https://uvadoc.uva.es/handle/10324/65189 2026-04-25T11:57:00Z 2026-04-25T11:57:00Z Iglesias Álvarez, María del Rosario Ferreras Rodríguez, José Miguel Di Maro, Antimo Citores González, Lucía https://uvadoc.uva.es/handle/10324/65488 2024-02-01T20:02:03Z 2018-01-01T00:00:00Z

Background: Sambucus ebulus is a rich source of ribosome-inactivating proteins (RIPs) and RIP-related lectins generated from multiple genes. These proteins differ in their structure, enzymatic activity and sugar binding specificity. Methods: We have purified and characterized ebulin-RP from S. ebulus leaves and determined the amino acid sequence by cDNA cloning. Cytotoxicity was studied in a variety of cancer cells and a comparative study of the ability of ebulin-RP to bind sugars using "in vitro" and "in silico" approaches was performed. Results: Ebulin-RP is a novel heterodimeric type 2 RIP present in S. ebulus leaves together with the type 2 RIP ebulin l, which displayed rRNA N-glycosidase activity but unlike ebulin l, lacked functional sugar binding domains. As a consequence of changes in its B-chain, ebulin-RP displayed lower cytotoxicity than ebulin l towards cancer cells and induced apoptosis as the predominant pattern of cell death. Conclusions: Ebulin-RP is a novel member of the ebulin gene family with low cytotoxicity as a result of deficient sugar binding domains. Type 2 RIP genes from Sambucus have evolved to render proteins with different sugar affinities that may be related to different biological activities and could result in an advantage for the plant. General significance: The ebulin family of RIPs and lectins can serve as a good model for studying the evolutionary process which may have occurred in RIPs. The lack of cytotoxicity of ebulin-RP makes it a good candidate as a toxic moiety in the construction of immunotoxins and conjugates directed against specific targets.

2018-01-01T00:00:00Z Citores González, Lucía Ragucci, Sara Ferreras Rodríguez, José Miguel Di Maro, Antimo Iglesias Álvarez, María del Rosario https://uvadoc.uva.es/handle/10324/65470 2024-01-31T20:02:11Z 2019-01-01T00:00:00Z

Ribotoxins make up a group of extracellular rRNA endoribonucleases produced by ascomycetes that display cytotoxicity toward animal cells, having been proposed as insecticidal agents. Recently, the ribotoxin Ageritin has been isolated from the basidiomycetes Agrocybe aegerita (poplar mushroom), suggesting that ribotoxins are widely distributed among fungi. To gain insights into the protective properties of Ageritin against pathogens and its putative biotechnological applications, we have tested several biological activities of Ageritin, comparing them with those of the well-known ribotoxin α-sarcin, and we found that Ageritin displayed, in addition to the already reported activities, (i) antibacterial activity against Micrococcus lysodeikticus, (ii) activity against the tobacco mosaic virus RNA, (iii) endonuclease activity against a supercoiled plasmid, (iv) nuclease activity against genomic DNA, (v) cytotoxicity to COLO 320, HeLa, and Raji cells by promoting apoptosis, and (vi) antifungal activity against the green mold Penicillium digitatum. Therefore, Ageritin and α-sarcin can induce resistance not only to insects but also to viruses, bacteria, and fungi. The multiple biological activities of Ageritin could be exploited to improve resistance to different pathogens by engineering transgenic plants. Furthermore, the induction of cell death by different mechanisms turns these ribotoxins into useful tools for cancer therapy.

2019-01-01T00:00:00Z Citores González, Lucía Iglesias Álvarez, María del Rosario Ragucci, Sara Di Maro, Antimo Ferreras Rodríguez, José Miguel https://uvadoc.uva.es/handle/10324/65447 2024-01-31T20:02:10Z 2018-01-01T00:00:00Z

Among the putative defense proteins that occur in fungi, one of the best studied is α-sarcin, produced by the mold Aspergillus giganteus. This protein is the most significant member of the ribotoxin family, which consists of extracellular rRNA ribonucleases that display cytotoxic activity toward animal cells. Ribotoxins are rRNA endonucleases that catalyze the hydrolysis of the phosphodiester bond between G4325 and A4326 from the rat 28S rRNA. The results of several experimental approaches have led to propose ribotoxins as insecticidal agents. In this work, we report that α-sarcin displays a strong antifungal activity against Penicillium digitatum, being able to enter into the cytosol where it inactivates the ribosomes, thus killing the cells and arresting the growth of the fungus. This is the first time that a ribotoxin has been found to display antifungal activity. Therefore, this protein could play, besides the already proposed insecticidal function, a role in nature as an antifungal agent.

2018-01-01T00:00:00Z