ORIGINAL ARTICLECloning and expression of three thaumatin-like protein genes from Polyporus umbellatus

Genes encoding thaumatin-like protein (TLPs) are frequently found in fungal genomes. However, information on TLP genes in Polyporus umbellatus is still limited. In this study, three TLP genes were cloned from P. umbellatus. The full-length coding sequence of PuTLP1, PuTLP2 and PuTLP3 were 768, 759 and 561 bp long, respectively, encoding for 256, 253 and 187 amino acids. Phylogenetic trees showed that P. umbellatus PuTLP1, PuTLP2 and PuTLP3 were clustered with sequences from Gloeophyllum trabeum, Trametes versicolor and Stereum hirsutum, respectively. The expression patterns of the three TLP genes were higher in P. umbellatus with Armillaria mellea infection than in the sclerotia without A. mellea. Furthermore, over-expression of three PuTLPs were carried out in Escherichia coli BL21 (DE3) strain, and high quality proteins were obtained using Ni-NTA resin that can be used for preparation of specific antibodies. These results suggest that PuTLP1, PuTLP2 and PuTLP3 in P. umbellatus may be involved in the defense response to A. mellea infections.

For the first time, we have cloned, expressed, and characterized three new PuTLPs from P. umbellatus. These PuTLPs genes contain N-terminal cleavable signal sequence and are rich in Cys 816 residues. Changes in TLP protein levels after A. mellea infection in P. umbellatus indicated that TLP did play a role in the defense action. The discovery of genes encoding the three TLP in P. umbellatus will shed light on further investigations of defense reactions in P. umbellatus. The purified protein with high quality will be the raw material for the production of antibodies to further define the specific function of PuTLPs.187