Structural insights into the inhibition mechanism of bacterial toxin LsoA by bacteriophage antitoxin Dmd
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- 英文论文题名：Structural insights into the inhibition mechanism of bacterial toxin LsoA by bacteriophage antitoxin Dmd
- 论文作者：Hua Wan ; Yuichi Otsuka ; Zeng-Qiang Gao ; Heng Zhang ; Yu-Hui Dong
- 英文论文作者：Hua Wan ; Yuichi Otsuka ; Zeng-Qiang Gao ; Heng Zhang ; Yu-Hui Dong ; Beijing Synchrotron Radiation Facility ; Institute of High Energy Physics ; Chinese Academy of Sciences ; Department of Microbiology ; School of Medicine ; Dokkyo Medical University
- 年：2016
- 作者机构：Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences;Department of Microbiology, School of Medicine, Dokkyo Medical University;
- 会议召开时间：2016-04-27
- 会议录名称：第五届中国结构生物学学术讨论会摘要集
- 语种：英文
- 分类号：Q93
- 学会代码：ZGWI
- 会议名称：第五届中国结构生物学学术讨论会
- 会议地点：中国广东深圳
- 主办单位：中国生物物理学会分子生物物理学专业委员会
- 学会名称：中国生物物理学会
- 页数：1
- 文件大小：76k
- 原文格式：D
- 会议级别：全国
摘要
Bacteria can defend themselves against bacteriophages(phages) infections by toxin-antitoxin(TA) systems during their co-evolution. We identified Dmd as an antitoxin from T4 phage, can simultaneously suppress the toxicities of homologous toxins Lso A and Rnl A from enterohaemorrhagic Escherichia coli O157:H7 and E. coli K-12, respectively, representing the first example of a phage with an antitoxin against multiple toxins. Here, we reported the crystal structure of Lso A-Dmd complex as well as in vivo functional studies to demonstrate how Lso A is recognized and inhibited by Dmd in this novel TA system. Los A adopts a novel fold similar to our recently reported Rnl A structure composed of NTD(N-terminal domain), NRD(N-terminal repeated domain) and DBD(Dmd-binding domain). Dmd inserted into the deep groove between NRD and DBD of Los A by making extensive direct contacts. Meanwhile, NRD undergoes a significant shift rendering its conformation from "closed" to "open" upon Dmd-binding. The pull-down and cell toxicity assays on the structure-based mutagenesis of Dmd revealed the key residues(W31 and N40) located in its only helix, are necessary for Lso A-binding and toxicity suppression. Further mutagenesis of Lso A identified the strictly conserved Dmd-interacting residues(R243, E246 and R305), are vital for its toxicity, and suggested Dmd and Lso B have different inhibitory mechanisms against Lso A toxicity. Our structure-function studies demonstrate Dmd can serve as an antitoxin by occupying Lso A active site possibly via substrate mimicry to inhibit Lso A activity. These findings have elucidated unique insights into the defense and counter-defense mechanisms between bacteria and phages in their coevolution.
Bacteria can defend themselves against bacteriophages(phages) infections by toxin-antitoxin(TA) systems during their co-evolution. We identified Dmd as an antitoxin from T4 phage, can simultaneously suppress the toxicities of homologous toxins Lso A and Rnl A from enterohaemorrhagic Escherichia coli O157:H7 and E. coli K-12, respectively, representing the first example of a phage with an antitoxin against multiple toxins. Here, we reported the crystal structure of Lso A-Dmd complex as well as in vivo functional studies to demonstrate how Lso A is recognized and inhibited by Dmd in this novel TA system. Los A adopts a novel fold similar to our recently reported Rnl A structure composed of NTD(N-terminal domain), NRD(N-terminal repeated domain) and DBD(Dmd-binding domain). Dmd inserted into the deep groove between NRD and DBD of Los A by making extensive direct contacts. Meanwhile, NRD undergoes a significant shift rendering its conformation from "closed" to "open" upon Dmd-binding. The pull-down and cell toxicity assays on the structure-based mutagenesis of Dmd revealed the key residues(W31 and N40) located in its only helix, are necessary for Lso A-binding and toxicity suppression. Further mutagenesis of Lso A identified the strictly conserved Dmd-interacting residues(R243, E246 and R305), are vital for its toxicity, and suggested Dmd and Lso B have different inhibitory mechanisms against Lso A toxicity. Our structure-function studies demonstrate Dmd can serve as an antitoxin by occupying Lso A active site possibly via substrate mimicry to inhibit Lso A activity. These findings have elucidated unique insights into the defense and counter-defense mechanisms between bacteria and phages in their coevolution.
Bacteria can defend themselves against bacteriophages(phages) infections by toxin-antitoxin(TA) systems during their co-evolution. We identified Dmd as an antitoxin from T4 phage, can simultaneously suppress the toxicities of homologous toxins Lso A and Rnl A from enterohaemorrhagic Escherichia coli O157:H7 and E. coli K-12, respectively, representing the first example of a phage with an antitoxin against multiple toxins. Here, we reported the crystal structure of Lso A-Dmd complex as well as in vivo functional studies to demonstrate how Lso A is recognized and inhibited by Dmd in this novel TA system. Los A adopts a novel fold similar to our recently reported Rnl A structure composed of NTD(N-terminal domain), NRD(N-terminal repeated domain) and DBD(Dmd-binding domain). Dmd inserted into the deep groove between NRD and DBD of Los A by making extensive direct contacts. Meanwhile, NRD undergoes a significant shift rendering its conformation from "closed" to "open" upon Dmd-binding. The pull-down and cell toxicity assays on the structure-based mutagenesis of Dmd revealed the key residues(W31 and N40) located in its only helix, are necessary for Lso A-binding and toxicity suppression. Further mutagenesis of Lso A identified the strictly conserved Dmd-interacting residues(R243, E246 and R305), are vital for its toxicity, and suggested Dmd and Lso B have different inhibitory mechanisms against Lso A toxicity. Our structure-function studies demonstrate Dmd can serve as an antitoxin by occupying Lso A active site possibly via substrate mimicry to inhibit Lso A activity. These findings have elucidated unique insights into the defense and counter-defense mechanisms between bacteria and phages in their coevolution.
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