Back to Search
Start Over
Trypanosoma brucei bloodstream forms express highly specific and separate transporters for adenine and hypoxanthine; evidence for a new protozoan purine transporter family?
- Source :
-
Molecular and biochemical parasitology [Mol Biochem Parasitol] 2018 Mar; Vol. 220, pp. 46-56. Date of Electronic Publication: 2018 Jan 31. - Publication Year :
- 2018
-
Abstract
- The transport of nucleobases and nucleosides in protozoan parasites is known to be performed by Equilibrative Nucleoside Transporter (ENT) family members, including the extensively studied P1 and P2 nucleoside transporters of T. brucei bloodstream forms. Studies with P2 knockout parasites suggested the existence of as yet uncharacterised purine transport mechanisms in these cells. Here, we deleted several ENT genes, in addition to P2, including an array comprising three genes encoding for high-affinity broad-selectivity nucleobase transporters - the longest multi-gene locus deletion in T. brucei to date. It was verified that none of them appreciably contributed to the transport of hypoxanthine in bloodstream forms grown axenically in HMI-9 medium, which was mainly performed by a previously not described hypoxanthine-specific transporter (HXT1) with a K <subscript>m</subscript> of 22 ± 1.7 μM and V <subscript>max</subscript> of 0.49 ± 0.06 pmol(10 <superscript>7</superscript> cells) <superscript>-1</superscript> s <superscript>-1</superscript> . The uptake of adenine was also assessed in the knockout cells and was performed by a highly specific adenine transporter (ADET1) with a K <subscript>m</subscript> of 573 ± 62 nM and V <subscript>max</subscript> of 0.23 ± 0.06 pmol(10 <superscript>7</superscript> cells) <superscript>-1</superscript> s <superscript>-1</superscript> . Neither HXT1 nor ADET1 displayed any affinity for other natural purines or pyrimidines and could not be completely inhibited by hypoxanthine or adenine analogues. These carriers may be the final pieces in the substantial transporter array trypanosomes can employ to fine-tune the uptake of purines from diverse environments during their life cycles, and may be encoded by genes other than those of the ENT family.<br /> (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Subjects :
- Culture Media chemistry
Gene Deletion
Kinetics
Nucleobase Transport Proteins genetics
Substrate Specificity
Trypanosoma brucei brucei genetics
Trypanosoma brucei brucei growth & development
Adenine metabolism
Hypoxanthine metabolism
Nucleobase Transport Proteins metabolism
Trypanosoma brucei brucei enzymology
Trypanosoma brucei brucei metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1872-9428
- Volume :
- 220
- Database :
- MEDLINE
- Journal :
- Molecular and biochemical parasitology
- Publication Type :
- Academic Journal
- Accession number :
- 29371154
- Full Text :
- https://doi.org/10.1016/j.molbiopara.2018.01.005