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Role of Cys‐295 on subunit interactions and allosteric regulation of phosphofructokinase‐2 from Escherichia coli
Author(s) -
Caniuguir Andrés,
Cabrera Ricardo,
Báez Mauricio,
Vásquez Claudio C.,
Babul Jorge,
Guixé Victoria
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.02.078
Subject(s) - tetramer , allosteric regulation , chemistry , enzyme , escherichia coli , phosphofructokinase , dimer , protein subunit , biochemistry , phosphofructokinase 1 , mutant , stereochemistry , heterotetramer , glycolysis , organic chemistry , gene
In a previous work, chemical modification of Cys‐238 of Escherichia coli Pfk‐2 raised concerns on the importance of the dimeric state of Pfk‐2 for enzyme activity, whereas modification of Cys‐295 impaired the enzymatic activity and the MgATP‐induced tetramerization of the enzyme. The results presented here demonstrate that the dimeric state of Pfk‐2 is critical for the stability and the activity of the enzyme. The replacement of Cys‐238 by either Ala or Phe shows no effect on the kinetic parameters, allosteric inhibition, dimer stability and oligomeric structure of Pfk‐2. However, the mutation of Cys‐295 by either Ala or Phe provokes a decrease in the k cat value and an increment in the K m values for both substrates. We suggest that the Cys‐295 residue participates in intersubunit interactions in the tetramer since the Cys‐295‐Phe mutant exhibits higher tetramer stability, which in turn results in an increase in the fructose‐6‐P concentration required for the reversal of the MgATP inhibition relative to the wild type enzyme.