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Title: Purification, identification and functional characterization of a novel immunomodulatory protein from Pleurotus eryngii

Author
item HU, QIUHUI - Nanjing University Of Finance And Economics
item DU, HENGJUN - Nanjing University Of Finance And Economics
item Nakata, Paul
item PEI, FEI - Nanjing University Of Finance And Economics
item MA, NING - Nanjing University Of Finance And Economics
item ZHAO, LIYAN - Nanjing University Of Finance And Economics
item YANG, WENJIAN - Nanjing University Of Finance And Economics

Submitted to: Food and Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2018
Publication Date: 6/13/2018
Publication URL: http://handle.nal.usda.gov/10113/6182492
Citation: Hu, Q., Du, H., Nakata, P.A., Pei, F., Ma, N., Zhao, L., Yang, W. 2018. Purification, identification and functional characterization of a novel immunomodulatory protein from Pleurotus eryngii. Food and Function. https://doi.org/10.1039/c8fo00604k.
DOI: https://doi.org/10.1039/c8fo00604k

Interpretive Summary: The giant oyster mushroom (Pleurotus eryngii) has been shown to contain bioactive compounds that have been used for hundreds of years for its health promoting properties. The exact identity of these health promoting substances and an understanding of how these substances confer health-promoting benefits remain largely unknown. As a step toward identifying these substances and determining how they confer their healthful benefits we report here the discovery, purification, and functional characterization of a P. eryngii protein (PEP) 1b. By coupling protein fractionation and a biological assay for nitric oxide production we screen mushroom fruiting body protein extracts for bioactivity. This led to the identification and purification of a protein we named PEP 1b. In addition, utilizing biochemical and biological methodologies we discovered that the immune boosting response to PEP 1b exposure occurred through the TLR4-NF-kB and MAPK signaling pathways. It is our hope that the discovery of such new bioactive proteins, coupled with knowledge into their mechanism(s) of function, will lead to the development of new functional foods and/or pharmaceutical products that find use in the promotion of optimal human health and well-being.

Technical Abstract: Pleurotus eryngii contains bioactive compounds that can activate the immune system. The identity of many of these compounds and an understanding of how they confer these health-promoting benefits has been elusive. Here we report the identification, purification, and functional characterization of the bioactive P. eryngii protein (PEP) 1b. PEP 1b was discovered to be a 21.9 kDa protein with the ability to induce M1-polarization of macrophages. Biochemical measurements showed that PEP 1b stimulated nitric oxide (NO), IL-1beta, IL-6 and TNF-alpha production and regulated inducible NO synthase(iNOS). Phosphorylation and inhibitor studies revealed that PEP 1b promoted the translocation of NF-kB from the cytosol to the nucleus allowing the induction of target gene expression and NO production. Phosphorylation of JNK and ERK1/2 was also found necessary for maximal NO production. Each phosphorylation pathway was found to require a functional Toll-like receptor (TLR) 4 as a prerequisite for PEP1b-induced NO production. This study suggests that PEP 1b is an immunomodulatory protein that can boost cellular immune responses through activation of the TLR4-NF-kB and MAPK signaling pathways. These new insights may prove useful in efforts to design nutritional strategies that promote optimal health and well-being.