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
To enhance the mechanical properties of polypropylene random copolymer(PPR),polystyrene(PS)with four different contents were added to the PPR matrix through melt blending.Subsequently,using the Multi-Flow Vibration In...To enhance the mechanical properties of polypropylene random copolymer(PPR),polystyrene(PS)with four different contents were added to the PPR matrix through melt blending.Subsequently,using the Multi-Flow Vibration Injection Molding(MFVIM)technology,PPR/PS in situ microfiber composites(MFC)with different blending ratios were prepared.The results indicated that blending ratio had a great impact on the phase morphology and crystal structure of MFVIM samples,which was different from those of conventional injection molding(CIM)samples.PS ultrafine fibers could be formed under the shear field and could absorb the PPR molecular chains to form hybrid shish-kebab structures.Meanwhile,the PPR matrix could also form shish-kebab structures under the effect of strong shear.When the PS content reached 20%,under the combined action of PS in situ microfibers and highly oriented crystal structure,the tensile strength and Young’s modulus of the sample were obviously improved and the impact strength remained at a relatively high level.So a strong and tough balanced PPR based material was obtained.These results provide valuable insights for expanding the industrial and daily-life applications of PPR and show promising development prospects.展开更多
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(No.21627804).
文摘To enhance the mechanical properties of polypropylene random copolymer(PPR),polystyrene(PS)with four different contents were added to the PPR matrix through melt blending.Subsequently,using the Multi-Flow Vibration Injection Molding(MFVIM)technology,PPR/PS in situ microfiber composites(MFC)with different blending ratios were prepared.The results indicated that blending ratio had a great impact on the phase morphology and crystal structure of MFVIM samples,which was different from those of conventional injection molding(CIM)samples.PS ultrafine fibers could be formed under the shear field and could absorb the PPR molecular chains to form hybrid shish-kebab structures.Meanwhile,the PPR matrix could also form shish-kebab structures under the effect of strong shear.When the PS content reached 20%,under the combined action of PS in situ microfibers and highly oriented crystal structure,the tensile strength and Young’s modulus of the sample were obviously improved and the impact strength remained at a relatively high level.So a strong and tough balanced PPR based material was obtained.These results provide valuable insights for expanding the industrial and daily-life applications of PPR and show promising development prospects.
