Nucleotide Sequence of a Genomic Clone Encoding Arcelin, a Lectin-Like Seed Protein from Phaseolus vulgaris.

Arcelin is a novel seed protein first found in several accessions of the wild Mexican bean, Phaseolus vulgaris L. var aborigeneus (8). It is closely related to bean lectin, both at the amino acid and nucleotide levels (5). There are five allelic variants of arcelin (4, 6). The Arc 1 (Table I, Fig. 1) protein migrates as two bands on polyacrylamide gels with Mr of 35,000 to 38,000. These two bands are glycosylation variants, because a single band is seen following chemical deglycosylation (7). The presence of arcelin correlates with reduced expression of phaseolin (9), the major seed storage protein in beans. In these seeds, arcelin accounts for about 10% of the total seed protein. Arcelin has been found to have insecticidal properties on bruchid beetles (bean weevils), a prominent bean pest (5). Naturally occurring seeds containing arcelin and artificial seeds containing purified arcelin were resistant to attack by the Mexican bean weevil Zabrotes subfasciatus. Reproduction of the bruchid beetle Callosobruchus maculatus was reduced in the presence of black bean phytohemagglutinin, another plant lectin (2). Two arcelin cDNA sequences have been reported, for Arc 1 (5) and for Arc 2 (3). The sequence reported here is a genomic clone of Arc 1. It is identical with the cDNA for Arc 1 with the exception of a single nucleotide in the 3'-untranslated region.