In a full-length cDNA library from the compound ascidian Botryllus schlosseri, we identified, by BLAST search against UniProt database, five transcripts, each with complete coding sequence, homologous to known rhamnose-binding lectins (RBLs). Comparisons of the predicted amino acid sequences suggest that they represent different isoforms of a novel RBL, called BsRBL-1–5. Four of these isolectins were found in Botryllus homogenate after purification by affinity chromatography on acid-treated Sepharose, analysis by reverse-phase HPLC and mass spectrometry. Analysis of both molecular masses and tryptic digests of BsRBLs indicated that the N-terminal sequence of the purified proteins starts from residue 22 of the putative amino acid sequence, and residues 1–21 represent a signal peptide. Analysis by mass spectrometry of V8-protease digests confirmed the presence and alignments of the eight cysteines involved in the disulphide bridges that characterise RBLs. Functional studies proved the enhancing effect on phagocytosis of the affinity-purified material. Results are discussed in terms of phylogenetic relationships of BsRBLs with orthologous molecules from protostomes and deuterostomes.

Novel rhamnose-binding lectins from the colonial ascidian Botryllus schlosseri

GASPARINI, FABIO;FRANCHI, NICOLA;SPOLAORE, BARBARA;BALLARIN, LORIANO
2008

Abstract

In a full-length cDNA library from the compound ascidian Botryllus schlosseri, we identified, by BLAST search against UniProt database, five transcripts, each with complete coding sequence, homologous to known rhamnose-binding lectins (RBLs). Comparisons of the predicted amino acid sequences suggest that they represent different isoforms of a novel RBL, called BsRBL-1–5. Four of these isolectins were found in Botryllus homogenate after purification by affinity chromatography on acid-treated Sepharose, analysis by reverse-phase HPLC and mass spectrometry. Analysis of both molecular masses and tryptic digests of BsRBLs indicated that the N-terminal sequence of the purified proteins starts from residue 22 of the putative amino acid sequence, and residues 1–21 represent a signal peptide. Analysis by mass spectrometry of V8-protease digests confirmed the presence and alignments of the eight cysteines involved in the disulphide bridges that characterise RBLs. Functional studies proved the enhancing effect on phagocytosis of the affinity-purified material. Results are discussed in terms of phylogenetic relationships of BsRBLs with orthologous molecules from protostomes and deuterostomes.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2469868
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