Across different kingdoms of life, ATP citrate lyase (ACLY, also known as ACL) catalyses the ATP-dependent and coenzyme A (CoA)-dependent conversion of citrate, a metabolic product of the Krebs cycle, to oxaloacetate and the high-energy biosynthetic precursor acetyl-CoA 1 ...
Across different kingdoms of life, ATP citrate lyase (ACLY, also known as ACL) catalyses the ATP-dependent and coenzyme A (CoA)-dependent conversion of citrate, a metabolic product of the Krebs cycle, to oxaloacetate and the high-energy biosynthetic precursor acetyl-CoA 1 . The latter fuels pivotal biochemical reactions such as the synthesis of fatty acids, cholesterol and acetylcholine 2 , and the acetylation of histones and proteins 3,4 . In autotrophic prokaryotes, ACLY is a hallmark enzyme of the reverse Krebs cycle (also known as the reductive tricarboxylic acid cycle), which fixates two molecules of carbon dioxide in acetyl-CoA 5,6 . In humans, ACLY links carbohydrate and lipid metabolism and is strongly expressed in liver and adipose tissue 1 and in cholinergic neurons 2,7 . The structural basis of the function of ACLY remains unknown. Here we report high-resolution crystal structures of bacterial, archaeal and human ACLY, and use distinct substrate-bound states to link the conformational plasticity of ACLY to its multistep catalytic itinerary. Such detailed insights will provide the framework for targeting human ACLY in cancer 8-11 and hyperlipidaemia 12,13 . Our structural studies also unmask a fundamental evolutionary relationship that links citrate synthase, the first enzyme of the oxidative Krebs cycle, to an ancestral tetrameric citryl-CoA lyase module that operates in the reverse Krebs cycle. This molecular transition marked a key step in the evolution of metabolism on Earth.
Organizational Affiliation:
Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium. kenneth.verstraete@ugent.be.
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