Mutational bisection of the mitochondrial DNA stability and amino acid biosynthetic functions of ilv5p of budding yeast.
Genetics
; 161(3): 1043-52, 2002 Jul.
Article
en En
| MEDLINE
| ID: mdl-12136009
ABSTRACT
Ilv5p is a bifunctional yeast mitochondrial enzyme required for branched chain amino acid biosynthesis and for the stability of mitochondrial DNA (mtDNA) and its parsing into nucleoids. The latter occurs when the general amino acid control (GAC) pathway is activated. We have isolated ilv5 mutants that lack either the enzymatic (a(-)D(+)) or the mtDNA stability function (a(+)D(-)) of the protein. The affected residues in these two mutant classes cluster differently when mapped to the 3-D structure of the spinach ortholog of Ilv5p. a(-)D(+) mutations map to conserved internal domains known to be important for substrate and cofactor binding, whereas the a(+)D(-) mutations map to a C-terminal region on the surface of the protein. The a(+)D(-) mutants also have a temperature-sensitive phenotype when grown on a glycerol medium, which correlates with their degree of mtDNA instability. Analysis of an a(+)D(-) mutant with a strong mtDNA instability phenotype shows that it is also unable to parse mtDNA into nucleoids when activated by the GAC pathway. Finally, the wild-type Escherichia coli ortholog of Ilv5p behaves like a(+)D(-) mutants when expressed and targeted to mitochondria in ilv5Delta yeast cells, suggesting that yeast Ilv5p acquired its mtDNA function after the endosymbiotic event.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Schizosaccharomyces
/
ADN Mitocondrial
/
Proteínas Fúngicas
/
Proteínas Mitocondriales
/
Oxidorreductasas de Alcohol
/
Aminoácidos
Idioma:
En
Revista:
Genetics
Año:
2002
Tipo del documento:
Article
País de afiliación:
Estados Unidos