Formation of adenosine 5 '-tetraphosphate from the acyl phosphate intermediate: a difference between the MurC and MurD synthetases of Escherichia coli

The mechanism of the Mur synthetases of peptidoglycan biosynthesis is thoug ht to involve in each case the successive formation of an acyl phosphate an d a tetrahedral intermediate. The existence of the acyl phosphates for the MurC and MurD enzymes from Escherichia coli was firmly established by their in situ reduction by sodium borohydride followed by acid hydrolysis, yield ing the corresponding amino alcohols. Furthermore, it was found that MurD, but not MurC, catalyses the synthesis of adenosine 5'-tetraphosphate from t he acyl phosphate, thereby substantiating its existence and pointing out a difference between the two enzymes. (C) 1999 Federation of European Biochem ical Societies.