The Effect Of PPR-like Motif Of Ppr10 Protein In Schizosaccharomyces Pombe On Mitochondrial Protein

Mitochondria have their own genome(mtDNA).In Schizosaccharomyces pombe(S.pombe),mtDNA encodes key enzymes of the oxidative phosphorylation system,so normal expression of mtDNA is essential for the function of mitochondria.PPR proteins are protein family that mainly regulate the expression of organelle genes.S.pombe Ppr10 protein is a member of the PPR family,which is mainly involved in the synthesis of respiratory chain proteins encoded by mtDNA and is closely related to the function of mitochondria.The PPR motif is a repeat unit composed of 35 consecutively arranged amino acids.Ppr10 has two PPR motifs that are essential for Ppr10.Using the protein structure prediction software HHrep ID to further analyze the structure of Ppr10,it was found that Ppr10 protein has thirteen repeat sequences.These repeats are rich in hydrophobic amino acids such as leucine and are similar to the characteristics of the PPR motif.Therefore,this article named it as PPR-like motif and studied its function.First,a single PPR motif-deficient strain was constructed and named ppr10?1-ppr10?13.The experimental results showed that single deletion of PPR-like motif 1-7 leads to severely damage to mitochondrial function,while deletion of PPR-like motif 8 insignificant affects the mitochondrial function,and single deletion of PPR motif 1-7 and 10 cause a large number of cell deaths at stabilization phase.Using immunoblotting method to detect the steady-state level of respiratory chain complex subunits Cob1,Cox1,Cox2 and Atp6 encoded by mtDNA in mutant stains,the results showed that single deletion of PPR-like motif 1-7 led to a significant reduction in the steady-state level of respiratory chain protein,and the single deletion of PPR-like motif 8 caused a steady decrease in the level of respiratory chain protein,but not significantly.The deletion of PPR-like motif 10 only resulted in a significant decrease in the steady-state level of respiratory chain protein in the late stabilization phase(84 h).Next,the expression of Ppr10 protein in mutant strains were detected by immunoblotting.The results showed that Ppr10 protein could be expressed in all mutant strains.Only the deletion of PPR-like motif 1 caused the decrease of Ppr10 protein expression,which was about 35% of the level of wild-type.In summary,we believe that the PPR-like motifs 1-8 and 10 of the Ppr10 protein are important functional regions,which are closely related to the steady-state level of respiratory chain proteins.And the deletion of PPR-like motifs 1-8 and 10 affect the function of respiratory chain,resulting in the damage of mitochondrial function.But the deletion of PPR-like motif 10 of Ppr10 protein only causes a decrease in the steady-state level of respiratory chain protein in the late stabilization phase.Among them,only the deletion of PPR-like motif 1 causes a decrease in the level of Ppr10.This article lays the foundation for further research on the structure and function of Ppr10,and provides a theoretical basis for further understanding the expression regulation of mitochondrial genes and mitochondrial function.