Characterization of a Molecularly Engineered Banlec-Type Lectin (rBTL).

Lectins are proteins that reversibly bind to carbohydrates and are commonly found across many species. The Banana Lectin (BanLec) is a member of the Jacalin-related Lectins, heavily studied for its immunomodulatory, antiproliferative, and antiviral activity. In this study, a novel sequence was generated in silico considering the native BanLec amino acid sequence and 9 other lectins belonging to JRL. Based on multiple alignment of these proteins, 11 amino acids of the BanLec sequence were modified because of their potential for interference in active binding site properties resulting in a new lectin named recombinant BanLec-type Lectin (rBTL). rBTL was expressed in E. coli and was able to keep biological activity in hemagglutination assay (rat erythrocytes), maintaining similar structure with the native lectin. Antiproliferative activity was demonstrated on human melanoma lineage (A375), evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT). rBTL was able to inhibit cellular growth in a concentration-dependent manner, in an 8-h incubation, 12 µg/mL of rBTL led to a 28.94% of cell survival compared to cell control with 100%. Through a nonlinear fit out log-concentration versus biological response, an IC50% of 3.649 µg/mL of rBTL was determined. In conclusion, it is possible to state that the changes made to the rBTL sequence maintained the structure of the carbohydrate-binding site without changing specificity. The new lectin is biologically active, with an improved carbohydrate recognition spectrum compared to nBanLec, and can also be considered cytotoxic for A375 cells.

Heterologous expression and characterization of a new galactose-binding lectin from Bauhinia forficata with antiproliferative activity.

In this study, we describe the characterization of a new lectin, BfL-II, purified from the seeds of Bauhinia forficata, which is distinct, at sequence-level, from the previously reported lectin from the same specie (BfL). In addition, the gene for this lectin was cloned and expressed in Escherichia coli and its antiproliferative activity was evaluated against human breast and colorectal cancer cells (MCF-7 and HT-29, respectively). The treatment with 100 µg/µL of either native or recombinant BfL (nBfL or rBfL) significantly reduced the proliferation of both cancer cell lines (p < 0.01). The inhibition of HT-29 cell proliferation was as high as 82.5% and 93.6% with 100 µg/µL of rBfL-I and nBfL after 24 h, respectively. Therefore, BfL-II presents a promising antiproliferative activity, which may be applied in the development of new anticancer treatments.