circular dichroism (CD), and isothermal titration calorimetry (ITC). Furthermore, the binding of two peptides, encompassing the first and the second NLS regions, was also studied using the same methods and molecular docking simulations. PADI4 interacted with both importin species, with affinity constants of ~1–5 µM. The isolated peptides also interacted with both importins. The molecular simulations predict that the anchoring of both peptides takes place in the major binding site of Impα3 for the NLS of cargo proteins. These findings suggest that both NLS regions were essentially responsible for the binding of PADI4 to the two importin species. Our data are discussed within the framework of a cell mechanism of nuclear transport that is crucial in cancer.