Proteome analysis reveals global response to deletion of mrflbA in Monascus ruber

Abstract

Monascus spp. are commonly used for a wide variety of applications in the food and pharmaceutical industries. In previous studies, the knock-out of mrflbA (a putative regulator of the G protein α subunit) in M. ruber led to autolysis of the mycelia, decreased pigmentation and lowered mycotoxin production. Therefore, we aimed to obtain a comprehensive overview of the underlying mechanism of mrflbA deletion at the proteome level. A two-dimensional gel electrophoresis analysis of mycelial proteins indicated that the abundance of 178 proteins was altered in the ΔmrflbA strain, 33 of which were identified with high confidence. The identified proteins are involved in a range of activities, including carbohydrate and amino acid metabolism, hyphal development and the oxidative stress response, protein modification, and the regulation of cell signaling. Consistent with these findings, the activity of antioxidative enzymes and chitinase was elevated in the supernatant of the ΔmrflbA strain. Furthermore, deletion of mrflbA resulted in the transcriptional reduction of secondary metabolites (pigment and mycotoxin). In short, the mutant phenotypes induced by the deletion of mrflbA were consistent with changes in the expression levels of associated proteins, providing direct evidence of the regulatory functions mediated by mrflbA in M. ruber.

Histone deacetylase MrHos3 negatively regulates the production of citrinin and pigments in Monascus ruber

“…Two hundred microliters of conidial suspension (10 5 conidia mL −1 ) for each strain were inoculated into 100 mL of PDB at 28°C with shaking for 7 days, and the mycelia were collected and ground in liquid nitrogen to extract total protein and histone following the previous description [33,34]. The extracted proteins were separated in 5% stacking-15% separating gels by SDS-PAGE according to the established protocols [35] with minor modifications.…”

Quantitative Proteomics Analysis by Sequential Window Acquisition of All Theoretical Mass Spectra–Mass Spectrometry Reveals Inhibition Mechanism of Pigments and Citrinin Production of Monascus Response to High Ammonium Chloride Concentration

“…However, compared to other filamentous fungi such as Aspergillus and Penicillium , besides a few 2-DE, studies have been performed on Monascus , and the quantitative and qualitative proteomic studies of Monascus are very few . − More importantly, accurate quantification and large-scale identification of differentially expressed proteins cannot be provided by 2-DE and iTRAQ proteomics approach. Now, SWATH-MS (sequential window acquisition of all theoretical mass spectra–mass spectrometry) can acquire data by repeatedly cycling through sequential mass windows over the whole chromatographic elution range generating a complete recording of all analyses in the sample and collect data on the low-intensity proteins that are commonly missed in data-dependent acquisition (DDA) methods .…”