179594.fig.007
Figure 7: A schematic pathway of recombination repair and structures of the proteins involved in T. thermophilus. Recombination repair of DSBs is initiated by an end resection step in which DSB ends are processed by the concerted action of RecJ nuclease (TTHA1167; PDB ID: 2ZXR) and SSB (TTHA0244; PDB ID: 2CWA) to form 3 -ssDNA tails. After end resection, the SSB-ssDNA complex is disassembled and RecA recombinase (TTHA1818) is loaded onto ssDNA by “mediators”, RecF (TTHA0264), RecO (TTHA0623), and RecR (TTHA1600), to promote strand invasion. DNA repair synthesis is primed by PolI (TTHA1054) and PolIII (TTHA0180) from the invaded strand of the D-loop structure. Alternatively, second-end capture is mediated by RecO and SSB and branch migration mediated by the RuvA-RuvB complex (TTHA0291-TTHA0406; PDB ID: 1IXR) and RecG (TTHA1266) to yield HJs. HJs are cleaved by RuvC resolvase (TTHA1090) and the nicks sealed by LigA (TTHA1097). Newly synthesized DNA is colored in blue. The model structures of T. thermophilus RecA, RecF, RecO, RecR, PolI, PolIII 𝛼 subunit, RecG, RuvC, and LigA were generated using SWISS-MODEL. The models were based on the structures of Mycobacterium smegmatis RecA (PDB ID: 2OE2), D. radiodurans RecF (PDB ID: 2O5V), RecO (PDB ID: 1U5K), RecR (PDB ID: 1VDD), E. coli PolI (PDB ID: 1TAU), PolIII 𝛼 subunit (PDB ID: 2HNH), RuvC (PDB ID: 1HJR), LigA (PDB ID: 2OWO), and Thermotoga maritima RecG (PDB ID: 1GM5).