Expression and characterization of two domains of Pinellia ternata agglutinin (PTA), a plant agglutinin from Pinellia ternata with antifungal activity

Pinellia ternata agglutinin (PTA) from P. ternata f. angustata is a two-domain GNA-related lectin. The current study indicates that the PTA gene encodes a precursor consisting of two tandemly arrayed domains, N-terminal domain (PTA-DOM1) and C-terminal domain (PTA-DOM2). Both domains and the precursor without signal peptide (PTA-P) present different number of activity mannose-binding sites which play key roles for the lectin function. Analyses of the three fusion proteins, PTA-DOM1, PTA-DOM2 and PTA-P, expressed in Escherichia coli revealed that one mannose-binding site the agglutination activity while the additional sites do not possess such activity. However, the number of carbohydrate-binding sites suggests some significant properties on the antifungal effectiveness. In addition, each of the PTA domains has the same function when compared with the natural PTA (N-PTA). The information on PTA gene obtained in this study will served as baseline information in developing this protein as a form of transgenic plant protection.