Phosphorylation and inactivation of yeast 6-phosphofructo-2-kinase contribute to the regulation of glycolysis under hypotonic stress.
Phosphorylation of yeast 6-phosphofructo-2-kinase and its role for the regulation of glycolysis under hypoosmotic conditions were investigated. 6-Phosphofructo-2-kinase was found to be phosphorylated in vitro by protein kinase C at serine 652 and thereby inactivated. Protein phosphatase 2A reversed the phosphorylative inhibition of the enzyme. When yeast cells were shifted to hypotonic media, 6-phosphofructo-2-kinase was found to be phosphorylated and inactivated. Under in vivo conditions, two phosphate residues were incorporated into the enzyme. One of them is bound to serine 652, indicating that this modification was probably caused by yeast protein kinase C1. The second phosphate is bound to Ser8 within the N-terminal peptide T(1-41) which contains several serine residues but no protein kinase C recognition sequence. Site-directed mutagenesis confirmed that the phosphorylation of serine 652 but not the N-terminal modification is responsible for the in vivo inactivation of 6-phosphofructo-2-kinase. The obtained results suggest that the phosphorylation of 6-phosphofructo-2-kinase mediates a response of the cells to an activation of the hypoosmolarity MAP kinase pathway. Via a suppression of glycolysis, the inactivation of 6-phosphofructo-2-kinase is expected to be responsible for the observed accumulation of glucose 6-phosphate, an essential precursor of the cell wall glucans, and the decrease of glycerol, an important osmolyte.
Dihazi
H
H
Institute of Biochemistry, Medical Faculty, University of Leipzig, Liebigstrasse 16, D-04103 Leipzig, Germany.
Kessler
R
R
Eschrich
K
K
D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D019298:Glucose-6-Phosphate / Q000032:analysis; D005990:Glycerol / Q000032:analysis; D006019:Glycolysis / Q000502:physiology*; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000378:metabolism; D025481:Phosphofructokinase-2 / Q000737:chemistry / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids; D011493:Protein Kinase C / Q000378:metabolism; D054648:Protein Phosphatase 2; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012694:Serine / Q000737:chemistry; D014357:Trypsin / Q000378:metabolism
D010446:Peptide Fragments; D011994:Recombinant Proteins; D012694:Serine; D019298:Glucose-6-Phosphate; D025481:Phosphofructokinase-2; D011493:Protein Kinase C; C031915:phosphofructokinase phosphatase; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D014357:Trypsin; D005990:Glycerol