期刊
FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY
卷 12, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fcimb.2022.992198
关键词
IFN-inducible GTPase; Irgb6; GTPase; membrane; T; gondii
资金
- Ministry of Education, Science, Sports, and Culture of Japan [21K19484, 20K08591, 22K06580]
- Joint Usage/Research Center for Proteo-Interactome (PRiME)
- Proteo-Science Center, Ehime University
- Japan Agency for Medical Research and Development (AMED) [JP22wm0325010]
The study revealed that Irgb6 can directly deform lipid membranes, and this deformation is influenced by GTPase activity, with GTP-bound state aiding in the detachment of Irgb6 from the membrane.
Irgb6 is a member of interferon gamma-induced immunity related GTPase (IRG), and one of twenty effector IRGs, which coordinately attack parasitophorous vacuole membrane (PVM), causing death of intracellular pathogen. Although Irgb6 plays a pivotal role as a pioneer in the process of PVM disruption, the direct effect of Irgb6 on membrane remained to be elucidated. Here, we utilized artificial lipid membranes to reconstitute Irgb6-membrane interaction in vitro, and revealed that Irgb6 directly deformed the membranes. Liposomes incubated with recombinant Irgb6 were drastically deformed generating massive tubular protrusions in the absence of guanine nucleotide, or with GMP-PNP. Liposome deformation was abolished by incubating with Irgb6-K275A/R371A, point mutations at membrane targeting residues. The membrane tubules generated by Irgb6 were mostly disappeared by the addition of GTP or GDP, which are caused by detachment of Irgb6 from membrane. Binding of Irgb6 to the membrane, which was reconstituted in vitro using lipid monolayer, was stimulated at GTP-bound state. Irgb6 GTPase activity was stimulated by the presence of liposomes more than eightfold. Irgb6 GTPase activity in the absence of membrane was also slightly stimulated, by lowering ionic strength, or by increasing protein concentration, indicating synergistic stimulation of the GTPase activity. These results suggest that membrane targeting of Irgb6 and resulting membrane deformation does not require GTP, but converting into GTP-bound state is crucial for detaching Irgb6 from the membrane, which might coincident with local membrane disruption.
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