Conversion of a reporter gene for mitochondrial gene expression using iterative mega-prime PCR.

Mammalian mitochondria possess their own multicopy genome, mtDNA. Although much is known about mtDNA replication and transcription, our knowledge of the mechanisms governing mt-RNA processing, stability and translation remains rudimentary. We have taken a step towards addressing these issues by altering the luciferase reporter gene to accommodate the variation in mitochondrial codon recognition. 19 essential substitutions have been generated by an iterative mega-primer PCR technique. To mimic mt-mRNA species and to optimise intramitochondrial translation, further engineering has produced a template which, when transcribed in vitro, generates an RNA species with only two nucleotides upstream from the initiation codon, an absence of a 3' untranslated region and a polyadenylated tail of 40 residues. It is intended that mt-luciferase (mt-luc) RNA will be an excellent reporter for revealing cis-acting elements essential for in organello RNA processing, maturation and expression. Additionally, the mt-luc gene can be readily incorporated into any novel mitochondrial transducing vectors to assess intra-organellar transcription and translation.