Identification of three podoviruses infecting Klebsiella encoding capsule depolymerases that digest specific capsular types

Abstract

Summary Klebsiella pneumoniae is an important human pathogen causing opportunistic nosocomial and community‐acquired infections. A major public health concern regarding K. pneumoniae is the increasing incidence of multidrug‐resistant strains. Here, we isolated three novel Klebsiella bacteriophages, KN 1‐1, KN 3‐1 and KN 4‐1, which infect KN 1, KN 3 and K56, and KN 4 types respectively. We determined their genome sequences and conducted a comparative analysis that revealed a variable region containing capsule depolymerase‐encoding genes. Recombinant depolymerase proteins were produced, and their enzymatic activity and specificity were evaluated. We identified four capsule depolymerases in these phages that could only digest the capsule types of their respective hosts. Our results demonstrate that the activities of these capsule depolymerases were correlated with the host range of each phage; thus, the capsule depolymerases are host specificity determinants. By generating a capsule mutant, we demonstrate that capsule was essential for phage adsorption and infection. Further, capsule depolymerases can enhance bacterial susceptibility to serum killing. The discovery of these phages and depolymerases lays the foundation for the typing of KN 1, KN 3, KN 4 and K56 Klebsiella and could be useful alternative therapeutics for the treatment of K. pneumoniae infections.

Modular prophage interactions driven by capsule serotype select for capsule loss under phage predation

“…Venturini et al 2019). The CLT-specificity of phage-encoded depolymerases(Hsieh et al 2017, Lin et al 2014, Majkowska-Skrobek et al 2018, Niemann et al 1977a, Niemann et al 1977b, Pan et al 2017, Pan et al 2019, Thurow et al 1974 could explain these results. Yet, in our set, few of such enzymes were detected, they exhibited very low identity to known depolymerases, and did not seem to correlate with the CLT.…”

“…Since depolymerases are specific to one or a few capsule types (Lin et al 2014, Thurow et al 1974, this implicates that some phages interact with capsules in a serotype-specific manner (Pan et al 2017, Pan et al 2019, Thurow et al 1974. Additionally, the capsule could facilitate cell infection because phages bind reversibly to it, prior to the irreversible binding to the specific cell receptor (Bertozzi Silva et al 2016).…”

Identification of a newly isolated lytic bacteriophage against K24 capsular type, carbapenem resistant Klebsiella pneumoniae isolates

“…The most important virulence factors of K. pneumoniae are the capsular polysaccharides (CPS) and lipopolysaccharides (LPS) typically used for K-, and O-serotyping respectively. Over 80 capsular types have been defined, including 77 types from reference strains identified between 1926 and 1977 using serological tests, and 5 new types (KN1 to KN5) characterized by molecular genotyping and structural analyses in recent years [22][23][24] .…”

Identification of Two Depolymerases From Phage IME205 and Their Antivirulent Functions on K47 Capsule of Klebsiella pneumoniae

“…Unlike conventional antibiotics that kill bacterial cells or inhibit their growth, capsule depolymerases degrade bacterial surface polysaccharides to reduce their virulence and expose bacteria to host immune attack (Majkowska-Skrobek et al, 2016Liu et al, 2019a,b;Oliveira et al, 2019). The potential of phage-encoded depolymerases of targeting various K. pneumoniae capsules have been demonstrated previously (Hsu et al, 2013;Lin et al, 2014;Pan et al, 2015Pan et al, , 2017Pan et al, , 2019Majkowska-Skrobek et al, 2016Hsieh et al, 2017;Cai et al, 2019;Wu et al, 2019). Recently, the depolymerase Dep42 encoded by phage SH-KP152226 could specifically degrade the K47 capsule of K. pneumoniae and was able to significantly inhibit biofilm formation or degrade formed biofilms (Wu et al, 2019).…”