RT Journal Article SR Electronic T1 Structural basis of membrane recognition of Toxoplasma gondii vacuole by Irgb6 JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202101149 DO 10.26508/lsa.202101149 VO 5 IS 1 A1 Yumiko Saijo-Hamano A1 Aalaa Alrahman Sherif A1 Ariel Pradipta A1 Miwa Sasai A1 Naoki Sakai A1 Yoshiaki Sakihama A1 Masahiro Yamamoto A1 Daron M Standley A1 Ryo Nitta YR 2022 UL https://www.life-science-alliance.org/content/5/1/e202101149.abstract AB The p47 immunity-related GTPase (IRG) Irgb6 plays a pioneering role in host defense against Toxoplasma gondii infection. Irgb6 is recruited to the parasitophorous vacuole membrane (PVM) formed by T. gondii and disrupts it. Despite the importance of this process, the molecular mechanisms accounting for PVM recognition by Irgb6 remain elusive because of lack of structural information on Irgb6. Here we report the crystal structures of mouse Irgb6 in the GTP-bound and nucleotide-free forms. Irgb6 exhibits a similar overall architecture to other IRGs in which GTP binding induces conformational changes in both the dimerization interface and the membrane-binding interface. The membrane-binding interface of Irgb6 assumes a unique conformation, composed of N- and C-terminal helical regions forming a phospholipid binding site. In silico docking of phospholipids further revealed membrane-binding residues that were validated through mutagenesis and cell-based assays. Collectively, these data demonstrate a novel structural basis for Irgb6 to recognize T. gondii PVM in a manner distinct from other IRGs.