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. Author manuscript; available in PMC: 2020 Jan 1.
Published in final edited form as: Enzymes. 2019;45:311–341. doi: 10.1016/bs.enz.2019.08.004

Fig. 2.

Fig. 2

Structural basis and proposed mechanism of TFAM-promoted abasic DNA strand scission. (A) Crystal structure of TFAM in complex with DNA containing the mitochondrial light-strand promoter (LSP) sequence (PDB: 3TQ6). The two high-mobility group (HMG) box domains of TFAM are in purple (HMG1) and blue (HMG2), and the inter-domain linker is in wheat. Potentially reactive (with AP sites) lysine residues within the two HMGs are highlighted in red. The heavy strand is in cyan, and the light strand is in green with the position of AP lesions shown in the dashed lines. (B) The proposed mechanism of TFAM-mediated DNA strand cleavage at AP sites via Schiff base intermediates (DNA-TFAM cross-links, DPC) to form single-strand breaks (SSB).