Mechanisms of proton relay and product release by Class A β‐lactamase at ultrahigh resolution

• DOI: 10.1111/febs.14315
• Publication Date: 2017-11-21T04:57:10Z
• Authors: Eric M. Lewandowski; Kathryn G. Lethbr...; Ruslan Sanishvili; Joanna Skiba; Konrad Kowalski; Yu Chen
• Keywords: Hydrolase; Catalytic cycle

The β‐lactam antibiotics inhibit penicillin‐binding proteins ( PBP s) by forming a stable, covalent, acyl‐enzyme complex. During the evolution from s to Class A β‐lactamases, β‐lactamases acquired Glu166 activate catalytic water and cleave bond. Here we present three product complex crystal structures of CTX ‐M‐14 β‐lactamase with ruthenocene‐conjugated penicillin—a 0.85 Å resolution structure E166A mutant complexed penilloate product, 1.30 same penicilloate 1.18 S70G epimer—shedding light on mechanisms inhibition β‐lactamases. E166A–penilloate captured hydrogen bonding network following protonation leaving group and, for first time, unambiguously show that ring nitrogen donates proton Ser130, which in turn Lys73. These observations indicate absence Glu166, equivalent lysine would be neutral therefore capable serving as general base serine. Together previous results, this suggests common relay shared s, serine lysine, ultimately nitrogen. Additionally, E166A–penicilloate reveals previously unseen conformational changes key residues during release is capture hydrolyzed presence an unmutated Database Structural data are available PDB database under accession numbers 5TOP , 5TOY 5VLE