The Tail Associated Protein of Acinetobacter baumannii Phage ΦAB6 Is the Host Specificity Determinant Possessing Exopolysaccharide Depolymerase Activity

Lai, Ming-Kuen; Chang, Kai‐Chih; Huang, Shiuan-Wen; Luo, Cheng-Hung; Chiou, Pei-Yu; Wu, Chung Chih; Lin, Ning

doi:10.1371/journal.pone.0153361

Cited by 54 publications

(68 citation statements)

References 28 publications

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“…The presence of depolymerization activity in phages is usually identified by the formation of a halo surrounding phage plaques. Previously, several A. baumannii phages encoding depolymerases that infect specific host capsular types (K-types), K1, K2, K3, K9, K19, K27, and K44, have been reported (16)(17)(18)(19)(20). However, there is only one study that characterized a recombinant depolymerase demonstrating its ability to degrade capsular polysaccharides extracted from planktonic cells or biofilm matrices (21).…”

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confidence: 99%

Functional Analysis and Antivirulence Properties of a New Depolymerase from a Myovirus That Infects Acinetobacter baumannii Capsule K45

Oliveira

Costa

Ferreira

et al. 2019

J Virol

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Acinetobacter baumannii is an important pathogen causative of health care-associated infections and is able to rapidly develop resistance to all known antibiotics, including colistin. As an alternative therapeutic agent, we have isolated a novel myovirus (vB_AbaM_B9) which specifically infects and makes lysis from without in strains of the K45 and K30 capsule types, respectively. Phage B9 has a genome of 93,641 bp and encodes 167 predicted proteins, of which 29 were identified by mass spectrometry. This phage holds a capsule depolymerase (B9gp69) able to digest extracted exopolysaccharides of both K30 and K45 strains and remains active in a wide range of pH values (5 to 9), ionic strengths (0 to 500 mM), and temperatures (20 to 80°C). B9gp69 was demonstrated to be nontoxic in a cell line model of the human lung and to make the K45 strain fully susceptible to serum killing in vitro. Contrary to the case with phage, no resistance development was observed by bacteria targeted with the B9gp69. Therefore, capsular depolymerases may represent attractive antimicrobial agents against A. baumannii infections. IMPORTANCE Currently, phage therapy has revived interest for controlling hard-to-treat bacterial infections. Acinetobacter baumannii is an emerging Gram-negative pathogen able to cause a variety of nosocomial infections. Additionally, this species is becoming more resistant to several classes of antibiotics. Here we describe the isolation of a novel lytic myophage B9 and its recombinant depolymerase. While the phage can be a promising alternative antibacterial agent, its success in the market will ultimately depend on new regulatory frameworks and general public acceptance. We therefore characterized the phage-encoded depolymerase, which is a natural enzyme that can be more easily managed and used. To our knowledge, the therapeutic potential of phage depolymerase against A. baumannii is still unknown. We show for the first time that the K45 capsule type is an important virulence factor of A. baumannii and that capsule removal via the recombinant depolymerase activity helps the host immune system to combat the bacterial infection.

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confidence: 99%

Functional Analysis and Antivirulence Properties of a New Depolymerase from a Myovirus That Infects Acinetobacter baumannii Capsule K45

Oliveira

Costa

Ferreira

et al. 2019

J Virol

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“…It is expectable that phages targeting ACB species will be able to recognize and degrade their capsule, as already demonstrated for phage ØAB6 (Lai et al ., ). Likewise, the composition of the capsule will certainly dictate the ability of the phage to infect the strains.…”

Section: Introductionmentioning

confidence: 97%

Ability of phages to infect Acinetobacter calcoaceticus‐Acinetobacter baumannii complex species through acquisition of different pectate lyase depolymerase domains

Oliveira

Costa

Konstantinides

et al. 2017

Environmental Microbiology

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Bacteriophages are ubiquitous in nature and represent a vast repository of genetic diversity, which is driven by the endless coevolution cycle with a diversified group of bacterial hosts. Studying phage-host interactions is important to gain novel insights into their dynamic adaptation. In this study, we isolated 12 phages infecting species of the Acinetobacter baumannii-Acinetobacter calcoaceticus complex which exhibited a narrow host range and similar morphological features (podoviruses with short tails of 9-12 nm and isometric heads of 50-60 nm). Notably, the alignment of the newly sequenced phage genomes (40-41 kb of DNA length) and all Acinetobacter podoviruses deposited in Genbank has shown high synteny, regardless of the date and source of isolation that spans from America to Europe and Asia. Interestingly, the C-terminal pectate lyase domain of these phage tail fibres is often the only difference found among these viral genomes, demonstrating a very specific genomic variation during the course of their evolution. We proved that the pectate lyase domain is responsible for phage depolymerase activity and binding to specific Acinetobacter bacterial capsules. We discuss how this mechanism of phage-host co-evolution impacts the tail specificity apparatus of Acinetobacter podoviruses.

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“…Although its host range is limited, it has potential use in therapeutic phage preparations. Although Petty's genome is smaller than those of known KMV-like Acinetobacter phages (26,42,43), it contains 8 genes with hypothetical function that share homology to genes exclusively found in other Acinetobacter phages of this group.…”

Section: Discussionmentioning

confidence: 99%

Genomic and Biochemical Characterization of Acinetobacter Podophage Petty Reveals a Novel Lysis Mechanism and Tail-Associated Depolymerase Activity

Hernandez-Morales

Lessor

Wood

et al. 2018

J Virol

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The increased prevalence of drug-resistant, nosocomial infections, particularly from pathogenic members of the complex, necessitates the exploration of novel treatments such as phage therapy. In the present study, we characterize phage Petty, a novel podophage that infects multidrug-resistant and Genome analysis reveals that phage Petty is a 40,431bp ϕKMV-like phage, with a coding density of 92.2% and a G+C content of 42.3%. Interestingly, the lysis cassette encodes a class I holin and a single subunit endolysin, but lacks canonical spanins to disrupt the outer membrane. Analysis of other ϕKMV-like genomes revealed that spanin-less lysis cassettes are a feature of phages infecting within this subfamily of bacteriophages. The observed halo surrounding Petty's large clear plaques indicated the presence of a phage-encoded depolymerase capable of degrading capsular exopolysaccharides (EPS). Gene, a putative tail fiber, was hypothesized to possess depolymerase activity based on weak homology to previously reported phage tail fibers. The 101.4 kDa protein gp was cloned and expressed, and its activity against EPS in solution was determined. The enzyme degraded purified EPS from its host strain AU0783, reducing its viscosity, and generated reducing ends in solution, indicative of hydrolase activity. Given that the accessibility to cells within a biofilm is enhanced by degradation of EPS, phages with depolymerases may have enhanced diagnostic and therapeutic potential against drug-resistant strains. Bacteriophage therapy is being revisited as a treatment for difficult-to-treat infections. This is especially true for infections, which are notorious for being resistant to antimicrobials. Thus, sufficient data needs to be generated with regard to phages with therapeutic potential, if they are to be successfully employed clinically. In this study, we describe the isolation and characterization of phage Petty, a novel lytic podophage, and its depolymerase. To our knowledge, it is the first phage reported able to infect both and The lytic phage has potential as an alternative therapeutic agent, and the depolymerase could be used for modulating EPS both during infections and in biofilms on medical equipment, as well as for capsular typing. We also highlight the lack of predicted canonical spanins in the phage genome, and confirm that, unlike the rounding of λ lysogens lacking functional spanin genes, cells infected with phage Petty lyse by bursting. This suggests phages like Petty employ a different mechanism to disrupt the outer membrane of hosts during lysis.

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The Tail Associated Protein of Acinetobacter baumannii Phage ΦAB6 Is the Host Specificity Determinant Possessing Exopolysaccharide Depolymerase Activity

Cited by 54 publications

References 28 publications

Functional Analysis and Antivirulence Properties of a New Depolymerase from a Myovirus That Infects Acinetobacter baumannii Capsule K45

Functional Analysis and Antivirulence Properties of a New Depolymerase from a Myovirus That Infects Acinetobacter baumannii Capsule K45

Ability of phages to infect Acinetobacter calcoaceticus‐Acinetobacter baumannii complex species through acquisition of different pectate lyase depolymerase domains

Genomic and Biochemical Characterization of Acinetobacter Podophage Petty Reveals a Novel Lysis Mechanism and Tail-Associated Depolymerase Activity

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