Riemerella anatipestifer UvrC is required for iron utilization, biofilm formation and virulence

ABSTRACT

UvrC is a subunit of excinuclease ABC, which mediates nucleotide excision repair (NER) in bacteria. Our previous studies showed that transposon Tn4531 insertion in the UvrC encoding gene Riean_1413 results in reduced biofilm formation by Riemerella anatipestifer strain CH3 and attenuates virulence of strain YZb1. In this study, whether R. anatipestifer UvrC has some biological functions other than NER was investigated. Firstly, the uvrC of R. anatipestifer strain Yb2 was in-frame deleted by homologous recombination, generating deletion mutant ΔuvrC, and its complemented strain cΔuvrC was constructed based on Escherichia coli – R. anatipestifer shuttle plasmid pRES. Compared to the wild-type (WT) R. anatipestifer strain Yb2, uvrC deleted mutant ΔuvrC significantly reduced biofilm formation, tolerance to H₂O₂- and HOCl-induced oxidative stress, iron utilization, and adhesion to and invasion of duck embryonic hepatocytes, but not its growth curve and proteolytic activity. In addition, animal experiments showed that the LD₅₀ value of ΔuvrC in ducklings was about 13-fold higher than that of the WT, and the bacterial loads in ΔuvrC infected ducklings were significantly lower than those in Yb2-infected ducklings, indicating uvrC deletion in R. anatipestifer attenuated virulence. Taken together, the results of this study indicate that R. anatipestifer UvrC is required for iron utilization, biofilm formation, oxidative stress tolerance and virulence of strain Yb2, demonstrating multiple functions of UvrC.

RESEARCH HIGHLIGHTS

• Deletion of uvrC in R. anatipestfer Yb2 significantly reduced its biofilm formation.

• uvrC deletion led to reduced tolerance to H₂O₂- and HOCl-induced oxidative stress.

• The iron utilization of uvrC deleted mutant was significantly reduced.

• The uvrC deletion in R. anatipestifer Yb2 attenuated its virulence.

KEYWORDS:

• Riemerella anatipestifer
• UvrC
• biofilm formation
• virulence
• iron utilization
• oxidative stress tolerance

Acknowledgements

We wish to thank our colleagues at the Animal Experiment Center for their strong assistance and support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Natural Science Foundation of Shanghai (23ZR1476700) and the National Natural Science Foundation of China (31772770 and 31472224). The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.