Plant cells have two endosymbiotic organelles,chloroplasts,and mitochondria.These organelles perform specific functions that depend on organelle-specific proteins.The majority of chloroplast and mitochondrial proteins...Plant cells have two endosymbiotic organelles,chloroplasts,and mitochondria.These organelles perform specific functions that depend on organelle-specific proteins.The majority of chloroplast and mitochondrial proteins are specifically imported by the transit peptide and presequence,respectively.However,a significant number of proteins are also dually targeted to these two organelles.Currently,it is not fully understood how proteins are dually targeted to both chloroplasts and mitochondria.In this study,the mechanism underlying mitochondrial targeting of dual targeting At Suf E1 in Arabidopsis was elucidated.The N-terminal fragment containing 80 residues of AtSufE1(AtSufE1N80)was sufficient to confer dual targeting of reporter protein,At SufE1N80:GFP,in protoplasts.Two sequence motifs,two arginine residues at 15and 21positions,and amino acid(aa)sequence motif AKTLLLRPLK from the 31to 40aa position,were responsible for targeting to mitochondria a portion of reporter proteins amid the chloroplast targeting.The sequence motif PSEVPFRRT from the 41 stto 50 thaa position constitutes a common motif for targeting to both chloroplasts and mitochondria.For mitochondrial import of At Suf E1:N80,Metaxin played a critical role.In addition,Bi FC and protein pull-down experiments showed that At Suf E1N80 specifically interacts with import receptors,Metaxin and Tom20.The interaction of At Suf E1N80 with Metaxin was required for the interaction with Tom20.Based on these results,we propose that mitochondrial targeting of dual-targeting At Suf E1 is mediated by both mitochondria-specific and common sequence motifs in the signal sequence through the interaction with import receptors,Metaxin and Tom20,in a successive manner.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2019R1A2B5B03099982)the support of“Cooperative Research Program for Agriculture Science and Technology Development(Project No.PJ015701012022)”Rural Development Administration,Republic of Korea。
文摘Plant cells have two endosymbiotic organelles,chloroplasts,and mitochondria.These organelles perform specific functions that depend on organelle-specific proteins.The majority of chloroplast and mitochondrial proteins are specifically imported by the transit peptide and presequence,respectively.However,a significant number of proteins are also dually targeted to these two organelles.Currently,it is not fully understood how proteins are dually targeted to both chloroplasts and mitochondria.In this study,the mechanism underlying mitochondrial targeting of dual targeting At Suf E1 in Arabidopsis was elucidated.The N-terminal fragment containing 80 residues of AtSufE1(AtSufE1N80)was sufficient to confer dual targeting of reporter protein,At SufE1N80:GFP,in protoplasts.Two sequence motifs,two arginine residues at 15and 21positions,and amino acid(aa)sequence motif AKTLLLRPLK from the 31to 40aa position,were responsible for targeting to mitochondria a portion of reporter proteins amid the chloroplast targeting.The sequence motif PSEVPFRRT from the 41 stto 50 thaa position constitutes a common motif for targeting to both chloroplasts and mitochondria.For mitochondrial import of At Suf E1:N80,Metaxin played a critical role.In addition,Bi FC and protein pull-down experiments showed that At Suf E1N80 specifically interacts with import receptors,Metaxin and Tom20.The interaction of At Suf E1N80 with Metaxin was required for the interaction with Tom20.Based on these results,we propose that mitochondrial targeting of dual-targeting At Suf E1 is mediated by both mitochondria-specific and common sequence motifs in the signal sequence through the interaction with import receptors,Metaxin and Tom20,in a successive manner.
