LIMLIN, A NOVEL LEGUMINOUS PEROXIDASE WITH ANTIFUNGAL ACTIVITY FROM PHASEOLUS LIMENSIS

Abstract

Plants have been one of the hot research topics in the search for potent antifungals. The objective of this study was to isolate a novel antifungal protein from Phaseolus limensis. A protein designated Limlin, with both antifungal and antibacterial activity was isolated and characterized. The isolation procedure entailed extraction, precipitation, affinity chromatography on Affi – gel blue gel, ion chromatography on SP-Toyopearl and gel filtration on Sephadex G-75. The protein exhibited a molecular mass of 34 kDa in SDS-polyacrylamide gel electrophoresis both under reducing and non-reducing conditions. Its N-terminal sequence was determined as QNNPAGFKGDKANAMLKMGNLSFQT, showing some homology to peroxidases and peroxidase precursors from plants. It potently suppressed mycelial growth of Fusarium solani, Mycosphaerella arachidicola and Pythium aphanidermatum. Moreover, this novel protein showed antiproliferative activity towards human liver hepatoma cells Bel-7402 and neuroblastoma cells SHSY5Y. This investigation first demonstrates an antifungal peroxidase with antiproliferative activity in large lima legume. PRACTICAL APPLICATIONS Plants are an important and indispensable part of life. Plants have evolved a variety of potent defense mechanisms because they are exposed to a large number of pathogenic organisms. They synthesize proteins and peptides that have antifungal activity. As their names imply, antifungal proteins and peptides serve a protective function against fungal invasion and play an important role in the defense of crops against fungal attack, thus diminishing serious economic losses. In this study, it is the first that demonstrates an antifungal peroxidase in large lima beans. The newly purified antifungal protein Limlin manifests antifungal, antibacterial activity and antiproliferative activity toward tumor cells. The aforementioned activities shown by peroxidase, provide further evidence for the potential significance in both medicine and agriculture.