Expression and properties of the glyoxysomal and cytosolic forms of isocitrate lyase in Amaranthus caudatus L.

Organic Acids: The Pools of Fixed Carbon Involved in Redox Regulation and Energy Balance in Higher Plants

“…The coordinated operation of isoenzymes of the TCA cycle enzymes in mitochondria, cytosol and other organelles balances the intercompartmental redox regulation, supplies intermediates for biosynthetic pathways and provides the flexibility of the TCA cycle operation in open versus closed form. An important role in the coordination of regulation of two branches of the TCA cycle may belong to the non-glyoxysomal isocitrate lyase, which operates in the cytosol at low pH and activated by manganese ( Eprintsev et al, 2015b ). It may link the TCA cycle with glyoxylate/glycine metabolism, and, therefore, either supply glyoxylate for glycine and oxalate biosynthesis or utilize the photorespiratory glyoxylate in the reverse (synthase) reaction ( Igamberdiev and Lea, 2002 ).…”

Plant Glyoxylate/Succinic Semialdehyde Reductases: Comparative Biochemical Properties, Function during Chilling Stress, and Subcellular Localization

“…SSA is typically oxidized to succinate via SSA dehydrogenase ( Tuin and Shelp, 1994 ; Bouché et al, 2003 ), but evidence is available for the generation of 4-hydroxybutyrate (GHB) from SSA in response to hypoxia, high light, salinity, drought and chilling ( Allan et al, 2003 , 2008 , 2012 ; Breitkreuz et al, 2003 ; Fait et al, 2005 ). Glyoxylate can be generated in various subcellular compartments and biochemical processes: the peroxisome during the photorespiratory or non-photorespiratory synthesis of serine ( Bauwe et al, 2010 ; Hoover et al, 2013 ; Ros et al, 2014 ); the glyoxysome during fatty acid catabolism ( Kunze et al, 2006 ); the cytosol during the interconversion of organic acids ( Eprintsev et al, 2015 ); and the endoplasmic reticulum during purine catabolism ( Werner and Witte, 2011 ). Glycolate, the precursor of glyoxylate in photorespiration, is known to accumulate under hypoxic conditions, and both glycolate and glyoxylate accumulate with the suppression of glycolate oxidase ( Narsai et al, 2009 ; Lu et al, 2014 ).…”

Phosphoenolpyruvate carboxykinase, pyruvate orthophosphate dikinase and isocitrate lyase in both tomato fruits and leaves, and in the flesh of peach and some other fruits

“…However, recent studies have shown that plants also possess a 302 cytosolic form of ICL with limited sequence similarity to the glyoxysomal form (Eprintsev et al, 2015). This enzyme 303 is thought to function in organic acid interconversions (eg oxalate synthesis in some leaves) and not in the glyoxylate 304 cycle (Eprintsev et al, 2015). Our results do not preclude the presence of this enzyme in fruits, and indeed there is 305 evidence for the occurrence of this enzyme in banana flesh (Eprintsev et al, 2015).…”

“…This enzyme 303 is thought to function in organic acid interconversions (eg oxalate synthesis in some leaves) and not in the glyoxylate 304 cycle (Eprintsev et al, 2015). Our results do not preclude the presence of this enzyme in fruits, and indeed there is 305 evidence for the occurrence of this enzyme in banana flesh (Eprintsev et al, 2015). 306 and this is the most likely source of this malate.…”

“…The very low abundance of gyoxysomal ICL in both tomato flesh and that of other fruits, suggests that 300 in these, the conversion of pyruvate/acetyl-CoA to malate by the glyoxylate cycle is not a major pathway utilised by 301 gluconeogenesis under normal conditions of growth. However, recent studies have shown that plants also possess a 302 cytosolic form of ICL with limited sequence similarity to the glyoxysomal form (Eprintsev et al, 2015). This enzyme 303 is thought to function in organic acid interconversions (eg oxalate synthesis in some leaves) and not in the glyoxylate 304 cycle (Eprintsev et al, 2015).…”