Isolation and characterization of a 30 kDa protein with antifungal activity from leaves of Engelmannia pinnatifida

Abstract

During the course of screening plants for novel antifungal activity, we found that a high-molecular-mass fraction of an extract from leaves of Engelmannia pinnatifida exhibited potent and broad-spectrum antifungal activity. In this study a 30 kDa protein from E. pinnatifida leaves was purified to homogeneity by ammonium sulphate precipitation, gel filtration, Mono-Q and C18 reverse-phase column chromatographies. The purified protein showed potent antifungal activity against various plant pathogens with as little as 50 ng. The N-terminal amino acid sequence of the purified protein was determined as XXTKFDFFTLALQXPAXF, where X indicates an unidentified residue. This sequence showed 35-50% sequence identity with purified style glycoproteins associated with self-incompatibility from wild tomato, tobacco and petunia, a phosphate-starvation-induced ribonuclease from cultured tomato cells and the SIR 63.4 kDa protein from yeast.

Isolation and characterization of a 29-kDa glycoprotein with antifungal activity from bulbs of Urginea indica

“…Results from the computer search for similarity with other protein sequences showed that the above sequence had no significant similarity with any of the antifungal proteins published so far [34]. Thus, the purified 29 kDa antifungal glycoprotein might be a representative of a novel class of antifungal proteins.…”

Antifungal Proteins

“…Snakin-1 isolated from potato has a molecular mass of 6.9 kDa and is active at 10 M (156). A 30-kDa protein with very potent antifungal activity (50 ng/disk in an agar diffusion assay) was isolated from Engelmann's daisy (Engelmannia pinnatifida); this protein showed 35 to 50% identity to self-incompatibility glycoproteins, not previously known to be antifungal (64). The mechanism of action of none of these proteins is known.…”

Four Chitinase cDNAs from Chenopodium amaranticolor.

“…A few clones that hybridized to the probes were obtained and the cDNA inserts were sequenced on both strands by automated dideoxy methods. One of these clones, CAP9, encoded a 29 kDa polypeptide, and it was characterized to a class IV chitinase from the identity, 56.7% to bean PR 4 chitinase [9], 55.0% to rapeseed ChB4 chitinase [3], and 62.1% to maize seed chitinase A [10]. Using a labeled CAP9 insert, we isolated three additive cDNA clones (CAM18, CAM19 and CAM24).…”