David L. Pompliano

Antibiotic sensitization using biphenyl tetrazoles as potent inhibitors of Bacteroides fragilis metallo-β-lactamase

BACKGROUNDnHigh level resistance to carbapenem antibiotics in gram negative bacteria such as Bacteroides fragilis is caused, in part, by expression of a wide-spectrum metallo-beta-lactamase that hydrolyzes the drug to an inactive form. Co-administration of metallo-beta-lactamase inhibitors to resistant bacteria is expected to restore the antibacterial activity of carbapenems.nnnRESULTSnBiphenyl tetrazoles (BPTs) are a structural class of potent competitive inhibitors of metallo-beta-lactamase identified through screening and predicted using molecular modeling of the enzyme structure. The X-ray crystal structure of the enzyme bound to the BPT L-159,061 shows that the tetrazole moiety of the inhibitor interacts directly with one of the two zinc atoms in the active site, replacing a metal-bound water molecule. Inhibition of metallo-beta-lactamase by BPTs in vitro correlates well with antibiotic sensitization of resistant B. fragilis.nnnCONCLUSIONSnBPT inhibitors can sensitize a resistant B. fragilis clinical isolate expressing metallo-beta-lactamase to the antibiotics imipenem or penicillin G but not to rifampicin.

Synthesis and SAR of thioester and thiol inhibitors of IMP-1 Metallo-β-Lactamase

Potent thioester and thiol inhibitors of IMP-1 metallo-β-lactamase have been synthesized employing a solid-phase Mitsunobu reaction as the key step.

Cloning and expression of Staphylococcus aureus and Streptococcus pyogenes murD genes encoding uridine diphosphate N-acetylmuramoyl-l-alanine:d-glutamate ligases

Bacterial UDP-N-acetylmuramyl-L-alanine:D-glutamate ligase (MurD), a cytoplasmic peptidoglycan biosynthetic enzyme, catalyzes the ATP-dependent addition of D-glutamate to an alanyl residue of the UDP-N-acetylmuramyl-L-alanine precursor, generating the dipeptide. The murD gene was cloned from both Staphylococcus aureus and Streptococcus pyogenes. Sequence analysis of the S. aureus murD gene revealed an open reading frame of 449 amino acids. The deduced aa sequence of S. aureus MurD is highly homologous to MurD from Escherichia coli, Haemophilus influenzae, Bacillus subtilis and St. pyogenes. Recombinant MurD protein from both S. aureus and St. pyogenes was separately overproduced in E. coli and purified as His-tagged fusion. Both recombinant enzymes catalyzed the ATP-dependent addition of D-glutamate to the precursor sugar peptide.