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Ribotoxin genes in isolates of Aspergillus section Clavati.

Varga J, Samson RA - Antonie Van Leeuwenhoek (2008)

Bottom Line: All species assigned to this section have been found to carry ribotoxin genes.These data indicate that these genes probably encode active ribotoxins.Further studies are in progress to examine the secretion and activities of these new ribotoxins.

View Article: PubMed Central - PubMed

Affiliation: CBS Fungal Biodiversity Centre, Uppsalalaan 8, Utrecht, The Netherlands. j.varga@cbs.knaw.nl

ABSTRACT
Ribotoxins are ribosome inactivator proteins with high specificity against the sarcin/ricin domain of the 28S ribosomal RNA. We examined the presence of ribotoxin genes in isolates of species recently assigned to Aspergillus section Clavati using specific primer pairs. All species assigned to this section have been found to carry ribotoxin genes. Phylogenetic analysis of the sequences of the amplified gene fragments allowed us to classify the genes to different groups including the alpha-sarcin, gigantin, c-sarcin and mitogillin/restrictocin families. Two species, A. longivesica and N. acanthosporus produced ribotoxins which were only distantly related to gigantins and c-sarcins, respectively. Comparison of the protein sequences of the genes to known ribotoxin sequences revealed that all of them carry the presumed catalytic residues of ribotoxins, the cystein residues, and also the two Trp residues of alpha-sarcin conserved in all ribotoxins known so far. These data indicate that these genes probably encode active ribotoxins. Further studies are in progress to examine the secretion and activities of these new ribotoxins.

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Alignment of amino acid sequences of the ribotoxin genes identified. The amino acids found to be involved in proton transfer (His50, Glu96 and His137) are labelled with *, the two Trp residues of α-sarcin are labelled with #, while the Cys residues are labelled with C. The main regions of the ribotoxin genes are shown above the alignment (Lacadena et al. 2007)
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Fig2: Alignment of amino acid sequences of the ribotoxin genes identified. The amino acids found to be involved in proton transfer (His50, Glu96 and His137) are labelled with *, the two Trp residues of α-sarcin are labelled with #, while the Cys residues are labelled with C. The main regions of the ribotoxin genes are shown above the alignment (Lacadena et al. 2007)

Mentions: Comparison of the amino acid sequences of the ribotoxin genes of Aspergillus section Clavati to those of α-sarcin, gigantin and mitogillin is presented in Fig. 2. The amino acid sequences of the ribotoxin genes examined were highly similar in agreement with previous findings (Lin et al. 1995; Lacadena et al. 2007). The amino acids found to be involved in proton transfer (His50, Glu96 and His137, labelled with *), the two Trp residues of α-sarcin conserved in all ribotoxins known so far (labelled with #) and the Cys residues (labelled with C) have been found in all sequences (Fig. 2; Lacadena et al. 2007). The ribotoxin gene sequences of A. longivesica and N. acanthosporus isolates differ from the other known ribotoxins in other, less conserved regions, indicating that these genes could encode for functional ribotoxins. However, further studies are needed to clarify if the ribotoxin genes of A. longivesica and N. acanthosporus encode functional ribosome-inactivating proteins.Fig. 2


Ribotoxin genes in isolates of Aspergillus section Clavati.

Varga J, Samson RA - Antonie Van Leeuwenhoek (2008)

Alignment of amino acid sequences of the ribotoxin genes identified. The amino acids found to be involved in proton transfer (His50, Glu96 and His137) are labelled with *, the two Trp residues of α-sarcin are labelled with #, while the Cys residues are labelled with C. The main regions of the ribotoxin genes are shown above the alignment (Lacadena et al. 2007)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2519116&req=5

Fig2: Alignment of amino acid sequences of the ribotoxin genes identified. The amino acids found to be involved in proton transfer (His50, Glu96 and His137) are labelled with *, the two Trp residues of α-sarcin are labelled with #, while the Cys residues are labelled with C. The main regions of the ribotoxin genes are shown above the alignment (Lacadena et al. 2007)
Mentions: Comparison of the amino acid sequences of the ribotoxin genes of Aspergillus section Clavati to those of α-sarcin, gigantin and mitogillin is presented in Fig. 2. The amino acid sequences of the ribotoxin genes examined were highly similar in agreement with previous findings (Lin et al. 1995; Lacadena et al. 2007). The amino acids found to be involved in proton transfer (His50, Glu96 and His137, labelled with *), the two Trp residues of α-sarcin conserved in all ribotoxins known so far (labelled with #) and the Cys residues (labelled with C) have been found in all sequences (Fig. 2; Lacadena et al. 2007). The ribotoxin gene sequences of A. longivesica and N. acanthosporus isolates differ from the other known ribotoxins in other, less conserved regions, indicating that these genes could encode for functional ribotoxins. However, further studies are needed to clarify if the ribotoxin genes of A. longivesica and N. acanthosporus encode functional ribosome-inactivating proteins.Fig. 2

Bottom Line: All species assigned to this section have been found to carry ribotoxin genes.These data indicate that these genes probably encode active ribotoxins.Further studies are in progress to examine the secretion and activities of these new ribotoxins.

View Article: PubMed Central - PubMed

Affiliation: CBS Fungal Biodiversity Centre, Uppsalalaan 8, Utrecht, The Netherlands. j.varga@cbs.knaw.nl

ABSTRACT
Ribotoxins are ribosome inactivator proteins with high specificity against the sarcin/ricin domain of the 28S ribosomal RNA. We examined the presence of ribotoxin genes in isolates of species recently assigned to Aspergillus section Clavati using specific primer pairs. All species assigned to this section have been found to carry ribotoxin genes. Phylogenetic analysis of the sequences of the amplified gene fragments allowed us to classify the genes to different groups including the alpha-sarcin, gigantin, c-sarcin and mitogillin/restrictocin families. Two species, A. longivesica and N. acanthosporus produced ribotoxins which were only distantly related to gigantins and c-sarcins, respectively. Comparison of the protein sequences of the genes to known ribotoxin sequences revealed that all of them carry the presumed catalytic residues of ribotoxins, the cystein residues, and also the two Trp residues of alpha-sarcin conserved in all ribotoxins known so far. These data indicate that these genes probably encode active ribotoxins. Further studies are in progress to examine the secretion and activities of these new ribotoxins.

Show MeSH