Newman, Hector (2021) Biophysical and biochemical studies of penicillin binding proteins and novel PBP3 inhibitors. PhD thesis, University of Warwick.

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Abstract

Antimicrobial resistance presents a worrying and growing threat to modern medicine. Combatting this challenge requires the discovery of new antimicrobial compounds, which are insensitive to current resistance pathways. One of the most important classes of antibiotics, β-lactams, target penicillin binding proteins (PBPs), a family of enzymes that synthesise the bacterial cell wall. In most clinically important gram-negative bacteria, PBP3 is a ubiquitous and essential drug target, whose inhibition can prevent the growth of bacterial cells. Novel mode of action inhibitors of PBPs are needed to combat rising resistance to β-lactams, but finding such inhibitors requires improved understanding of these proteins and new discovery methods.

This thesis describes the development of two tools for inhibitor discovery: biophysical methods (surface plasmon resonance) in an attempt to characterise the interactions of PBP3 with its ligands; and a high throughput microbiology platform designed to provide low cost, low volume, rapid screening of early stage compounds.

PBP3 mutation-mediated resistance mechanisms have been investigated by analysing structural data to provide insight into how mutations distal to the active site may lower the susceptibility of PBPs to β-lactams. Novel compounds are used to show the indirect link between the active site and these distant regions.

A crystallographic fragment screen, and follow up medicinal chemistry, was used to identify benzoxaboroles as inhibitors of PBP3 with a novel, di-covalent binding mode, engaging two highly conserved serines in the active site. Studies with a non-clinical probe β-lactam, nitrocefin, also appear to show an unprecedented binding mode involving engagement of two serines. These results introduce benzoxaboroles and other compounds as warheads that can bind both serine residues, thereby opening up new avenues for research in the pursuit of non-β-lactam PBP inhibitors.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry Q Science > QR Microbiology R Medicine > RM Therapeutics. Pharmacology
Library of Congress Subject Headings (LCSH):	Drug resistance in microorganisms, Penicillin resistance, Beta lactam antibiotics, Beta lactamases -- Inhibitors, Protein binding, Gram-negative bacteria
Official Date:	June 2021
Dates:	Date Event June 2021 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Dowson, Chris ; McAuley, Katherine ; Paterson, Neil
Format of File:	pdf
Extent:	277 leaves : illustrations
Language:	eng

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