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The conservative cysteines in transmembrane domain of AtVKOR/LTO1 are critical for photosynthetic growth and photosystem II activity in Arabidopsis.

Du JJ, Zhan CY, Lu Y, Cui HR, Wang XY - Front Plant Sci (2015)

Bottom Line: Consistently, the maximum and actual efficiency of photosystem II (PSII) in double-cysteine mutation plants decreased significantly to the level similar to that of the vkor mutant line both under normal growth light and high light.A significantly decreased amount of D1 protein and increased accumulation of reactive oxygen species were observed in two double-cysteine mutations under high light.All of the results above indicated that the conservative cysteines in transmembrane domains were the functional sites of AtVKOR in Arabidopsis and that the oxidoreductase activities of AtVKOR were directly related to the autotrophic photosynthetic growth and PSII activity of Arabidopsis thaliana.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University Tai´an, China.

ABSTRACT
Thylakoid protein vitamin K epoxide reductase (AtVKOR/LTO1) is involved in oxidoreduction. The deficiency of this compound causes pleiotropic defects in Arabidopsis thaliana, such as severely stunted growth, smaller sized leaves, and delay of flowering. Transgenic complementation of wild-type AtVKOR (VKORWT) to vkor mutant lines ultimately demonstrates that the phenotype changes are due to this gene. However, whether AtVKOR functions in Arabidopsis through its protein oxidoreduction is unknown. To further study the redox-active sites of AtVKOR in vivo, a series of plasmids containing cysteine-mutant VKORs were constructed and transformed into vkor deficient lines. Compared with transgenic AtVKORWT plants, the size of the transgenic plants with a single conservative cysteine mutation (VKORC109A, VKORC116A, VKORC195A, and VKORC198A) were smaller, and two double-cysteine mutations (VKORC109AC116A and VKORC195AC198A) showed significantly stunted growth, similar with the vkor mutant line. However, mutations of two non-conservative cysteines (VKORC46A and VKORC230A) displayed little obvious changes in the phenotypes of Arabidopsis. Consistently, the maximum and actual efficiency of photosystem II (PSII) in double-cysteine mutation plants decreased significantly to the level similar to that of the vkor mutant line both under normal growth light and high light. A significantly decreased amount of D1 protein and increased accumulation of reactive oxygen species were observed in two double-cysteine mutations under high light. All of the results above indicated that the conservative cysteines in transmembrane domains were the functional sites of AtVKOR in Arabidopsis and that the oxidoreductase activities of AtVKOR were directly related to the autotrophic photosynthetic growth and PSII activity of Arabidopsis thaliana.

No MeSH data available.


Related in: MedlinePlus

Characteristics of cysteine-mutant AtVKORs plants. (A) The phenotypes of cysteine-mutant AtVKORs plants; plants were grown on soil for 8 weeks under normal growth conditions. (B) Transcriptional level analysis of AtVKOR in plants of cysteine-mutant AtVKORs.
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Figure 1: Characteristics of cysteine-mutant AtVKORs plants. (A) The phenotypes of cysteine-mutant AtVKORs plants; plants were grown on soil for 8 weeks under normal growth conditions. (B) Transcriptional level analysis of AtVKOR in plants of cysteine-mutant AtVKORs.

Mentions: Six cysteines exist in the transmembrane domain of AtVKOR, including two non-conservative cysteines (Cys46, Cys230) and four conservative cysteines forming two pairs (Cys109/Cys116 and Cys195/Cys198) (Feng et al., 2011). Single/double-cysteine(s) mutant VKORs and wild-type AtVKOR (VKORWT) were successfully expressed in vkor mutant lines, respectively (Figure 1B). The representative phenotypes of the vkor homozygosities with the insertion of cysteine-mutant VKORs are shown in Figure 1A. While the AtVKORWT transgenic plants can completely recover the phenotype defects in the vkor line, transgenic plants with a single conservative cysteine mutation (AtVKORC109A, AtVKORC116A, AtVKORC195A, AtVKORC198A) did only partly recover the phenotype defects in the vkor mutant lines (Figure 1A). When double conservative cysteines were mutated to alanines, the AtVKORC109AC116A and AtVKORC195AC198A transgenic plants completely lost the ability to compensate for these defects in the vkor mutant, displaying significantly stunted growth, smaller sized leaves, and delayed flowering, quite similar to the defects of the vkor mutant line. However, the transgenic plants with non-conservative cysteine mutations (AtVKORC46A, AtVKORC230A) showed no obvious difference, compared with WT plants and AtVKORWT plants.


The conservative cysteines in transmembrane domain of AtVKOR/LTO1 are critical for photosynthetic growth and photosystem II activity in Arabidopsis.

Du JJ, Zhan CY, Lu Y, Cui HR, Wang XY - Front Plant Sci (2015)

Characteristics of cysteine-mutant AtVKORs plants. (A) The phenotypes of cysteine-mutant AtVKORs plants; plants were grown on soil for 8 weeks under normal growth conditions. (B) Transcriptional level analysis of AtVKOR in plants of cysteine-mutant AtVKORs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400859&req=5

Figure 1: Characteristics of cysteine-mutant AtVKORs plants. (A) The phenotypes of cysteine-mutant AtVKORs plants; plants were grown on soil for 8 weeks under normal growth conditions. (B) Transcriptional level analysis of AtVKOR in plants of cysteine-mutant AtVKORs.
Mentions: Six cysteines exist in the transmembrane domain of AtVKOR, including two non-conservative cysteines (Cys46, Cys230) and four conservative cysteines forming two pairs (Cys109/Cys116 and Cys195/Cys198) (Feng et al., 2011). Single/double-cysteine(s) mutant VKORs and wild-type AtVKOR (VKORWT) were successfully expressed in vkor mutant lines, respectively (Figure 1B). The representative phenotypes of the vkor homozygosities with the insertion of cysteine-mutant VKORs are shown in Figure 1A. While the AtVKORWT transgenic plants can completely recover the phenotype defects in the vkor line, transgenic plants with a single conservative cysteine mutation (AtVKORC109A, AtVKORC116A, AtVKORC195A, AtVKORC198A) did only partly recover the phenotype defects in the vkor mutant lines (Figure 1A). When double conservative cysteines were mutated to alanines, the AtVKORC109AC116A and AtVKORC195AC198A transgenic plants completely lost the ability to compensate for these defects in the vkor mutant, displaying significantly stunted growth, smaller sized leaves, and delayed flowering, quite similar to the defects of the vkor mutant line. However, the transgenic plants with non-conservative cysteine mutations (AtVKORC46A, AtVKORC230A) showed no obvious difference, compared with WT plants and AtVKORWT plants.

Bottom Line: Consistently, the maximum and actual efficiency of photosystem II (PSII) in double-cysteine mutation plants decreased significantly to the level similar to that of the vkor mutant line both under normal growth light and high light.A significantly decreased amount of D1 protein and increased accumulation of reactive oxygen species were observed in two double-cysteine mutations under high light.All of the results above indicated that the conservative cysteines in transmembrane domains were the functional sites of AtVKOR in Arabidopsis and that the oxidoreductase activities of AtVKOR were directly related to the autotrophic photosynthetic growth and PSII activity of Arabidopsis thaliana.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University Tai´an, China.

ABSTRACT
Thylakoid protein vitamin K epoxide reductase (AtVKOR/LTO1) is involved in oxidoreduction. The deficiency of this compound causes pleiotropic defects in Arabidopsis thaliana, such as severely stunted growth, smaller sized leaves, and delay of flowering. Transgenic complementation of wild-type AtVKOR (VKORWT) to vkor mutant lines ultimately demonstrates that the phenotype changes are due to this gene. However, whether AtVKOR functions in Arabidopsis through its protein oxidoreduction is unknown. To further study the redox-active sites of AtVKOR in vivo, a series of plasmids containing cysteine-mutant VKORs were constructed and transformed into vkor deficient lines. Compared with transgenic AtVKORWT plants, the size of the transgenic plants with a single conservative cysteine mutation (VKORC109A, VKORC116A, VKORC195A, and VKORC198A) were smaller, and two double-cysteine mutations (VKORC109AC116A and VKORC195AC198A) showed significantly stunted growth, similar with the vkor mutant line. However, mutations of two non-conservative cysteines (VKORC46A and VKORC230A) displayed little obvious changes in the phenotypes of Arabidopsis. Consistently, the maximum and actual efficiency of photosystem II (PSII) in double-cysteine mutation plants decreased significantly to the level similar to that of the vkor mutant line both under normal growth light and high light. A significantly decreased amount of D1 protein and increased accumulation of reactive oxygen species were observed in two double-cysteine mutations under high light. All of the results above indicated that the conservative cysteines in transmembrane domains were the functional sites of AtVKOR in Arabidopsis and that the oxidoreductase activities of AtVKOR were directly related to the autotrophic photosynthetic growth and PSII activity of Arabidopsis thaliana.

No MeSH data available.


Related in: MedlinePlus