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Molecular Basis for Acetyl‐CoA Production by ATP‐Citrate Lyase
Author(s) -
Wei Xuepeng,
Schultz Kollin,
Bazilevsky Gleb,
Vogt Austin,
Marmorstein Ronen
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.08807
Subject(s) - atp citrate lyase , citrate synthase , lyase , chemistry , acetyl coa , biochemistry , enzyme
ATP‐citrate lyase (ACLY) synthesizes cytosolic acetyl‐CoA, a fundamental cellular building block. Accordingly, aberrant ACLY activity is observed in many diseases. Here we report cryo‐EM structures of human ACLY alone or bound to substrates or products. ACLY forms a homotetramer with a rigid citrate synthase homology (CSH) module, flanked by four flexible actyl‐CoA synthetase homology (ASH) domains; CoA is bound at the CSH‐ASH interface in mutually exclusive productive or unproductive conformations. The structure of a catalytic mutant of ACLY in the presence of ATP, citrate and CoA substrates reveals a phospho‐citryl‐CoA intermediate in the ASH domain. ACLY with acetyl‐CoA and oxaloacetate (OAA) products shows the products bound in the ASH domain, with an additional OAA in the CSH domain, which could function in ACLY autoinhibition. These structures, which are supported by biochemical and biophysical data, challenge previous proposals of the ACLY catalytic mechanism and suggest additional therapeutic possibilities for ACLY‐associated metabolic disorders. Support or Funding Information U.S. Department of Health & Human Services | NIH | Office of Extramural Research, National Institutes of Health (OER) ‐ R35 GM118090 [Marmorstein] U.S. Department of Health & Human Services | NIH | Office of Extramural Research, National Institutes of Health (OER) ‐ P01 AG031862 [Marmorstein]a, Two views of the ACLY structure with citrate and CoA. b, Enlarged view of CoA bound at the ASH–CSH interface, highlighting the corresponding cryo‐EM density. b and c, Close‐up view of CoA–protein interactions. d,Superimposition of ACLY bound with the extended CoA and bent CoA conformations. e, Relative enzyme activity of ACLY mutant constructs.ACLY‐apo is suboptimal for productive CoA binding and that CoA can bind in an non‐productive conformation, but CoA cannot be converted to acetyl‐CoA until ATP and citrate substrates bind. The ACLY‐E599Q mutant in the presence of CoA, citrate and ATP reveals that a phospho‐citrate‐CoA intermediate forms prior to formation of acetyl‐CoA and OAA. Following cleavage of the phospho‐citrate‐CoA, the ACLY–OAA–acetyl‐CoA structure reveals that acetyl‐ CoA and OAA products are formed in the ASH domain.