 Additional structures of heteromeric ACLY-A/B from the green sulfur bacteria "Chlorobium limicola" and the archaeon "Methanosaeta concilii" show that the architecture of ACLY is evolutionarily conserved.Full length ACLY structures showed that the tetrameric protein oligomerizes via its C-terminal domain.The C-terminal domain had not been observed in the previously determined truncated crystal structures.