Nuances of Mechanisms and Their Implications for Evolution of the Versatile β-Lactamase Activity: From Biosynthetic Enzymes to Drug Resistance Factors

β-Lactamases of classes A and C are believed to have evolved from bacterial enzymes involved in biosynthesis of the peptidoglycan, the so-called penicillin-binding proteins. All these enzymes undergo acylation at an active-site serine by β-lactam antibiotics as a common feature. However, the fate of the acyl-enzyme species is different for β-lactamases and penicillin-binding proteins; deacylation is rapid for the former, whereas it is slow for the latter. It is believed that the acquisition of the ability to deacylate the acyl-enzyme intermediate led to the evolution of β-lactamase activity, which is indispensable for the survival of bacteria in the face of challenge by β-lactam antibiotics. The mechanisms of deacylation of acyl-enzyme intermediates for β-lactamases are examined as a means to investigate structural factors in evolutionary descendency of classes A and C of β-lactamases from penicillin-binding proteins. It is known that in class A β-lactamases the hydrolytic water approaches the acyl-enzyme...