<i>Riemerella anatipestifer</i> UvrC is required for iron utilization, biofilm formation and virulence
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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 <i>Riemerella anatipestifer</i> strain CH3 and attenuates virulence of strain YZb1. In this study, whether <i>R. anatipestifer</i> UvrC has some biological functions other than NER was investigated. Firstly, the <i>uvrC</i> of <i>R. anatipestifer</i> strain Yb2 was in-frame deleted by homologous recombination, generating deletion mutant ΔuvrC, and its complemented strain cΔuvrC was constructed based on <i>Escherichia coli</i> – <i>R. anatipestifer</i> shuttle plasmid pRES. Compared to the wild-type (WT) <i>R. anatipestifer</i> strain Yb2, <i>uvrC</i> deleted mutant ΔuvrC significantly reduced biofilm formation, tolerance to H<sub>2</sub>O<sub>2</sub>- 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 LD<sub>50</sub> 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 <i>uvrC</i> deletion in <i>R. anatipestifer</i> attenuated virulence. Taken together, the results of this study indicate that <i>R. anatipestifer</i> UvrC is required for iron utilization, biofilm formation, oxidative stress tolerance and virulence of strain Yb2, demonstrating multiple functions of UvrC. <b>RESEARCH HIGHLIGHTS</b>Deletion of <i>uvrC</i> in <i>R. anatipestfer</i> Yb2 significantly reduced its biofilm formation.<i>uvrC</i> deletion led to reduced tolerance to H<sub>2</sub>O<sub>2</sub>- and HOCl-induced oxidative stress.The iron utilization of <i>uvrC</i> deleted mutant was significantly reduced.The <i>uvrC</i> deletion in <i>R. anatipestifer</i> Yb2 attenuated its virulence. Deletion of <i>uvrC</i> in <i>R. anatipestfer</i> Yb2 significantly reduced its biofilm formation. <i>uvrC</i> deletion led to reduced tolerance to H<sub>2</sub>O<sub>2</sub>- and HOCl-induced oxidative stress. The iron utilization of <i>uvrC</i> deleted mutant was significantly reduced. The <i>uvrC</i> deletion in <i>R. anatipestifer</i> Yb2 attenuated its virulence.
