Combined N-glycome and N-glycoproteome analysis of the Lotus japonicus seed globulin fraction shows conservation of protein structure and glycosylation in legumes

J Proteome Res. 2013 Jul 5;12(7):3383-92. doi: 10.1021/pr400224s. Epub 2013 Jun 25.

Abstract

Legume food allergy, such as allergy toward peanuts and soybeans, is a health issue predicted to worsen as dietary advice recommends higher intake of legume-based foods. Lotus japonicus (Lotus) is an established legume plant model system for studies of symbiotic and pathogenic microbial interactions and, due to its well characterized genotype/phenotype and easily manipulated genome, may also be suitable for studies of legume food allergy. Here we present a comprehensive study of the Lotus N-glycoproteome. The global and site-specific N-glycan structures of Lotus seed globulins were analyzed using mass spectrometry-based glycomics and glycoproteomics techniques. In total, 19 N-glycan structures comprising high mannose (∼20%), pauci-mannosidic (∼40%), and complex forms (∼40%) were determined. The pauci-mannosidic and complex N-glycans contained high amounts of the typical plant determinants β-1,2-xylose and α-1,3-fucose. Two abundant Lotus seed N-glycoproteins were site-specifically profiled; a predicted lectin containing two fully occupied N-glycosylation sites carried predominantly pauci-mannosidic structures in different distributions. In contrast, Lotus convicilin storage protein 2 (LCP2) carried exclusively high mannose N-glycans similar to its homologue, Ara h 1, which is the major allergen in peanut. In silico investigation confirmed that peanut Ara h 1 and Lotus LCP2 are highly similar at the primary and higher protein structure levels. Hence, we suggest that Lotus has the potential to serve as a model system for studying the role of seed proteins and their glycosylation in food allergy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Conserved Sequence
  • Globulins / classification
  • Globulins / genetics*
  • Globulins / isolation & purification
  • Glycoproteins / isolation & purification*
  • Glycoproteins / metabolism
  • Glycosylation
  • Lotus / genetics
  • Lotus / metabolism*
  • Mass Spectrometry
  • Plant Proteins / genetics
  • Plant Proteins / isolation & purification*
  • Plant Proteins / metabolism
  • Seeds / metabolism

Substances

  • Globulins
  • Glycoproteins
  • Plant Proteins