Effect of Ferulic Acid, a Phenolic Inducer of Fungal Laccase, on 26S Proteasome Activities In Vitro

Abstract

The 26S proteasome is an ATP-dependent protease complex (2.5 MDa) that degrades most cellular proteins in Eukaryotes, typically those modified by a polyubiquitin chain. The proteasome-mediated proteolysis regulates a variety of critical cellular processes such as transcriptional control, cell cycle, oncogenesis, apoptosis, protein quality control, and stress response. Previous studies conducted in our laboratory have shown that 26S proteasomes are involved in the regulation of ligninolytic enzymes (such as laccase) in white-rot fungi in response to nutrient starvation, cadmium exposure, and ER stress. Laccases are useful biocatalysts for a wide range of biotechnological applications. The goal of the current study was to determine the effect of ferulic acid (4-hydroxy-3-methoxycinnamic acid), a phenolic compound known to induce some ligninolytic enzymes, on proteasomes isolated from mycelia of the wood-decomposing basidiomycete Trametes versicolor. The peptidase activities of 26S proteasomes were assayed by measuring the hydrolysis of fluorogenic peptide substrates specific for each active site: Suc-LLVY-AMC, Z-GGR-AMC and Z-LLE-AMC for chymotrypsin-like, trypsin-like, and caspase-like site, respectively. Ferulic acid affected all peptidase activities of the 26S fungal proteasomes in a concentration-dependent manner. A possible inhibitory effect of ferulic acid on peptidase activities of the 26S human proteasomes was tested as well. Moreover, the ability of ferulic acid to inhibit (at concentrations known to induce laccase activity in white-rot fungi) the rate of 26S proteasome-catalyzed degradation of a model full-length protein substrate (β-casein) was demonstrated by a fluorescamine assay and by a gel-electrophoretic analysis. Our findings provide new insights into the role of ferulic acid in lignin-degrading fungi. However, the detailed molecular mechanisms involved remain to be elucidated by future studies.

Design, Synthesis, and Antifungal Activities of Hymexazol Glycosides Based on a Biomimetic Strategy

“…The biosynthesis and degradation of proteins, which participate in the most important life activities, is the most basic metabolic process in organisms. In eukaryotic cells, the 26S proteasome is mainly responsible for protein degradation, which is distributed in both the cytoplasm and nucleus . When A.…”

“…In eukaryotic cells, the 26S proteasome is mainly responsible for protein degradation, which is distributed in both the cytoplasm and nucleus. 47 When A. alternata was exposed to glycoside 15 for 24 h, the three subunit proteins of the 26S proteasome, RPT4 (26S protease regulatory subunit S10B), RPT6 (26S protease regulatory subunit 8), and TBP1 (26S protease regulatory subunit), were significantly downregulated. Additionally, glycoside 15 also perturbed the protein biosynthesis of A. alternata, which resulted in upregulation of alanine-tRNA ligase (ALA1), asparaginyl-tRNA synthetase (DED81), and 60S ribosomal protein (RPL5) and downregulation of isoleucyl-tRNA synthetase and methionine-tRNA ligase (93G11.130).…”

Lighting Conditions Influence the Dynamics of Protease Synthesis and Proteasomal Activity in the White Rot Fungus Cerrena unicolor

“…The analysis of the C. unicolor transcriptome also suggests differences in the abundance of transcripts associated with the synthesis of ubiquitin, that is, a small molecule directly cooperating with the proteasomal complex towards degradation of intracellular proteins. Selective ubiquitin/proteasome-mediated proteolysis is known to play a crucial role in the response of white rot fungi to various stresses such as nutrient limitation, heat shock, ferulic acid and heavy metal [ 8 , 25 , 35 ]. Available data indicate involvement of the ubiquitin-proteasome pathway in the regulation of ligninolytic enzyme activities in starvation conditions and stress caused by the presence of Cd 2+ ions [ 35 ].…”

“…Selective ubiquitin/proteasome-mediated proteolysis is known to play a crucial role in the response of white rot fungi to various stresses such as nutrient limitation, heat shock, ferulic acid and heavy metal [ 8 , 25 , 35 ]. Available data indicate involvement of the ubiquitin-proteasome pathway in the regulation of ligninolytic enzyme activities in starvation conditions and stress caused by the presence of Cd 2+ ions [ 35 ].…”

Cerrena unicolor Laccases, Genes Expression and Regulation of Activity

“…Fungal peroxidases and laccases have already been proven to be differentially regulated by the pH and temperature [ 19 ] or different media components [ 20 ]. Though, nutrient deficiency, copper, manganese, and aromatic compounds such as 2,5-xylidine and ferulic acid increase individual laccase gene transcripts [ 20 , 21 ]. Staszczak and Jarosz-Wilkolazka [ 22 ] proved that inhibition of proteasomal activity in Trametes versicolor may stimulate laccase synthesis by cadmium ions.…”