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Benjamin, A. B.

Publications and source records attributed to Benjamin, A. B..

2 recordsLinked to original sources

Peptide-mimetic treatment of Pseudomonas aeruginosa in a mouse model of respiratory infection

The rise of drug resistance has become a global crisis, with >1 million deaths due to resistant bacterial infections each year. Pseudomonas aeruginosa, in particular, remains a serious problem with limited solutions due to complex resistance mechanisms that now lead to more than 32,000 multidrug-resistant (MDR) infections and over 2,000 deaths annually. While the emergence of resistant bacteria has become concerningly common, identification of useful new drug classes has been limited over the past 40+ years. We found that a potential novel therapeutic, the peptide-mimetic TM5, is effective at killing P. aeruginosa and displays sufficiently low toxicity for mammalian cells to allow for use in treatment of infections. Interestingly, TM5 kills P. aeruginosa more rapidly than traditional antibiotics, within 30-60 minutes in vitro, and is effective against a range of clinical isolates. In vivo, TM5 significantly reduced bacterial load in the lungs within 24 hours compared to untreated mice and demonstrated few adverse effects. Taken together, these observations suggest that TM5 shows promise as an alternative therapy for MDR P. aeruginosa respiratory infections.

microbiology↗

Structures of chloramphenicol acetyltransferase III and E. coli β-ketoacylsynthase III co-crystallized with partially hydrolysed acetyl-oxa(dethia)CoA

Acetyl-CoA is a reactive metabolite that non-productively hydrolyzes in a number of enzyme active sites on the crystallization time frame. In order to elucidate enzyme:acetyl-CoA interactions leading to catalysis, acetyl-CoA substrate analogs are needed. One possible analog for use in structural studies is acetyl-oxa(dethia)CoA (AcOCoA), where the thioester sulfur of CoA is replaced by an oxygen. Here we present structures of chloramphenicol acetyltransferase III (CATIII) and E. coli ketoacylsynthase III (FabH) from crystals grown in the presence of partially hydrolyzed AcOCoA and the respective nucleophile. Based on the structures, the behaviour of AcOCoA differs between the enzymes, with FabH reacting with AcOCoA and CATIII being unreactive. The structure of CATIII reveals insight into the catalytic mechanism, with one active site of the trimer having relatively clear electron density for AcOCoA and chloramphenicol, and the other active sites having weaker density for AcOCoA. One FabH structure has a hydrolyzed AcOCoA product oxa(dethia)CoA (OCoA) and the other FabH structure has an acyl-enzyme intermediate with OCoA. Together these structures provide preliminary insight into the use of AcOCoA for enzyme structure-function studies with different nucleophiles. SynopsisStable analogs of acetyl-CoA are needed to support structure-function studies of acetyltransferase enzymes. We report structures of two enzymes in the presence of an acetyl-CoA analog where the thioester is replaced by an ester.

biochemistry↗