Characterization of a new toxin from the entomopathogenic fungus Metarhizium anisopliae: the ribotoxin anisoplin

Abstract

Abstract:Metarhizium anisopliae is an entomopathogenic fungus relevant in biotechnology with applications like malaria vector control. Studies of its virulence factors are therefore of great interest. Fungal ribotoxins are toxic ribonucleases with extraordinary efficiency against ribosomes and suggested as potential insecticides. Here we describe this ribotoxin characteristic activity in M. anisopliae cultures. Anisoplin has been obtained as a recombinant protein and further characterized. It is structurally similar to hirsutellin A, the ribotoxin from the entomopathogen Hirsutella thompsonii. Moreover, anisoplin shows the ribonucleolytic activity typical of ribotoxins and cytotoxicity against insect cells. How Metarhizium uses this toxin and possible applications are of interest.

Fungal Ribotoxins: A Review of Potential Biotechnological Applications

“…As mentioned before, the production of ribotoxins is not restricted to Aspergillus [ 2 , 3 , 6 , 18 , 19 , 55 ]. The genus Hirsutella includes over 50 fungal species that infect many species of invertebrates.…”

“…Of course, in a natural environment additional factors may influence their efficiency, such as their natural biosynthesis and extracellular export, stability in a particular environment or accessibility to their target. Reinforcing this hypothesis about their insecticidal natural function, a new ribotoxin, very similar to HtA, has been recently cloned and characterized [ 6 ]. This small ribotoxin is produced by the fungus M. anisopliae and therefore has been named as anisoplin.…”

“…They are not the only extracellular ribonucleases (RNases) produced by filamentous fungi, but are the only ones shown to display cytotoxic activity ( Figure 1 ). Ribotoxins are produced by several fungi species, mostly from the genus Aspergillus , although other entomopathogenic fungi such as Hirsutella thompsonii or Metarhizium anisopliae also produce them [ 2 , 3 , 4 , 5 , 6 ]. They are highly specific, exerting their ribonucleolytic activity on the larger RNA molecule (rRNA) of the ribosome.…”

Análisis de las investigaciones sobre Metarhizium anisopliae en los últimos 40 años

“…Otra sub-área de investigación de relevancia para este microorganismo es el aspecto molecular. Diversas investigaciones han analizado el rol de varias enzimas (Dextruxinas, MaNAG1, MaNAG2, MaNAG3 y MaNAG4) durante el ciclo de vida del Metarhizium anisopliae (de Oliveira et al, 2018), caracterizado las ribonucleasas tóxicas de este microorganismo como insecticidas potenciales contra ribosomas para el control de vectores de enfermedades (Olombrada et al, 2017), así como la función de algunos genes sobre la adaptación al ambiente de este microorganismo (Zeng et al, 2018) y en su nivel de virulencia (Santos et al, 2017).…”

High cell density fed-batch production of insecticidal recombinant ribotoxin hirsutellin A from Pichia pastoris

“…Ribotoxins produced by some fungal species, such as Aspergillus , Hirsutella thompsonii and other entomopathogenic fungi, have the potential to be used as biological pesticides [ 10 , 12 , 13 ]. Specifically, the fungal ribotoxin hirsutellin A (HtA) produced by the invertebrate fungal pathogen H. thompsonii exhibits insect-specific cytotoxicity and strong insecticidal properties [ 14 , 15 ].…”