Bacterial fumarase and L-malic acid are evolutionary ancient components of the DNA damage response

Abstract

Fumarase is distributed between two compartments of the eukaryotic cell. The enzyme catalyses the reversible conversion of fumaric to L-malic acid in mitochondria as part of the tricarboxylic acid (TCA) cycle, and in the cytosol/nucleus as part of the DNA damage response (DDR). Here, we show that fumarase of the model prokaryote Bacillus subtilis (Fum-bc) is induced upon DNA damage, co-localized with the bacterial DNA and is required for the DDR. Fum-bc can substitute for both eukaryotic functions in yeast. Furthermore, we found that the fumarase-dependent intracellular signaling of the B. subtilis DDR is achieved via production of L-malic acid, which affects the translation of RecN, the first protein recruited to DNA damage sites. This study provides a different evolutionary scenario in which the dual function of the ancient prokaryotic fumarase, led to its subsequent distribution into different cellular compartments in eukaryotes.