A puromycin-sensitive aminopeptidase is essential for meiosis in Arabidopsis thaliana.
Puromycin-sensitive aminopeptidases (PSAs) participate in a variety of proteolytic events essential for cell growth and viability, and in fertility in a broad range of organisms. We have identified and characterized an Arabidopsis thaliana mutant (mpa1) from a pool of T-DNA tagged lines that lacks PSA activity. This line exhibits reduced fertility, producing shorter siliques (fruits) bearing a lower number of seeds compared with wild-type plants. Cytogenetic characterization of meiosis in the mutant line reveals that both male and female meiosis are defective. In mpa1, early prophase I appears normal, but after pachytene most of the homologous chromosomes are desynaptic, thus, by metaphase I a high level of univalence is observed subsequently leading to abnormal chromosome segregation. Wild-type plants treated with specific inhibitors of PSA show a very similar desynaptic phenotype to that of the mutant line. A fluorescent PSA-specific bioprobe, DAMPAQ-22, reveals that the protein is maximally expressed in wild-type meiocytes during prophase I and is absent in mpa1. Immunolocalization of meiotic proteins showed that the meiotic recombination pathway is disrupted in mpa1. Chromosome pairing and early recombination appears normal, but progression to later stages of recombination and complete synapsis of homologous chromosomes are blocked.
Sánchez-Morán
Eugenio
E
School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
Jones
Gareth H
GH
Franklin
F Christopher H
FC
Santos
Juan Luis
JL
D000595:Amino Acid Sequence / Q000235:genetics; D000626:Aminopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence / Q000235:genetics; D023902:Chromosome Pairing / Q000235:genetics; D020090:Chromosome Segregation / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005298:Fertility / Q000235:genetics; D008540:Meiosis / Q000502:physiology*; D049469:Meiotic Prophase I / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; C036483:T-DNA; D000626:Aminopeptidases; C497725:MPA1 protein, Arabidopsis; C025579:enkephalin degrading enzyme