Identification of bacterial posttranslational modifications that regulate antimicrobial resistance

Barlow, Victoria 2022. Identification of bacterial posttranslational modifications that regulate antimicrobial resistance. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Rapidly spreading antimicrobial resistance is one of the greatest threats to human health of our time. There exists many mechanisms by which bacteria evade destruction by antibiotics and various research is being conducted globally in an attempt to combat this alarming situation. A so far under-researched area is the hypothesised role of protein post-translational modifications in the regulation of antimicrobial resistance responses. This thesis identifies two proteins involved in antimicrobial resistance and known to undergo post-translational modification, then uses genetic code expansion and unnatural amino acid incorporation to characterise the effect of these modifications on protein function. The first protein is AdeT1, a component of a multi-drug efflux pump from the multidrug resistant pathogen Acinetobacter baumannii, which undergoes lysine propionylation at Lys280 in vivo. Here, such propionylation is shown to modulate function of the efflux pump in living cells, with the propionylated protein complex demonstrating increased ethidium bromide efflux. Further, cells producing propionylated AdeT1 required a 6-fold higher concentration of erythromycin to inhibit their growth compared to cells producing unmodified AdeT1. The second protein investigated is the DNA-binding protein HU from Escherichia coli, which undergoes acetylation at five lysine residues in vivo. The protein was characterised in DNA-binding assays in vitro, which revealed that protein acetylated at Lys86 has significantly lower affinity for DNA compared to its wildtype counterpart. The consequences of such altered binding on bacterial gene expression and antimicrobial resistance are contemplated. Together, the results presented here are in agreement with the known roles of post-translational modifications in modulating protein function and provide evidence toward a novel analysis of posttranslational modifications as regulatory components in antimicrobial resistance responses

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	6 December 2022
Last Modified:	06 Jul 2023 02:30
URI:	https://orca.cardiff.ac.uk/id/eprint/154680

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