Identification and characterization of a cathepsin K homologue that interacts with pathogen bacteria in black rockfish, Sebastes schlegelii
Identification and characterization of a cathepsin K homologue that interacts with pathogen bacteria in black rockfish, Sebastes schlegelii
复制标题
与黑石斑鱼 Sebastes schlegelii 中的病原体细菌相互作用的组织蛋白酶 K 同源物的鉴定和表征
DOI：
10.1016/j.fsi.2020.01.050
复制
发表时间：
2020-03-01
影响因子：
4.7
通讯作者：
Gu, Han-jie
中科院分区：
文献类型：
--
作者：
He, Shu-wen;Du, Xue;Gu, Han-jie
组织蛋白酶K属于半胱氨酸组织蛋白酶家族。半胱氨酸组织蛋白酶参与哺乳动物的多种生理过程和宿主免疫防御。然而，在硬骨鱼中，组织蛋白酶K的功能非常有限。在本研究中，组织蛋白酶K同源物（SsCTSK）从硬骨鱼黑岩鱼（Schlegelii）的鉴定和研究在表达和功能水平。计算机模拟分析表明，SsCTSK蛋白含有信号肽、组织蛋白酶前肽抑制剂129结构域和功能结构域Pept_C1。SsCTSK还具有肽酶结构域，其具有三个催化必需残基（Cys 25、His 162和Asn 183）。系统发育分析表明，SsCTSK是进化接近其他硬骨鱼类的组织蛋白酶K。SsCTSK在多种组织中表达，并由细菌感染诱导。纯化的重组SsCTSK（rSsCTSK）在45 ℃时表现出明显的最大肽酶活性，并且在组织蛋白酶抑制剂E - 64的存在下，其酶活性显著下降。此外，rSsCTSK具有与PAMPs和细菌结合的能力。最后，敲低SsCTSK表达促进了黑岩鱼中的细菌入侵。这些结果表明，SsCTSK作为半胱氨酸蛋白酶的功能，并可能作为一个目标，病原体操纵宿主防御系统。
Cathepsin K belongs to the family of cysteine cathepsins. It is well known that the cysteine cathepsins participate in various physiological processes and host immune defense in mammals. However, in teleost fish, the function of cathepsin K is very limited. In the present study, a cathepsin K homologue (SsCTSK) from the teleost black rockfish (Sebastes schlegelii) was identified and examined at expression and functional levels. In silico analysis showed that three domains, including signal peptide, cathepsin propeptide inhibitor 129 domain, and functional domain Pept_C1, are existed in SsCTSK. SsCTSK also possesses a peptidase domain with three catalytically essential residues (Cys25, His162 and Asn183). Phylogenetic profiling indicated that SsCTSK was evolutionally close to the cathepsin K of other teleost fish. Expression of SsCTSK occurred in multiple tissues and was induced by bacterial infection. Purified recombinant SsCTSK (rSsCTSK) exhibited apparent maximal peptidase activity at 45 degrees C, and its enzymatic activity was remarkably declined in the presence of the cathepsin inhibitor E - 64. Moreover, rSsCTSK possesses the ability to bind with PAMPs and bacteria. Finally, knockdown of SsCTSK expression facilitated bacterial invasion in black rockfish. Collectively, these results indicated that SsCTSK functions as a cysteine protease and may serves as a target for pathogen manipulation of host defense system.