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Identification and functional characterization of a novel fungal immunomodulatory protein from Postia placenta

Author:
Li, Shu Ying, Shi, Li Jun, Ding, Yang, Nie, Ying, Tang, Xuan Ming
Source:
Food and chemical toxicology 2015 v.78 pp. 64-70
ISSN:
0278-6915
Subject:
Escherichia coli, Rhodonia placenta, apoptosis, baits, cell proliferation, databases, erythrocytes, fungi, genes, glutathione transferase, hemagglutination, hepatoma, humans, interleukin-2, mice, neoplasm cells, nucleotide sequences, rabbits, recombinant proteins, splenocytes, thrombin, toxicology
Abstract:
In this study, a previously unknown fungal immunomodulatory protein (FIP), here called FIP-ppl, was identified from the basidiomycete fungus Postia placenta by searching its genome sequence database using known FIPs as baits, which was the first basidiomycete FIP to be identified outside the order of edible macro fungi. The gene FIP-ppl was synthesized and expressed in Escherichia coli to produce a glutathione S-transferase (GST) fusion protein. The fusion protein was purified on a GST affinity column and the protein tag was removed using in situ thrombin cleavage. The purified recombinant protein (rFIP-ppl) displayed hemagglutination activity toward rabbit red blood cells but not against human red blood cells. RFIP-ppl stimulated mouse splenocyte cell proliferation and enhanced interleukin-2 (IL-2) release. Antitumor assays indicated that rFIP-ppl had significant cell proliferation inhibitory activity and apoptotic effects in human tumor cells with more pronounced inhibiting proliferation and inducing apoptotic effects on gastric tumor cells (MGC823) than against hepatoma (HepG2) cells. This study confirms an alternative means of identifying, producing, and isolating new FIPs. It may provide convenient access to FIP-ppl with potential human therapeutic applications.
Agid:
5419606