Cloning and antibacterial activity analysis of KL2 type Acinetobacter baumannii bacteriophage depolymerase

Abstract:

[Background] Bacteriophage depolymerase is a kind of antibacterial protein produced by bacteriophage in the process of bacterial lysis. There are few reports on the capsule typing and common types of Acinetobacter baumannii bacteriophage depolymerases. [Objective] The KL2 type A. baumannii was selected as the research object. The depolymerase was cloned from the phage IME-AB2, and soluble expression was carried out in Escherichia coli, and its activity in vitro was studied. [Methods] A. baumannii capsular typing was identified through next generation sequencing and bioinformatics analysis. The IME-AB2 whole genome was analyzed. The putative tail fiber gene of ORF76 was cloned. The recombinant expression vector pEASY-Blunt-E1-gp76 was constructed and induced to express in E. coli BL21(DE3). The depolymerase was purified by Ni-NTA affinity chromatography and the gp76 antibacterial activity was studied in vitro. [Results] The recombinant plasmid of pEASY-Blunt-E1-gp76 was successfully constructed and expressed in E. coli. In vitro activity analysis was showed that the recombinant protein had good antibacterial activity against all KL2 type A. baumannii in vitro, and the depolymerase combined with human or dog serum had good bactericidal activity. [Conclusion] It is of great significance to identify depolymerase and improve its antibacterial spectrum, and it is also one of the important problems to be solved urgently in the field of bacteriophage and depolymerase used in the treatment of drug-resistant bacteria.