Characterization of a type D1A EUL-related lectin from rice expressed in Pichia pastoris
Al Atalah, Bassam × Vanderschaeghe, Dieter Bloch, Yehudi Proost, Paul Plas, Kirsten Callewaert, Nico Savvides, Savvas N Van Damme, Els J M #
W. de Gruyter
Biological Chemistry vol:395 issue:4 pages:413-24
Abstract OrysaEULD1A is one of the five EUL genes in rice (Oryza sativa) encoding a putative carbohydrate-binding protein belonging to the family of Euonymus related lectins (EUL). The OrysaEULD1A sequence comprises two highly similar EUL domains (91% sequence similarity and 72% sequence identity) separated by a 23 amino acid linker sequence and preceded by a 19 amino acid N-terminal sequence. In the present study, the full-length protein OrysaEULD1A as well as its individual domains OrysaEULD1A domain 1 and 2 were expressed in Pichia pastoris. After purification of the recombinant proteins, their carbohydrate-binding specificity was analyzed and compared. Interestingly, all recombinant lectins showed clear specificity towards galactosylated structures. Furthermore, all recombinant proteins agglutinated red blood cells, indicating that the full-length protein OrysaEULD1A and its domains are true lectins. These results taken together with data previously reported for single-domain EUL proteins indicate that although the amino acids - responsible for the formation of the carbohydrate-binding site - are identical for all EUL proteins in rice, these lectins show different carbohydrate specificities. This promiscuity of the carbohydrate-binding site can be attributed to gene divergence.