Insertion sequences(ISs)exist widely in bacterial genomes,but their roles in the evolution of bacterial antiphage defense remain to be clarified.Here,we report that,under the pressure of phage infection,the IS1o96 tra...Insertion sequences(ISs)exist widely in bacterial genomes,but their roles in the evolution of bacterial antiphage defense remain to be clarified.Here,we report that,under the pressure of phage infection,the IS1o96 transposition of Mycobacterium smegmatis into the Isr2 gene can occur at high frequencies,which endows the mutant mycobacterium with a broad-spectrum antiphage ability.Lsr2 functions as a negative regulator and directly silences expression of a gene island composed of 11 lipid metabolism-related genes.The complete or partial loss of the gene island leads to a significant decrease of bacteriophage adsorption to the mycobacterium,thus defending against phage infection.Strikingly,a phage that has evolved mutations in two tail-filament genes can re-escape from the Isr2 inactivation-triggered host defense.This study uncovered a new signaling pathway for activating antimycobacteriophage immunity by Is transposition and provided insight into the natural evolution of bacterial antiphage defense.展开更多
The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with som...The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence(IS) elements, which are usually regarded as representatives of ‘selfish' genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cep A(penicillin and cephalosporin), cfx A(cephamycin), cfi A(carbapenem), nim(metronidazole) and erm F(clindamycin) resistance genes. This is achieved by outwardoriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of theantibiotic resistance mechanisms of Bacteroides, which will have clinical implications.展开更多
通过DNA从头测序分析人胸膜间皮瘤发生的高关联度突变基因。提取恶性胸膜间皮瘤(MPM)组织和正常胸膜组织DNA,构建基因文库,用Illumina HiSeqX Ten PE 150平台测序,将测序结果与人类基因组数据库的参考序列进行比对、注释,并对测序结果...通过DNA从头测序分析人胸膜间皮瘤发生的高关联度突变基因。提取恶性胸膜间皮瘤(MPM)组织和正常胸膜组织DNA,构建基因文库,用Illumina HiSeqX Ten PE 150平台测序,将测序结果与人类基因组数据库的参考序列进行比对、注释,并对测序结果进行过滤、错误率分布检查、GC含量分布检查分析。MPM组织DNA平均过滤37829946 bp,错误率小于0.12%,GC含量占41.17%,而正常胸膜组织DNA平均过滤39089681 bp,错误率小于0.1%,GC含量占41.7%,两者测序质量均在Q 30(≥80%)以上,MPM为87.43%,正常胸膜为88.36%。以上高质量测序数据通过BWA比对到参考基因组(GRCh 37/hg 19),得到最初比对序列,利用重复标记后的比对序列进行覆盖度、深度等统计,覆盖深度达到10 X以上该突变位点可信。结果显示,实验病例XL14覆盖深度达到10 X的占98.59%,覆盖率达到99.83%;对照病例Z5占98.50%,覆盖率达到99.79%。对该序列进行基因注释分析,发现一系列单核苷酸多态性、基因插入缺失、基因结构变异、基因拷贝数变异,筛选出总变异位点数29277个,可能致病的变异位点数22个,致病性的变异位点数5个,不确定变异有害性的位点数为3353个,其余变异位点均为良性。进一步对突变基因进行富集、关联性分析,预测出突变基因TXNDC2与人胸膜间皮瘤的发生高度相关,相关系数达到0.8以上;突变基因PIEN、ABCC1、UGT1A7、UGT1A3、UGT1A4、UGT1A9、ALDH3B1、UGT1A5等与人胸膜间皮瘤有一定关联性,关联度在0~0.2之间。基因TXNDC2、PIEN、ABCC1、UGT1A7、UGT1A3、UGT1A4、UGT1A9、ALDH3B1、UGT1A5的变异可能与人胸膜间皮瘤的发生发展有关。本实验为人胸膜间皮瘤分子诊断提供了参考。展开更多
Insertion sequences(ISs)promote the transmission of antimicrobial resistance genes(ARGs)across bacterial populations.However,their contributions and dynamics during the transmission of resistance remain unclear.In thi...Insertion sequences(ISs)promote the transmission of antimicrobial resistance genes(ARGs)across bacterial populations.However,their contributions and dynamics during the transmission of resistance remain unclear.In this study,we selected is26 as a representative transposable element to decipher the relationship between ISs and ARGs and to investigate their transfer features and transmission trends.We retrieved 2656 translocatable IS26-bounded units with ARGs(tiS26-bUs-ARGs)in complete bacterial genomes from the NCBI RefSeq database.In total,124 ARGs spanning 12 classes of antibiotics were detected,and the average contribution rate of IS26 to these genes was 41.2%.We found that IS26-bounded units(IS26-bUs)mediated extensive ARG dissemination within the bacteria of the Gammaproteobacteria class,showing strong transfer po-tential between strains,species,and even phyla.The Is26-bUs expanded in bacterial populations over time,and their temporal expansion trend was significantly correlated with antibiotic usage.This wide dissemination could be due to the nonspecific target site preference of is26.Finally,we experimentally confirmed that the introduction of a single copy of is26 could lead to the formation of a composite transposon mediating the transmission of“passenger”genes.These observations extend our knowledge of the IS26 and provide new insights into the mediating role of ISs in the dissemination of antibiotic resistance.展开更多
基金supported by the National Natural Science Foundation of China(32230002)the National Key R&D Program of China(2020YFA0907200),and the Ba-Gui Scholar Program of Guangxi(To Z.G.H).
文摘Insertion sequences(ISs)exist widely in bacterial genomes,but their roles in the evolution of bacterial antiphage defense remain to be clarified.Here,we report that,under the pressure of phage infection,the IS1o96 transposition of Mycobacterium smegmatis into the Isr2 gene can occur at high frequencies,which endows the mutant mycobacterium with a broad-spectrum antiphage ability.Lsr2 functions as a negative regulator and directly silences expression of a gene island composed of 11 lipid metabolism-related genes.The complete or partial loss of the gene island leads to a significant decrease of bacteriophage adsorption to the mycobacterium,thus defending against phage infection.Strikingly,a phage that has evolved mutations in two tail-filament genes can re-escape from the Isr2 inactivation-triggered host defense.This study uncovered a new signaling pathway for activating antimycobacteriophage immunity by Is transposition and provided insight into the natural evolution of bacterial antiphage defense.
基金Supported by The Center of Excellence at the University of Szeged(TáMOP-421B)to József Sóki.
文摘The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence(IS) elements, which are usually regarded as representatives of ‘selfish' genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cep A(penicillin and cephalosporin), cfx A(cephamycin), cfi A(carbapenem), nim(metronidazole) and erm F(clindamycin) resistance genes. This is achieved by outwardoriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of theantibiotic resistance mechanisms of Bacteroides, which will have clinical implications.
基金supported by the National Key R&D Program of China(grant No.2021YFC2302005)the National Natural Science Foundation of China(grant Nos.32300162 and 32070075).
文摘Insertion sequences(ISs)promote the transmission of antimicrobial resistance genes(ARGs)across bacterial populations.However,their contributions and dynamics during the transmission of resistance remain unclear.In this study,we selected is26 as a representative transposable element to decipher the relationship between ISs and ARGs and to investigate their transfer features and transmission trends.We retrieved 2656 translocatable IS26-bounded units with ARGs(tiS26-bUs-ARGs)in complete bacterial genomes from the NCBI RefSeq database.In total,124 ARGs spanning 12 classes of antibiotics were detected,and the average contribution rate of IS26 to these genes was 41.2%.We found that IS26-bounded units(IS26-bUs)mediated extensive ARG dissemination within the bacteria of the Gammaproteobacteria class,showing strong transfer po-tential between strains,species,and even phyla.The Is26-bUs expanded in bacterial populations over time,and their temporal expansion trend was significantly correlated with antibiotic usage.This wide dissemination could be due to the nonspecific target site preference of is26.Finally,we experimentally confirmed that the introduction of a single copy of is26 could lead to the formation of a composite transposon mediating the transmission of“passenger”genes.These observations extend our knowledge of the IS26 and provide new insights into the mediating role of ISs in the dissemination of antibiotic resistance.
基金This work was supported by the Natural Science Foundation of Zhejiang Province (No.Y304083), the Science Foundation of De-partment of Education at Zhejiang Province (No.20040069) and the Science Foundation for the talents of Hangzhou Normal Col-lege (No.87).
