A new chitin-binding lectin from rhizome of Setcreasea purpurea with antifungal, antiviral and apoptosis-inducing activities

Qing Yao; Chuan-Fang Wu; Ping Luo; Xiao-Cong Xiang; Jun-Jie Liu; Lin Mou; Jin-Ku Bao

doi:10.1016/j.procbio.2010.05.026

A new chitin-binding lectin from rhizome of Setcreasea purpurea with antifungal, antiviral and apoptosis-inducing activities

Process Biochem. 2010 Sep;45(9):1477-1485. doi: 10.1016/j.procbio.2010.05.026. Epub 2010 May 27.

Authors

Qing Yao¹, Chuan-Fang Wu¹, Ping Luo¹, Xiao-Cong Xiang¹, Jun-Jie Liu¹, Lin Mou¹, Jin-Ku Bao¹

Affiliation

¹ School of Life Science & State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610064, China.

Abstract

A 48 kDa, chitin-binding lectin with antifungal, antiviral and apoptosis-inducing activities was isolated from the rhizomes of Setcreasea purpurea Boom, a member of family Commelinaceae. Setcreasea purpurea lectin (designated as SPL) is a homotetrameric protein consisting of 12031.9 Da subunits linked by non-covalent bonds as determined by SDS-PAGE, gel filtration and MS. The N-terminal 25 amino-acid sequence of SPL, NVLGRDAYCGSQNPGATCPGLCCSK was determined and homology analysis suggested that SPL belongs to the family of chitin-binding plant lectins composed of hevein domains. The lectin exhibited strong hemagglutinating activity towards rabbit erythrocytes at 0.95 μg/ml and the activity could be reversed exclusively by chitin hydrolysate (oligomers of GlcNAc). Its hemagglutinating activity was stable in pH range of 2.0-9.0 and it showed excellent thermal tolerance. SPL showed antifungal activity against Rhizoctonia solani, Sclerotinia sclerotiorum, Penicillium italicum and Helminthosporiun maydis. It also exhibited inhibitory effect on HIV-1 (IIIB) and HIV-2 (ROD), with an EC₅₀ of 13.8 ± 1.3 and 57.1 ± 15 μg/ml, respectively. Subsequently, MTT method, cell morphological analysis and LDH activity-based cytotoxicity assays demonstrated that SPL was highly cytotoxic to CNE-1 cells and induced apoptosis in a dose-dependent manner. Moreover, due to the caspase inhibitors analyses, caspase was also found to play an important role in the potential apoptotic mechanism of SPL.

Keywords: Antifungal activity; Antiviral activity; Apoptosis-inducing activity; Chitin-binding specificity; Setcreasea purpurea lectin; Thermostability.