Shen Ruyu, Yu Yang, Chen Zongchao, Zhu Min, Feng Yating, Niu Pengfei, Yu Shengqing
Jiangsu Agri-Animal Husbandry Vocational College, Veterinary Bio-Pharmaceutical, Jiangsu Key Laboratory for High-Tech Research and Development of Veterinary Biopharmaceuticals, Taizhou, Jiangsu, China; Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, China; College of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China.
Jiangsu Agri-Animal Husbandry Vocational College, Veterinary Bio-Pharmaceutical, Jiangsu Key Laboratory for High-Tech Research and Development of Veterinary Biopharmaceuticals, Taizhou, Jiangsu, China.
Vet Microbiol. 2023 May;280:109700. doi: 10.1016/j.vetmic.2023.109700. Epub 2023 Feb 16.
Riemerella anatipestifer is an important pathogen of waterfowl, causing septicemic and exudative diseases. We previously reported that the R. anatipestifer AS87_RS02625 is a secretory protein of the type IX secretion system (T9SS). In this study, R. anatipestifer T9SS protein AS87_RS02625 was determined to be a functional Endonuclease I (EndoI), which has DNase and RNase activities. Optimal temperature and pH of the recombinant R. anatipestifer EndoI (rEndoI) to cleave λDNA were determined as 55-60 °C and 7.5 respectively. The DNase activity of the rEndoI was dependent on the presence of divalent metal ions. Presence of Mg at a concentration range of 7.5-15 mM in the rEndoI reaction buffer displayed the highest DNase activity. In addition, the rEndoI displayed RNase activity to cleave MS2-RNA (ssRNA), either in the absence or presence of divalent cations Mg, Mn, Ca, Zn and Cu. The DNase activity of the rEndoI was significantly enhanced by Mg, Mn and Ca but not Zn and Cu. Moreover, we indicated that R. anatipestifer EndoI functioned on the bacterial adherence, invasion, in vivo survival and inducing inflammatory cytokines. These results indicate that the R. anatipestifer T9SS protein AS87_RS02625 is a novel EndoI, displays endonuclease activity and plays an important role in bacterial virulence.
鸭疫里默氏菌是水禽的一种重要病原体，可引起败血性和渗出性疾病。我们之前报道过鸭疫里默氏菌AS87_RS02625是IX型分泌系统（T9SS）的一种分泌蛋白。在本研究中，鸭疫里默氏菌T9SS蛋白AS87_RS02625被确定为一种功能性核酸内切酶I（EndoI），具有DNA酶和RNA酶活性。重组鸭疫里默氏菌EndoI（rEndoI）切割λDNA的最适温度和pH分别确定为55 - 60°C和7.5。rEndoI的DNA酶活性依赖于二价金属离子的存在。在rEndoI反应缓冲液中存在浓度范围为7.5 - 15 mM的Mg时，显示出最高的DNA酶活性。此外，无论是否存在二价阳离子Mg、Mn、Ca、Zn和Cu，rEndoI都表现出切割MS2 - RNA（单链RNA）的RNA酶活性。Mg、Mn和Ca显著增强了rEndoI的DNA酶活性，但Zn和Cu没有。而且，我们表明鸭疫里默氏菌EndoI在细菌黏附、侵袭、体内存活以及诱导炎性细胞因子方面发挥作用。这些结果表明，鸭疫里默氏菌T9SS蛋白AS87_RS02625是一种新型EndoI，具有核酸内切酶活性，并在细菌毒力中起重要作用。
