Recombinant expression of Polygonatum cyrtonema lectin with anti-viral, apoptosis-inducing activities and preliminary crystallization

Polygonatum cyrtonema lectin (PCL) has been drawing rising attention due to its remarkable bioactivities. Whereas, large-scale isolation and purification of PCL from Polygonatum cyrtonema Hua is not feasible due to the extremely low propagation rate of this plant. Herein, an alternative method to produce large amount of PCL by Escherichia coli expression system was proposed, and recombinant Polygonatum cyrtonema lectin (rPCL) was successfully obtained under the optimized conditions (OD600=0.6 30 degrees C, 0.5 mM IPTG, pH 7.2). Subsequent SDS-PAGE and MALDI-TOF analysis confirmed that the molecular mass of rPCL was approximate to 12 kDa. After further identification of rPCL by Western blot and N-terminal amino acid sequence analysis, the comparisons of hemagglutinating and carbohydrate-binding activities as well as the anti-viral and apoptosis-inducing properties between rPCL and native Polygonatum cyrtonema lectin (nPCL) were made. It was verified that the bioactivities of rPCL were relatively weaker than that of nPa. Moreover, for future exploring three-dimensional structure and structure-bioactivity relationship of rPCL, circular dichroism and fluorescence spectroscopy, preliminary crystallization and X-ray diffraction were determined. Taken together, these findings provide novel evidence that rPCL could replace nPCL as a potential anti-tumor and anti-viral protein in possible medical application and large-scale pharmaceutical industry. (C) 2010 Elsevier Ltd. All rights reserved.