Splicing defective mutants of the COXI gene of yeast mitochondrial DNA: initial definition of the maturase domain of the group II intron aI2.
Six mutations blocking the function of a seven intron form of the mitochondrial gene encoding subunit I of cytochrome c oxidase (COXI) and mapping upstream of exon 3 were isolated and characterized. A cis-dominant mutant of the group IIA intron 1 defines a helical portion of the C1 substructure of domain 1 as essential for splicing. A trans-recessive mutant confirms that the intron 1 reading frame encodes a maturase function. A cis-dominant mutant in exon 2 was found to have no effect on the splicing of intron 1 or 2. A trans-recessive mutant, located in the group IIA intron 2, demonstrates for the first time that intron 2 encodes a maturase. A genetic dissection of the five missense mutations present in the intron 2 reading frame of that strain demonstrates that the maturase defect results from one or both of the missense mutations in a newly-recognized conserved sequence called domain X.
Moran
J V
JV
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
Mecklenburg
K L
KL
Sass
P
P
Belcher
S M
SM
Mahnke
D
D
Lewin
A
A
Perlman
P
P
D001483:Base Sequence; D004271:DNA, Fungal; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics*; D004722:Endoribonucleases / Q000378:metabolism*; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D009713:Nucleotidyltransferases / Q000378:metabolism*; D016366:Open Reading Frames; D012326:RNA Splicing / Q000235:genetics*; D012331:RNA, Fungal; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D012331:RNA, Fungal; D003576:Electron Transport Complex IV; D009713:Nucleotidyltransferases; C034038:mRNA maturase; D004722:Endoribonucleases