TY - JOUR
T1 - A deleterious Sar1c variant in rice inhibits export of seed storage proteins from the endoplasmic reticulum
AU - Bao, Xiuhao
AU - Wang, Yongfei
AU - Qi, Yanzhou
AU - Lei, Cailin
AU - Wang, Yunlong
AU - Pan, Tian
AU - Yu, Mingzhou
AU - Zhang, Yu
AU - Wu, Hongming
AU - Zhang, Pengcheng
AU - Ji, Yi
AU - Yang, Hang
AU - Jiang, Xiaokang
AU - Jing, Ruonan
AU - Yan, Mengyuan
AU - Zhang, Binglei
AU - Gu, Chuanwei
AU - Zhu, Jianping
AU - Hao, Yuanyuan
AU - Lei, Jie
AU - Zhang, Shuang
AU - Chen, Xiaoli
AU - Chen, Rongbo
AU - Sun, Yinglun
AU - Zhu, Yun
AU - Zhang, Xin
AU - Jiang, Ling
AU - Visser, Richard G.F.
AU - Ren, Yulong
AU - Wang, Yihua
AU - Wan, Jianmin
PY - 2023/2
Y1 - 2023/2
N2 - Key message: We identified a dosage-dependent dominant negative form of Sar1c, which confirms the essential role of COPII system in mediating ER export of storage proteins in rice endosperm. Abstract: Higher plants accumlate large amounts of seed storage proteins (SSPs). However, mechanisms underlying SSP trafficking are largely unknown, especially the ER-Golgi anterograde process. Here, we showed that a rice glutelin precursor accumulation13 (gpa13) mutant exhibited floury endosperm and overaccumulated glutelin precursors, which phenocopied the reported RNAi-Sar1abc line. Molecular cloning revealed that the gpa13 allele encodes a mutated Sar1c (mSar1c) with a deletion of two conserved amino acids Pro134 and Try135. Knockdown or knockout of Sar1c alone caused no obvious phenotype, while overexpression of mSar1c resulted in seedling lethality similar to the gpa13 mutant. Transient expression experiment in tobacco combined with subcellular fractionation experiment in gpa13 demonstrated that the expression of mSar1c affects the subcellular distribution of all Sar1 isoforms and Sec23c. In addition, mSar1c failed to interact with COPII component Sec23. Conversely, mSar1c competed with Sar1a/b/d to interact with guanine nucleotide exchange factor Sec12. Together, we identified a dosage-dependent dominant negative form of Sar1c, which confirms the essential role of COPII system in mediating ER export of storage proteins in rice endosperm.
AB - Key message: We identified a dosage-dependent dominant negative form of Sar1c, which confirms the essential role of COPII system in mediating ER export of storage proteins in rice endosperm. Abstract: Higher plants accumlate large amounts of seed storage proteins (SSPs). However, mechanisms underlying SSP trafficking are largely unknown, especially the ER-Golgi anterograde process. Here, we showed that a rice glutelin precursor accumulation13 (gpa13) mutant exhibited floury endosperm and overaccumulated glutelin precursors, which phenocopied the reported RNAi-Sar1abc line. Molecular cloning revealed that the gpa13 allele encodes a mutated Sar1c (mSar1c) with a deletion of two conserved amino acids Pro134 and Try135. Knockdown or knockout of Sar1c alone caused no obvious phenotype, while overexpression of mSar1c resulted in seedling lethality similar to the gpa13 mutant. Transient expression experiment in tobacco combined with subcellular fractionation experiment in gpa13 demonstrated that the expression of mSar1c affects the subcellular distribution of all Sar1 isoforms and Sec23c. In addition, mSar1c failed to interact with COPII component Sec23. Conversely, mSar1c competed with Sar1a/b/d to interact with guanine nucleotide exchange factor Sec12. Together, we identified a dosage-dependent dominant negative form of Sar1c, which confirms the essential role of COPII system in mediating ER export of storage proteins in rice endosperm.
KW - COPII
KW - Dominant-negative effect
KW - Intracellular protein transport
KW - Oryza sativa
KW - Sar1
KW - Seed storage protein
U2 - 10.1007/s11103-022-01327-z
DO - 10.1007/s11103-022-01327-z
M3 - Article
AN - SCOPUS:85143358789
SN - 0167-4412
VL - 111
SP - 291
EP - 307
JO - Plant Molecular Biology
JF - Plant Molecular Biology
IS - 3
ER -