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Identification and characterization of the capsule depolymerase Dpo27 from phage IME-Ap7 specific to Acinetobacter
Rentao Wang1, Yannan Liu2, Yaqian Zhang3,4
1Senior Department of Respiratory and Critical Care Medicine, the Eighth Medical Center of Chinese PLA General Hospital, Beijing, China.
Abstract:
Among the Acinetobacter genus, Acinetobacter pittii stands out as an important opportunistic infection causative agent commonly found in hospital settings, which poses a serious threat to human health. Recently, the high prevalence of carbapenem-resistant A. pittii isolates has created significant therapeutic challenges for clinicians. Bacteriophages and their derived enzymes are promising therapeutic alternatives or adjuncts to antibiotics effective against multidrug-resistant bacterial infections. However, studies investigating the depolymerases specific to A. pittii strains are scarce. In this study, we identified and characterized a capsule depolymerase, Dpo27, encoded by the bacteriophage IME-Ap7, which targets A. pittii. A total of 23 clinical isolates of Acinetobacter spp. were identified as A. pittii (21.91%, 23/105), and seven A. pittii strains with various K locus (KL) types (KL14, KL32, KL38, KL111, KL163, KL207, and KL220) were used as host bacteria for phage screening. The lytic phage IME-Ap7 was isolated using A. pittii 7 (KL220) as an indicator bacterium and was observed for depolymerase activity. A putative tail fiber gene encoding a polysaccharide-degrading enzyme (Dpo27) was identified and expressed. The results of the modified single-spot assay showed that both A. pittii 7 and 1492 were sensitive to Dpo27, which was assigned the KL220 type. After incubation with Dpo27, A. pittii strain was susceptible to killing by human serum; moreover, the protein displayed no hemolytic activity against erythrocytes. Furthermore, the protein exhibited sustained activity across a wide pH range (5.0-10.0) and at temperatures between 20 and 50°C. In summary, the identified capsule depolymerase Dpo27 holds promise as an alternative treatment for combating KL220-type A. pittii infections.
Insights
This study identifies Dpo27, a capsule depolymerase targeting carbapenem-resistant Acinetobacter pittii. Dpo27 shows promise as a novel therapeutic agent against specific A. pittii strains, offering a new strategy against multidrug-resistant infections.
Area of Science:
- Microbiology
- Biochemistry
- Infectious Diseases
Background:
- Acinetobacter pittii is a significant opportunistic pathogen, frequently causing hospital-acquired infections.
- The rise of carbapenem-resistant A. pittii strains presents critical challenges in clinical treatment.
- Bacteriophage-derived enzymes, like depolymerases, are explored as alternatives to antibiotics for multidrug-resistant bacteria.
Purpose of the Study:
- To identify and characterize a novel capsule depolymerase targeting Acinetobacter pittii.
- To evaluate the potential of this depolymerase as a therapeutic agent against specific A. pittii strains.
Main Methods:
- Isolation and characterization of bacteriophage IME-Ap7 targeting A. pittii.
- Identification, expression, and enzymatic assay of the capsule depolymerase Dpo27.
- Assessment of Dpo27 activity against various A. pittii K locus types and its effect on bacterial susceptibility to human serum.
Main Results:
- The capsule depolymerase Dpo27 was identified from bacteriophage IME-Ap7.
- Dpo27 effectively targeted and degraded the capsule of KL220-type A. pittii strains.
- Dpo27 treatment enhanced the susceptibility of A. pittii to human serum killing and showed no hemolytic activity.
- The enzyme maintained activity across a broad pH range (5.0-10.0) and temperature range (20-50°C).
Conclusions:
- The capsule depolymerase Dpo27 is a promising candidate for therapeutic intervention against KL220-type Acinetobacter pittii infections.
- Dpo27 represents a potential alternative or adjunct therapy to combat multidrug-resistant A. pittii.
- Further research into phage-derived depolymerases could yield new strategies against challenging bacterial pathogens.
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