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Grain setting defect1 (GSD1) function in rice depends on S-acylation and interacts with actin 1 (OsACT1) at its C-terminal.

Gui J, Zheng S, Shen J, Li L - Front Plant Sci (2015)

Bottom Line: Association with the PM is mediated by S-acylation of cysteine residues Cys-524 and Cys-527, in a sequence of 45 amino acid residues essential for GSD1 function in rice.Furthermore, the coiled-coil domain in GSD1 is necessary for sufficient interaction with OsACT1.Together, these results reveal that GSD1 attaches to the PM through S-acylation and interacts with OsACT1 through its coiled-coil domain structure to regulate plasmodesmata conductance for photoassimilate transport in rice.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences Shanghai, China.

ABSTRACT
Grain setting defect1 (GSD1), a plant-specific remorin protein specifically localized at the plasma membrane (PM) and plasmodesmata of phloem companion cells, affects grain setting in rice through regulating the transport of photoassimilates. Here, we show new evidence demonstrating that GSD1 is localized at the cytoplasmic face of the PM and a stretch of 45 amino acid residues at its C-terminal is required for its localization. Association with the PM is mediated by S-acylation of cysteine residues Cys-524 and Cys-527, in a sequence of 45 amino acid residues essential for GSD1 function in rice. Furthermore, the coiled-coil domain in GSD1 is necessary for sufficient interaction with OsACT1. Together, these results reveal that GSD1 attaches to the PM through S-acylation and interacts with OsACT1 through its coiled-coil domain structure to regulate plasmodesmata conductance for photoassimilate transport in rice.

No MeSH data available.


Related in: MedlinePlus

S-acylation is crucial for GSD1 regulation of the PD conductance. (A) and (B) Statistical analyses of grain setting rate (A) and spikelet number (B) in WT, GSD1 cysteine mutants (GSD1M3OX, GSD1M6OX, GSD1M7OX) and GSD1 deletion mutant (GSD1ΔCOX) transgenic plants. Values are means ± SE of 15 independent plants. (C) Quantitative RT-PCR analyses of the GSD1 expression in panicles at flowering stage. Results are means ± SE of three individual samples. (D–F) Measurement of the 13C-labeled sucrose in flag leaf blades (D), flag leaf sheaths (E) and phloem exudate (F) after flag leaf blade photosynthesis fed with 13CO2.
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Figure 6: S-acylation is crucial for GSD1 regulation of the PD conductance. (A) and (B) Statistical analyses of grain setting rate (A) and spikelet number (B) in WT, GSD1 cysteine mutants (GSD1M3OX, GSD1M6OX, GSD1M7OX) and GSD1 deletion mutant (GSD1ΔCOX) transgenic plants. Values are means ± SE of 15 independent plants. (C) Quantitative RT-PCR analyses of the GSD1 expression in panicles at flowering stage. Results are means ± SE of three individual samples. (D–F) Measurement of the 13C-labeled sucrose in flag leaf blades (D), flag leaf sheaths (E) and phloem exudate (F) after flag leaf blade photosynthesis fed with 13CO2.

Mentions: Deletion of the 12 C-terminal amino acid residues and mutation of the Cys-524 and Cys-527 residues in GSD1, which abolishes GSD1 S-acylation, results in the disassociation of GSD1 from the PM. We next investigated how the deletions and mutations affected the functionality of GSD1 in rice. Our previous study demonstrated that GSD1 overexpression (GSD1OX) caused a reduction in grain setting in rice as a result of inhibiting photoassimilate transport. Four modified GSD1 constructs (a GSD1 deletion of the 12 amino acid sequence in the C-terminal, GSD1ΔC and the three cysteine mutants, GSD1M3, GSD1M6, and GSD1M7) were constructed and overexpressed in rice to generate GSD1ΔCOX, GSD1M3OX, GSD1M6OX, and GSD1M7OX transgenics. 15 independent transgenic lines from each construct were examined and results showed that GSD1M6OX and GSD1M7OX transgenic rice plants similar to GSD1OX exhibited obvious defects in grain setting compared with wild-type, whereas GSD1ΔCOX and GSD1M3OX transgenics exhibited no obvious defects in grain setting in compared with the wild-type, despite all of the transgenics displaying similar expression level (Figures 6A,C). Spikelet number in GSD1M6OX and GSD1M7OX transgenics were also significantly reduced as compared to the wild-type, GSD1ΔCOX or GSD1M3OX transgenics (Figure 6B).


Grain setting defect1 (GSD1) function in rice depends on S-acylation and interacts with actin 1 (OsACT1) at its C-terminal.

Gui J, Zheng S, Shen J, Li L - Front Plant Sci (2015)

S-acylation is crucial for GSD1 regulation of the PD conductance. (A) and (B) Statistical analyses of grain setting rate (A) and spikelet number (B) in WT, GSD1 cysteine mutants (GSD1M3OX, GSD1M6OX, GSD1M7OX) and GSD1 deletion mutant (GSD1ΔCOX) transgenic plants. Values are means ± SE of 15 independent plants. (C) Quantitative RT-PCR analyses of the GSD1 expression in panicles at flowering stage. Results are means ± SE of three individual samples. (D–F) Measurement of the 13C-labeled sucrose in flag leaf blades (D), flag leaf sheaths (E) and phloem exudate (F) after flag leaf blade photosynthesis fed with 13CO2.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590517&req=5

Figure 6: S-acylation is crucial for GSD1 regulation of the PD conductance. (A) and (B) Statistical analyses of grain setting rate (A) and spikelet number (B) in WT, GSD1 cysteine mutants (GSD1M3OX, GSD1M6OX, GSD1M7OX) and GSD1 deletion mutant (GSD1ΔCOX) transgenic plants. Values are means ± SE of 15 independent plants. (C) Quantitative RT-PCR analyses of the GSD1 expression in panicles at flowering stage. Results are means ± SE of three individual samples. (D–F) Measurement of the 13C-labeled sucrose in flag leaf blades (D), flag leaf sheaths (E) and phloem exudate (F) after flag leaf blade photosynthesis fed with 13CO2.
Mentions: Deletion of the 12 C-terminal amino acid residues and mutation of the Cys-524 and Cys-527 residues in GSD1, which abolishes GSD1 S-acylation, results in the disassociation of GSD1 from the PM. We next investigated how the deletions and mutations affected the functionality of GSD1 in rice. Our previous study demonstrated that GSD1 overexpression (GSD1OX) caused a reduction in grain setting in rice as a result of inhibiting photoassimilate transport. Four modified GSD1 constructs (a GSD1 deletion of the 12 amino acid sequence in the C-terminal, GSD1ΔC and the three cysteine mutants, GSD1M3, GSD1M6, and GSD1M7) were constructed and overexpressed in rice to generate GSD1ΔCOX, GSD1M3OX, GSD1M6OX, and GSD1M7OX transgenics. 15 independent transgenic lines from each construct were examined and results showed that GSD1M6OX and GSD1M7OX transgenic rice plants similar to GSD1OX exhibited obvious defects in grain setting compared with wild-type, whereas GSD1ΔCOX and GSD1M3OX transgenics exhibited no obvious defects in grain setting in compared with the wild-type, despite all of the transgenics displaying similar expression level (Figures 6A,C). Spikelet number in GSD1M6OX and GSD1M7OX transgenics were also significantly reduced as compared to the wild-type, GSD1ΔCOX or GSD1M3OX transgenics (Figure 6B).

Bottom Line: Association with the PM is mediated by S-acylation of cysteine residues Cys-524 and Cys-527, in a sequence of 45 amino acid residues essential for GSD1 function in rice.Furthermore, the coiled-coil domain in GSD1 is necessary for sufficient interaction with OsACT1.Together, these results reveal that GSD1 attaches to the PM through S-acylation and interacts with OsACT1 through its coiled-coil domain structure to regulate plasmodesmata conductance for photoassimilate transport in rice.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences Shanghai, China.

ABSTRACT
Grain setting defect1 (GSD1), a plant-specific remorin protein specifically localized at the plasma membrane (PM) and plasmodesmata of phloem companion cells, affects grain setting in rice through regulating the transport of photoassimilates. Here, we show new evidence demonstrating that GSD1 is localized at the cytoplasmic face of the PM and a stretch of 45 amino acid residues at its C-terminal is required for its localization. Association with the PM is mediated by S-acylation of cysteine residues Cys-524 and Cys-527, in a sequence of 45 amino acid residues essential for GSD1 function in rice. Furthermore, the coiled-coil domain in GSD1 is necessary for sufficient interaction with OsACT1. Together, these results reveal that GSD1 attaches to the PM through S-acylation and interacts with OsACT1 through its coiled-coil domain structure to regulate plasmodesmata conductance for photoassimilate transport in rice.

No MeSH data available.


Related in: MedlinePlus