Filamentous fungi frequently degenerate during subculturing,which manifests as the reduction or loss of coni-diation,sexuality,secondary metabolite production,and/or virulence against hosts.The underlying mechanism of...Filamentous fungi frequently degenerate during subculturing,which manifests as the reduction or loss of coni-diation,sexuality,secondary metabolite production,and/or virulence against hosts.The underlying mechanism of spontaneous fungal degeneration is still elusive.In this study,the fluffy mycelium-type sector variants formed by three ascomycete fungi were transferred and found to show the typical features of culture degeneration.The variant cells were evidenced with the accumulation of reactive oxygen species(ROS),and the ROS-associated formation of hyphal coils.Genome resequencing of these sector cultures identified substantial random mutation sites in each variant in a trend associated with fungal reproduction style.The high bias towards transversions over transitions was similarly detected in degenerate genomes.Otherwise,a higher number of mutations were accumulated in the intergenic regions of the Metarhizium robertsii and Cordyceps militaris sector genomes,whereas the exonic regions of the Aspergillus nidulans variant genes were detected with a higher mutation rate.Unexpect-edly,none of those mutated genes had orthologous relationships among the three sectors,while only a few of them were shared between two fungi.A few transcription factor genes with frameshift mutations in sectors were selected for deletions in parental strains,and the null mutants demonstrated the varied degrees of degenerate phenotypes.In addition to reasoning the causal mechanism of fungal degeneration,our data provide insights to better maintain and monitor fungal culture stability.展开更多
The cis-acting regulatory elements, e.g., promoters and ribosome binding sites （RBSs） with various desired properties, are building blocks widely used in synthetic biology for fine tuning gene expression. In the las...The cis-acting regulatory elements, e.g., promoters and ribosome binding sites （RBSs） with various desired properties, are building blocks widely used in synthetic biology for fine tuning gene expression. In the last decade, acquisition of a controllable regulatory element from a random library has been established and applied to control the protein expression and metabolic flux in different chassis cells. However, more rational strategies are still urgently needed to improve the efficiency and reduce the laborious screening and multifaceted characterizations. Building precise computational models that can predict the activity of regulatory elements and quantitatively design elements with desired strength have been demonstrated tremendous potentiality. Here, recent progress on construction of cis- acting regulatory element library and the quantitative predicting models for design of such elements are reviewed and discussed in detail.展开更多
The MutS protein plays an important role in the DNA mismatch repair system. Mutations in the mutS gene can lead to genome instability and ultimately cell malfunction. Here we have established a method for identifying ...The MutS protein plays an important role in the DNA mismatch repair system. Mutations in the mutS gene can lead to genome instability and ultimately cell malfunction. Here we have established a method for identifying functional defective mutants of MutS by random mutation and rifampicin screening. Some novel functional sites in MutS were identified. The MutS mutant strains were analyzed using surface plasmon resonance, gel filtration and far-western methods to determine the molecular mechanisms behind the DNA mismatch repair function of MutS.展开更多
基金This work was supported by the National Key R&D Program of China(2018YFA0900502)the National Natural Science Foundation of China(32021001 and 32230087).
文摘Filamentous fungi frequently degenerate during subculturing,which manifests as the reduction or loss of coni-diation,sexuality,secondary metabolite production,and/or virulence against hosts.The underlying mechanism of spontaneous fungal degeneration is still elusive.In this study,the fluffy mycelium-type sector variants formed by three ascomycete fungi were transferred and found to show the typical features of culture degeneration.The variant cells were evidenced with the accumulation of reactive oxygen species(ROS),and the ROS-associated formation of hyphal coils.Genome resequencing of these sector cultures identified substantial random mutation sites in each variant in a trend associated with fungal reproduction style.The high bias towards transversions over transitions was similarly detected in degenerate genomes.Otherwise,a higher number of mutations were accumulated in the intergenic regions of the Metarhizium robertsii and Cordyceps militaris sector genomes,whereas the exonic regions of the Aspergillus nidulans variant genes were detected with a higher mutation rate.Unexpect-edly,none of those mutated genes had orthologous relationships among the three sectors,while only a few of them were shared between two fungi.A few transcription factor genes with frameshift mutations in sectors were selected for deletions in parental strains,and the null mutants demonstrated the varied degrees of degenerate phenotypes.In addition to reasoning the causal mechanism of fungal degeneration,our data provide insights to better maintain and monitor fungal culture stability.
基金This work was supported by the National Basic Research Program of China （973 Program, grant No. 2012CB721104）, the National High Technology Research and Development Program （863 Program, grant No. 2012AA02A701）, the National Natural Science Foundation of China （grant Nos. 31170101 and 31301017）, and the Natural Science Foundation of Guangdong Province, China （grant No. 2015A030310317）.
文摘The cis-acting regulatory elements, e.g., promoters and ribosome binding sites （RBSs） with various desired properties, are building blocks widely used in synthetic biology for fine tuning gene expression. In the last decade, acquisition of a controllable regulatory element from a random library has been established and applied to control the protein expression and metabolic flux in different chassis cells. However, more rational strategies are still urgently needed to improve the efficiency and reduce the laborious screening and multifaceted characterizations. Building precise computational models that can predict the activity of regulatory elements and quantitatively design elements with desired strength have been demonstrated tremendous potentiality. Here, recent progress on construction of cis- acting regulatory element library and the quantitative predicting models for design of such elements are reviewed and discussed in detail.
基金supported by the National Natural Science Foundation of China (Grant No. 30670443)the Chinese Academy of Sciences (Grant Nos. KSCX1-YW-R-63, KSCX2-YW-G-017 and KZCX2-YW-420)
文摘The MutS protein plays an important role in the DNA mismatch repair system. Mutations in the mutS gene can lead to genome instability and ultimately cell malfunction. Here we have established a method for identifying functional defective mutants of MutS by random mutation and rifampicin screening. Some novel functional sites in MutS were identified. The MutS mutant strains were analyzed using surface plasmon resonance, gel filtration and far-western methods to determine the molecular mechanisms behind the DNA mismatch repair function of MutS.
