sentence: For bacterial two ‐ hybrid assays , comN was PCR amplified from chromosomal DNA of B. subtilis wild ‐ type strain 168CA using primer pairs oTK11 / oTK15 , and cloned into the KpnI , XbaI sites of plasmids pKT25 and pUT18 ( Karimova et al ., 2005 ) to create both N ‐ and C ‐ terminal fusions to adenylate cyclase fragments T25 and T18 .