Manganese （Mn） is an essential catalytic metal in the Mn-cluster that oxidizes water to produce oxygen dur- ing photosynthesis. However, the transport protein（s） responsible for Mn2＋ import into the chloroplast r...Manganese （Mn） is an essential catalytic metal in the Mn-cluster that oxidizes water to produce oxygen dur- ing photosynthesis. However, the transport protein（s） responsible for Mn2＋ import into the chloroplast re- mains unknown. Here, we report the characterization ofArabidopsis CMT1 （Chloroplast Manganese Trans- porter 1）, an evolutionarily conserved protein in the Uncharacterized Protein Family 0016 （UPFO016）, that is required for manganese accumulation into the chloroplast. CMT1 is expressed primarily in green tissues, and its encoded product is localized in the inner envelope membrane of the chloroplast. Disruption of CMT1 in the T-DNA insertional mutant cmtl-1 resulted in stunted plant growth, defective thylakoid stacking, and severe reduction of photosystem II complexes and photosynthetic activity. Consistent with reduced oxy- gen evolution capacity, the mutant chloroplasts contained less manganese than the wild-type ones. In sup- port of its function as a Mn transporter, CMT1 protein supported the growth and enabled Mn2＋ accumula- tion in the yeast cells of Mn2＋-uptake deficient mutant （3smfl）. Taken together, our results indicate that CMT1 functions as an inner envelope Mn transporter responsible for chloroplast Mn2＋ uptake.展开更多
Manganese(Mn)serves as an essential cofactor for many enzymes in various compartments of a plant cell.Allocation of Mn among various organelles thus plays a central role in Mn homeostasis to support metabolic processe...Manganese(Mn)serves as an essential cofactor for many enzymes in various compartments of a plant cell.Allocation of Mn among various organelles thus plays a central role in Mn homeostasis to support metabolic processes.We report the identification of a Golgi-localized Mn transporter(named PML3)that is essential for rapid cell elongation in young tissues such as emerging leaves and the pollen tube.In particular,the pollen tube defect in the pml3 loss-of-function mutant caused severe reduction in seed yield,a critical agronomic trait.Further analysis suggested that a loss of pectin deposition in the pollen tube might cause the pollen tube to burst and slow its elongation,leading to decreased male fertility.As the Golgi apparatus serves as the major hub for biosynthesis and modification of cell-wall components,PML3 may function in Mn homeostasis of this organelle,thereby controlling metabolic and/or trafficking processes required for pectin deposition in rapidly elongating cells.展开更多
文摘Manganese （Mn） is an essential catalytic metal in the Mn-cluster that oxidizes water to produce oxygen dur- ing photosynthesis. However, the transport protein（s） responsible for Mn2＋ import into the chloroplast re- mains unknown. Here, we report the characterization ofArabidopsis CMT1 （Chloroplast Manganese Trans- porter 1）, an evolutionarily conserved protein in the Uncharacterized Protein Family 0016 （UPFO016）, that is required for manganese accumulation into the chloroplast. CMT1 is expressed primarily in green tissues, and its encoded product is localized in the inner envelope membrane of the chloroplast. Disruption of CMT1 in the T-DNA insertional mutant cmtl-1 resulted in stunted plant growth, defective thylakoid stacking, and severe reduction of photosystem II complexes and photosynthetic activity. Consistent with reduced oxy- gen evolution capacity, the mutant chloroplasts contained less manganese than the wild-type ones. In sup- port of its function as a Mn transporter, CMT1 protein supported the growth and enabled Mn2＋ accumula- tion in the yeast cells of Mn2＋-uptake deficient mutant （3smfl）. Taken together, our results indicate that CMT1 functions as an inner envelope Mn transporter responsible for chloroplast Mn2＋ uptake.
基金supported by the National Natural Science Foundation of China(31900220 to C.Z.)the National Science Foundation(1714795 to S.L.).
文摘Manganese(Mn)serves as an essential cofactor for many enzymes in various compartments of a plant cell.Allocation of Mn among various organelles thus plays a central role in Mn homeostasis to support metabolic processes.We report the identification of a Golgi-localized Mn transporter(named PML3)that is essential for rapid cell elongation in young tissues such as emerging leaves and the pollen tube.In particular,the pollen tube defect in the pml3 loss-of-function mutant caused severe reduction in seed yield,a critical agronomic trait.Further analysis suggested that a loss of pectin deposition in the pollen tube might cause the pollen tube to burst and slow its elongation,leading to decreased male fertility.As the Golgi apparatus serves as the major hub for biosynthesis and modification of cell-wall components,PML3 may function in Mn homeostasis of this organelle,thereby controlling metabolic and/or trafficking processes required for pectin deposition in rapidly elongating cells.
