RESUMO
Recent transcriptomic and biochemical studies have revealed that light influences the global gene expression profile and metabolism of the white-rot fungus Cerrena unicolor. Here, we aimed to reveal the involvement of proteases and ubiquitin-mediated proteolysis by the 26S proteasome in the response of this fungus to white, red, blue and green lighting conditions and darkness. The changes in the expression profile of C. unicolor genes putatively engaged in proteolysis were found to be unique and specific to the applied wavelength of light. It was also demonstrated that the activity of proteases in the culture fluid and mycelium measured using natural and synthetic substrates was regulated by light and was substrate-dependent. A clear influence of light on protein turnover and the qualitative and quantitative changes in the hydrolytic degradation of proteins catalyzed by various types of proteases was shown. The analysis of activity associated with the 26S proteasome showed a key role of ATP-dependent proteolysis in the initial stages of adaptation of fungal cells to the stress factors. It was suggested that the light-sensing pathways in C. unicolor are cross-linked with stress signaling and secretion of proteases presumably serving as regulatory molecules.
Assuntos
Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica/efeitos da radiação , Peptídeo Hidrolases/genética , Polyporales/efeitos da radiação , Madeira/microbiologia , Criptocromos/genética , Criptocromos/metabolismo , Proteínas Fúngicas/classificação , Proteínas Fúngicas/metabolismo , Perfilação da Expressão Gênica , Ontologia Genética , Luz , Transdução de Sinal Luminoso , Anotação de Sequência Molecular , Opsinas/genética , Opsinas/metabolismo , Peptídeo Hidrolases/classificação , Peptídeo Hidrolases/metabolismo , Fitocromo/genética , Fitocromo/metabolismo , Doenças das Plantas/microbiologia , Polyporales/genética , Polyporales/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Complexo de Endopeptidases do Proteassoma/efeitos da radiação , Proteólise/efeitos da radiaçãoRESUMO
The laccase from Steccherinum murashkinskyi is a member of the large family of multicopper oxidases that catalyze the oxidation of a wide range of organic and inorganic substrates, accompanied by the reduction of dioxygen to water. The reducing properties of X-ray radiation and the high quality of the laccase crystals allow the study of the catalytic reduction of dioxygen to water directly in a crystal. A series of diffraction data sets with increasing absorbed radiation dose were collected from a single crystal of Steccherinum murashkinskyi laccase at 1.35â Å resolution. Changes in the active-site structure associated with the reduction of molecular oxygen to water on increasing the absorbed dose of ionizing radiation were detected. The structures in the series are mixtures of different states of the enzyme-substrate complex. Nevertheless, it was possible to interpret these structures as complexes of various oxygen ligands with copper ions in different oxidation states. The results allowed the mechanism of oxygen reduction catalyzed by laccases to be refined.
