High impact information on AT3G21720

• We transferred genes encoding the glyoxysome-specific enzymes isocitrate lyase (IL) and malate synthase into Arabidopsis plants and showed, in cell fractionation and immunogold localization experiments, that the glyoxysomal proteins were imported into leaf-type and root peroxisomes [1].
• By localizing deletion and fusion derivatives of IL, we showed that the polypeptide's carboxyl terminus is both necessary for its transport to peroxisomes and sufficient to redirect a passenger protein from the cytosol to both glyoxysomes and leaf-type peroxisomes [1].
• We next defined the sequences that target IL to peroxisomes and asked whether the same targeting determinant is recognized by different classes of the organelle [1].
• An isocitrate lyase mutant has provided the first opportunity to test the biochemical and physiological functions of the glyoxylate cycle in vivo in an oilseed species [2].
• We hypothesized that in the absence of MLS, succinate produced by isocitrate lyase (ICL) could still feed into the tricarboxylic acid cycle, whereas glyoxylate could be converted to sugars using enzymes of the photorespiratory pathway [3].

Biological context of AT3G21720

• We conclude that a combination of elements is involved in regulating the isocitrate lyase gene and that distinct DNA sequences play primary roles in activating the gene in embryos and in seedlings [4].
• DNA sequences that activate isocitrate lyase gene expression during late embryogenesis and during postgerminative growth [4].
• Only in developing siliques of the tag1 mutant, deficient in the accumulation of triacylglycerols and shown to have a substantial futile cycling of fatty acids toward beta-oxidation, have some changes in gene expression been detected, notably the induction of the isocitrate lyase gene [5].
• The mRNA abundance and enzyme activities increase to a peak at stage 2, 48 h after the onset of seed germination, and decline thereafter either to undetectable levels (for malate synthase and isocitrate lyase) or low basal levels (for the genes of beta-oxidation and gluconeogenesis) [6].

Analytical, diagnostic and therapeutic context of AT3G21720

• Immunoblotting confirmed that neither malate synthase nor the other unique glyoxylate cycle enzyme isocitrate lyase are expressed in senescent leaves [7].

References