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A Frameshift Mutation in wcaJ Associated with Phage Resistance in Klebsiella pneumoniae
Demeng Tan1, Yiyuan Zhang1, Jinhong Qin2
1Shanghai Public Health Clinical Center, Fudan University, Shanghai 201508, China.
Abstract:
Phage therapy is a potential and promising avenue for controlling the emergence and spread of multidrug-resistant (MDR) Klebsiella pneumoniae, however, the rapid development of anti-phage resistance has been identified as an obstacle to the development of phage therapy. Little is known about the mechanism employed by MDR K. pneumoniae strains and how they protect themselves from lytic phage predation in vitro and in vivo. In this study, comparative genomic analysis shows undecaprenyl-phosphate glucose-1-phosphate transferase (WcaJ), the initial enzyme catalyzing the biosynthesis of colanic acid, is necessary for the adsorption of phage 117 (Podoviridae) to the host strain Kp36 to complete its lytic life cycle. In-frame deletion of wcaJ alone was sufficient to provide phage 117 resistance in the Kp36 wild-type strain. Complementation assays demonstrated the susceptibility of phage 117, and the mucoid phenotype could be restored in the resistant strain Kp36-117R by expressing the wild-type version of wcaJ. Remarkably, we found that bacterial mobile genetic elements (insA and insB) block phage 117 infections by disrupting the coding region of wcaJ, thus preventing phage adsorption to its phage receptor. Further, we revealed that the wcaJ mutation likely occurred spontaneously rather than adapted by phage 117 predation under unfavorable environments. Taken together, our results address a crucial evolutionary question around the mechanisms of phage-host interactions, increasing our current understandings of anti-phage defense mechanisms in this important MDR pathogen.
Insights
Multidrug-resistant Klebsiella pneumoniae develops phage resistance by disrupting the wcaJ gene, which is essential for phage adsorption. This discovery sheds light on phage-host interactions and anti-phage defense mechanisms.
Area of Science:
- Microbiology
- Genomics
- Bacteriology
Background:
- Phage therapy offers a promising strategy against multidrug-resistant (MDR) Klebsiella pneumoniae.
- Anti-phage resistance is a significant hurdle in the clinical application of phage therapy.
- Mechanisms of phage resistance in MDR K. pneumoniae remain largely unexplored.
Purpose of the Study:
- To investigate the mechanisms by which MDR K. pneumoniae develops resistance to lytic phages.
- To identify specific genes and pathways involved in phage resistance in K. pneumoniae.
- To understand the evolutionary basis of phage-host interactions in this pathogen.
Main Methods:
- Comparative genomic analysis of MDR K. pneumoniae strains.
- In-frame deletion mutagenesis to assess gene function.
- Complementation assays to validate gene roles.
- Investigation of bacterial mobile genetic elements' impact on phage resistance.
Main Results:
- The undecaprenyl-phosphate glucose-1-phosphate transferase (WcaJ) gene was identified as essential for phage 117 adsorption and lytic cycle completion.
- Deletion of wcaJ conferred resistance to phage 117 in the Kp36 wild-type strain.
- Bacterial mobile genetic elements (insA and insB) were found to disrupt the wcaJ gene, leading to phage resistance.
- wcaJ mutations likely arise spontaneously rather than through phage-induced adaptation.
Conclusions:
- WcaJ is a critical host factor for phage 117 infection, and its disruption confers resistance.
- Mobile genetic elements play a role in the evolution of phage resistance in K. pneumoniae.
- Understanding these phage-host interaction mechanisms is vital for advancing phage therapy against MDR pathogens.
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