In plants, RNA editing is a post-transcriptional process that changes specific cytidine to uridine in both mitochondria and plastids. Most pentatricopeptide repeat（PPR） proteins are involved in organelle RNA editing...In plants, RNA editing is a post-transcriptional process that changes specific cytidine to uridine in both mitochondria and plastids. Most pentatricopeptide repeat（PPR） proteins are involved in organelle RNA editing by recognizing specific RNA sequences. We here report the functional characterization of a PPR protein from the DYW subclass, Baili Xi（BLX）, which contains five PPR motifs and a DYW domain. BLX is essential for early seed development, as plants lacking the BLX gene was embryo lethal and the endosperm failed to initiate cellularization. BLX was highly expressed in the embryo and endosperm, and the BLX protein was specifically localized in mitochondria, which is essential for BLX function. We found that BLX was required for the efficient editing of 36 editing sites in mitochondria. Moreover, BLX was involved in the splicing regulation of the fourth intron of nad1 and the first intron of nad2. The loss of BLX function impaired the mitochondrial function and increased the reactive oxygen species（ROS） level. Genetic complementation with truncated variants of BLX revealed that, in addition to the DYW domain, only the fifth PPR motif was essential for BLX function. The upstream sequences of the BLX-targeted editing sites are not conserved, suggesting that BLX serves as a novel and major mitochondrial editing factor（MEF） via a new non-RNA-interacting manner. This finding provides new insights into how a DYW-type PPR protein with fewer PPR motifs regulates RNA editing in plants.展开更多
Pentatricopeptide repeat(PPR)proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression.Here,we report the function of PPR21 in mitochondrial intro...Pentatricopeptide repeat(PPR)proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression.Here,we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development.PPR21 is a typical P-type PPR protein targeted to mitochondria.The ppr21 mutants are arrested in embryogenesis and endosperm development,leading to embryo lethality.Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1,2,and 4 and impair the assembly and activity of mitochondrial complex I.Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns.However,our protein interaction analyses reveal that PPR21 does not interact with EMP12.Instead,both PPR21 and EMP12 interact with the small MutS-related(SMR)domain-containing PPR protein 1(PPR-SMR1)and the short P-type PPR protein 2(SPR2).PPR-SMR1 interacts with SPR2,and both proteins are required for the splicing of many introns in mitochondria,including nad2 intron 1,2,and 4.These results suggest that a PPR21-(PPR-SMR1/SPR2)-EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria.展开更多
Pentatricopeptide repeat(PPR)proteins perform essential functions in post-transcriptional regulation of gene expression,particularly RNA editing and RNA splicing,in plant organelles.Although research on chloroplast bi...Pentatricopeptide repeat(PPR)proteins perform essential functions in post-transcriptional regulation of gene expression,particularly RNA editing and RNA splicing,in plant organelles.Although research on chloroplast biogenesis and development has been extensive,the functions of most PPR genes in this process in rice(Oryza sativa)remain incompletely understood.This study identifies a novel P-type PPR protein,YELLOW-GREEN LEAF AND SEEDLING LETHALITY(YGS),which localizes to rice chloroplasts.YGS shows predominant expression in leaves.The ygs mutants,generated through CRISPR/Cas9-mediated genome editing of the YGS gene,displayed yellow-green leaves and seedling lethality.These phenotypes corresponded with reduced pigment levels and disrupted chloroplast ultrastructure compared to wild-type plants.Furthermore,the expression of genes associated with chloroplast development and chlorophyll biosynthesis showed significant alterations in the ygs mutants.The absence of YGS function affected RNA editing of rpl2 and intron splicing of ycf3-1 in the plastid genome.Additionally,YGS demonstrated interaction with the chloroplast signal recognition particle protein Oscp SRP54b in yeast two-hybrid and bimolecular fluorescence complementation analyses.These results indicate that YGS participates in RNA editing and RNA splicing in chloroplasts,thus serving a vital role in rice chloroplast development.展开更多
Chloroplasts are essential for normal plant growth and development.In plants,pentatricopeptide repeat(PPR)proteins mediate RNA processing in chloroplasts.Here,we characterized a rice albino leaf 5(al5)mutant which exh...Chloroplasts are essential for normal plant growth and development.In plants,pentatricopeptide repeat(PPR)proteins mediate RNA processing in chloroplasts.Here,we characterized a rice albino leaf 5(al5)mutant which exhibits albinism during early leaf development.The MutMap+analysis and transformation experiments revealed that AL5 encodes a chloroplast-localized P-type PPR protein.The AL5 mutation resulted in the defective splicing of ribosomal protein L2(rpl2)and ribosomal protein S12(rps12),which are involved in the synthesis of chloroplast 50S and 30S ribosomal subunits,respectively.The RNA-electrophoretic mobility shift assay(REMSA)further demonstrated that AL5 directly binds to rpl2 transcripts.Finally,disruption of AL5 led to reduced expression of plastid-encoded polymerase(PEP)-dependent plastid genes and nuclear-encoded photosynthetic genes.Notably,the albino al5 mutant phenotype was regulated by low temperature.These results suggest that AL5 participates in plastid RNA splicing and plays an important role in chloroplast development in rice.展开更多
基金supported by the National Natural Science Foundation of China(Nos.31620103903 and 31621001)partially by the 111 projectsupported by the Peking-Tsinghua Joint Center for Life Sciences
文摘In plants, RNA editing is a post-transcriptional process that changes specific cytidine to uridine in both mitochondria and plastids. Most pentatricopeptide repeat（PPR） proteins are involved in organelle RNA editing by recognizing specific RNA sequences. We here report the functional characterization of a PPR protein from the DYW subclass, Baili Xi（BLX）, which contains five PPR motifs and a DYW domain. BLX is essential for early seed development, as plants lacking the BLX gene was embryo lethal and the endosperm failed to initiate cellularization. BLX was highly expressed in the embryo and endosperm, and the BLX protein was specifically localized in mitochondria, which is essential for BLX function. We found that BLX was required for the efficient editing of 36 editing sites in mitochondria. Moreover, BLX was involved in the splicing regulation of the fourth intron of nad1 and the first intron of nad2. The loss of BLX function impaired the mitochondrial function and increased the reactive oxygen species（ROS） level. Genetic complementation with truncated variants of BLX revealed that, in addition to the DYW domain, only the fifth PPR motif was essential for BLX function. The upstream sequences of the BLX-targeted editing sites are not conserved, suggesting that BLX serves as a novel and major mitochondrial editing factor（MEF） via a new non-RNA-interacting manner. This finding provides new insights into how a DYW-type PPR protein with fewer PPR motifs regulates RNA editing in plants.
基金supported by the National Natural Science Foundation of China(32072126 and 32230075)the Shandong Provincial Natural Science Foundation(ZR2019MC005).
文摘Pentatricopeptide repeat(PPR)proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression.Here,we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development.PPR21 is a typical P-type PPR protein targeted to mitochondria.The ppr21 mutants are arrested in embryogenesis and endosperm development,leading to embryo lethality.Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1,2,and 4 and impair the assembly and activity of mitochondrial complex I.Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns.However,our protein interaction analyses reveal that PPR21 does not interact with EMP12.Instead,both PPR21 and EMP12 interact with the small MutS-related(SMR)domain-containing PPR protein 1(PPR-SMR1)and the short P-type PPR protein 2(SPR2).PPR-SMR1 interacts with SPR2,and both proteins are required for the splicing of many introns in mitochondria,including nad2 intron 1,2,and 4.These results suggest that a PPR21-(PPR-SMR1/SPR2)-EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria.
基金supported by the National Natural Science Foundation of China(32201784,32072048,and U2004204)the Natural Science Foundation of Shandong Province,China(ZR2020QC111 and ZR2022QC176)the Talent Introduction Project of Dezhou University,China(2020xjrc207)。
文摘Pentatricopeptide repeat(PPR)proteins perform essential functions in post-transcriptional regulation of gene expression,particularly RNA editing and RNA splicing,in plant organelles.Although research on chloroplast biogenesis and development has been extensive,the functions of most PPR genes in this process in rice(Oryza sativa)remain incompletely understood.This study identifies a novel P-type PPR protein,YELLOW-GREEN LEAF AND SEEDLING LETHALITY(YGS),which localizes to rice chloroplasts.YGS shows predominant expression in leaves.The ygs mutants,generated through CRISPR/Cas9-mediated genome editing of the YGS gene,displayed yellow-green leaves and seedling lethality.These phenotypes corresponded with reduced pigment levels and disrupted chloroplast ultrastructure compared to wild-type plants.Furthermore,the expression of genes associated with chloroplast development and chlorophyll biosynthesis showed significant alterations in the ygs mutants.The absence of YGS function affected RNA editing of rpl2 and intron splicing of ycf3-1 in the plastid genome.Additionally,YGS demonstrated interaction with the chloroplast signal recognition particle protein Oscp SRP54b in yeast two-hybrid and bimolecular fluorescence complementation analyses.These results indicate that YGS participates in RNA editing and RNA splicing in chloroplasts,thus serving a vital role in rice chloroplast development.
基金supported by the Open Competition Program of Top Ten Critical Priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(2022SDZG05)the Guangdong Province Rural Revitalization Strategy Special Fund Seed Industry Revitalization Project(2022-NJS-15-001)the Key-Area Research and Development Program of Guangdong Province(2022B0202060005).
文摘Chloroplasts are essential for normal plant growth and development.In plants,pentatricopeptide repeat(PPR)proteins mediate RNA processing in chloroplasts.Here,we characterized a rice albino leaf 5(al5)mutant which exhibits albinism during early leaf development.The MutMap+analysis and transformation experiments revealed that AL5 encodes a chloroplast-localized P-type PPR protein.The AL5 mutation resulted in the defective splicing of ribosomal protein L2(rpl2)and ribosomal protein S12(rps12),which are involved in the synthesis of chloroplast 50S and 30S ribosomal subunits,respectively.The RNA-electrophoretic mobility shift assay(REMSA)further demonstrated that AL5 directly binds to rpl2 transcripts.Finally,disruption of AL5 led to reduced expression of plastid-encoded polymerase(PEP)-dependent plastid genes and nuclear-encoded photosynthetic genes.Notably,the albino al5 mutant phenotype was regulated by low temperature.These results suggest that AL5 participates in plastid RNA splicing and plays an important role in chloroplast development in rice.
