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Two major proteins, a-sarcin and an antifungal polypeptide AFP , are secreted by the mould Ž . Aspergillus giganteus MDH 18894 when it is cultured for 70–80 h. A third major protein is also found in the extracellular medium at 48–60 h, but it disappears as the culture proceeds. This protein has been isolated and characterized in terms of apparent molecular mass, electrophoretic and chromatographic behaviour, NH -terminal primary structure, amino acid content, spectroscopical 2 features, reactivity against anti-AFP antibodies, and antifungal activity. Based on the obtained results it would be an extracellular inactive precursor form of AFP, designated as the large form of AFP lf-AFP . Its amino acid composition is Ž . identical to that of AFP but containing six extra residues. NH -terminal sequence analysis of the first eight amino acid 2 residues of this polypeptide revealed that the extra residues can be perfectly accommodated within the DNA-deduced sequence of the precursor form of AFP. Its alignment with precursor sequences of different proteins, secreted by a variety of Aspergillus spp., reveals the existence of a common tetrapeptide at the carboxy-terminal end of their leader peptides. This sequence would be IlerLeu-Xaa-Yaa-Arg, being mostly Xaa and Yaa an acid residue Asp Ž . rGlu and alanine, respectively. The presence of lf-AFP as an extracellular protein would be in perfect agreement with the existence of this tetrapeptide motif, that can be involved in the protein secretion mechanisms of filamentous fungi., Depto. de Bioquímica y Biología Molecular, Fac. de Ciencias Químicas, TRUE, pub

a-Sarcin, restrictocin and mitogillin are the best known members of the family of fungal ribotoxins. In recent years, new members of this family have been discovered and characterised. In this work, we study the occurrence of ribotoxins among di erent species of fungi. The presence of ribotoxins has been identi®ed in some new species by means of genetic studies, as well as expression and activity assays. The ribotoxin genes have been partially sequenced, and demonstrate a high degree of similarity. These studies demonstrate that these toxins are more widespread than previously considered. This is surprising, considering the ribotoxins are such speci®c and potent toxins, of unknown biological function. These studies con®rm the hypothesis that these proteins are naturally engineered toxins derived from ribonucleases of broad substrate speci®city., Depto. de Bioquímica y Biología Molecular, Fac. de Ciencias Químicas, TRUE, pub

Sticholysins are pore-forming toxins produced by the sea anemone Stichodactyla helianthus. When they encounter a sphingomyelin-containing membrane, these proteins bind to it and oligomerize, a process that ends in pore formation. Mounting evidence indicates that StnII can favour the activity of StnI. Previous results have shown that these two isotoxins can oligomerize together. Furthermore, StnII appeared to potentiate the activity of StnI through the membrane-binding step of the process. Hence, isotoxin interaction should occur prior to membrane encounter. Here, we have used analytical ultracentrifugation to investigate the oligomerization of Stns in solution, both separately and together. Our results indicate that while StnI seems to be more prone to oligomerize in water solution than StnII, a small percentage of StnII in StnI-StnII mixtures promotes oligomerization.

Azúcares, hidratos de carbono, fibra, grasas o lípidos, minerales, proteínas y vitaminas son los componentes básicos de los alimentos, son las moléculas que comemos. ¿Cuáles son sus propiedades? ¿Por qué son importantes para nuestro desarrollo y salud? ¿Cómo proporcionan a los alimentos sus diferentes aromas, colores, sabores y texturas? ¿Qué tipo de reacciones químicas se producen al cocinar? ¿Qué enfermedades están vinculadas a la dieta? ¿Por qué los llamados superalimentos son falsos mitos de la alimentación? Esta obra es una guía didáctica que responde a estas y a otras preguntas que cualquiera se habrá planteado en algún momento sobre la alimentación y sobre las moléculas presentes en nuestra dieta. Con sencillas explicaciones y una amplia variedad de experimentos y talleres, en versión bilingüe español-inglés, que pueden hacerse tanto en la cocina de casa como en el colegio, este libro da a conocer la bioquímica de nuestra alimentación. Las moléculas que comemos está adaptado a los niveles educativos de primaria y secundaria.

The identification or design of biocatalysts to mitigate the accumulation of plastics, including sub-micro- and nano-sized polyethylene terephthalate (nPET), is becoming a global challenge. Here we computationally incorporated two hydrolytic active sites with geometries similar to that of Idionella sakaiensis PET hydrolase, to fragaceatoxin C (FraC), a membrane pore-forming protein. FraCm1/m2 could be assembled into octameric nanopores (7.0 nm high × 1.6–6.0 nm entry), which deconstructed (40 °C, pH 7.0) nPET from GoodFellow, commodities and plastic bottles. FraCm1 and FraCm2 degrade nPET by endo- and exo-type chain scission. While FraCm1 produces bis(2-hydroxyethyl) terephthalate as the main product, FraCm2 yields a high diversity of oligomers and terephthalic acid. Mechanistic and biochemical differences with benchmark PET hydrolases, along with pore and nPET dynamics, suggest that these pore-forming protein catalytic nanoreactors do not deconstruct macro-PET but are promising in nanotechnology for filtering, capturing and breaking down nPET, for example, in wastewater treatment plants. [Figure not available: see fulltext.]. © 2023, The Author(s).

Sticholysins are pore-forming toxins produced by the sea anemone Stichodactyla helianthus. When they encounter a sphingomyelin-containing membrane, these proteins bind to it and oligomerize, a process that ends in pore formation. Mounting evidence indicates that StnII can favour the activity of StnI. Previous results have shown that these two isotoxins can oligomerize together. Furthermore, StnII appeared to potentiate the activity of StnI through the membrane-binding step of the process. Hence, isotoxin interaction should occur prior to membrane encounter. Here, we have used analytical ultracentrifugation to investigate the oligomerization of Stns in solution, both separately and together. Our results indicate that while StnI seems to be more prone to oligomerize in water solution than StnII, a small percentage of StnII in StnI–StnII mixtures promotes oligomerization., Para defenderse y atacar a sus presas, las anémonas marinas producen una serie de toxinas, entre las que se encuentran las actinoporinas (proteínas formadoras de poros). Es habitual que una anémona produzca varias isoformas de estas porinas, como es el caso de la anémona caribeña Stichodactyla helianthus, de la cual se han aislado hasta tres variantes, las conocidas como esticolisinas (Stn) I, II y III. Estas toxinas se unen a membranas en las que la esfingomielina, el lípido que reconocen específicamente, esté presente y disponible. Una vez unidas, es necesario que oligomericen para formar los poros que son, en definitiva, su forma activa final. En trabajos anteriores habíamos obtenido indicios que apuntaban a que tanto StnI como StnII eran capaces de formar oligómeros en ausencia de membranas. No solo eso, si no que StnII parecía capaz de favorecer la actividad de StnI si se las hacía actuar conjuntamente. Partiendo de la hipótesis de que estas dos ideas podían estar relacionadas, realizamos una serie de estudios de centrifugación analítica para evaluar cuantitativamente la oligomerización de StnI, StnII, y mezclas de StnI y StnII en diferentes proporciones. Los resultados obtenidos nos han permitido comprobar que StnI es más dada a formar homo-oligómeros que StnII. Además, revelan que pequeñas proporciones de StnII en una mezcla dominada por StnI resultan en una población de oligómeros mayor de lo que se anticiparía si StnI y StnII se asociaran independientemente. Un resultado que nos acerca a entender el mecanismo de acción de estas toxinas, y a vislumbrar la ventaja evolutiva que puede suponer a las anémonas la producción de varias isoformas de estas proteínas formadoras de poros., Ministerio de Ciencia e Innovación (MICINN), Universidad Complutense de Madrid/Banco de Santander, UnaEuropa, Juselius Foundation, CIB/CSIC, Internation Network of Computational and Structural Biology / Åbo Akademi, Sección Deptal. de Bioquímica y Biología Molecular (Biológicas), Fac. de Ciencias Biológicas, TRUE, pub