Structural and enzymatic properties of Ageritin, a novel metal-dependent ribotoxin-like protein with antitumor activity

• Published in: Biochimica et biophysica acta. General subjects Vol. 1862; no. 12; pp. 2888 - 2894
• Main Authors: Ruggiero, Alessia, García-Ortega, Lucía, Ragucci, Sara, Russo, Rosita, Landi, Nicola, Berisio, Rita, Di Maro, Antimo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2018
• Subjects: Ageritin; Agrocybe - chemistry; Agrocybe aegerita; Animals; antineoplastic activity; Antineoplastic Agents - chemistry; Antineoplastic Agents - metabolism; Antineoplastic Agents - pharmacology; binding properties; Calorimetry; Circular Dichroism; denaturation; EDTA (chelating agent); Electrophoresis, Polyacrylamide Gel; ions; magnesium; Magnesium - metabolism; Metal-protein; mushrooms; Protein Binding; Protein Stability; Protein Structure, Secondary; prototypes; Rabbits; reticulocytes; Ribonuclease activity; Ribosomes - drug effects; Ribosomes - metabolism; Ribotoxins; Spectrophotometry, Ultraviolet; Toxins, Biological - chemistry; Toxins, Biological - pharmacology; Ribotoxins; Ribonuclease activity; Metal-protein; Protein stability; Ageritin; Agrocybe aegerita
• ISSN: 0304-4165; 1872-8006; 1872-8006
• DOI: 10.1016/j.bbagen.2018.09.010

Ageritin has been recently described as the first ribotoxin-like from Basidiomycota division (mushroom Agrocybe aegerita) with known antitumor activity (BBA 2017, 1861: 1113-1121). By investigating structural, catalytic and binding properties, we demonstrate that Ageritin is a unique ribotoxin-like protein. Indeed, typical of the ribotoxin family, it shows the specific ribonucleolytic activity against the ribosomal Sarcin-Ricin Loop in a rabbit reticulocytes assay. However, it displays several elements of novelty, as this activity is strongly metal-dependent and completely suppressed in the presence of EDTA, different from other representative members of the ribotoxin family. Consistently, we prove that Ageritin is able to bind magnesium ions with low micromolar affinity. We also show that Ageritin is significantly more stable than other ribotoxins in thermal and chemical denaturation experiments. These peculiar features make Ageritin the prototype of a new ribotoxin-like family present in basidiomycetes. Finally, given its high stability, this enzyme is a promising candidate as a new tool in immunoconjugates and nanoconstructs. [Display omitted] •Ribonucleolytic activity of Ageritin against the ribosome is suppressed by EDTA.•Ageritin is a novel metal-binding ribotoxin.•Ageritin is the most stable ribotoxin so far reported.