Desialylation by Edwardsiella tarda is the initial step in the regulation of its invasiveness.
Desialylation by Edwardsiella tarda is the initial step in the regulation of its invasiveness.
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DOI：
10.1042/bcj20190367
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
L. Vo;Toshiharu Tsuzuki;Yuko Kamada-Futagami;P. Chigwechokha;Akinobu Honda;Kazuki Oishi;M. Komatsu;K. Shiozaki
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文献类型：
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作者：
L. Vo;Toshiharu Tsuzuki;Yuko Kamada-Futagami;P. Chigwechokha;Akinobu Honda;Kazuki Oishi;M. Komatsu;K. Shiozaki
迟缓爱德华氏菌是一种革兰氏阴性细菌，给水产养殖业造成重大经济损失。E. tarda具有NanA唾液酸酶，其从宿主细胞的α 2 -3唾液酸糖蛋白去除唾液酸。而NanA唾液酸酶活性与E.迟发性侵袭仍然知之甚少。此外，还对E.延迟仍有待阐明。我们研究了几种大肠杆菌的唾液酸酶活性。tarda菌株中，发现致病菌株比非致病菌株具有更高的唾液酸酶活性和更大的NanA mRNA水平上调。致病菌株在GAKS细胞中也表现出较高的感染率，并且感染被唾液酸酶抑制剂显著抑制。此外，NanA基因的过表达显著增加了E. tarda与游离唾液酸的作用增强了GAKS细胞的感染率。唾液酸处理增强了两个N-乙酰神经氨酸裂解酶和一个N-乙酰神经氨酸胞苷酰转移酶的mRNA水平。E. Tarda使用唾液酸作为碳源，通过N-乙酰神经氨酸裂解酶进行生长。具有高N-乙酰神经氨酸胞苷酰转移酶水平的菌株表现出更大的脂多糖和糖蛋白的唾液酸化。我们的研究确立了E. tarda唾液酸酶在调节其侵袭性中的作用。
Edwardsiella tarda is a gram-negative bacterium causing significant economic losses to aquaculture. E. tarda possesses NanA sialidase which removes sialic acids from a2-3 sialo-glycoprotein of host cells. However, the relationship between NanA sialidase activity and E. tarda invasiveness remains poorly understood. Furthermore, the pathway of sialic acid metabolism in E. tarda remains to be elucidated. We studied sialidase activity in several E. tarda strains and found that the pathogenic strains exhibited higher sialidase activity and greater up-regulation of the NanA mRNA level than non-pathogenic strain. Pathogenic strains also showed higher rates of infection in GAKS cells, and the infection was drastically suppressed by sialidase inhibitor. Additionally, NanA gene over-expression significantly increased infection and treatment of E. tarda with free sialic acid enhanced the rate of infection in GAKS cells. Sialic acid treatment enhanced mRNA levels of two N-acetylneuraminate lyases and one N-acetylneuraminate cytidylyltransferase. E. tarda uses sialic acid as a carbon source for growth via N-acetylneuraminate lyases. The strains with high N-acetylneuraminate cytidylyltransferase level showed greater sialylation of the lipopolysaccharides and glycoproteins. Our study establishes the significance of desialylation by E. tarda sialidase in the regulation of its invasiveness.