“…However, in the B. subtilis SufS-SufU complex, the Zn site contains Asp43, Cys66, and Cys128 of SufU, and His342 of SufS, which resulted from a ligand swapping [116]. This His residue is unique to SufS associated with SufU in the SUFlike system [75,116,117], but not to SufS associated with SufE in the SUF system. The importance of His342 was confirmed by studying the B. subtilis SufS H342Y variant, which showed no interaction to SufS and very low activity.…”