Research Articles

Plant Molecular Biology

, Volume 23, Issue 2, pp 365-376

First online:

Cloning and characterization of the lectin cDNA clones from onion, shallot and leek

  • Els J. M. Van DammeAffiliated withLaboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven
  • , Koen SmeetsAffiliated withLaboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven
  • , Iris EngelborghsAffiliated withLaboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven
  • , Helen AelbersAffiliated withLaboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven
  • , Jan BalzariniAffiliated withLaboratory of Experimental Chemotherapy, Rega Institute for Medical Research, Katholieke Universiteit Leuven
  • , Arpad PusztaiAffiliated withThe Rowette Research Institute
  • , Fred van LeuvenAffiliated withCenter for Human Genetics, Katholieke Universiteit Leuven
  • , Irwin J. GoldsteinAffiliated withDepartment of Biological Chemistry, University of Michigan
  • , Willy J. PeumansAffiliated withLaboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven

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Abstract

Characterization of the lectins from onion (Allium cepa), shallot (A. ascalonicum) and leek (A. porrum) has shown that these lectins differ from previously isolated Alliaceae lectins not only in their molecular structure but also in their ability to inhibit retrovirus infection of target cells.

cDNA libraries constructed from poly(A)-rich RNA isolated from young shoots of onion, shallot and leek were screened for lectin cDNA clones using colony hybridization. Sequence analysis of the lectin cDNA clones from these three species revealed a high degree of sequence similarity both at the nucleotide and at the amino acid level.

Apparently the onion, shallot and leek lectins are translated from mRNAs of ca. 800 nucleotides. The primary translation products are preproproteins (ca. 19 kDa) which are converted into the mature lectin polypeptides (12.5–13 kDa) after post-translational modifications.

Southern blot analysis of genomic DNA has shown that the lectins are most probably encoded by a family of closely related genes which is in good agreement with the sequence heterogeneity found between different lectin cDNA clones of one species.

Key words

Allium cDNA cloning lectin retrovirus inhibition