User:Nkuldell/mtDNA

From Fred Sherman fact sheet

in Guthrie and Fink Ch1 and [1]

• ~10% total cellular DNA content is mtDNA encoding mt translation machinery and 15% of mt proteins
• averages 50 copies mtDNA/cell (range 8-130), each with 70-76 kb dsDNA
• nonMendelian inheritance, but since daughter cells receive few mitochondria find genes quickly segragate (see Guthrie and Fink Ch 5 by Bonnefory and Fox)
• wild type mtDNA is designated rho+
• cells lacking mtDNA are designated rho0 and are respiration deficient (lack cytochrome b and subunits of cytochrome oxidase and ATPase comples), retain mitochondria though they are morphologically abnormal
• cells with mutant mtDNA are described as rho- . Described mutations include cytochromes a*a3, b
• mutant phenotypes:
  • inability to grow on Nfs (nonfermentable substrates = Nfs- ) such as ethanol or glycerol though this can arise from mutations in nuclear genes (e.g. pet1, cox4, hem1, cyc3) or single gene mutations in mtDNA , termed "mit-" "syn-" or "antR"
  • "mit-" are Nfs- from mtDNA single mutations that are respiration- but mt translation+ (e.g. cox1, cox2, cox3, cob1 or box, atp6, atp8, atp9 or pho2
  • "syn-" are Nfs- from mtDNA single mutation that results in respiration- and mt translation- (e.g. tRNAasp or M7-37)
  • "antR" is another mutant phenotype associated with mtDNA mutations. These result in antibiotic resistance e.g. rib1 for resistance to erythromycin from 21SrRNA change, rib3 for resistance to chrolampenical from 21S rRNA change, par1 for resistance to paromomycin from 16S rRNA change, and oli1 for resistance to oligomycin from ATPase subunit 9 mutation. have also described mutations in cytochrome b leading to diuron resistance.

From Bonnefoy and Fox, Ch5 in Guthrie and Fink

• replication of mtDNA poorly understood but is known to depend on mtDNA ori sequences and (for reasons unknown) on mt protein synthesis.
• only species to date in which homologous recombination can be used to rewrite mtDNA
• transformable with ballistics (ref for this is 1991 Meth in Enzym)
• drug resistant phenotypes associated with "antR" mutations are only detected when strains are grown on Nfs in respiration+ strains and can arise spontaneously so they are not good transformation markers
• nuclear auxotrophic markers such as URA3 and TRP1 are not expressed when inserted into mtDNA but (dna? rna?) can escape from mt into nucleus, readily scored on SC-ura or SC-trp.
• to express nuclear genes in mt need to rewrite in mt genetic code (ref for this is Fox in Annu Rev Genet (1987) 21:67-91). One useful example is ARG8m, which is nuclear ARG8 gene recoded for mtDNA expression. Gene is transcribed and translated in mt then diffuses to cytoplasm and complements arg- p-type. File:Macintosh HD-Users-nkuldell-Desktop-recodeformtDNA PNAS96.pdf
• Similarly GFPm has been reported in which nuclear GFP has been recoded for mt expression [2]

other detailed yeast mt reviews

• Butow et al in Methods in Enzymology (1996) 264:265
• Perlman et al in Methods in Enzymology (1979) 56:139
• Fox et al in Methods in Enzymology (1991) 194:149
• B. Dujon in The Molecular Biology of S.c.: Life cycle and inheritance" CSHLP (1981)