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J. Bacteriol., 05 1996, 2846-2852, Vol 178, No. 10
DW Pettigrew, WZ Liu, C Holmes, ND Meadow and S Roseman
Escherichia coli glycerol kinase (EC 2.7.1.30; ATP:glycerol 3-
phosphotransferase) is a key element in glucose control of glycerol
metabolism. Its catalytic activity is inhibited allosterically by the
glycolytic intermediate, fructose 1,6-biphosphate, and by the
phosphotransferase system phosphocarrier protein, IIIGlc (also known as
IIAGlc). These inhibitors provide mechanisms by which glucose blocks
glycerol utilization in vivo. We report here the cloning and sequencing of
the glpK22 gene isolated from E. C. C. Lin strain 43, a strain that shows
the loss of glucose control of glycerol utilization. DNA sequencing shows a
single missense mutation that translates to the amino acid change Gly-304
to Ser (G-304-S) in glycerol kinase. The effects of this substitution on
the functional and physical properties of the purified mutant enzyme were
determined. Neither of the allosteric ligands inhibits it under conditions
that produce strong inhibition of the wild-type enzyme, which is sufficient
to explain the phenotype of strain 43. However, IIIGlc activates the mutant
enzyme, which could not be predicted from the phenotype. In the wild-type
enzyme, G-304 is located 1.3 nm from the active site and 2.5 nm from the
IIIGlc binding site (M. Feese, D. W. Pettigrew, N. D. Meadow, S. Roseman,
and S. J. Remington, Proc. Natl. Acad. Sci. USA 91:3544-3548, 1994). It is
located in the same region as amino acid substitutions in the related
protein DnaK which alter its catalytic and regulatory properties and which
are postulated to interfere with a domain closure motion (A. S.
Kamath-Loeb, C. Z. Lu, W.-C. Suh, M. A. Lonetto, and C. A. Gross, J. Biol.
Chem. 270:30051-30059, 1995). The global effect of the G-304-S substitution
on the conformation and catalytic and regulatory properties of glycerol
kinase is consistent with a role for the domain closure motion in the
molecular mechanism for glucose control of glycerol utilization.
Copyright © 1996, American Society for Microbiology
A single amino acid change in Escherichia coli glycerol kinase abolishes glucose control of glycerol utilization in vivo
Department of Biochemistry & Biophysics, Texas A&M University, College Station 77843-2128, USA. PETTIGREW@BIOCH.TAMU.EDU
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