Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof
Thesis (PhD)--University of Pretoria, 2013.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | Eng |
| Published: |
University of Pretoria
2014
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613519455715328 |
|---|---|
| access_status_str | Open Access |
| author2 | Birkholtz, Lyn-Marie |
| author_browse | Birkholtz, Lyn-Marie |
| author_facet | Birkholtz, Lyn-Marie |
| collection | Thesis |
| dc_rights_str_mv | © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 2013. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/32965 |
| institution | University of Pretoria (South Africa) |
| language | Eng |
| last_indexed | 2026-06-10T12:37:26.341Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/32965 Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof Birkholtz, Lyn-Marie Reeksting, S.B. (Shaun Bernard) Vitamin b6 PLP Malaria Pyridoxal 5'-phosphate Pdx1 Drug design Plasmodium falciparum Therapeutics UCTD Thesis (PhD)--University of Pretoria, 2013. Malaria is caused by the parasite Plasmodium falciparum and still plagues many parts of the world. To date, efforts to control the spread of the parasites have been largely ineffective. Due to development of resistance by the parasites to current therapeutics there is an urgent need for new classes of therapeutics. The vitamin B6 biosynthetic pathway consists of a PLP synthase which produces pyridoxal 5'-phosphate (PLP) within the parasite. The absence of this pathway in humans makes it attractive for selective targeting using small chemical molecules. The PLP synthase condenses D-ribose 5-phosphate (R5P) and DL-glyceraldehyde 3-phosphate (G3P) with ammonia to form PLP. Two proteins make up this PLP synthase – PfPdx1 and PfPdx2. Computational modelling of Pf Pdx1, and mapping of the R5P-binding site pharmacophore facilitated the identification of several ligands with predicted favourable binding interactions. Confirmatory testing of these on the purified Pf Pdx1 in vitro revealed D-erythrose 4-phosphate (E4P) and an analogue 4-phospho-D-erythronhydrazide (4PEHz) were capable of dose-dependently inhibiting the enzyme. The acyclic tetrose scaffold of E4P, with both aldehyde and phosphate group moieties, was thought to affect R5P imine bond formation in Pf Pdx1, possibly allowing the molecule to enter the R5P-binding site of Pf Pdx1. This hypothesis was supported by molecular docking simulations, and suggested that 4PEHz could similarly enter the R5P-binding site. 4PEHz was detrimental to the proliferation of cultured P. falciparum intraerythrocytic parasites and had an inhibitory concentration (IC50) of 10 µM. The selectivity of 4PEHz in targeting Pf Pdx1 was investigated using transgenic cell lines over-expressing Pf Pdx1 and Pf Pdx2, revealing that complementation of PLP biosynthesis rescued the parasites from the detrimental effects of 4PEHz. Functional transcriptomic and proteomic characterisation of 4PEHz-treated parasites revealed that the expression of Pf Pdx2 increased during 4PEHz treatment, moreover showed that other PLP-related processes were affected. These results supported that Pf Pdx1 is targeted by 4PEHz, and affected PLP biosynthesis de novo. Results from this study allude to alternative regulation of de novo PLP biosynthesis within the parasites by E4P. Moreover, contributions from this work showed that the de novo vitamin B6 pathway of P. falciparum is chemically targetable, and a potential strategy for the development of newer antimalarials. gm2013 Biochemistry Unrestricted 2014-01-09T11:16:05Z 2014-01-09T11:16:05Z 2013-09-06 2013 Thesis Reeksting, S.B. 2013, Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/32965> B13/9/887/gm http://hdl.handle.net/2263/32965 Eng © 2013 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Vitamin b6 PLP Malaria Pyridoxal 5'-phosphate Pdx1 Drug design Plasmodium falciparum Therapeutics UCTD Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof |
| title | Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof |
| title_full | Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof |
| title_fullStr | Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof |
| title_full_unstemmed | Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof |
| title_short | Targeted inhibition of the Plasmodium falciparum Vitamin B6 producing enzyme Pdx1 and the biochemical and functional consequences thereof |
| title_sort | targeted inhibition of the plasmodium falciparum vitamin b6 producing enzyme pdx1 and the biochemical and functional consequences thereof |
| topic | Vitamin b6 PLP Malaria Pyridoxal 5'-phosphate Pdx1 Drug design Plasmodium falciparum Therapeutics UCTD |
| url | http://hdl.handle.net/2263/32965 |