A Temperature-sensitive mutation in the Arabidopsis thaliana phosphomannomutase gene disrupts protein glycosylation and triggers cell death.
Eukaryotic phosphomannomutases (PMMs) catalyze the interconversion of mannose 6-phosphate to mannose 1-phosphate and are essential to the biosynthesis of GDP-mannose. As such, plant PMMs are involved in ascorbic acid (AsA) biosynthesis and N-glycosylation. We report on the conditional phenotype of the temperature-sensitive Arabidopsis thaliana pmm-12 mutant. Mutant seedlings were phenotypically similar to wild type seedlings when grown at 16-18 degrees C but died within several days after transfer to 28 degrees C. This phenotype was observed throughout both vegetative and reproductive development. Protein extracts derived from pmm-12 plants had lower PMM protein and enzyme activity levels. In vitro biochemical analysis of recombinant proteins showed that the mutant PMM protein was compromised in its catalytic efficiency (K cat/K m). Despite significantly decreased AsA levels in pmm-12 plants, AsA deficiency could not account for the observed phenotype. Since, at restrictive temperature, total glycoprotein patterns were altered and glycosylation of protein-disulfide isomerase was perturbed, we propose that a deficiency in protein glycosylation is responsible for the observed cell death phenotype.
Hoeberichts
Frank A
FA
Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), Ghent University, 9052 Gent, Belgium.
Vaeck
Elke
E
Kiddle
Guy
G
Coppens
Emmy
E
van de Cotte
Brigitte
B
Adamantidis
Antoine
A
Ormenese
Sandra
S
Foyer
Christine H
CH
Zabeau
Marc
M
Inzé
Dirk
D
Périlleux
Claire
C
Van Breusegem
Frank
F
Vuylsteke
Marnik
M
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D001205:Ascorbic Acid / Q000096:biosynthesis / Q000235:genetics; D002384:Catalysis; D016923:Cell Death / Q000235:genetics; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics; D006031:Glycosylation; D006155:Guanosine Diphosphate Mannose / Q000096:biosynthesis / Q000235:genetics; D006358:Hot Temperature; D008360:Mannosephosphates / Q000096:biosynthesis / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D017875:Phosphotransferases (Phosphomutases) / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology / Q000235:genetics
D006023:Glycoproteins; D008360:Mannosephosphates; D010940:Plant Proteins; D011994:Recombinant Proteins; C047217:mannose 1-phosphate; D006155:Guanosine Diphosphate Mannose; D019704:Protein Disulfide-Isomerases; D017875:Phosphotransferases (Phosphomutases); C052799:phosphomannomutase; D001205:Ascorbic Acid