TRANSLATIONAL CONTROL OF ENDOGENOUS AND RECODED NUCLEAR GENES IN YEAST MITOCHONDRIA - REGULATION AND MEMBRANE TARGETING

Mitochondrial gene expression in yeast, Saccharomyces cerevisiae, depe nds on translational activation of individual mRNAs by distinct protei ns encoded in the nucleus. These nuclearly coded mRNA-specific transla tional activators are bound to the inner membrane and function to medi ate the interaction between mRNAs and mitochondrial ribosomes. This co mplex system, found to date only in organelles, appears to be an adapt ation for targeting the synthesis of mitochondrially coded integral me mbrane proteins to the membrane. In addition, mRNA-specific translatio nal activation is a rate-limiting step used to modulate expression of at least one mitochondrial gene in response to environmental condition s. Direct study of mitochondrial gene regulation and the targeting of mitochondrially coded proteins in vivo will now be possible using synt hetic genes inserted into mtDNA that encode soluble reporter/passenger proteins.