Sharma Varshni, Pal Jyoti, Dashora Vishal, Chattopadhyay Somdeb, Kapoor Yogita, Singha Biplab, Arimbasseri G Aneeshkumar, Saha Swati
Department of Microbiology, University of Delhi South Campus, New Delhi, India.
National Institute of Immunology, New Delhi, India.
J Biol Chem. 2025 Mar;301(3):108208. doi: 10.1016/j.jbc.2025.108208. Epub 2025 Jan 20.
SET proteins are lysine methyltransferases. In investigating Leishmania donovani SET29, we found depletion of LdSET29 by two-thirds did not affect promastigote growth, nor alter the parasite's response to UV-induced or HU-induced stress, but made it more tolerant to HO-induced oxidizing environment. The deviant response to oxidative stress was coupled to lowered accumulation of reactive oxygen species, which was linked to enhanced scavenging activity. The set29 mutants' response to HO exposure was similar to that of set7 mutants, prompting an investigation into genetic and physical interactions between the two proteins. While neither protein could rescue the aberrant phenotypes of the other set mutant, the two proteins interacted physically in vitro and in vivo. Transcriptome analyses revealed that neither protein regulated global gene expression, but LdSET7 controlled transcript levels of a limited number of genes, including several peroxidases. In working towards identifying targets through which SET7/SET29 mediate the cell's response to an oxidative milieu, we found HSP60/CNP60 and TCP1 to be possible candidates. LdHSP60 has earlier been implicated in the regulation of the response of virulent promastigotes to HO exposure, and LdTCP1 has previously been found to have a protective effect against oxidative stress. set7 and set29 mutants survived more proficiently in host macrophages as well. The data suggest an alliance between LdSET29 and LdSET7 in mounting the parasite's response to oxidative stress, each protein playing its own distinctive role. They ensure the parasite not only establishes infection but also maintains the balance with host cells to enable the persistence of infection.
SET蛋白是赖氨酸甲基转移酶。在对杜氏利什曼原虫SET29进行研究时，我们发现LdSET29的表达量减少三分之二并不影响前鞭毛体的生长，也不会改变该寄生虫对紫外线诱导或羟基脲诱导的应激反应，但会使其对过氧化氢诱导的氧化环境更具耐受性。对氧化应激的异常反应与活性氧积累的降低有关，而这又与清除活性的增强相关。set29突变体对过氧化氢暴露的反应与set7突变体相似，这促使我们对这两种蛋白之间的遗传和物理相互作用进行研究。虽然这两种蛋白都无法挽救另一种set突变体的异常表型，但它们在体外和体内都存在物理相互作用。转录组分析表明，这两种蛋白都不调控全局基因表达，但LdSET7控制着有限数量基因的转录水平，包括几种过氧化物酶。在努力确定SET7/SET29介导细胞对氧化环境反应的靶点时，我们发现热休克蛋白60/冷休克蛋白60（HSP60/CNP60）和TCP1可能是候选靶点。LdHSP60早前就被认为参与调控有毒力的前鞭毛体对过氧化氢暴露的反应，而LdTCP1此前也被发现对氧化应激具有保护作用。set7和set29突变体在宿主巨噬细胞中也能更有效地存活。这些数据表明LdSET29和LdSET7在寄生虫对氧化应激的反应中存在协同关系，每种蛋白都发挥着独特作用。它们确保寄生虫不仅能够建立感染，还能与宿主细胞维持平衡，以使感染持续存在。
