Helicobacter pylori (Hp) is a human pathogen that lives in the gastric mucosa of approximately 50% of the world's population causing gastritis, peptic ulcers, and gastric cancer. An increase in resistance to current drugs has sparked the search for new Hp drug targets and therapeutics. One target is the disruption of nucleic acid production, which can be achieved by impeding the synthesis of 6-oxopurine nucleoside monophosphates, the precursors of DNA and RNA. These metabolites are synthesized by Hp xanthine-guanine-hypoxanthine phosphoribosyltransferase (XGHPRT). Here, nucleoside phosphonates have been evaluated, which inhibit the activity of this enzyme with Ki values as low as 200 nM. The prodrugs of these compounds arrest the growth of Hp at a concentration of 50 μM in cell-based assays. The kinetic properties of HpXGHPRT have been determined together with its X-ray crystal structure in the absence and presence of 9-[(N-3-phosphonopropyl)-aminomethyl-9-deazahypoxanthine, providing a basis for new antibiotic development.
- MeSH
- antibakteriální látky chemie metabolismus farmakologie terapeutické užití MeSH
- bakteriální proteiny chemie metabolismus MeSH
- gastrointestinální nemoci farmakoterapie mikrobiologie patologie MeSH
- Helicobacter pylori účinky léků enzymologie MeSH
- hypoxanthinfosforibosyltransferasa chemie metabolismus MeSH
- hypoxanthiny chemie metabolismus farmakologie terapeutické užití MeSH
- infekce vyvolané Helicobacter pylori farmakoterapie patologie MeSH
- kinetika MeSH
- krystalografie rentgenová MeSH
- lidé MeSH
- organofosfonáty chemie metabolismus farmakologie terapeutické užití MeSH
- pentosyltransferasy chemie metabolismus MeSH
- prekurzory léčiv chemie metabolismus farmakologie terapeutické užití MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- simulace molekulární dynamiky MeSH
- vazebná místa MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The 6-oxopurine phosphoribosyltransferases (PRTs) are drug targets for the treatment of parasitic diseases. This is due to the fact that parasites are auxotrophic for the 6-oxopurine bases relying on salvage enzymes for the synthesis of their 6-oxopurine nucleoside monophosphates. In Trypanosoma brucei, the parasite that is the aetiological agent for sleeping sickness, there are three 6-oxopurine PRT isoforms. Two are specific for hypoxanthine and guanine, whilst the third, characterized here, uses all three naturally occurring bases with similar efficiency. Here, we have determined crystal structures for TbrHGXPRT in complex with GMP, XMP and IMP to investigate the structural basis for substrate specificity. The results show that Y201 and E208, not commonly observed within the purine binding pocket of 6-oxopurine PRTs, contribute to the versatility of this enzyme. The structures further show that a nearby water can act as an adaptor to facilitate the binding of XMP and GMP. When GMP binds, a water can accept a proton from the 2-amino group but when XMP binds, the equivalent water can donate its proton to the 2-oxo group. However, when IMP is bound, no water molecule is observed at that location. DATABASE: Coordinates and structure factors were submitted to the Protein Data Bank and have accession codes of 6MXB, 6MXC, 6MXD and 6MXG for the TbrHGXPRT.XMP complex, TbrHGXPRT.GMP complex, TbrHGXPRT.IMP complex, and TbrHGPRT.XMP complex, respectively.
- MeSH
- inosinmonofosfát chemie metabolismus MeSH
- konformace proteinů MeSH
- kyselina 5'-guanylová chemie metabolismus MeSH
- pentosyltransferasy chemie metabolismus MeSH
- ribonukleotidy chemie metabolismus MeSH
- sekvence aminokyselin MeSH
- substrátová specifita MeSH
- Trypanosoma brucei brucei enzymologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) are the foremost causative agents of malaria. Due to the development of resistance to current antimalarial medications, new drugs for this parasitic disease need to be discovered. The activity of hypoxanthine-guanine-[xanthine]-phosphoribosyltransferase, HG[X]PRT, is reported to be essential for the growth of both of these parasites, making it an excellent target for antimalarial drug discovery. Here, we have used rational structure-based methods to design an inhibitor, [3R,4R]-4-guanin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine, of PvHGPRT and PfHGXPRT that has Ki values of 8 and 7 nM, respectively, for these two enzymes. The crystal structure of PvHGPRT in complex with this compound has been determined to 2.85 Å resolution. The corresponding complex with human HGPRT was also obtained to allow a direct comparison of the binding modes of this compound with the two enzymes. The tetra-(ethyl l-phenylalanine) tetraamide prodrug of this compound was synthesized, and it has an IC50 of 11.7 ± 3.2 μM against Pf lines grown in culture and a CC50 in human A549 cell lines of 102 ± 11 μM, thus giving it a ∼10-fold selectivity index.
- MeSH
- antimalarika chemie farmakologie MeSH
- bisfosfonáty chemie farmakologie MeSH
- hypoxanthinfosforibosyltransferasa antagonisté a inhibitory chemie metabolismus MeSH
- katalytická doména MeSH
- konformace proteinů MeSH
- krystalografie rentgenová MeSH
- lidé MeSH
- molekulární modely MeSH
- pentosyltransferasy antagonisté a inhibitory chemie metabolismus MeSH
- Plasmodium vivax enzymologie MeSH
- proteiny z Escherichia coli chemie MeSH
- racionální návrh léčiv MeSH
- techniky syntetické chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Due to toxicity and compliance issues and the emergence of resistance to current medications new drugs for the treatment of Human African Trypanosomiasis are needed. A potential approach to developing novel anti-trypanosomal drugs is by inhibition of the 6-oxopurine salvage pathways which synthesise the nucleoside monophosphates required for DNA/RNA production. This is in view of the fact that trypanosomes lack the machinery for de novo synthesis of the purine ring. To provide validation for this approach as a drug target, we have RNAi silenced the three 6-oxopurine phosphoribosyltransferase (PRTase) isoforms in the infectious stage of Trypanosoma brucei demonstrating that the combined activity of these enzymes is critical for the parasites' viability. Furthermore, we have determined crystal structures of two of these isoforms in complex with several acyclic nucleoside phosphonates (ANPs), a class of compound previously shown to inhibit 6-oxopurine PRTases from several species including Plasmodium falciparum. The most potent of these compounds have Ki values as low as 60 nM, and IC50 values in cell based assays as low as 4 μM. This data provides a solid platform for further investigations into the use of this pathway as a target for anti-trypanosomal drug discovery.
- MeSH
- hypoxanthinfosforibosyltransferasa antagonisté a inhibitory chemie genetika metabolismus MeSH
- inhibitory enzymů chemie farmakologie MeSH
- katalytická doména MeSH
- lidé MeSH
- metabolické sítě a dráhy účinky léků MeSH
- molekulární modely MeSH
- objevování léků MeSH
- pentosyltransferasy antagonisté a inhibitory chemie genetika metabolismus MeSH
- purinony metabolismus MeSH
- RNA interference MeSH
- trypanocidální látky chemie farmakologie MeSH
- Trypanosoma brucei brucei účinky léků enzymologie genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Acyclic nucleoside phosphonates (ANPs) are a recognized class of antiviral and anticancer agents. Since the discovery of ANPs in the mid-1980s, ANPs have gained recognition in pharmaceutical research. Approvals of cidofovir (Vistide®) in 1996 and especially of tenofovir (disoproxyl fumarate, Viread®) in 2001 were important milestones in research of ANPs. It became clear that this class of antivirals has a full potential for the use in human medicine. The biological activity of ANPs is not restricted to antiviral and anticancer effects. This review highlights novel types of ANPs with antimalarial properties. The malarial parasites Plasmodium falciparum (Pf) and P. vivax (Pv) lack de novo pathway for synthesis of purine bases and rely on a salvage pathway enzyme, hypoxanthineguanine-( xanthine) phosphoribosyltransferase (HG(X)PRT) for the synthesis of 6-oxopurine nucleoside monophosphates. Specific ANPs can act as analogues of the enzymatic reaction products. They inhibit PfHGXPRT and/or PvHGPRT and show an antiplasmodial activity in vitro. In particular aza-ANP and bisphosphonate analogues were shown to become promising potential antimalarials.
- Klíčová slova
- 6-oxopurinfosforibosyltransferasa,
- MeSH
- antimalarika * farmakokinetika farmakologie chemie klasifikace terapeutické užití MeSH
- antivirové látky farmakokinetika farmakologie chemie klasifikace terapeutické užití MeSH
- inhibitory enzymů terapeutické užití MeSH
- lidé MeSH
- malárie * farmakoterapie MeSH
- nukleotidy farmakokinetika farmakologie chemie klasifikace terapeutické užití MeSH
- pentosyltransferasy farmakokinetika farmakologie chemie terapeutické užití MeSH
- Plasmodium účinky léků MeSH
- prekurzory léčiv MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
