Modulation of the mobility of a key region in human galactokinase

Impacts on catalysis and stability

Margaret McAuley, Meilan Huang, David J. Timson

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Galactokinase catalyses the phosphorylation of α-d-galactose and some structurally related monosaccharides. The enzyme is of interest due to its potential as a biocatalyst for the production of sugar 1-phosphates and due to its involvement in the inherited metabolic disease type II galactosemia. It has been previously shown that a region (residues 231–245) in human galactokinase often has altered mobility when active site residues are varied. We hypothesised that the reverse may be true and that designing changes to this region might affect the functioning of the active site of the enzyme. Focussing on four residues (Leu-231, Gln-242, Glu-244 and Glu-245) we conducted molecular dynamics simulations to explore the effects of changing these residues to glycine or serine. In most cases the variations resulted in local changes to the 231–245 region and global changes to the root mean squared fluctuation (RMSF) of the protein. The four serine variants were expressed as recombinant proteins. All had altered steady state enzyme kinetic parameters with α-d-galactose as a substrate. However, these changes were generally less than ten-fold in magnitude. Changes were also observed with 2-deoxy-α-d-galactose, α-d-galactosamine and α-d-talose as substrates, including (in some cases) loss of detectable activity, suggesting that these variations can tune the specificity of the enzyme. This study demonstrates that activity and specificity of human galactokinase can be modulated by variations designed to affect active site flexibility. It is likely that this principle can be generalised to other enzymes.
Original languageEnglish
Pages (from-to)649-657
Number of pages9
JournalBioorganic Chemistry
Volume81
DOIs
Publication statusPublished - 19 Sep 2018

Fingerprint

Galactokinase
Catalysis
Enzymes
Galactose
Catalytic Domain
Serine
Sugar Phosphates
Galactosemias
Galactosamine
Monosaccharides
Metabolic Diseases
Molecular Dynamics Simulation
Recombinant Proteins
Human Activities
Glycine
Phosphorylation

Keywords

  • Enzyme engineering
  • GHMP kinase
  • Molecular dynamics
  • Protein flexibility
  • α--galactose

Cite this

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title = "Modulation of the mobility of a key region in human galactokinase: Impacts on catalysis and stability",
abstract = "Galactokinase catalyses the phosphorylation of α-d-galactose and some structurally related monosaccharides. The enzyme is of interest due to its potential as a biocatalyst for the production of sugar 1-phosphates and due to its involvement in the inherited metabolic disease type II galactosemia. It has been previously shown that a region (residues 231–245) in human galactokinase often has altered mobility when active site residues are varied. We hypothesised that the reverse may be true and that designing changes to this region might affect the functioning of the active site of the enzyme. Focussing on four residues (Leu-231, Gln-242, Glu-244 and Glu-245) we conducted molecular dynamics simulations to explore the effects of changing these residues to glycine or serine. In most cases the variations resulted in local changes to the 231–245 region and global changes to the root mean squared fluctuation (RMSF) of the protein. The four serine variants were expressed as recombinant proteins. All had altered steady state enzyme kinetic parameters with α-d-galactose as a substrate. However, these changes were generally less than ten-fold in magnitude. Changes were also observed with 2-deoxy-α-d-galactose, α-d-galactosamine and α-d-talose as substrates, including (in some cases) loss of detectable activity, suggesting that these variations can tune the specificity of the enzyme. This study demonstrates that activity and specificity of human galactokinase can be modulated by variations designed to affect active site flexibility. It is likely that this principle can be generalised to other enzymes.",
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Modulation of the mobility of a key region in human galactokinase : Impacts on catalysis and stability. / McAuley, Margaret; Huang, Meilan; Timson, David J.

In: Bioorganic Chemistry, Vol. 81, 19.09.2018, p. 649-657.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Modulation of the mobility of a key region in human galactokinase

T2 - Impacts on catalysis and stability

AU - McAuley, Margaret

AU - Huang, Meilan

AU - Timson, David J.

PY - 2018/9/19

Y1 - 2018/9/19

N2 - Galactokinase catalyses the phosphorylation of α-d-galactose and some structurally related monosaccharides. The enzyme is of interest due to its potential as a biocatalyst for the production of sugar 1-phosphates and due to its involvement in the inherited metabolic disease type II galactosemia. It has been previously shown that a region (residues 231–245) in human galactokinase often has altered mobility when active site residues are varied. We hypothesised that the reverse may be true and that designing changes to this region might affect the functioning of the active site of the enzyme. Focussing on four residues (Leu-231, Gln-242, Glu-244 and Glu-245) we conducted molecular dynamics simulations to explore the effects of changing these residues to glycine or serine. In most cases the variations resulted in local changes to the 231–245 region and global changes to the root mean squared fluctuation (RMSF) of the protein. The four serine variants were expressed as recombinant proteins. All had altered steady state enzyme kinetic parameters with α-d-galactose as a substrate. However, these changes were generally less than ten-fold in magnitude. Changes were also observed with 2-deoxy-α-d-galactose, α-d-galactosamine and α-d-talose as substrates, including (in some cases) loss of detectable activity, suggesting that these variations can tune the specificity of the enzyme. This study demonstrates that activity and specificity of human galactokinase can be modulated by variations designed to affect active site flexibility. It is likely that this principle can be generalised to other enzymes.

AB - Galactokinase catalyses the phosphorylation of α-d-galactose and some structurally related monosaccharides. The enzyme is of interest due to its potential as a biocatalyst for the production of sugar 1-phosphates and due to its involvement in the inherited metabolic disease type II galactosemia. It has been previously shown that a region (residues 231–245) in human galactokinase often has altered mobility when active site residues are varied. We hypothesised that the reverse may be true and that designing changes to this region might affect the functioning of the active site of the enzyme. Focussing on four residues (Leu-231, Gln-242, Glu-244 and Glu-245) we conducted molecular dynamics simulations to explore the effects of changing these residues to glycine or serine. In most cases the variations resulted in local changes to the 231–245 region and global changes to the root mean squared fluctuation (RMSF) of the protein. The four serine variants were expressed as recombinant proteins. All had altered steady state enzyme kinetic parameters with α-d-galactose as a substrate. However, these changes were generally less than ten-fold in magnitude. Changes were also observed with 2-deoxy-α-d-galactose, α-d-galactosamine and α-d-talose as substrates, including (in some cases) loss of detectable activity, suggesting that these variations can tune the specificity of the enzyme. This study demonstrates that activity and specificity of human galactokinase can be modulated by variations designed to affect active site flexibility. It is likely that this principle can be generalised to other enzymes.

KW - Enzyme engineering

KW - GHMP kinase

KW - Molecular dynamics

KW - Protein flexibility

KW - α--galactose

U2 - 10.1016/j.bioorg.2018.09.002

DO - 10.1016/j.bioorg.2018.09.002

M3 - Article

VL - 81

SP - 649

EP - 657

JO - Bioorganic Chemistry

JF - Bioorganic Chemistry

SN - 0045-2068

ER -