Antibiotic resistance in gram-negative pathogens has become one of the most serious global public health threats.The role of the N-acyl homoserine lactone(AHL)-mediated signaling pathway,which is widespread in gram-ne...Antibiotic resistance in gram-negative pathogens has become one of the most serious global public health threats.The role of the N-acyl homoserine lactone(AHL)-mediated signaling pathway,which is widespread in gram-negative bacteria,in the bacterial resistance process should be studied in depth.Here,we report a degrading enzyme of AHLs,MomL,that inhibits the antibiotic resistance of Pseudomonas aeruginosa through a novel mechanism.The MomL-mediated reactivation of kanamycin is highly associated with the relA-mediated starvation stringent response.The degradation of AHLs by MomL results in the inability of LasR to activate relA,which,in turn,stops the activation of downstream rpoS.Further results show that rpoS directly regulates the type VI secretion system H2-T6SS.Under MomL treatment,inactivated RpoS fails to regulate H2-T6SS;therefore,the expression of effector phospholipase A is reduced,and the adaptability of bacteria to antibiotics is weakened.MomL in combination with kanamycin is effective against a wide range of gram-negative pathogenic bacteria.Therefore,this study reports a MomL-antibiotic treatment strategy on antibiotic-resistant bacteria and reveals its mechanism of action.展开更多
Nitrogen is an essential macronutrient for all living organisms and is critical for crop productivity and quality.In higher plants,inorganic nitrogen is absorbed through roots and then assimilated into amino acids by ...Nitrogen is an essential macronutrient for all living organisms and is critical for crop productivity and quality.In higher plants,inorganic nitrogen is absorbed through roots and then assimilated into amino acids by the highly conserved glutamine synthetase/glutamine:2-oxoglutarate aminotransferase(GS/GOGAT)cycle.How nitrogen metabolism and nitrogen starvation responses of plants are regulated remains largely unknown.Previous studies revealed that mutations in the rice ABNORMAL CYTOKININ RESPONSE1(ABC1)gene encoding Fd-GOGAT cause a typical nitrogen deficiency syndrome.Here,we show that ARE2(for ABC1 REPRESSOR2)is a key regulator of nitrogen starvation responses in rice.The are2 mutations partially rescue the nitrogen-deficient phenotype of abc1 and the are2 mutants show enhanced tolerance to nitrogen deficiency,suggesting that ARE2 genetically interacts with ABC1/Fd-GOGAT.ARE2 encodes a chloroplast-localized Rel A/Spo T homolog protein that catalyzes the hydrolysis of guanosine pentaphosphate or tetraphosphate(p)pp Gpp,an alarmone regulating the stringent response in bacteria under nutritional stress conditions.The are2 mutants accumulate excessive amounts of(p)pp Gpp,which correlate with lower levels of photosynthetic proteins and higher amino acid levels.Collectively,these observations suggest that the alarmone(p)pp Gpp mediates nitrogen stress responses and may constitute a highly conserved mechanism from bacteria to plants.展开更多
Lactic acid bacteria(LAB)are integral to fermented foods,the human gut,and environmental microbiomes;however,the functional potential of their resident prophages remains largely uncharacterized.Here,we con-ducted a la...Lactic acid bacteria(LAB)are integral to fermented foods,the human gut,and environmental microbiomes;however,the functional potential of their resident prophages remains largely uncharacterized.Here,we con-ducted a large-scale genome-wide analysis,encompassing 7178 high-quality LAB genomes,and uncovered a vast and previously uncharacterized reservoir of intact and near-intact phage elements across LAB.Clustering of highconfidence phage contigs based on average nucleotide identity(ANI)delineated 1375 viral operational taxo-nomic units(vOTUs)within the viral realm Duplodnaviria,spanning classical Siphovirus-like phages as well as numerous uncharacterized lineages within the class Caudoviricetes.Gene-sharing networks revealed significant divergence in gene composition at the amino acid level,indicating functional diversification and adaptation to distinct LAB hosts.Phylogenetic analyses have highlighted multiple novel clades that are often phylogenetically distant from known phages,indicating a deep evolutionary divergence.Additionally,prophage-encoded auxil-iary metabolic genes(AMGs)were identified that potentially enhance host metabolism and stress resilience,including genes involved in sulfur assimilation(cysH),carbohydrate utilization(dexA and pelB),and stringent-response modulation(mazG).Collectively,our findings redefine the diversity and functional capacity of LAB phages,illuminate their dynamic co-evolution with host genomes,and provide a valuable genomic resource for future studies.This work also highlighted the potential of LAB phages to diversify host genomes and influence metabolic capacity with potential implications for microbial ecology,industrial fermentation,and other biotechnological innovations.展开更多
Streptomyces are the well-known producers of biologically active pharmaceuticals and agricultural antibiotics.However,the production of the secondary metabolites was limited due to the unbalance of the cell growth and...Streptomyces are the well-known producers of biologically active pharmaceuticals and agricultural antibiotics.However,the production of the secondary metabolites was limited due to the unbalance of the cell growth and the activation of secondary metabolic pathway.Here,in order to improve the production of toyocamycin,a nucleoside antibiotic produced by Streptomyces diastatochromogenes 1628,with excellent antimicrobial characteristics to plant pathogens,we develop an endogenous non-inducer-dependent dynamic regulatory strategy based on the quorum sensing(QS)promoter to fine-tune the expression of an important signal molecule(ppGpp).Firstly,two QS promoter PstbA1 and PstbA2 were identified by the bioinformatic analysis.Then,the temporal profiles of PstbA1 and PstbA2 were characterized by the GusA activity.Afterwards,the ppGpp synthase was expressed under the PstbA1 and PstbA2 to improve the ppGpp concentration in vivo.The toyocamycin production reached 768.62 mg/L and 721.06 mg/L under the QS promoter PstbA1 and PstbA2,respectively,which represented increases of 508.81%and 471.14%over the wild-type at the tenth day.The autoregulated QS-based strategy is an effective method by balancing bacterial growth and metabolite synthesis in industrial processes.展开更多
基金the National Natural Science Foundation of China(Nos.42176108 and 31870023)the Young Taishan Scholars Program of Shandong Province(No.tsqn202103029)+2 种基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018SDKJ0406-4)the Fundamental Research Funds for the Central Universities(No.201941009)the open research funds of the State Key Laboratory of Ophthalmology(No.303060202400368).
文摘Antibiotic resistance in gram-negative pathogens has become one of the most serious global public health threats.The role of the N-acyl homoserine lactone(AHL)-mediated signaling pathway,which is widespread in gram-negative bacteria,in the bacterial resistance process should be studied in depth.Here,we report a degrading enzyme of AHLs,MomL,that inhibits the antibiotic resistance of Pseudomonas aeruginosa through a novel mechanism.The MomL-mediated reactivation of kanamycin is highly associated with the relA-mediated starvation stringent response.The degradation of AHLs by MomL results in the inability of LasR to activate relA,which,in turn,stops the activation of downstream rpoS.Further results show that rpoS directly regulates the type VI secretion system H2-T6SS.Under MomL treatment,inactivated RpoS fails to regulate H2-T6SS;therefore,the expression of effector phospholipase A is reduced,and the adaptability of bacteria to antibiotics is weakened.MomL in combination with kanamycin is effective against a wide range of gram-negative pathogenic bacteria.Therefore,this study reports a MomL-antibiotic treatment strategy on antibiotic-resistant bacteria and reveals its mechanism of action.
基金supported by grants from the Ministry of Agriculture and Rural Affairs of China(2016ZX08009003-0022016ZX08009003-005 and 2016ZX08009003-004)+2 种基金Chinese Academy of Sciences(XDA08010401-2)the Ministry of Science and Technology of the People’s Republic of China(2016YFD0100706)the State Key Laboratory of Plant Genomics。
文摘Nitrogen is an essential macronutrient for all living organisms and is critical for crop productivity and quality.In higher plants,inorganic nitrogen is absorbed through roots and then assimilated into amino acids by the highly conserved glutamine synthetase/glutamine:2-oxoglutarate aminotransferase(GS/GOGAT)cycle.How nitrogen metabolism and nitrogen starvation responses of plants are regulated remains largely unknown.Previous studies revealed that mutations in the rice ABNORMAL CYTOKININ RESPONSE1(ABC1)gene encoding Fd-GOGAT cause a typical nitrogen deficiency syndrome.Here,we show that ARE2(for ABC1 REPRESSOR2)is a key regulator of nitrogen starvation responses in rice.The are2 mutations partially rescue the nitrogen-deficient phenotype of abc1 and the are2 mutants show enhanced tolerance to nitrogen deficiency,suggesting that ARE2 genetically interacts with ABC1/Fd-GOGAT.ARE2 encodes a chloroplast-localized Rel A/Spo T homolog protein that catalyzes the hydrolysis of guanosine pentaphosphate or tetraphosphate(p)pp Gpp,an alarmone regulating the stringent response in bacteria under nutritional stress conditions.The are2 mutants accumulate excessive amounts of(p)pp Gpp,which correlate with lower levels of photosynthetic proteins and higher amino acid levels.Collectively,these observations suggest that the alarmone(p)pp Gpp mediates nitrogen stress responses and may constitute a highly conserved mechanism from bacteria to plants.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea,funded by the Ministry of Education(RS-2023-00241461)a part of the project titled'Global Bluefood leadership project(RS-2025-02373103)’,funded by the Ministry of Oceans and Fisheries,Korea.
文摘Lactic acid bacteria(LAB)are integral to fermented foods,the human gut,and environmental microbiomes;however,the functional potential of their resident prophages remains largely uncharacterized.Here,we con-ducted a large-scale genome-wide analysis,encompassing 7178 high-quality LAB genomes,and uncovered a vast and previously uncharacterized reservoir of intact and near-intact phage elements across LAB.Clustering of highconfidence phage contigs based on average nucleotide identity(ANI)delineated 1375 viral operational taxo-nomic units(vOTUs)within the viral realm Duplodnaviria,spanning classical Siphovirus-like phages as well as numerous uncharacterized lineages within the class Caudoviricetes.Gene-sharing networks revealed significant divergence in gene composition at the amino acid level,indicating functional diversification and adaptation to distinct LAB hosts.Phylogenetic analyses have highlighted multiple novel clades that are often phylogenetically distant from known phages,indicating a deep evolutionary divergence.Additionally,prophage-encoded auxil-iary metabolic genes(AMGs)were identified that potentially enhance host metabolism and stress resilience,including genes involved in sulfur assimilation(cysH),carbohydrate utilization(dexA and pelB),and stringent-response modulation(mazG).Collectively,our findings redefine the diversity and functional capacity of LAB phages,illuminate their dynamic co-evolution with host genomes,and provide a valuable genomic resource for future studies.This work also highlighted the potential of LAB phages to diversify host genomes and influence metabolic capacity with potential implications for microbial ecology,industrial fermentation,and other biotechnological innovations.
基金funded by the National Natural Science Foundation of China(32372628)the Fundamental Research Funds for the Provincial Universities of Zhejiang(2022YW17)。
文摘Streptomyces are the well-known producers of biologically active pharmaceuticals and agricultural antibiotics.However,the production of the secondary metabolites was limited due to the unbalance of the cell growth and the activation of secondary metabolic pathway.Here,in order to improve the production of toyocamycin,a nucleoside antibiotic produced by Streptomyces diastatochromogenes 1628,with excellent antimicrobial characteristics to plant pathogens,we develop an endogenous non-inducer-dependent dynamic regulatory strategy based on the quorum sensing(QS)promoter to fine-tune the expression of an important signal molecule(ppGpp).Firstly,two QS promoter PstbA1 and PstbA2 were identified by the bioinformatic analysis.Then,the temporal profiles of PstbA1 and PstbA2 were characterized by the GusA activity.Afterwards,the ppGpp synthase was expressed under the PstbA1 and PstbA2 to improve the ppGpp concentration in vivo.The toyocamycin production reached 768.62 mg/L and 721.06 mg/L under the QS promoter PstbA1 and PstbA2,respectively,which represented increases of 508.81%and 471.14%over the wild-type at the tenth day.The autoregulated QS-based strategy is an effective method by balancing bacterial growth and metabolite synthesis in industrial processes.
