Actinomycetes are the main sources of antibiotics.The onset and level of production of each antibiotic is subject to complex control by multi-level regulators.These regulators exert their functions at hierarchical lev...Actinomycetes are the main sources of antibiotics.The onset and level of production of each antibiotic is subject to complex control by multi-level regulators.These regulators exert their functions at hierarchical levels.At the lower level,cluster-situated regulators(CSRs)directly control the transcription of neighboring genes within the gene cluster.Higher-level pleiotropic and global regulators exert their functions mainly through modulating the transcription of CSRs.Advances in understanding of the regulation of antibiotic biosynthesis in actinomycetes have inspired us to engineer these regulators for strain improvement and antibiotic discovery.展开更多
Polyoxin is a group of structurally-related peptidyl nucleoside antibiotics bearing C-5 modifications on the nucleoside skeleton. Although the structural diversity and bioactivity preference of polyoxin are, to some e...Polyoxin is a group of structurally-related peptidyl nucleoside antibiotics bearing C-5 modifications on the nucleoside skeleton. Although the structural diversity and bioactivity preference of polyoxin are, to some extent, affected by such modifications, the biosynthetic logic for their occurence remains obscure. Here we report the identification of PolB in polyoxin pathway as an unusual UMP C-5 methylase with thymidylate syn- thase activity which is responsible for the C-5 methyla- tion of the nucleoside skeleton. To probe its molecular mechanism, we determined the crystal structures of PolB alone and in complexes with 5-Br UMP and 5-Br dUMP at 2.15 A, 1.76 A and 2.28 A resolutions, respec- tively. Loop 1 （residues 117-131）, Loop 2 （residues 192- 201） and the substrate recognition peptide （residues 94- 102） of PolB exhibit considerable conformational flexi-bility and adopt distinct structures upon binding to different substrate analogs. Consistent with the structural findings, a PolB homolog that harbors an identical function from Streptomyces viridochromogenes DSM 40736 was identified. The discovery of UMP C5-methy-lase opens the way to rational pathway engineering for polyoxin component optimization, and will also enrich the toolbox for natural nucleotide chemistry.展开更多
基金the National Natural Science Foundation of China(31470206 and 31870061)a start-up grant from Southwest University(SWU117015)+1 种基金grants from Chongqing Science and Technology Commission(cstc2017jcyjAX0467 and cstc2018jcyjAX0066)the Fundamental Research Funds for the Central Universities(XDJK2018B029)to G.N.
文摘Actinomycetes are the main sources of antibiotics.The onset and level of production of each antibiotic is subject to complex control by multi-level regulators.These regulators exert their functions at hierarchical levels.At the lower level,cluster-situated regulators(CSRs)directly control the transcription of neighboring genes within the gene cluster.Higher-level pleiotropic and global regulators exert their functions mainly through modulating the transcription of CSRs.Advances in understanding of the regulation of antibiotic biosynthesis in actinomycetes have inspired us to engineer these regulators for strain improvement and antibiotic discovery.
文摘Polyoxin is a group of structurally-related peptidyl nucleoside antibiotics bearing C-5 modifications on the nucleoside skeleton. Although the structural diversity and bioactivity preference of polyoxin are, to some extent, affected by such modifications, the biosynthetic logic for their occurence remains obscure. Here we report the identification of PolB in polyoxin pathway as an unusual UMP C-5 methylase with thymidylate syn- thase activity which is responsible for the C-5 methyla- tion of the nucleoside skeleton. To probe its molecular mechanism, we determined the crystal structures of PolB alone and in complexes with 5-Br UMP and 5-Br dUMP at 2.15 A, 1.76 A and 2.28 A resolutions, respec- tively. Loop 1 （residues 117-131）, Loop 2 （residues 192- 201） and the substrate recognition peptide （residues 94- 102） of PolB exhibit considerable conformational flexi-bility and adopt distinct structures upon binding to different substrate analogs. Consistent with the structural findings, a PolB homolog that harbors an identical function from Streptomyces viridochromogenes DSM 40736 was identified. The discovery of UMP C5-methy-lase opens the way to rational pathway engineering for polyoxin component optimization, and will also enrich the toolbox for natural nucleotide chemistry.
