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首页> 外文期刊>Journal of bacteriology >An Orthologue of Bacteroides fragilis NanH Is the Principal Sialidase in Tannerella forsythia
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An Orthologue of Bacteroides fragilis NanH Is the Principal Sialidase in Tannerella forsythia

机译：脆弱拟杆菌拟南芥是坦氏菌连翘中的主要唾液酸酶。

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Sialidase activity is a putative virulence factor of the anaerobic periodontal pathogen Tannerella forsythia, but it is uncertain which genes encode this activity. Characterization of a putative sialidase, SiaHI, by others, indicated that this protein alone may not be responsible for all of the sialidase activity. We describe a second sialidase in T. forsythia (TF0035), an orthologue of Bacteroides fragilis NanH, and its expression in Escherichia coli. Sialidase activity of the expressed NanH was confirmed by using 2′-(4-methylumbelliferyl)-α-d-N-acetylneuraminic acid as a substrate. Biochemical characterization of the recombinant T. forsythia NanH indicated that it was active over a broad pH range, with optimum activity at pH 5.5. This enzyme has high affinity for 2′-(4-methylumbelliferyl)-α-d-N-acetylneuraminic acid (Km of 32.9 ± 10.3 μM) and rapidly releases 4-methylumbelliferone (Vmax of 170.8 ± 11.8 nmol of 4-methylumbelliferone min?1 mg of protein?1). E. coli lysates containing recombinant T. forsythia NanH cleave sialic acid from a range of substrates, with a preference for α2-3 glycosidic linkages. The genes adjacent to nanH encode proteins apparently involved in the metabolism of sialic acid, indicating that the NanH sialidase is likely to be involved in nutrient acquisition.
机译：唾液酸酶活性是厌氧性牙周病原体 Tannerella Forsythia 的推定毒力因子，但尚不确定哪个基因编码该活性。其他人对推定的唾液酸酶SiaHI的表征表明，该蛋白可能并不对唾液酸酶的所有活性负责。我们在 T中描述了第二个唾液酸酶。脆弱拟南芥（Bacteroides fragilis） NanH的直系同源基因连翘（TF0035）及其在大肠杆菌中的表达。以2'-（4-甲基伞形酮）-α-d- N -乙酰神经氨酸为底物证实了表达的NanH的唾液酸酶活性。重组 T的生化特性。连翘NanH表明其在宽pH范围内均具有活性，在pH 5.5下具有最佳活性。该酶对2'-（4-甲基伞形酮）-α-d- N -乙酰神经氨酸具有高亲和力（ K m 为32.9± 10.3μM）并快速释放4-甲基伞形酮（ V max 为170.8±11.8 nmol的4-甲基伞形酮min ？1 mg蛋白？1 ）。 E。含有重组 T的大肠杆菌裂解物。连翘NanH可以切割多种底物的唾液酸，并优先选择α2-3糖苷键。与 nanH 相邻的基因编码的蛋白质显然参与了唾液酸的代谢，这表明NanH唾液酸酶可能与营养物的获取有关。

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