Crystal structure of a C-terminal deletion mutant of human protein kinase CK2 catalytic subunit

Inessa Ermakova, Brigitte Boldyreff, Olaf-Georg Issinger, Karsten Niefind

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Protein kinase CK2 (formerly called: casein kinase 2) is a heterotetrameric enzyme composed of two separate catalytic chains (CK2alpha) and a stable dimer of two non-catalytic subunits (CK2beta). CK2alpha is a highly conserved member of the superfamily of eukaryotic protein kinases. The crystal structure of a C-terminal deletion mutant of human CK2alpha was solved and refined to 2.5A resolution. In the crystal the CK2alpha mutant exists as a monomer in agreement with the organization of the subunits in the CK2 holoenzyme. The refined structure shows the helix alphaC and the activation segment, two main regions of conformational plasticity and regulatory importance in eukaryotic protein kinases, in active conformations stabilized by extensive contacts to the N-terminal segment. This arrangement is in accordance with the constitutive activity of the enzyme. By structural superimposition of human CK2alpha in isolated form and embedded in the human CK2 holoenzyme the loop connecting the strands beta4 and beta5 and the ATP-binding loop were identified as elements of structural variability. This structural comparison suggests that the ATP-binding loop may be the key region by which the non-catalytic CK2beta dimer modulates the activity of CK2alpha. The beta4/beta5 loop was found in a closed conformation in contrast to the open conformation observed for the CK2alpha subunits of the CK2 holoenzyme. CK2alpha monomers with this closed beta4/beta5 loop conformation are unable to bind CK2beta dimers in the common way for sterical reasons, suggesting a mechanism to protect CK2alpha from integration into CK2 holoenzyme complexes. This observation is consistent with the growing evidence that CK2alpha monomers and CK2beta dimers can exist in vivo independently from the CK2 holoenzyme and may possess physiological roles of their own.
Original languageEnglish
JournalJournal of Molecular Biology
Volume330
Issue number5
Pages (from-to)925-934
Number of pages9
ISSN0022-2836
DOIs
Publication statusPublished - 25. Jul 2003

Fingerprint

Casein Kinase II
Mutant Proteins
Holoenzymes
Catalytic Domain
Enzymes

Keywords

  • Adenosine Triphosphate
  • Amino Acid Sequence
  • Casein Kinase II
  • Catalytic Domain
  • Crystallography, X-Ray
  • Dimerization
  • Gene Deletion
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases
  • Sequence Homology, Amino Acid

Cite this

Ermakova, Inessa ; Boldyreff, Brigitte ; Issinger, Olaf-Georg ; Niefind, Karsten. / Crystal structure of a C-terminal deletion mutant of human protein kinase CK2 catalytic subunit. In: Journal of Molecular Biology. 2003 ; Vol. 330, No. 5. pp. 925-934.
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abstract = "Protein kinase CK2 (formerly called: casein kinase 2) is a heterotetrameric enzyme composed of two separate catalytic chains (CK2alpha) and a stable dimer of two non-catalytic subunits (CK2beta). CK2alpha is a highly conserved member of the superfamily of eukaryotic protein kinases. The crystal structure of a C-terminal deletion mutant of human CK2alpha was solved and refined to 2.5A resolution. In the crystal the CK2alpha mutant exists as a monomer in agreement with the organization of the subunits in the CK2 holoenzyme. The refined structure shows the helix alphaC and the activation segment, two main regions of conformational plasticity and regulatory importance in eukaryotic protein kinases, in active conformations stabilized by extensive contacts to the N-terminal segment. This arrangement is in accordance with the constitutive activity of the enzyme. By structural superimposition of human CK2alpha in isolated form and embedded in the human CK2 holoenzyme the loop connecting the strands beta4 and beta5 and the ATP-binding loop were identified as elements of structural variability. This structural comparison suggests that the ATP-binding loop may be the key region by which the non-catalytic CK2beta dimer modulates the activity of CK2alpha. The beta4/beta5 loop was found in a closed conformation in contrast to the open conformation observed for the CK2alpha subunits of the CK2 holoenzyme. CK2alpha monomers with this closed beta4/beta5 loop conformation are unable to bind CK2beta dimers in the common way for sterical reasons, suggesting a mechanism to protect CK2alpha from integration into CK2 holoenzyme complexes. This observation is consistent with the growing evidence that CK2alpha monomers and CK2beta dimers can exist in vivo independently from the CK2 holoenzyme and may possess physiological roles of their own.",
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Crystal structure of a C-terminal deletion mutant of human protein kinase CK2 catalytic subunit. / Ermakova, Inessa; Boldyreff, Brigitte; Issinger, Olaf-Georg; Niefind, Karsten.

In: Journal of Molecular Biology, Vol. 330, No. 5, 25.07.2003, p. 925-934.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Crystal structure of a C-terminal deletion mutant of human protein kinase CK2 catalytic subunit

AU - Ermakova, Inessa

AU - Boldyreff, Brigitte

AU - Issinger, Olaf-Georg

AU - Niefind, Karsten

PY - 2003/7/25

Y1 - 2003/7/25

N2 - Protein kinase CK2 (formerly called: casein kinase 2) is a heterotetrameric enzyme composed of two separate catalytic chains (CK2alpha) and a stable dimer of two non-catalytic subunits (CK2beta). CK2alpha is a highly conserved member of the superfamily of eukaryotic protein kinases. The crystal structure of a C-terminal deletion mutant of human CK2alpha was solved and refined to 2.5A resolution. In the crystal the CK2alpha mutant exists as a monomer in agreement with the organization of the subunits in the CK2 holoenzyme. The refined structure shows the helix alphaC and the activation segment, two main regions of conformational plasticity and regulatory importance in eukaryotic protein kinases, in active conformations stabilized by extensive contacts to the N-terminal segment. This arrangement is in accordance with the constitutive activity of the enzyme. By structural superimposition of human CK2alpha in isolated form and embedded in the human CK2 holoenzyme the loop connecting the strands beta4 and beta5 and the ATP-binding loop were identified as elements of structural variability. This structural comparison suggests that the ATP-binding loop may be the key region by which the non-catalytic CK2beta dimer modulates the activity of CK2alpha. The beta4/beta5 loop was found in a closed conformation in contrast to the open conformation observed for the CK2alpha subunits of the CK2 holoenzyme. CK2alpha monomers with this closed beta4/beta5 loop conformation are unable to bind CK2beta dimers in the common way for sterical reasons, suggesting a mechanism to protect CK2alpha from integration into CK2 holoenzyme complexes. This observation is consistent with the growing evidence that CK2alpha monomers and CK2beta dimers can exist in vivo independently from the CK2 holoenzyme and may possess physiological roles of their own.

AB - Protein kinase CK2 (formerly called: casein kinase 2) is a heterotetrameric enzyme composed of two separate catalytic chains (CK2alpha) and a stable dimer of two non-catalytic subunits (CK2beta). CK2alpha is a highly conserved member of the superfamily of eukaryotic protein kinases. The crystal structure of a C-terminal deletion mutant of human CK2alpha was solved and refined to 2.5A resolution. In the crystal the CK2alpha mutant exists as a monomer in agreement with the organization of the subunits in the CK2 holoenzyme. The refined structure shows the helix alphaC and the activation segment, two main regions of conformational plasticity and regulatory importance in eukaryotic protein kinases, in active conformations stabilized by extensive contacts to the N-terminal segment. This arrangement is in accordance with the constitutive activity of the enzyme. By structural superimposition of human CK2alpha in isolated form and embedded in the human CK2 holoenzyme the loop connecting the strands beta4 and beta5 and the ATP-binding loop were identified as elements of structural variability. This structural comparison suggests that the ATP-binding loop may be the key region by which the non-catalytic CK2beta dimer modulates the activity of CK2alpha. The beta4/beta5 loop was found in a closed conformation in contrast to the open conformation observed for the CK2alpha subunits of the CK2 holoenzyme. CK2alpha monomers with this closed beta4/beta5 loop conformation are unable to bind CK2beta dimers in the common way for sterical reasons, suggesting a mechanism to protect CK2alpha from integration into CK2 holoenzyme complexes. This observation is consistent with the growing evidence that CK2alpha monomers and CK2beta dimers can exist in vivo independently from the CK2 holoenzyme and may possess physiological roles of their own.

KW - Adenosine Triphosphate

KW - Amino Acid Sequence

KW - Casein Kinase II

KW - Catalytic Domain

KW - Crystallography, X-Ray

KW - Dimerization

KW - Gene Deletion

KW - Humans

KW - Models, Molecular

KW - Molecular Sequence Data

KW - Mutation

KW - Protein Binding

KW - Protein Conformation

KW - Protein Structure, Tertiary

KW - Protein-Serine-Threonine Kinases

KW - Sequence Homology, Amino Acid

U2 - 10.1016/S0022-2836(03)00638-7

DO - 10.1016/S0022-2836(03)00638-7

M3 - Journal article

VL - 330

SP - 925

EP - 934

JO - Journal of Molecular Biology

JF - Journal of Molecular Biology

SN - 0022-2836

IS - 5

ER -