Chaetomium globosum is one of the most common fungi in nature. It is best known for producing chaetoglobosins; however, the molecular basis of chaetoglobosin biosynthesis is poorly understood in this fungus. In this s...Chaetomium globosum is one of the most common fungi in nature. It is best known for producing chaetoglobosins; however, the molecular basis of chaetoglobosin biosynthesis is poorly understood in this fungus. In this study, we utilized RNA inter- ference （RNAi） to characterize a polyketide synthase gene, pks-1, in C. globosum that is involved in the production of chaeto- globosin A. When pks-1 was knocked down by RNAi, the production of chaetoglobosin A dramatically decreased. Knock-down mutants also displayed a pigment-deficient phenotype. These results suggest that the two polyketides, melanin and chaetoglobosin, are likely to share common biosynthetic steps. Most importantly, we found that pks-I also plays a critical role in sporulation. The silenced mutants ofpks-1 lost the ability to produce spores. We propose that polyketides may modulate cellular development via an unidentified action. We also suggest that C. globosum pks-1 is unique because of its triple role in melanin formation, chaetoglobosin biosynthesis and sporulation. This work may shed light on chaetoglobosin biosynthesis and indicates a relationship between secondary metabolism and fungal morphogenesis.展开更多
Cytochalasans,with diverse structures and pharmacological activities,are a class of compounds containing isoindolinone moieties fused to the tricyclic or tetracyclic ring system.Chaetoglobosin A(cheA),mainly produced ...Cytochalasans,with diverse structures and pharmacological activities,are a class of compounds containing isoindolinone moieties fused to the tricyclic or tetracyclic ring system.Chaetoglobosin A(cheA),mainly produced by Chaetomium globosum,is the most abundant cytochalasan.However,limited understanding of transcriptional regulation of morphological development and cheA biosynthesis in C.globosum has hindered cheA application in agriculture and biomedical field.This study examined the regulatory role of CgVeA gene in C.globosum.CgVeA had significant effect on secondary metabolites production in C.globosum,similar to that reported in other filamentous fungi.Inactivation of CgVeA caused an obvious decrease in cheA production from 51.32 to 19.76 mg/L under dark conditions.In contrast,CgVeA overexpression resulted in a dramatic increase in cheA production,reaching 206.59 mg/L under light conditions,which was higher than that noted under dark condition.The RT-qPCR results confirmed that CgVeA,as a light responsive regulator,positively regulated cheA biosynthesis by controlling the expression of core genes of the cheA biosynthetic gene cluster and other relevant regulators.Electrophoretic mobility shift assays proved that CgVeA directly regulated LaeA,cheR,and p450,and indirectly regulated PKS.Moreover,CgVeA had a significant effect on the regulation of asexual spores production.When compared with wild-type C.globosum,CgVeA-silenced and CgVeA overexpression mutants presented remarkable differences in sporulation,irrespective of light or dark condition.Besides,CgVeA expression was speculated to negatively regulate spore formation.These findings illustrated the regulatory mechanism of a hypothetical global regulator,CgVeA,in C.globosum,suggesting its potential application in industrial-scale cheA biosynthesis.展开更多
基金the National Natural Science Foundation of China (Grant No. 30970084)the National Basic Research Program of China (Grant No. 2007CB707801)
文摘Chaetomium globosum is one of the most common fungi in nature. It is best known for producing chaetoglobosins; however, the molecular basis of chaetoglobosin biosynthesis is poorly understood in this fungus. In this study, we utilized RNA inter- ference （RNAi） to characterize a polyketide synthase gene, pks-1, in C. globosum that is involved in the production of chaeto- globosin A. When pks-1 was knocked down by RNAi, the production of chaetoglobosin A dramatically decreased. Knock-down mutants also displayed a pigment-deficient phenotype. These results suggest that the two polyketides, melanin and chaetoglobosin, are likely to share common biosynthetic steps. Most importantly, we found that pks-I also plays a critical role in sporulation. The silenced mutants ofpks-1 lost the ability to produce spores. We propose that polyketides may modulate cellular development via an unidentified action. We also suggest that C. globosum pks-1 is unique because of its triple role in melanin formation, chaetoglobosin biosynthesis and sporulation. This work may shed light on chaetoglobosin biosynthesis and indicates a relationship between secondary metabolism and fungal morphogenesis.
基金This work was supported in part by grant from the Harbin Science and Technology Project(No.2016AB3AP042).
文摘Cytochalasans,with diverse structures and pharmacological activities,are a class of compounds containing isoindolinone moieties fused to the tricyclic or tetracyclic ring system.Chaetoglobosin A(cheA),mainly produced by Chaetomium globosum,is the most abundant cytochalasan.However,limited understanding of transcriptional regulation of morphological development and cheA biosynthesis in C.globosum has hindered cheA application in agriculture and biomedical field.This study examined the regulatory role of CgVeA gene in C.globosum.CgVeA had significant effect on secondary metabolites production in C.globosum,similar to that reported in other filamentous fungi.Inactivation of CgVeA caused an obvious decrease in cheA production from 51.32 to 19.76 mg/L under dark conditions.In contrast,CgVeA overexpression resulted in a dramatic increase in cheA production,reaching 206.59 mg/L under light conditions,which was higher than that noted under dark condition.The RT-qPCR results confirmed that CgVeA,as a light responsive regulator,positively regulated cheA biosynthesis by controlling the expression of core genes of the cheA biosynthetic gene cluster and other relevant regulators.Electrophoretic mobility shift assays proved that CgVeA directly regulated LaeA,cheR,and p450,and indirectly regulated PKS.Moreover,CgVeA had a significant effect on the regulation of asexual spores production.When compared with wild-type C.globosum,CgVeA-silenced and CgVeA overexpression mutants presented remarkable differences in sporulation,irrespective of light or dark condition.Besides,CgVeA expression was speculated to negatively regulate spore formation.These findings illustrated the regulatory mechanism of a hypothetical global regulator,CgVeA,in C.globosum,suggesting its potential application in industrial-scale cheA biosynthesis.
