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 HIGHLIGHTSDeletion 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.
摘要：
UvrC是超核酶ABC的一个亚基，介导细菌中的核苷酸切除修复（NER）。我们先前的研究表明，在UvrC编码基因Riean_1413中插入转座子Tn4531会导致抗鼠疫Riemerella菌株CH3的生物膜形成减少，并减弱菌株YZb1的毒力。在这项研究中,研究了R.anatipestiferUvrC是否具有NER以外的其他生物学功能。首先,通过同源重组在框内删除了抗鼠疫菌菌株Yb2的uvrC，产生缺失突变体ΔuvrC，基于大肠杆菌-R.anatipestifer穿梭质粒pRES构建了其互补菌株cΔuvrC。与野生型（WT）抗青霉菌株Yb2相比，uvrC缺失突变体ΔuvrC显着减少了生物膜的形成，对H2O2-和HOCl诱导的氧化应激的耐受性，铁的利用，以及对鸭胚肝细胞的粘附和侵袭，但不是它的生长曲线和蛋白水解活性。此外,动物实验表明，雏鸭ΔuvrC的LD50值比WT高约13倍，ΔuvrC感染的雏鸭的细菌负荷明显低于Yb2感染的雏鸭，表明R.anatipestifer中uvrC缺失减弱了毒力。一起来看,这项研究的结果表明，铁的利用需要R.anatipestiferUvrC，生物膜的形成，菌株Yb2的氧化应激耐受性和毒力，证明了UvrC的多种功能。研究重点在R.anatipestferYb2中uvrC的表达显着减少了其生物膜的形成。uvrC缺失导致对H2O2-和HOCl诱导的氧化应激的耐受性降低。uvrC缺失突变体的铁利用率显著降低。鼠疫菌Yb2中的uvrC缺失减弱了其毒力。
