Structural and functional studies of histidine biosynthesis in Acanthamoeba spp. demonstrates a novel molecular arrangement and target for antimicrobials

Christopher A. Rice, Sara J. Campbell, Claudine Bisson, Hayley J. Owen, Svetlana E. Sedelnikova, Patrick J. Baker, David W. Rice, Fiona L. Henriquez, Craig W. Roberts

Research output: Contribution to journalArticle

Abstract

Acanthamoeba is normally free-living, but sometimes facultative and occasionally opportunistic parasites. Current therapies are, by necessity, arduous and yet poorly effective due to their inabilities to kill cyst stages or in some cases to actually induce encystation. Acanthamoeba can therefore survive as cysts and cause disease recurrence. Herein, in pursuit of better therapies and to understand the biochemistry of this understudied organism, we characterize its histidine biosynthesis pathway and explore the potential of targeting this with antimicrobials. We demonstrate that Acanthamoeba is a histidine autotroph, but with the ability to scavenge preformed histidine. It is able to grow in defined media lacking this amino acid, but is inhibited by 3-amino-1,2,4-triazole (3AT) that targets Imidazoleglycerol-Phosphate Dehydratase (IGPD) the rate limiting step of histidine biosynthesis. The structure of Acanthamoeba IGPD has also been determined in complex with 2-hydroxy-3-(1,2,4-triazol-1-yl) propylphosphonate [(R)-C348], a recently described novel inhibitor of Arabidopsis thaliana IGPD. This compound inhibited the growth of four Acanthamoeba species, having a 50% inhibitory concentration (IC50) ranging from 250-526 nM. This effect could be ablated by the addition of 1 mM exogenous free histidine, but importantly not by physiological concentrations found in mammalian tissues. The ability of 3AT and (R)-C348 to restrict the growth of four strains of Acanthamoeba spp. including a recently isolated clinical strain, while not inducing encystment, demonstrates the potential therapeutic utility of targeting the histidine biosynthesis pathway in Acanthamoeba.

LanguageEnglish
Article numbere0198827
Number of pages19
JournalPLOS One
Volume13
Issue number7
DOIs
StatePublished - 3 Jul 2018

Fingerprint

Acanthamoeba
Biosynthesis
histidine
Histidine
anti-infective agents
biosynthesis
Amitrole
encystment
triazoles
phosphates
therapeutics
Inhibitory Concentration 50
inhibitory concentration 50
Cysts
Biochemistry
relapse
autotrophs
Growth
Arabidopsis
biochemistry

Keywords

  • Acanthamoeba
  • treatment
  • microbiology
  • parasitology
  • keratitis
  • drug discovery
  • target based therapy
  • essential amino acid biosynthesis
  • biochemistry
  • 3D crystallography

Cite this

Rice, Christopher A. ; Campbell, Sara J. ; Bisson, Claudine ; Owen, Hayley J. ; Sedelnikova, Svetlana E. ; Baker, Patrick J. ; Rice, David W. ; Henriquez, Fiona L. ; Roberts, Craig W./ Structural and functional studies of histidine biosynthesis in Acanthamoeba spp. demonstrates a novel molecular arrangement and target for antimicrobials. In: PLOS One. 2018 ; Vol. 13, No. 7.
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abstract = "Acanthamoeba is normally free-living, but sometimes facultative and occasionally opportunistic parasites. Current therapies are, by necessity, arduous and yet poorly effective due to their inabilities to kill cyst stages or in some cases to actually induce encystation. Acanthamoeba can therefore survive as cysts and cause disease recurrence. Herein, in pursuit of better therapies and to understand the biochemistry of this understudied organism, we characterize its histidine biosynthesis pathway and explore the potential of targeting this with antimicrobials. We demonstrate that Acanthamoeba is a histidine autotroph, but with the ability to scavenge preformed histidine. It is able to grow in defined media lacking this amino acid, but is inhibited by 3-amino-1,2,4-triazole (3AT) that targets Imidazoleglycerol-Phosphate Dehydratase (IGPD) the rate limiting step of histidine biosynthesis. The structure of Acanthamoeba IGPD has also been determined in complex with 2-hydroxy-3-(1,2,4-triazol-1-yl) propylphosphonate [(R)-C348], a recently described novel inhibitor of Arabidopsis thaliana IGPD. This compound inhibited the growth of four Acanthamoeba species, having a 50{\%} inhibitory concentration (IC50) ranging from 250-526 nM. This effect could be ablated by the addition of 1 mM exogenous free histidine, but importantly not by physiological concentrations found in mammalian tissues. The ability of 3AT and (R)-C348 to restrict the growth of four strains of Acanthamoeba spp. including a recently isolated clinical strain, while not inducing encystment, demonstrates the potential therapeutic utility of targeting the histidine biosynthesis pathway in Acanthamoeba.",
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Rice, CA, Campbell, SJ, Bisson, C, Owen, HJ, Sedelnikova, SE, Baker, PJ, Rice, DW, Henriquez, FL & Roberts, CW 2018, 'Structural and functional studies of histidine biosynthesis in Acanthamoeba spp. demonstrates a novel molecular arrangement and target for antimicrobials' PLOS One, vol. 13, no. 7, e0198827. DOI: 10.1371/journal.pone.0198827

Structural and functional studies of histidine biosynthesis in Acanthamoeba spp. demonstrates a novel molecular arrangement and target for antimicrobials. / Rice, Christopher A.; Campbell, Sara J.; Bisson, Claudine; Owen, Hayley J.; Sedelnikova, Svetlana E.; Baker, Patrick J.; Rice, David W.; Henriquez, Fiona L.; Roberts, Craig W.

In: PLOS One, Vol. 13, No. 7, e0198827, 03.07.2018.

Research output: Contribution to journalArticle

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T1 - Structural and functional studies of histidine biosynthesis in Acanthamoeba spp. demonstrates a novel molecular arrangement and target for antimicrobials

AU - Rice,Christopher A.

AU - Campbell,Sara J.

AU - Bisson,Claudine

AU - Owen,Hayley J.

AU - Sedelnikova,Svetlana E.

AU - Baker,Patrick J.

AU - Rice,David W.

AU - Henriquez,Fiona L.

AU - Roberts,Craig W.

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Rice CA, Campbell SJ, Bisson C, Owen HJ, Sedelnikova SE, Baker PJ et al. Structural and functional studies of histidine biosynthesis in Acanthamoeba spp. demonstrates a novel molecular arrangement and target for antimicrobials. PLOS One. 2018 Jul 3;13(7). e0198827. Available from, DOI: 10.1371/journal.pone.0198827