Abstract
The fluorouridine insensitive 1 (fur1) locus in Arabidopsis thaliana (L.) Heynh. has previously been identified in a screen for growth resistance towards the toxic compound fluorouridine. Mutation of this locus by ethylmethane sulfonate (EMS) allows mutants to grow on this uridine analogue. We identified that the A. thaliana equilibrative nucleoside transporter (AtENT3) was encoded by the fur1 locus. T-DNA insertional mutant plants for AtENT3 resemble the fur1 mutant phenotype: i.e. they grow on fluorouridine, and seedlings as well as leaf discs exhibit a markedly reduced uptake capacity for uridine and cytidine, but a less pronounced reduced uptake for adenosine and guanosine. These results indicate that AtENT3 is an important pyrimidine nucleoside transporter in Arabidopsis. In addition, we identified the mutation in fur1 as a single base-pair exchange, guanine --> adenine, leading to an amino acid exchange G --> R at position 281. Furthermore, we showed that this mutation is indeed responsible for the observed alterations in nucleoside transport in the fur1-1 line, because the introduction of this mutation in AtENT3 promoted fluorouridine resistance in yeast cells expressing this mutated protein. The biochemical characterization of AtENT3 expressed in Xenopus oocytes identified a proton-coupled concentrative mode of nucleoside transport, although this carrier possesses structural features characteristic for equilibrative nucleoside carriers.
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Claims 7
Claim · model-written summary
AtENT3 was identified as the gene encoded by fur1.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Gene
- AtENT3e0
- Outcome
- encoded by the fur1 locuse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the A. thaliana equilibrative nucleoside transporter (AtENT3) was encoded by the fur1 locus”
t0“Arabidopsis thaliana”
Claim · model-written summary
AtENT3 insertion mutants grew on fluorouridine, resembling fur1 mutants.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- T-DNA insertional mutant plants for AtENT3e0
- Gene
- AtENT3e0
- Outcome
- grow on fluorouridinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“T-DNA insertional mutant plants for AtENT3 resemble the fur1 mutant phenotype: i.e. they grow on fluorouridine”
t0“Arabidopsis thaliana”
Claim · model-written summary
AtENT3 insertion mutants had markedly reduced uridine and cytidine uptake.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Organ / stage
- seedlings as well as leaf discse0
- Gene
- AtENT3e1
- Outcome
- uptake capacity for uridine and cytidinee0
- Direction
- markedly reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seedlings as well as leaf discs exhibit a markedly reduced uptake capacity for uridine and cytidine”
e1“T-DNA insertional mutant plants for AtENT3”
t0“Arabidopsis thaliana”
Claim · model-written summary
AtENT3 insertion mutants showed a less pronounced reduction in adenosine and guanosine uptake.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- AtENT3e1
- Outcome
- uptake for adenosine and guanosinee0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a less pronounced reduced uptake for adenosine and guanosine”
e1“T-DNA insertional mutant plants for AtENT3”
t0“Arabidopsis thaliana”
Claim · model-written summary
The fur1 mutation was identified as a guanine-to-adenine base change causing a G-to-R substitution at position 281.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- fur1e0
- Outcome
- single base-pair exchange, guanine --> adenine, leading to an amino acid exchange G --> R at position 281e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mutation in fur1 as a single base-pair exchange, guanine --> adenine, leading to an amino acid exchange G --> R at position 281”
t0“Arabidopsis thaliana”
Claim · model-written summary
Introducing the fur1 mutation into AtENT3 conferred fluorouridine resistance in yeast, supporting its role in altered transport.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- introduction of this mutation in AtENT3e0
- Gene
- AtENT3e0
- Outcome
- fluorouridine resistance in yeast cellse0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the introduction of this mutation in AtENT3 promoted fluorouridine resistance in yeast cells expressing this mutated protein”
t0“Arabidopsis thaliana”
Claim · model-written summary
AtENT3 expressed in Xenopus oocytes showed proton-coupled concentrative nucleoside transport.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- AtENT3e0
- Outcome
- proton-coupled concentrative mode of nucleoside transporte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtENT3 expressed in Xenopus oocytes identified a proton-coupled concentrative mode of nucleoside transport”
t0“Arabidopsis thaliana”
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