Identification of six loci in which mutations partially restore peroxisome biogenesis and/or alleviate the metabolic defect of pex2 mutants in podospora.
Peroxins (PEX) are proteins required for peroxisome biogenesis. Mutations in PEX genes cause lethal diseases in humans, metabolic defects in yeasts, and developmental disfunctions in plants and filamentous fungi. Here we describe the first large-scale screening for suppressors of a pex mutation. In Podospora anserina, pex2 mutants exhibit a metabolic defect [inability to grow on medium containing oleic acid (OA medium) as sole carbon source] and a developmental defect (inability to differentiate asci in homozygous crosses). Sixty-three mutations able to restore growth of pex2 mutants on OA medium have been analyzed. They fall in six loci (suo1 to suo6) and act as dominant, allele-nonspecific suppressors. Most suo mutations have pleiotropic effects in a pex2(+) background: formation of unripe ascospores (all loci except suo5 and suo6), impaired growth on OA medium (all loci except suo4 and suo6), or sexual defects (suo4). Using immunofluorescence and GFP staining, we show that peroxisome biogenesis is partially restored along with a low level of ascus differentiation in pex2 mutant strains carrying either the suo5 or the suo6 mutations. The data are discussed with respect to beta-oxidation of fatty acids, peroxisome biogenesis, and cell differentiation.
Institut de Génétique et Microbiologie, UMR 8621, Centre National de la Recherche Scientifique-Université Paris-Sud, F-91405 Orsay, France.
Gwenaël
G
Ruprich-Robert
Véronique
V
Berteaux-Lecellier
Denise
D
Zickler
Arlette
A
Panvier-Adoutte
Marguerite
M
Picard
D001483:Base Sequence; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal / Q000235:genetics; D017931:DNA Primers; D005091:Exons; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins; D007438:Introns; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics*; D009154:Mutation; D016366:Open Reading Frames; D000074428:Peroxisomal Biogenesis Factor 2; D020675:Peroxisomes / Q000235:genetics*; D010641:Phenotype; D011995:Recombination, Genetic; D020037:Sordariales / Q000235:genetics*
D017931:DNA Primers; D008164:Luminescent Proteins; D008565:Membrane Proteins; C000614230:PEX2 protein, human; D000074428:Peroxisomal Biogenesis Factor 2; D049452:Green Fluorescent Proteins