ATP-citrate lyase from the green sulfur bacterium Chlorobium limicola is a heteromeric enzyme composed of two distinct gene products

Eur J Biochem. 2001 Mar;268(6):1670-8.


The reductive tricarboxylic acid cycle functions as a carbon dioxide fixation pathway in the green sulfur bacterium, Chlorobium limicola. ATP-citrate lyase, one of the key enzymes of this cycle, was partially purified from C. limicola strain M1 and the N-terminal sequence of a 65-kDa protein was found to show similarity toward eukaryotic ATP-citrate lyase. A DNA fragment was amplified with primers designed from this sequence and an internal sequence highly conserved among eukaryotic enzymes. Using this fragment as a probe, we isolated a DNA fragment containing two adjacent open reading frames, aclB (1197 bp) and aclA (1827 bp), whose products showed significant similarity to the N- and C-terminal regions of the human enzyme, respectively. Heterologous expression of these genes in Escherichia coli showed that both gene products were essential for ATP-citrate lyase activity. The recombinant enzyme was purified from the cell-free extract of E. coli harboring aclBA for further characterization. The molecular mass of the recombinant enzyme was determined to be approximately 532--557 kDa by gel-filtration. The enzyme catalyzed the cleavage of citrate in an ATP(-), CoA- and Mg(2+)-dependent manner, where ATP and Mg(2+) could be replaced by dATP and Mn(2+), respectively. ADP and oxaloacetate inhibited the reaction. These properties suggested that ATP-citrate lyase from C. limicola controlled the cycle flux depending on intracellular energy conditions. This paper provides the first direct evidence that a bacterial ATP-citrate lyase is a heteromeric enzyme, distinct from mammalian enzymes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Citrate (pro-S)-Lyase / chemistry
  • ATP Citrate (pro-S)-Lyase / isolation & purification*
  • ATP Citrate (pro-S)-Lyase / metabolism
  • Amino Acid Sequence
  • Base Sequence
  • Chlorobi / enzymology*
  • Electrophoresis, Polyacrylamide Gel
  • Molecular Sequence Data
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid


  • Recombinant Proteins
  • ATP Citrate (pro-S)-Lyase