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Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200

BACKGROUND: The emergence of multidrug- or extensively drug-resistant Acinetobacter baumannii has made it difficult to treat and control infections caused by this bacterium. It is urgently necessary to search for alternatives to conventional antibiotics for control of severe A. baumannii infections....

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Autores principales: Liu, Yannan, Mi, Zhiqiang, Mi, Liyuan, Huang, Yong, Li, Puyuan, Liu, Huiying, Yuan, Xin, Niu, Wenkai, Jiang, Ning, Bai, Changqing, Gao, Zhancheng
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336015/
https://www.ncbi.nlm.nih.gov/pubmed/30656071
http://dx.doi.org/10.7717/peerj.6173
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author Liu, Yannan
Mi, Zhiqiang
Mi, Liyuan
Huang, Yong
Li, Puyuan
Liu, Huiying
Yuan, Xin
Niu, Wenkai
Jiang, Ning
Bai, Changqing
Gao, Zhancheng
author_facet Liu, Yannan
Mi, Zhiqiang
Mi, Liyuan
Huang, Yong
Li, Puyuan
Liu, Huiying
Yuan, Xin
Niu, Wenkai
Jiang, Ning
Bai, Changqing
Gao, Zhancheng
author_sort Liu, Yannan
collection PubMed
description BACKGROUND: The emergence of multidrug- or extensively drug-resistant Acinetobacter baumannii has made it difficult to treat and control infections caused by this bacterium. It is urgently necessary to search for alternatives to conventional antibiotics for control of severe A. baumannii infections. In recent years, bacteriophages and their derivatives, such as depolymerases, showed great potential as antibacterial or antivirulence agents against bacterial infections. Nonetheless, unlike broad-spectrum bactericidal antibiotics, phage-encoded depolymerase targets only a limited number of bacterial strains. Therefore, identification of novel depolymerases and evaluation of their ability to control A. baumannii infections is important. METHODS: A bacteriophage was isolated from hospital sewage using an extensively drug-resistant A. baumannii strain as the host bacterium, and the phage’s plaque morphology and genomic composition were studied. A polysaccharide depolymerase (Dpo48) was expressed and identified, and the effects of pH and temperature on its activity were determined. Besides, a serum killing assay was conducted, and amino acid sequences homologous to those of putative polysaccharide depolymerases were compared. RESULTS: Phage IME200 yielded clear plaques surrounded by enlarged halos, with polysaccharide depolymerase activity against the host bacterium. A tail fiber protein with a Pectate_lyase_3 domain was identified as Dpo48 and characterized . Dpo48 was found to degrade the capsule polysaccharide of the bacterial surface, as revealed by Alcian blue staining. Dpo48 manifested stable activity over a broad range of pH (5.0–9.0) and temperatures (20–70 °C). Results from in vitro serum killing assays indicated that 50% serum was sufficient to cause a five log reduction of overnight enzyme-treated bacteria, with serum complement playing an important role in these killing assays. Moreover, Dpo48 had a spectrum of activity exactly the same as its parental phage IME200, which was active against 10 out of 41 A. baumannii strains. Amino acid sequence alignment showed that the putative tail fiber proteins had a relatively short, highly conserved domain in their N-terminal sequences, but their amino acid sequences containing pectate lyase domains, found in the C-terminal regions, were highly diverse. CONCLUSIONS: Phage-encoded capsule depolymerases may become promising antivirulence agents for preventing and controlling A. baumannii infections.
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spelling pubmed-63360152019-01-17 Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200 Liu, Yannan Mi, Zhiqiang Mi, Liyuan Huang, Yong Li, Puyuan Liu, Huiying Yuan, Xin Niu, Wenkai Jiang, Ning Bai, Changqing Gao, Zhancheng PeerJ Microbiology BACKGROUND: The emergence of multidrug- or extensively drug-resistant Acinetobacter baumannii has made it difficult to treat and control infections caused by this bacterium. It is urgently necessary to search for alternatives to conventional antibiotics for control of severe A. baumannii infections. In recent years, bacteriophages and their derivatives, such as depolymerases, showed great potential as antibacterial or antivirulence agents against bacterial infections. Nonetheless, unlike broad-spectrum bactericidal antibiotics, phage-encoded depolymerase targets only a limited number of bacterial strains. Therefore, identification of novel depolymerases and evaluation of their ability to control A. baumannii infections is important. METHODS: A bacteriophage was isolated from hospital sewage using an extensively drug-resistant A. baumannii strain as the host bacterium, and the phage’s plaque morphology and genomic composition were studied. A polysaccharide depolymerase (Dpo48) was expressed and identified, and the effects of pH and temperature on its activity were determined. Besides, a serum killing assay was conducted, and amino acid sequences homologous to those of putative polysaccharide depolymerases were compared. RESULTS: Phage IME200 yielded clear plaques surrounded by enlarged halos, with polysaccharide depolymerase activity against the host bacterium. A tail fiber protein with a Pectate_lyase_3 domain was identified as Dpo48 and characterized . Dpo48 was found to degrade the capsule polysaccharide of the bacterial surface, as revealed by Alcian blue staining. Dpo48 manifested stable activity over a broad range of pH (5.0–9.0) and temperatures (20–70 °C). Results from in vitro serum killing assays indicated that 50% serum was sufficient to cause a five log reduction of overnight enzyme-treated bacteria, with serum complement playing an important role in these killing assays. Moreover, Dpo48 had a spectrum of activity exactly the same as its parental phage IME200, which was active against 10 out of 41 A. baumannii strains. Amino acid sequence alignment showed that the putative tail fiber proteins had a relatively short, highly conserved domain in their N-terminal sequences, but their amino acid sequences containing pectate lyase domains, found in the C-terminal regions, were highly diverse. CONCLUSIONS: Phage-encoded capsule depolymerases may become promising antivirulence agents for preventing and controlling A. baumannii infections. PeerJ Inc. 2019-01-14 /pmc/articles/PMC6336015/ /pubmed/30656071 http://dx.doi.org/10.7717/peerj.6173 Text en ©2019 Liu et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Microbiology
Liu, Yannan
Mi, Zhiqiang
Mi, Liyuan
Huang, Yong
Li, Puyuan
Liu, Huiying
Yuan, Xin
Niu, Wenkai
Jiang, Ning
Bai, Changqing
Gao, Zhancheng
Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200
title Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200
title_full Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200
title_fullStr Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200
title_full_unstemmed Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200
title_short Identification and characterization of capsule depolymerase Dpo48 from Acinetobacter baumannii phage IME200
title_sort identification and characterization of capsule depolymerase dpo48 from acinetobacter baumannii phage ime200
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336015/
https://www.ncbi.nlm.nih.gov/pubmed/30656071
http://dx.doi.org/10.7717/peerj.6173
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