Fig. 5. (A) Excerpt of an alignment of the mycobacterial protein kinases PknB and PknG with the kinase domains of exemplary class III (AciKC, AplKC, LabKC) and class IV (SgbL, StcL, VenL) lanthipeptide synthetases. Conserved catalytic residues are shown in red and structural features important for activity are highlighted. (B) Comparison of the crystal structure of PknB binding the ATP-mimic adenosine 5′-[γ-thio]triphosphate (PDB code 1MRU) with the Phyre2 models of the LabKC and SgbL kinase domains. A close up of the active site of PknB is shown. Catalytic residues and regions of importance are highlighted in teal. (C) Structure of the RRE domain of the cyanobactin heterocyclase LynD from Lyngbya aestuarii with bound leader (PDB code 4V1T) compared with the segments of the LabKC and SgbL structure models that are implied⁹ in leader binding.