By transferring the mutant mtDNA in transmitochondrial cytoplasmic hybrid (cybrid) cells we established the pathogenic role of this mutation, which affects CI function in homoplasmic mutant cybrids.
Our results, obtained by transferring the mutant mtDNA from heteroplasmic fibroblasts into cybrids, after selecting mtDNA isogenic clones except for the m.3890G>A/ MT- ND1 mutant position, establish the pathogenic role of this rare mutation in affecting CI function.
Although wild-type ubiquitin is excluded from NEDD8's E1, a previous study found that NEDD8's E1 could transfer the "NEDD8ylized" ubiquitinArg72Leu mutant to NEDD8's E2 (Ubc12), albeit with less efficiency overall than the NEDD8 transthiolation cycle (22).
The current solution to this bottleneck consists of evolving E. coli RSs in yeast and transferring the resultant mutants to mammalian cells.
Each construct was moved into pBKJ401, a modified version of pBKJ258 containing sequence homology with the B. anthracis pXO1 virulence plasmid, and transferred into the mutant of choice via conjugation [29].
In addition, plasmid pBBR1MCS5 without the insert (empty vector) was also transferred into the mutant and wild-type strains via conjugation with WM3064.
We selected for conversion events in which information is transferred from the mutant ura3 -e allele to the wild-type allele using solid medium containing 5-FOA that selects against cells with wild-type URA3 activity (Boeke et al. 1987).
To determine if the myc-epitope tag contributes to impaired trafficking of co-expressed wild-type proinsulin, we compared results when transferring the tag to the mutant partner.
Critically, transfer of the mutant alleles into a wild-type E. coli background confirmed that the rpoB and rpoC mutations conferred the greatest increase in growth rate in the same medium.
Transfer of the mutant mtDNA in the cybrid cell system resulted in a marked reduction of CI activity and CI-dependent ATP synthesis in the presence of a normally assembled enzyme.
They were further able to show transfer of the mutant KRAS protein to DKO-8 cells inherently expressing only wild type KRAS, after co-culture with DKO-1 extracellular vesicles [ 12].
