Campus Units

Biochemistry, Biophysics and Molecular Biology

Document Type

Article

Publication Version

Published Version

Publication Date

3-2001

Journal or Book Title

Journal of Biological Chemistry

Volume

276

Issue

9

First Page

6119

Last Page

6124

DOI

10.1074/jbc.M009485200

Abstract

Residues 1–10 of porcine fructose-1,6-bisphosphatase (FBPase) are poorly ordered or are in different conformations, sensitive to the state of ligation of the enzyme. Deletion of the first 10 residues of FBPase reducesk cat by 30-fold and Mg2+ affinity by 20-fold and eliminates cooperativity in Mg2+ activation. Although a fluorescent analogue of AMP binds with high affinity to the truncated enzyme, AMP itself potently inhibits only 50% of the enzyme activity. Additional inhibition occurs only when the concentration of AMP exceeds 10 mM. Deletion of the first seven residues reduces k cat and Mg2+ affinity significantly but has no effect on AMP inhibition. The mutation of Asp9 to alanine reproduces the weakened affinity for Mg2+ observed in the deletion mutants, and the mutation of Ile10 to aspartate reproduces the AMP inhibition of the 10-residue deletion mutant. Changes in the relative stability of the known conformational states for loop 52–72, in response to changes in the quaternary structure of FBPase, can account for the phenomena above. Some aspects of the proposed model may be relevant to all forms of FBPase, including the thioredoxin-regulated FBPase from the chloroplast.

Comments

This article is from Journal of Biological Chemistry 276 (2001): 6119, doi:10.1074/jbc.M009485200. Posted with permission.

Copyright Owner

American Society for Biochemistry and Molecular Biology

Language

en

File Format

application/pdf

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