The Effect Of Mti2 And Mti3 Proteins Of Schizosaccharomyces Pombe On Mitochondrial Translation

The mitochondral genome(mtDNA)almost exclusively encodes a handful of transmembrane constituents of the oxidative phosphorylation(OXPHOS)system.Coordinate expression of these genes ensures the correct stoichiometry of the system's components.Translation initiation in mitochondria is assisted by two general initiation factors mIF2 and mIF3,orthologues of which in bacteria are indispensible for protein synthesis and viability.Loss of mIF3/Aim23 in Sacchaomyces erevisiae does not indiscriminately abrogate mitochondrial translation but rather causes an imbalance in protein production.In this article,we studied the effects of mIF2/Mti2(SPBC1271.15c)and mIF3/MtB(SPBC18E5.13)in Schizosaccharomyces pombe on mitochondrial translation.First,we constructed the ?mti2 and ?mti3 strain.Compared to yHL6381 wild strain,the growth of ?mti2 strain is significantly retarded.Whereas the growth of?mti3 strain doesn't get affected both in fermented and unfermented medium.Second,the results of Western Blot experiments show that Mti2 and Mti3 proteins located in mitoplast.Deletion of mti2 gene affected the stable level of Cobl,Cox1,Cox2 and Atp6.The stability of the Cox4 protein encoded by the nuclear gene was almost unaffected.The deletion of mti3 gene did not affect the protein stability.Third,we found that in ?mti2 strain,the synthesis of proteins encoded by mtDNA were affected except Cob1 and Atp6.The deletion of mti2 gene affects the synthesis of proteins encoded by mtDNA,and Cobl and Atp6 become unstable.So mti2 is closely related to the translation of mtDNA.Forth,we use sucrose density gradient centrifugation to seperate mitochondrial ribosomal subunits,preliminary results show that the distribution of Mti2 is similar to the large subunit(LSU),and Mti3 is similar to the small subunit(SSU).