title: UDP-N-acetylmuramic acid l-alanine ligase (MurC) inhibition in a tolC mutant Escherichia coli strain leads to cell death.
abstract: The Mur ligases play an essential role in the biosynthesis of bacterial peptidoglycan and hence are attractive antibacterial targets. A screen of the AstraZeneca compound library led to the identification of compound A, a pyrazolopyrimidine, as a potent inhibitor of Escherichia coli and Pseudomonas aeruginosa MurC. However, cellular activity against E. coli or P. aeruginosa was not observed. Compound A was active against efflux pump mutants of both strains. Experiments using an E. coli tolC mutant revealed accumulation of the MurC substrate and a decrease in the level of product upon treatment with compound A ,: indicating inhibition of MurC enzyme in these cells. Such a modulation was not observed in the E. coli wild-type cells. Further, overexpression of MurC in the E. coli tolC mutant led to an increase in the compound A MIC by ≥16-fold, establishing a correlation between MurC inhibition and cellular activity. In addition, estimation of the intracellular compound A level showed an accumulation of the compound over time in the tolC mutant strain. A significant compound A level was not detected in the wild-type E. coli strain even upon treatment with high concentrations of the compound. Therefore, the lack of MIC and absence of MurC inhibition in wild-type E. coli were possibly due to suboptimal compound concentration as a consequence of a high efflux level and/or poor permeativity of compound A.
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India.
authors.forename: Vaishali
authors.initials: V
authors.lastname: Humnabadkar
authors.affiliation: DMPK and Animal Sciences, AstraZeneca, Bangalore, India.
authors.forename: K R
authors.initials: KR
authors.lastname: Prabhakar
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India.
authors.forename: Ashwini
authors.initials: A
authors.lastname: Narayan
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India.
authors.forename: Sreevalli
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India.
authors.forename: Supreeth
authors.initials: S
authors.lastname: Guptha
authors.affiliation: Chemistry, AstraZeneca, Bangalore, India.
authors.forename: Praveena
authors.initials: P
authors.lastname: Manjrekar
authors.affiliation: Chemistry, AstraZeneca, Bangalore, India.
authors.forename: Murugan
authors.initials: M
authors.lastname: Chinnapattu
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India.
authors.forename: Vasanthi
authors.initials: V
authors.lastname: Ramachandran
authors.affiliation: Chemistry, AstraZeneca, Bangalore, India.
authors.forename: Shahul P
authors.initials: SP
authors.lastname: Hameed
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India.
authors.forename: Sudha
authors.initials: S
authors.lastname: Ravishankar
authors.affiliation: Biosciences, AstraZeneca, Bangalore, India monalisa.chatterji@astrazeneca.com.
authors.forename: Monalisa
authors.initials: M
authors.lastname: Chatterji
mesh_terms: D000409:Alanine / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D014538:Uridine Diphosphate N-Acetylmuramic Acid; C073126:tolC protein, E coli; D010453:Peptide Synthases; D000409:Alanine
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