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Degradation of MONOCULM 1 by APC/C(TAD1) regulates rice tillering.

Xu C, Wang Y, Yu Y, Duan J, Liao Z, Xiong G, Meng X, Liu G, Qian Q, Li J - Nat Commun (2012)

Bottom Line: A rice tiller is a specialized grain-bearing branch that contributes greatly to grain yield.Although the elucidation of co-activators and individual subunits of plant APC/C involved in regulating plant development have emerged recently, the understanding of whether and how this large cell-cycle machinery controls plant development is still very limited.Our findings uncovered a new mechanism underlying shoot branching and shed light on the understanding of how the cell-cycle machinery regulates plant architecture.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT
A rice tiller is a specialized grain-bearing branch that contributes greatly to grain yield. The MONOCULM 1 (MOC1) gene is the first identified key regulator controlling rice tiller number; however, the underlying mechanism remains to be elucidated. Here we report a novel rice gene, Tillering and Dwarf 1 (TAD1), which encodes a co-activator of the anaphase-promoting complex (APC/C), a multi-subunit E3 ligase. Although the elucidation of co-activators and individual subunits of plant APC/C involved in regulating plant development have emerged recently, the understanding of whether and how this large cell-cycle machinery controls plant development is still very limited. Our study demonstrates that TAD1 interacts with MOC1, forms a complex with OsAPC10 and functions as a co-activator of APC/C to target MOC1 for degradation in a cell-cycle-dependent manner. Our findings uncovered a new mechanism underlying shoot branching and shed light on the understanding of how the cell-cycle machinery regulates plant architecture.

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Determination of the interaction between TAD1 and MOC1 by coimmunoprecipitation and BiFC assays.(a) The conserved D-box motif at the MOC1 N-terminal and its mutated construct (mMOC1). (b) In vivo interaction between TAD1 and MOC1 revealed by the coimmunoprecipitation assay. (c) BiFC analysis of interaction between MOC1 and TAD1 in rice protoplasts. Scale bars, 10 μm. (d) Schematic representation of the truncated TAD1 proteins. Blue box refers to C-box, green to CSM, pink to WD repeats, white to RVL, and red to IR. (e) BiFC analyses of in vivo interaction between MOC1 and truncated TAD1 proteins indicated in (d). Scale bars, 10 μm.
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f4: Determination of the interaction between TAD1 and MOC1 by coimmunoprecipitation and BiFC assays.(a) The conserved D-box motif at the MOC1 N-terminal and its mutated construct (mMOC1). (b) In vivo interaction between TAD1 and MOC1 revealed by the coimmunoprecipitation assay. (c) BiFC analysis of interaction between MOC1 and TAD1 in rice protoplasts. Scale bars, 10 μm. (d) Schematic representation of the truncated TAD1 proteins. Blue box refers to C-box, green to CSM, pink to WD repeats, white to RVL, and red to IR. (e) BiFC analyses of in vivo interaction between MOC1 and truncated TAD1 proteins indicated in (d). Scale bars, 10 μm.

Mentions: The APC complex has been known to target its substrates conferred by co-activators (Cdc20 and Cdh1) through recognition of destruction motifs, predominantly the destruction box (D-box) and KEN-box3839. The amino-terminal D-box has been shown to have a critical role in directing the APC complex when recognizing its substrates38. Sequence analysis revealed that MOC1 harbours a typical D-box at the N-terminal (Fig. 4a). Therefore, it is very likely that MOC1 and TAD1 directly interact to control rice tillering. To investigate the interaction between MOC1 and TAD1, we carried out coimmunoprecipitation experiments by coexpressing TAD1–FLAG and MOC1–green fluorescent protein (MOC1–GFP) fusion proteins in protoplasts generated from rice suspension cells. The result showed that the MOC1–GFP fusion protein could capture the TAD1–FLAG fusion protein, suggesting an in vivo interaction between MOC1 and TAD1 (Fig. 4b). The interaction was further examined through a bimolecular fluorescence complementation (BiFC) analysis. As shown in Fig. 4c, when the full-length cDNAs of TAD1 and MOC1 were introduced into rice protoplasts simultaneously, the fluorescence signal was detected in the nucleus, indicating that TAD1 can directly interact with MOC1 in the nucleus. Furthermore, when two conserved residues, arginine and leucine, of the D-box at the N-terminal were changed into alanine (Fig. 4a), the MOC1 protein was unable to interact with TAD1, demonstrating that the D-box is indispensable for the interaction between MOC1 and TAD1 (Fig. 4c). In addition, a series of truncated TAD1 proteins were generated to determine the domains that are essential for the interaction with MOC1 via the BiFC analysis (Fig. 4d). The results showed that the N-terminal 203 amino acids of TAD1 are sufficient to interact with MOC1. However, the truncation mutant at C456, which lacks the N-terminal 67 amino acids of TAD1, could not recognize MOC1 in the BiFC analysis, suggesting that the 67-amino-acid N-terminal of TAD1 appears to be essential for its interaction with MOC1 (Fig. 4e).


Degradation of MONOCULM 1 by APC/C(TAD1) regulates rice tillering.

Xu C, Wang Y, Yu Y, Duan J, Liao Z, Xiong G, Meng X, Liu G, Qian Q, Li J - Nat Commun (2012)

Determination of the interaction between TAD1 and MOC1 by coimmunoprecipitation and BiFC assays.(a) The conserved D-box motif at the MOC1 N-terminal and its mutated construct (mMOC1). (b) In vivo interaction between TAD1 and MOC1 revealed by the coimmunoprecipitation assay. (c) BiFC analysis of interaction between MOC1 and TAD1 in rice protoplasts. Scale bars, 10 μm. (d) Schematic representation of the truncated TAD1 proteins. Blue box refers to C-box, green to CSM, pink to WD repeats, white to RVL, and red to IR. (e) BiFC analyses of in vivo interaction between MOC1 and truncated TAD1 proteins indicated in (d). Scale bars, 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3316885&req=5

f4: Determination of the interaction between TAD1 and MOC1 by coimmunoprecipitation and BiFC assays.(a) The conserved D-box motif at the MOC1 N-terminal and its mutated construct (mMOC1). (b) In vivo interaction between TAD1 and MOC1 revealed by the coimmunoprecipitation assay. (c) BiFC analysis of interaction between MOC1 and TAD1 in rice protoplasts. Scale bars, 10 μm. (d) Schematic representation of the truncated TAD1 proteins. Blue box refers to C-box, green to CSM, pink to WD repeats, white to RVL, and red to IR. (e) BiFC analyses of in vivo interaction between MOC1 and truncated TAD1 proteins indicated in (d). Scale bars, 10 μm.
Mentions: The APC complex has been known to target its substrates conferred by co-activators (Cdc20 and Cdh1) through recognition of destruction motifs, predominantly the destruction box (D-box) and KEN-box3839. The amino-terminal D-box has been shown to have a critical role in directing the APC complex when recognizing its substrates38. Sequence analysis revealed that MOC1 harbours a typical D-box at the N-terminal (Fig. 4a). Therefore, it is very likely that MOC1 and TAD1 directly interact to control rice tillering. To investigate the interaction between MOC1 and TAD1, we carried out coimmunoprecipitation experiments by coexpressing TAD1–FLAG and MOC1–green fluorescent protein (MOC1–GFP) fusion proteins in protoplasts generated from rice suspension cells. The result showed that the MOC1–GFP fusion protein could capture the TAD1–FLAG fusion protein, suggesting an in vivo interaction between MOC1 and TAD1 (Fig. 4b). The interaction was further examined through a bimolecular fluorescence complementation (BiFC) analysis. As shown in Fig. 4c, when the full-length cDNAs of TAD1 and MOC1 were introduced into rice protoplasts simultaneously, the fluorescence signal was detected in the nucleus, indicating that TAD1 can directly interact with MOC1 in the nucleus. Furthermore, when two conserved residues, arginine and leucine, of the D-box at the N-terminal were changed into alanine (Fig. 4a), the MOC1 protein was unable to interact with TAD1, demonstrating that the D-box is indispensable for the interaction between MOC1 and TAD1 (Fig. 4c). In addition, a series of truncated TAD1 proteins were generated to determine the domains that are essential for the interaction with MOC1 via the BiFC analysis (Fig. 4d). The results showed that the N-terminal 203 amino acids of TAD1 are sufficient to interact with MOC1. However, the truncation mutant at C456, which lacks the N-terminal 67 amino acids of TAD1, could not recognize MOC1 in the BiFC analysis, suggesting that the 67-amino-acid N-terminal of TAD1 appears to be essential for its interaction with MOC1 (Fig. 4e).

Bottom Line: A rice tiller is a specialized grain-bearing branch that contributes greatly to grain yield.Although the elucidation of co-activators and individual subunits of plant APC/C involved in regulating plant development have emerged recently, the understanding of whether and how this large cell-cycle machinery controls plant development is still very limited.Our findings uncovered a new mechanism underlying shoot branching and shed light on the understanding of how the cell-cycle machinery regulates plant architecture.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT
A rice tiller is a specialized grain-bearing branch that contributes greatly to grain yield. The MONOCULM 1 (MOC1) gene is the first identified key regulator controlling rice tiller number; however, the underlying mechanism remains to be elucidated. Here we report a novel rice gene, Tillering and Dwarf 1 (TAD1), which encodes a co-activator of the anaphase-promoting complex (APC/C), a multi-subunit E3 ligase. Although the elucidation of co-activators and individual subunits of plant APC/C involved in regulating plant development have emerged recently, the understanding of whether and how this large cell-cycle machinery controls plant development is still very limited. Our study demonstrates that TAD1 interacts with MOC1, forms a complex with OsAPC10 and functions as a co-activator of APC/C to target MOC1 for degradation in a cell-cycle-dependent manner. Our findings uncovered a new mechanism underlying shoot branching and shed light on the understanding of how the cell-cycle machinery regulates plant architecture.

Show MeSH
Related in: MedlinePlus