A Temperature-sensitive Mutation in theArabidopsis thalianaPhosphomannomutase Gene Disrupts Protein Glycosylation and Triggers Cell Death

摘要: Eukaryotic phosphomannomutases (PMMs) catalyze the interconversion of mannose 6-phosphate to 1-phosphate and are essential biosynthesis GDP-mannose. As such, plant PMMs involved in ascorbic acid (AsA) N-glycosylation. We report on conditional phenotype temperature-sensitive Arabidopsis thaliana pmm-12 mutant. Mutant seedlings were phenotypically similar wild type when grown at 16–18 °C but died within several days after transfer 28 °C. This was observed throughout both vegetative reproductive development. Protein extracts derived from plants had lower PMM protein enzyme activity levels. In vitro biochemical analysis recombinant proteins showed that mutant compromised its catalytic efficiency (Kcat/Km). Despite significantly decreased AsA levels plants, deficiency could not account for phenotype. Since, restrictive temperature, total glycoprotein patterns altered glycosylation protein-disulfide isomerase perturbed, we propose a is responsible cell death