Nature Communications, Volume: 5, Article number:4244, DOI: doi:10.1038/ncomms5244
Structure and mechanism of an intramembrane liponucleotide synthetase central for phospholipid biosynthesis
Xiuying Liu,1, 3, Yan Yin,1, 2, 3, Jinjun Wu1, & Zhenfeng Liu1,
Abstract
Abstract Introduction Results Discussion Methods Additional information Accession codes References Acknowledgements Author information Supplementary information Phospholipids are elemental building-block molecules for biological membranes. Biosynthesis of phosphatidylinositol, phosphatidylglycerol and phosphatidylserine requires a central liponucleotide intermediate named cytidine-diphosphate diacylglycerol (CDP-DAG). The CDP-DAG synthetase (Cds) is an integral membrane enzyme catalysing the formation of CDP-DAG, an essential step for phosphoinositide recycling during signal transduction. Here we report the structure of the Cds from Thermotoga maritima (TmCdsA) at 3.4 resolution. TmCdsA forms a homodimer and each monomer contains nine transmembrane helices arranged into a novel fold with three domains. An unusual funnel-shaped cavity penetrates half way into the membrane, allowing the enzyme to simultaneously accept hydrophilic substrate (cytidine 5′-triphosphate (CTP)/deoxy-CTP) from cytoplasm and hydrophobic substrate (phosphatidic acid) from membrane. Located at the bottom of the cavity, a Mg2+-K+ hetero-di-metal centre coordinated by an Asp-Asp dyad serves as the cofactor of TmCdsA. The results suggest a two-metal-ion catalytic mechanism for the Cds-mediated synthesis of CDP-DAG at the membrane–cytoplasm interface.
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文章链接：http://www.nature.com/ncomms/2014/140627/ncomms5244/full/ncomms5244.html
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