Abstract
The P1B ATPase heavy metal ATPase 4 (HMA4) is responsible for zinc and cadmium translocation from roots to shoots in Arabidopsis thaliana. It couples ATP hydrolysis to cytosolic domain movements, enabling metal transport across the membrane. The detailed mechanism of metal permeation by HMA4 through the membrane remains elusive. Here, homology modeling of the HMA4 transmembrane region was conducted based on the crystal structure of a ZntA bacterial homolog. The analysis highlighted amino acids forming a metal permeation pathway, whose importance was subsequently investigated functionally through mutagenesis and complementation experiments in plants. Although the zinc pathway displayed overall conservation among the two proteins, significant differences were observed, especially in the entrance area with altered electronegativity and the presence of a ionic interaction/hydrogen bond network. The analysis also newly identified amino acids whose mutation results in total or partial loss of the protein function. In addition, comparison of zinc and cadmium accumulation in shoots of A. thaliana complemented lines revealed a number of HMA4 mutants exhibiting different abilities in zinc and cadmium translocation. These observations could be instrumental to design low cadmium-accumulating crops, hence decreasing human cadmium exposure.
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Claims 5
Claim · model-written summary
HMA4 and its bacterial homolog had broadly conserved zinc pathways, with entrance-region differences.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae1 - Gene
- HMA4e1
- Outcome
- zinc pathway displayed overall conservatione0
- Qualifier
- significant differencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Although the zinc pathway displayed overall conservation among the two proteins, significant differences were observed, especially in the entrance area with altered electronegativity and the presence of a ionic interaction/hydrogen bond network.”
e1“The P1B ATPase heavy metal ATPase 4 (HMA4) is responsible for zinc and cadmium translocation from roots to shoots in Arabidopsis thaliana.”
Claim · model-written summary
The pathway entrance differed in electronegativity and ionic or hydrogen-bond network.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Organ / stage
- entrance areae0
- Gene
- HMA4e1
- Outcome
- altered electronegativity and the presence of a ionic interaction/hydrogen bond networke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant differences were observed, especially in the entrance area with altered electronegativity and the presence of a ionic interaction/hydrogen bond network.”
e1“The P1B ATPase heavy metal ATPase 4 (HMA4) is responsible for zinc and cadmium translocation from roots to shoots in Arabidopsis thaliana.”
Claim · model-written summary
Newly identified amino acids lost all or some protein function when mutated.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- mutatione0
- Gene
- HMA4e1
- Outcome
- protein functione0
- Direction
- losse0
- Qualifier
- total or partiale0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The analysis also newly identified amino acids whose mutation results in total or partial loss of the protein function.”
e1“The P1B ATPase heavy metal ATPase 4 (HMA4) is responsible for zinc and cadmium translocation from roots to shoots in Arabidopsis thaliana.”
Claim · model-written summary
HMA4 mutants differed in their zinc translocation ability.
- Taxon
- A. thalianaArabidopsis thalianae0
- Material
- mutantse0
- Organ / stage
- shootse0
- Gene
- HMA4e0
- Outcome
- zinc and cadmium translocatione0
- Direction
- differente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“comparison of zinc and cadmium accumulation in shoots of A. thaliana complemented lines revealed a number of HMA4 mutants exhibiting different abilities in zinc and cadmium translocation.”
Claim · model-written summary
HMA4 mutants differed in cadmium translocation ability.
- Taxon
- A. thalianaArabidopsis thalianae0
- Material
- mutantse0
- Organ / stage
- shootse0
- Gene
- HMA4e0
- Outcome
- cadmium translocatione0
- Direction
- differente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“comparison of zinc and cadmium accumulation in shoots of A. thaliana complemented lines revealed a number of HMA4 mutants exhibiting different abilities in zinc and cadmium translocation.”
The same questions in other papers
loss of function · quality: protein · Arabidopsis thaliana (thale cress)Positive and negative results
7 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- negative
5 papers more in this group
See all 9 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.