Yeast nuclear PET127 gene can suppress deletions of the SUV3 or DSS1 genes: An indication of a functional interaction between 3 ' and 5 ' ends of mitochondrial mRNAs

Saccharomyces cerevisiae nuclear genes SUV3 and DSS1 encode putative RNA he licase and RNase II, respectively, which are subunits of the mitochondrial degradosome (mtEXO): a three-protein complex which has a 3' to 5' exoribonu clease activity and plays a major role in regulating stability of mitochond rial RNA. Lack of either of the two gene products results in a respiratory negative phenotype, while on the molecular level it causes a total block of mitochondrial translation, loss of the in vitro exoribonuclease activity a nd changes in stability and processing of many mtRNAs. We have found that t he yeast nuclear gene PET127 present on a low or high copy number vector ca n effectively suppress the effects of the SUV3 or DSS1 gene disruptions. Si nce the product of the PET127 gene is involved in processing of the 5' ends of mitochondrial mRNAs, we suggest that there is a functional coupling bet ween the 5' and 3' ends of mitochondrial mRNAs.