Structural analyses of sugar chains from ricin A-chain variant

Area of Science:

• Biochemistry
• Glycobiology
• Protein Chemistry

Background:

• Ricin A-chain is a critical component of the ricin toxin.
• Understanding ricin A-chain glycosylation is important for toxin characterization and potential therapeutic development.
• Previous studies have characterized the glycosylation of the major ricin A-chain.

Purpose of the Study:

• To identify and characterize the N-linked glycosylation sites and associated sugar chains of a ricin A-chain variant.
• To compare the glycosylation pattern of the ricin A-chain variant with that of the major ricin A-chain.

Main Methods:

• Tryptic digestion of ricin A-chain variant.
• Isolation of glycopeptides using gel filtration and reversed-phase High-Performance Liquid Chromatography (HPLC).
• Liberation and analysis of sugar chains via hydrazynolysis, N-acetylation, and pyridylamination.
• Characterization of pyridylamino (PA-) sugar chains using reversed-phase HPLC and size fractionation HPLC.

Main Results:

• Two glycopeptides were isolated from the ricin A-chain variant.
• Amino acid analysis confirmed glycosylation at Asn-10 and Asn-236.
• Component analysis and HPLC elution profiles indicated that both sugar chains are of the M3FX type.
• The M3FX sugar chains at Asn-10 and Asn-236 of the variant are identical to the sugar chain at Asn-10 of the major ricin A-chain.

Conclusions:

• The ricin A-chain variant possesses N-linked glycosylation at Asn-10 and Asn-236.
• The glycosylation pattern at these sites involves M3FX sugar chains, consistent with the major ricin A-chain.
• This finding contributes to the detailed structural understanding of ricin A-chain variants and their post-translational modifications.