d-GLYCERATE 3-KINASE, the Last Unknown Enzyme in the Photorespiratory Cycle in Arabidopsis, Belongs to a Novel Kinase Family

Algal evolution in relation to atmospheric CO 2 : carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles

“…Parts of the PCOC (glycerate dehydrogenase, serine transminases and serine hydroxymethyltransferase) could have been recruited from core metabolism synthesizing serine and glycine from glycolytic intermediates, while others (glycolate dehydrogenase/oxidase, glycine decarboxylase and glycerate kinase) have no known roles other than in the metabolism of glycolate to PCRC intermediates [93,94].…”

An Autoinhibitory Domain Confers Redox Regulation to Maize Glycerate Kinase

“…Hence, we used the Arabidopsis (Arabidopsis thaliana) GLYK sequence (Boldt et al, 2005) for similarity searches in maize EST libraries and identified several overlapping ESTs, which were combined to a continuous nucleotide sequence encoding the full-length putative ZmGLYK. This sequence was recently deposited in GenBank, and the gene product was tentatively annotated as hypothetical protein LOC100274052 (Alexandrov et al, 2009).…”

“…Glycerate 2-kinases are involved in the degradation of Glc and other metabolic pathways in animals and bacteria (Guo et al, 2006;Kehrer et al, 2007) but have not been reported for plants. Instead, a glycerate 3-kinase (GLYK) occurs in plant chloroplasts and many cyanobacteria, where it produces glycerate 3-phosphate (3PGA) from glycerate in the last step of the photorespiratory C 2 cycle (Boldt et al, 2005;Bartsch et al, 2008). This pathway is an indispensable auxiliary component of the photosynthetic CO 2 assimilation network in cyanobacteria and plants (Eisenhut et al, 2008), and its operation is most evident in higher plants with the C 3 pathway of photosynthesis.…”

High-throughput colorimetric method for the parallel assay of glyoxylic acid and ammonium in a single extract

“…Mutations in enzymes of this pathway usually are lethal, underlining the importance of this salvage pathway [2][3][4]. Although all enzymes and some of the metabolite transporters involved in this highly compartmentalized pathway have been identified [5][6][7][8][9], information about the majority of the transport proteins and the processes regulating the pathway is still missing [1,4], possibly because mutations in the corresponding genes cause subtle metabolic phenotypes. Thus, a high-throughput method to quantify metabolites known to accumulate in photorespiratory mutants, glyoxylate and ammonium, is desirable.…”

“…For glyoxylate quantification, 450 ll of the supernatant is mixed with 50 ll of a freshly prepared 1% (v/v) solution of phenylhydrazine in 100 mM HCl, and the sample is incubated at 95°C for 2 min and cooled on ice for 6 min. The sample is acidified by adding 250 ll of concentrated HCl and is divided into three 225-ll aliquots in cavities of a 96-well plate; two technical replicates are oxidized with 25 ll of a solution of 1.6% (w/v) K 3 Fe(CN) 6 with 25 ll of water added. Color formation is measured exactly 6 min after the addition of K 3 Fe(CN) 6 solution because the reaction reaches a plateau after 4 min and the colored reaction product slowly decomposes with time afterward.…”