Characterization of the gene encoding α-sarcin, a ribosome-inactivating protein secreted by Aspergillus giganteus

The Action Mode of the Ribosome-Inactivating Protein α-Sarcin

“…The amino acid sequence of ·-sarcin that was deduced from the coded DNA sequence was found to be identical to that reported previously [33,36,42]. The genomic structure of the ·-sarcin gene carries an intron of 64 nucleotides with a typical group II splicing signal [17].…”

“…This suggestion is based on the findings that the short peptide loop at the ß-hairpin (positions [16][17][18][19] carries a guanine base-binding motif of N-K-Y-E [6]. Such a sequence is conserved among ribosome-inactivating proteins [15,18,24,33,42]. In the Xray crystal data for restrictocin [46], this short loop was located at the surface of the molecule and was predicted to be dynamic because the loop was not in the diffraction map [46].…”

“…The intron disrupts the coding sequence of the mature sarcin protein at the second codon. This intron disruption has been characteristically found among the fungal-originated ribosome-inactivating proteins [15,24,27,42].…”

“…The tetranucleotides GAGA, at the apex of the singlestranded loop of the sarcin domain, form the site at which the ribosome-inactivating protein acts [4,10,11,32,43,44]. On the other hand, despite several genes of ribosomeinactivating proteins having been determined [15,18,24,33,42], the structure of the ribosome-inactivating protein that participates in catalyzing the hydrolysis of ribosomes or ribonucleic acids has not been completely revealed yet. Elucidation of the action of ribosome-inactivating protein on its substrates has been attempted using genetic manipulation, with limited success, however, because of the lethality of the protein-inactivating protein to the host cells [19,22,23,45].…”

Expression of ribonucleolytic toxin restrictocin in Escherichia coli: purification and characterization

“…Earlier gene and cDNA coding for restrictocin have been expressed in Aspergillus nidulans and Saccharomyces cerevisiae, respectively, to study the role of leader peptide on the survival of the host [7,8]. Ribotoxins, ~-sarcin and mitogillin have been expressed earlier using ompA and pelB signal sequences but the protein levels obtained were low [9][10][11][12][13]. Asp f L a homologue of mitogillin has also been expressed in E. coli but the recombinant protein was 10-fold less active than the native toxin [14].…”