Abstract
Fungal immunoregulatory proteins (FIP) are effective small molecule proteins with broad-spectrum immunomodulatory and anti-cancer activities and can be potential agents for the development of clinical drugs and health food additives. In this study, a new member of FIP named FIP-bbo was obtained through Botryobasidium botryosum genome mining. FIP-bbo has the typical characteristics of FIP but is genetically distant from other FIPs. Recombinant FIP-bbo (rFIP-bbo) was produced in an optimized E. coli expression system, and the pure protein was isolated using a Ni-NTA column. Antineoplastic experiments suggested that FIP-bbo is similar to LZ-8 in inhibiting various cancer cells (Hela, Spac-1, and A549) at lower concentrations, but it is not as potent as LZ-8. The molecular mechanism by which FIP-bbo, FIP-fve, and LZ-8 are cytotoxic to cancer cells has been discussed based on molecular dynamics simulation. Point mutations that may improve the thermal stability of FIP-fve and FIP-bbo were predicted. These results not only present a new candidate protein for the development of anticancer adjuvants, but also provide an approach for designing FIPs with high anticancer activity.