Identification of Mga1, a G-protein alpha-subunit gene involved in regulating citrinin and pigment production in Monascus ruber M7.

The filamentous fungi Monascus spp., which have been used in traditional fermented food in Asia for centuries, are well-known producers of a group of bioactive metabolites that are widely used as food additives and nutraceutical supplements worldwide. However, its potential to produce the mycotoxin citrinin poses a threat to food safety. Here, a G-protein alpha-subunit-encoding gene, Mga1 (Monascus G-protein alpha-subunit 1), which encodes a protein showing a high degree of identity to Group I alpha-subunits of fungal heterotrimeric G-proteins, was cloned from Monascus ruber M7. An Mga1-disrupted strain was obtained by homologous recombination. The disruptant produced approximately nine times more citrinin and 71% more pigments than the wild-type strain M7, indicating that the G-protein alpha-subunit encoded by Mga1 is involved in a signal transduction pathway regulating citrinin and pigment biosynthesis in M. ruber M7.