GDGT cyclization proteins identify the dominant archaeal sources of tetraether lipids in the ocean

著者: Zhirui Zeng, Xiao-Lei Liu, Kristen R. Farley, Jeremy H. Wei, William W. Metcalf, Roger E. Summons, Paula V. Welander - Proceedings of the National Academy of Sciences, PNAS 2019 被引用: 142

Both proteins are radical S-adenosylmethionine proteins, indicating that GDGT cyclization occurs through a free radical mechanism. In addition, we demonstrate that GrsA introduces rings specifically at the C-7 position of the core GDGT lipid, while GrsB cyclizes at the C-3 position, suggesting that cyclization patterns are differentially controlled by 2 separate enzymes and potentially influenced by distinct environmental factors. Finally, phylogenetic analyses of the Grs proteins reveal that marine Thaumarchaeota, and not Euryarchaeota, are the dominant source of cyclized GDGTs in open ocean settings, addressing a major source of uncertainty in GDGT-based paleotemperature proxy applications.