The single cyclic nucleotide-specific phosphodiesterase of the intestinal parasite Giardia lamblia represents a potential drug target.

Kunz, Stefan; Balmer, Vreni; Sterk, Geert Jan; Pollastri, Michael P; Leurs, Rob; Müller, Norbert; Hemphill, Andrew; Spycher, Cornelia (2017). The single cyclic nucleotide-specific phosphodiesterase of the intestinal parasite Giardia lamblia represents a potential drug target. PLoS neglected tropical diseases, 11(9), e0005891. Public Library of Science 10.1371/journal.pntd.0005891

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BACKGROUND Giardiasis is an intestinal infection correlated with poverty and poor drinking water quality, and treatment options are limited. According to the Center for Disease Control and Prevention, Giardia infections afflict nearly 33% of people in developing countries, and 2% of the adult population in the developed world. This study describes the single cyclic nucleotide-specific phosphodiesterase (PDE) of G. lamblia and assesses PDE inhibitors as a new generation of anti-giardial drugs. METHODS An extensive search of the Giardia genome database identified a single gene coding for a class I PDE, GlPDE. The predicted protein sequence was analyzed in-silico to characterize its domain structure and catalytic domain. Enzymatic activity of GlPDE was established by complementation of a PDE-deficient Saccharomyces cerevisiae strain, and enzyme kinetics were characterized in soluble yeast lysates. The potency of known PDE inhibitors was tested against the activity of recombinant GlPDE expressed in yeast and against proliferating Giardia trophozoites. Finally, the localization of epitope-tagged and ectopically expressed GlPDE in Giardia cells was investigated. RESULTS Giardia encodes a class I PDE. Catalytically important residues are fully conserved between GlPDE and human PDEs, but sequence differences between their catalytic domains suggest that designing Giardia-specific inhibitors is feasible. Recombinant GlPDE hydrolyzes cAMP with a Km of 408 μM, and cGMP is not accepted as a substrate. A number of drugs exhibit a high degree of correlation between their potency against the recombinant enzyme and their inhibition of trophozoite proliferation in culture. Epitope-tagged GlPDE localizes as dots in a pattern reminiscent of mitosomes and to the perinuclear region in Giardia. CONCLUSIONS Our data strongly suggest that inhibition of G. lamblia PDE activity leads to a profound inhibition of parasite proliferation and that GlPDE is a promising target for developing novel anti-giardial drugs.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Research Foci > Host-Pathogen Interaction
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Institute of Parasitology
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP)

UniBE Contributor:

Kunz, Stefan; Balmer, Vreni; Müller, Norbert; Hemphill, Andrew and Spycher, Cornelia

Subjects:

600 Technology > 630 Agriculture
500 Science
500 Science > 570 Life sciences; biology

ISSN:

1935-2727

Publisher:

Public Library of Science

Language:

English

Submitter:

Andrew Hemphill

Date Deposited:

17 May 2018 16:57

Last Modified:

16 Aug 2018 15:03

Publisher DOI:

10.1371/journal.pntd.0005891

PubMed ID:

28915270

BORIS DOI:

10.7892/boris.113108

URI:

https://boris.unibe.ch/id/eprint/113108

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