The trypsin-like serine protease domain of Paralichthys olivaceus complement factor I regulates complement activation and inhibits bacterial growth
The trypsin-like serine protease domain of Paralichthys olivaceus complement factor I regulates complement activation and inhibits bacterial growth
复制标题
牙鲆补体因子 I 的胰蛋白酶样丝氨酸蛋白酶结构域调节补体激活并抑制细菌生长
DOI：
10.1016/j.fsi.2019.12.019
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发表时间：
2020-02-01
影响因子：
4.7
通讯作者：
Li, Mo-fei
中科院分区：
文献类型：
--
作者：
Jia, Bei-bei;Jin, Cheng-dong;Li, Mo-fei
在哺乳动物中，补体因子I（CFI）是血清中的丝氨酸蛋白酶，并且在补体激活的调节中起关键作用。在辅因子的存在下，CFI将C3 b裂解为iC 3b，并进一步将iC 3b降解为C3 c和C3 d。在硬骨鱼中，CFI的功能知之甚少。本文研究了具有重要经济价值的硬骨鱼类--牙鲆（Paralichthys olivaceus）的免疫学特性。PoCFI由597个氨基酸残基组成，具有胰蛋白酶样丝氨酸蛋白酶（Tryp）结构域。我们发现PoCFI表达发生在九种不同的组织中，并且通过细菌挑战而上调。重组PoCFI-Tryp（rPoCFI-Tryp）抑制补体激活并降解血清中的C3 b。rPoCFI-Tryp表现出明显的结合能力，以板谱的细菌和抑制细菌的生长。这些结果首次表明，硬骨鱼类CFI通过降解C3 b负调控补体激活，并可能在宿主对细菌感染的免疫防御中发挥作用。
In mammals, complement factor I (CFI) is a serine protease in serum and plays a pivotal role in the regulation of complement activation. In the presence of cofactor, CFI cleaves C3b to iC3b, and further degrades iC3b to C3c and C3d. In teleost, the function of CFI is poorly understood. In this study, we examined the immunological property of CFI from Japanese flounder (Paralichthys olivaceus) (PoCFI), a teleost species with important economic value. PoCFI is composed of 597 amino acid residues and possesses a trypsin-like serine protease (Tryp) domain. We found that PoCFI expressions occurred in nine different tissues and were upregulated by bacterial challenge. Recombinant PoCFI-Tryp (rPoCFI-Tryp) inhibited complement activation and degraded C3b in serum. rPoCFI-Tryp exhibited apparent binding capacities to a board-spectrum of bacteria and inhibited bacterial growth. These results provide the first evidence to indicate that CFI in teleost negatively regulates complement activation via degradation C3b, and probably plays a role in host immune defense against bacterial infection.