Amycolatopsis mediterranei is used for industry-scale production of rifamycin, which plays a vital role in antimyco- bacterial therapy. As the first sequenced genome of the genus Amycolatopsis, the chromosome of strai...Amycolatopsis mediterranei is used for industry-scale production of rifamycin, which plays a vital role in antimyco- bacterial therapy. As the first sequenced genome of the genus Amycolatopsis, the chromosome of strain U32 comprising 10 236 715 base pairs, is one of the largest prokaryotic genomes ever sequenced so far. Unlike the linear topology found in streptomycetes, this chromosome is circular, particularly similar to that of Saccharopolyspora erythraea and Nocardia farcinica, representing their close relationship in phylogeny and taxonomy. Although the predicted 9 228 protein-coding genes in the A. mediterranei genome shared the greatest number of orthologs with those of S. erythraea, it was unexpectedly followed by Streptomyces coelicolor rather than N. farcinica, indicating the distinct metabolic characteristics evolved via adaptation to diverse ecological niches. Besides a core region analogous to that common in streptomycetes, a novel ＇quasicore＇ with typical core characteristics is defined within the non-core region, where 21 out of the total 26 gene clusters for secondary metabolite production are located. The rifamycin biosynthesis gene cluster located in the core encodes a cytochrome P450 enzyme essential for the conversion of rifamycin SV to B, revealed by comparing to the highly homologous cluster of the rifamycin B-producing strain S699 and further confirmed by genetic complementation. The genomic information of A. mediterranei demonstrates a metabolic network orchestrated not only for extensive utilization of various carbon sources and inorganic nitrogen compounds but also for effective funneling of metabolic intermediates into the secondary antibiotic synthesis process under the control of a seemingly complex regulatory mechanism.展开更多
In this paper we outline the science,engineering,and societal considerations of the prototype Earthquake Early Warning System( EEWS) in California and detail the development and testing of methodologies in the last 10...In this paper we outline the science,engineering,and societal considerations of the prototype Earthquake Early Warning System( EEWS) in California and detail the development and testing of methodologies in the last 10 years in America. Also,we give a brief introduction of Earthquake Early Warning( EEW) in China,and based on the summary of EEW in California we make an analysis of the perspectives,misconceptions,and challenges that China may have.展开更多
基金This paper is dedicated to the late Professor JS Chiao, who initiated the research in China for rifamycin production employing A. mediterranei more than 30 years ago and who continued the endeavor to resolve the mechanism of the ＇nitrate stimulating effect＇ up to the last breath of his life. This work was supported by the National Natural Science Foundation of China （30830002）, the National High Technology Research and Development Program of China （2007AA021301, 2007AA021503）, and the Research Unit Fund of Li Ka Shing Institute of Health Sciences （7103506）.
文摘Amycolatopsis mediterranei is used for industry-scale production of rifamycin, which plays a vital role in antimyco- bacterial therapy. As the first sequenced genome of the genus Amycolatopsis, the chromosome of strain U32 comprising 10 236 715 base pairs, is one of the largest prokaryotic genomes ever sequenced so far. Unlike the linear topology found in streptomycetes, this chromosome is circular, particularly similar to that of Saccharopolyspora erythraea and Nocardia farcinica, representing their close relationship in phylogeny and taxonomy. Although the predicted 9 228 protein-coding genes in the A. mediterranei genome shared the greatest number of orthologs with those of S. erythraea, it was unexpectedly followed by Streptomyces coelicolor rather than N. farcinica, indicating the distinct metabolic characteristics evolved via adaptation to diverse ecological niches. Besides a core region analogous to that common in streptomycetes, a novel ＇quasicore＇ with typical core characteristics is defined within the non-core region, where 21 out of the total 26 gene clusters for secondary metabolite production are located. The rifamycin biosynthesis gene cluster located in the core encodes a cytochrome P450 enzyme essential for the conversion of rifamycin SV to B, revealed by comparing to the highly homologous cluster of the rifamycin B-producing strain S699 and further confirmed by genetic complementation. The genomic information of A. mediterranei demonstrates a metabolic network orchestrated not only for extensive utilization of various carbon sources and inorganic nitrogen compounds but also for effective funneling of metabolic intermediates into the secondary antibiotic synthesis process under the control of a seemingly complex regulatory mechanism.
基金supported by the China Scholarship Council (CSC)China Earthquake Administration (CEA)+1 种基金Earthquake Administration of Hebei Provincepartially funded by the U. S. Geological Survey (USGS)
文摘In this paper we outline the science,engineering,and societal considerations of the prototype Earthquake Early Warning System( EEWS) in California and detail the development and testing of methodologies in the last 10 years in America. Also,we give a brief introduction of Earthquake Early Warning( EEW) in China,and based on the summary of EEW in California we make an analysis of the perspectives,misconceptions,and challenges that China may have.
