Functional analysis of folate polyglutamylation and its essential role in plant metabolism and development.

摘要: Cellular folates function as co-enzymes in one-carbon metabolism and are predominantly decorated with a polyglutamate tail that enhances co-enzyme affinity, subcellular compartmentation stability. Polyglutamylation is catalysed by folylpolyglutamate synthetases (FPGSs) specified three genes Arabidopsis, FPGS1, 2 3, which reportedly encode plastidic, mitochondrial cytosolic isoforms, respectively. A mutational approach was used to probe the functional importance of folate polyglutamylation development. Biochemical analysis single FPGS loss-of-function mutants established essential for organellar whole-plant homeostasis. However, polyglutamylated were still detectable, albeit at lower levels, organelles isolated from corresponding isozyme knockout lines, e.g. plastids mitochondria fpgs1 (plastidial) fpgs2 (mitochondrial) mutants. This result surprising given purported single-compartment targeting each isozyme. These results indicate redundancy compartmentalised activity, turn explains lack anticipated phenotypic defects In agreement this hypothesis, double embryo-lethal, fpgs3 exhibited seedling lethality, dwarfed reduced fertility. phenotypic, metabolic genetic observations consistent one or more isozymes multiple organelles. data confirm compartmentation, homeostasis folate-dependent processes, including photorespiration, methionine pantothenate biosynthesis.