High impact information on PFK2

• A stimulation of the HOG-MAPK pathway by increasing the medium osmolarity through addition of salt or glucose to cultivated yeast leads to an activation of 6-phosphofructo-2-kinase (PFK2), which is accompanied by a complex phosphorylation pattern of the enzyme [1].
• In the case of hyperosmolar glucose a 5-fold PFK2 activation was achieved by a single phosphorylation with protein kinase A near the carboxyl terminus of the protein on Ser(644) and an additional 5-fold phosphorylation within the same amino-terminal fragment as in the presence of salt [1].
• When intracellular glucose-6-P levels were increased by mutating the PFK2 gene, glycogen storage due to the wild-type enzyme was increased, whereas that associated with R579A/R580A/R582A [corrected] was not greatly changed [2].
• Yeast cells containing PFK2 accumulate three times more glycerol than cells lacking PFK2, which are not able to grow under hypertonic stress [1].
• The activation of PFK2 leads to an activation of the upper part of glycolysis, which is a precondition for glycerol accumulation [1].

Biological context of PFK2

• By in vitro mutagenesis, we introduced this mutation in either PFK1 or PFK2 and found that the exchange in either subunit drastically reduced the sensitivity of the holoenzyme to ATP inhibition [3].
• PFK2 was mapped previously to the right arm of chromosome XIII, locating the latter three genes to the same chromosome [4].
• Interactions between the two phosphofructo-1-kinase subunits PFK1 and PFK2, interactions between the phosphofructo-2-kinase subunits, and dimerization of phosphoglucose isomerase were demonstrated [5].
• By contrast, like glucose, these agents also caused, under most experimental conditions, a detectable rise in cyclic AMP concentration and a series of cyclic-AMP-dependent effects such as an activation of phosphofructokinase 2 and of trehalase and an increase in the concentration of fructose 2,6-bisphosphate and in the rate of glycolysis [6].
• Wild-type PFK2 without any tag sequence was found to be acetylated and two times phosphorylated at the N-terminal peptide T(1-40) carrying the acetylation [7].

Anatomical context of PFK2

• 5'-Rapid amplification of cDNA ends analysis and Northern blot analysis revealed that rat pancreatic islets express the brain isoform of PFK-2/FBPase-2 [8].

Associations of PFK2 with chemical compounds

• Loss of PFK2 causes elevated levels of metabolites such as glucose-6-P, hyperaccumulation of glycogen, and activation of glycogen synthase, whereas glucose-6-P is reduced in snf1 cells [9].
• A 'hyper-allosteric' mutant altered in the regulatory subunit encoded by the gene PFK2 showed characteristics of glucose fermentation and ethanol oxidation very similar to those of wild-type organisms [10].
• Here we provide data demonstrating that an alanine residue at positions 874 (for the PFK1-encoded alpha-subunit) or 868 (for the PFK2-encoded beta-subunit) is crucial to achieve this structure [11].
• Phosphate also enhances the inactivation of PFK2 by citrate, suggesting that phosphate acts as a regulator of PFK2 [12].
• Inorganic phosphate also activates PFK2, and the optimum pH for the PFK2 activity varies with the concentration of phosphate [12].

Regulatory relationships of PFK2

• This has been achieved by overexpression of the latter in a PFK-deficient strain of Saccharomyces cerevisiae under the control of the PFK2 promoter [13].

Other interactions of PFK2

• From a genetic screen, we have found that mutation of the PFK2 gene, which encodes the beta-subunit of 6-phosphofructo-1-kinase, restores glycogen accumulation in snf1 cells [9].
• 6-Phosphofructo-2-kinase (PFK2) is activated by a cAMP-dependent protein kinase, and inactivated by phosphatase, indicating the interconversion of PFK2 [12].
• The latter is not capable of complementing an icl1 deletion for growth on ethanol neither in its original context, nor when expressed under the control of the glycolytic PFK2 promoter [14].
• Higher level expression under the control of the yeast PFK2 promoter partially complemented the gpm1 defects, without restoring detectable enzymatic activity [15].
• Reaction of phosphofructokinase 2/fructose 2,6-bisphosphatase with monoclonal antibodies. A proof of the bifunctionality of the enzyme [16].

Analytical, diagnostic and therapeutic context of PFK2

• Immunofluorescence microscopy displayed a conspicuously filamentous arrangement of the Pfk-1 mutant protein, exclusively in the pfk2 single deletion mutant [17].
• Phosphofructokinase 2 from Saccharomyces cerevisiae was purified 8500-fold by chromatography on blue Trisacryl, gel filtration on Superose 6B and chromatography on ATP-agarose [18].
• Returned to yeast on a multicopy plasmid, phosphofructokinase 2 activity was considerably above the wild-type level, as was polypeptide revealed by immunoblotting [19].

References