Jinling Liu, Hong Chen, Li Liu, Xiangzhao Meng, Qianwen Liu, Qinyi Ye, Jiangqi Wen, Tao Wang, Jiangli Dong
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引用次数: 0
Abstract
Nucleus-encoded chloroplast proteins can be transported via the secretory pathway. The molecular mechanisms underlying the trafficking of chloroplast proteins between the intracellular compartments are largely unclear, and a cargo sorting receptor has not previously been identified in the secretory pathway. Here, we report a cargo sorting receptor that is specifically present in Viridiplantae and mediates the transport of cargo proteins to the chloroplast. Using a forward genetic analysis, we identified a gene encoding a transmembrane protein (MtTP930) in barrel medic (Medicago truncatula). Mutation of MtTP930 resulted in impaired chloroplast function and a dwarf phenotype. MtTP930 is highly expressed in the aerial parts of the plant and is localized to the endoplasmic reticulum (ER) exit sites and Golgi. MtTP930 contains typical cargo sorting receptor motifs, interacts with Sar1, Sec12, and Sec24, and participates in coat protein complex II vesicular transport. Importantly, MtTP930 can recognize the cargo proteins plastidial N-glycosylated nucleotide pyrophosphatase/phosphodiesterase (MtNPP) and α-carbonic anhydrase (MtCAH) in the ER and then transport them to the chloroplast via the secretory pathway. Mutation of a homolog of MtTP930 in Arabidopsis (Arabidopsis thaliana) resulted in a similar dwarf phenotype. Furthermore, MtNPP-GFP failed to localize to chloroplasts when transgenically expressed in Attp930 protoplasts, implying that these cargo sorting receptors are conserved in plants. These findings fill a gap in our understanding of the mechanism by which chloroplast proteins are sorted and transported via the secretory pathway.
期刊介绍:
Title: Plant Cell
Publisher:
Published monthly by the American Society of Plant Biologists (ASPB)
Produced by Sheridan Journal Services, Waterbury, VT
History and Impact:
Established in 1989
Within three years of publication, ranked first in impact among journals in plant sciences
Maintains high standard of excellence
Scope:
Publishes novel research of special significance in plant biology
Focus areas include cellular biology, molecular biology, biochemistry, genetics, development, and evolution
Primary criteria: articles provide new insight of broad interest to plant biologists and are suitable for a wide audience
Tenets:
Publish the most exciting, cutting-edge research in plant cellular and molecular biology
Provide rapid turnaround time for reviewing and publishing research papers
Ensure highest quality reproduction of data
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