Gu Weijing, Gao Shujuan, Wang Huan, Fleming Kaelin D, Hoffmann Reece M, Yang Jong Won, Patel Nimi M, Choi Yong Mi, Burke John E, Reue Karen, Airola Michael V
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA.
Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Nat Commun. 2021 Aug 5;12(1):4718. doi: 10.1038/s41467-021-24929-5.
Phospholipid synthesis and fat storage as triglycerides are regulated by lipin phosphatidic acid phosphatases (PAPs), whose enzymatic PAP function requires association with cellular membranes. Using hydrogen deuterium exchange mass spectrometry, we find mouse lipin 1 binds membranes through an N-terminal amphipathic helix, the Ig-like domain and HAD phosphatase catalytic core, and a middle lipin (M-Lip) domain that is conserved in mammalian and mammalian-like lipins. Crystal structures of the M-Lip domain reveal a previously unrecognized protein fold that dimerizes. The isolated M-Lip domain binds membranes both in vitro and in cells through conserved basic and hydrophobic residues. Deletion of the M-Lip domain in lipin 1 reduces PAP activity, membrane association, and oligomerization, alters subcellular localization, diminishes acceleration of adipocyte differentiation, but does not affect transcriptional co-activation. This establishes the M-Lip domain as a dimeric protein fold that binds membranes and is critical for full functionality of mammalian lipins.
作为甘油三酯的磷脂合成和脂肪储存受脂滴磷脂酸磷酸酶（PAP）调控，其酶促PAP功能需要与细胞膜结合。使用氢氘交换质谱法，我们发现小鼠脂滴蛋白1通过N端两亲性螺旋、免疫球蛋白样结构域和HAD磷酸酶催化核心以及在哺乳动物和类哺乳动物脂滴蛋白中保守的中间脂滴蛋白（M-Lip）结构域与膜结合。M-Lip结构域的晶体结构揭示了一种以前未被识别的二聚化蛋白质折叠。分离的M-Lip结构域通过保守的碱性和疏水残基在体外和细胞内与膜结合。脂滴蛋白1中M-Lip结构域的缺失会降低PAP活性、膜结合和寡聚化，改变亚细胞定位，减少脂肪细胞分化的加速，但不影响转录共激活。这确立了M-Lip结构域作为一种结合膜的二聚体蛋白质折叠，对哺乳动物脂滴蛋白的完整功能至关重要。
