结核病（Tuberculosis，TB）是由结核分枝杆菌（Mycobacterium tuberculosis，Mtb）引起的一种严重危害人类健康并对畜牧业造成巨大威胁的人畜共患传染病。近年来，TB在全球范围内流行更为广泛，根据2022年世界卫生组织（WHO）的报告，2022年共有987万人患TB，其中死亡128万人。同时，TB与HIV的混合感染以及多重耐药TB的出现，为TB的防控带来了新的挑战。因此，解析Mtb的致病机制迫在眉睫。

丝氨酸蛋白酶在细菌入侵宿主以及免疫调节过程中发挥重要作用，我们的研究发现Rv1043c蛋白是Mtb细胞壁相关的丝氨酸蛋白酶，1-18位氨基酸为其信号肽序列，在致病性分枝杆菌中高度保守。我们以Rv1043c蛋白为研究对象，开展了该蛋白的酶学特性及其在致病性中的研究。

首先通过原核表达和亲和层析纯化获得Rv1043c蛋白，酶活性测定结果显示Rv1043c能够切割Casein底物，其最适温度为45 ℃、最适pH值为9.0，且Ca²⁺ 和Mg²⁺能够促进其活性的发挥，279位丝氨酸（S）为蛋白酶的关键活性位点，表明Rv1043c蛋白酶为丝氨酸蛋白酶。圆二色分析结果显示，Rv1043c蛋白酶在温度10 ℃-70 ℃、pH3.0-pH4.0和pH7.0-pH10.0的范围内二级结构稳定，在pH5.0和pH6.0条件下Rv1043c蛋白二级结构稳定性发生改变。

为了研究Rv1043c在分枝杆菌感染中的作用，我们构建了重组耻垢分枝杆菌Msg_pAIN、Msg_Rv1043c和Msg_Rv1043c^S279A。亚细胞定位和免疫电镜分析显示，Rv1043c蛋白定位于Mtb的表面；重组菌Msg_pAIN、Msg_Rv1043c和Msg_Rv1043c^S279A感染小鼠腹腔巨噬细胞，经细胞毒性和凋亡分析显示，Rv1043c丝氨酸蛋白酶活性能够明显促进小鼠腹腔巨噬细胞的LDH释放；重组菌Msg_pAIN、Msg_Rv1043c和Msg_Rv1043c^S279A感染C57BL/6小鼠，经病理学、组织病理学、肺细胞凋亡、菌落定殖和炎性细胞因子分析显示，Rv1043c丝氨酸蛋白酶活性促进分枝杆菌在小鼠肺脏中的定殖，诱导肺细胞凋亡和肺的病理损伤，促进小鼠炎性细胞因子IL-1β、IL-6和TNF-α的释放。

以上研究结果表明Rv1043c丝氨酸蛋白酶在分枝杆菌致病过程中发挥重要作用，本研究为进一步解析Mtb的致病机制提供理论基础。

Oxalic acid (OA) is considered as an important pathogenetic factor of some destructive diseases caused by some fungal pathogens such as Sclerotinia sclerotiorum. Oxalate degradation is important for plant health, and plants that contain oxalate oxidase (OXO) enzymes could breakdown oxalate into CO2 and H2O2, which subsequently evokes defense responses. However, some species, such as Arabidopsis thaliana, have no oxalate oxidase activity identified to date. The present study aims to develop transgenic Arabidopsis expressing a wheat oxalate oxidase, to test for the response to OA exposure and fungal infection by S. sclerotiorum. The results showed that the transgenic Arabidopsis lines that expressed the wheat OXO exhibited enhanced resistance to OA exposure and S. sclerotiorum infection in the tolerance assays. In the same manner, it could convert OA to CO2 and H2O2 to a higher extent than the wild-type. Intensive osmotic adjustments were also detected in the transgenic Arabidopsis lines. The higher level of produced H2O2 subsequently induced an elevated activity of antioxidant enzymes including superoxide dismutase (SOD) and peroxidase (POD) in the transgenic Arabidopsis plants. The present study indicated that the expression of a gene encoding wheat OXO could induce intensive osmotic adjustments and hydrogen peroxide related defense response, and subsequently increased tolerance to S. sclerotiorum in transgenic A. thaliana.