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The hexameric structures of human heat shock protein 90.

Lee CC, Lin TW, Ko TP, Wang AH - PLoS ONE (2011)

Bottom Line: HSP90 identified on the cell surface has been found to play a crucial role in cancer invasion and metastasis, and has become a validated anti-cancer target for drug development.The crystal structure of MC-HSP90 reveals that, in addition to the C-terminal dimerization domain, the residue W320 in the M domain plays a critical role in its oligomerization.This study not only demonstrates how the human MC-HSP90 forms a hexamer, but also justifies the similar formation of HSP90N by using 3D modeling analysis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.

ABSTRACT

Background: The human 90-kDa heat shock protein (HSP90) functions as a dimeric molecular chaperone. HSP90 identified on the cell surface has been found to play a crucial role in cancer invasion and metastasis, and has become a validated anti-cancer target for drug development. It has been shown to self-assemble into oligomers upon heat shock or divalent cations treatment, but the functional role of the oligomeric states in the chaperone cycle is not fully understood.

Principal findings: Here we report the crystal structure of a truncated HSP90 that contains the middle segment and the carboxy-terminal domain, termed MC-HSP90. The structure reveals an architecture with triangular bipyramid geometry, in which the building block of the hexameric assembly is a dimer. In solution, MC-HSP90 exists in three major oligomer states, namely dimer, tetramer and hexamer, which were elucidated by size exclusion chromatography and analytical ultracentrifugation. The newly discovered HSP90 isoform HSP90N that lacks the N-terminal ATPase domain also exhibited similar oligomerization states as did MC-HSP90.

Conclusions: While lacking the ATPase domain, both MC-HSP90 and HSP90N can self-assemble into a hexameric structure, spontaneously. The crystal structure of MC-HSP90 reveals that, in addition to the C-terminal dimerization domain, the residue W320 in the M domain plays a critical role in its oligomerization. This study not only demonstrates how the human MC-HSP90 forms a hexamer, but also justifies the similar formation of HSP90N by using 3D modeling analysis.

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Comparison of HSP90 structures.(A) Disordered regions of MC-HSP90. The protomers A and B in the C2221 crystal are superimposed with RMSD of 0.637 Å between 367 Cα atom pairs. The residue number of N- and C-termini and the terminal ends of disordered loops in protomer A are indicated. The protein models are presented with ramped colors according to the B values. The start of the curved α-helix (α9) and the extended arm (α10) at C domain show high temperature factors. (B) The monomer structure of human MC-HSP90 (orange) is superimposed on the MC domains of closed-form yeast HSP82 (green) and open-form canine GRP94 (blue). (C) The dimer structure of human MC-HSP90 (orange) is superimposed on the MC domains of close-form yeast HSP82 (green). (D) Stereo view of superposed hexameric structures. The human MC-HSP90 hexamer and the N-terminal truncated yeast HSP82 (PDB: 2CGE) hexamer are superimposed. The protomers of Human MC-HSP90 dimer are colored in blue and orange, respectively, and six protomers of yeast HSP82 are colored in green. See Video S1 for more comprehensive aspects.
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pone-0019961-g003: Comparison of HSP90 structures.(A) Disordered regions of MC-HSP90. The protomers A and B in the C2221 crystal are superimposed with RMSD of 0.637 Å between 367 Cα atom pairs. The residue number of N- and C-termini and the terminal ends of disordered loops in protomer A are indicated. The protein models are presented with ramped colors according to the B values. The start of the curved α-helix (α9) and the extended arm (α10) at C domain show high temperature factors. (B) The monomer structure of human MC-HSP90 (orange) is superimposed on the MC domains of closed-form yeast HSP82 (green) and open-form canine GRP94 (blue). (C) The dimer structure of human MC-HSP90 (orange) is superimposed on the MC domains of close-form yeast HSP82 (green). (D) Stereo view of superposed hexameric structures. The human MC-HSP90 hexamer and the N-terminal truncated yeast HSP82 (PDB: 2CGE) hexamer are superimposed. The protomers of Human MC-HSP90 dimer are colored in blue and orange, respectively, and six protomers of yeast HSP82 are colored in green. See Video S1 for more comprehensive aspects.

Mentions: In the current structure, each molecule folds into three major domains (Figure 2A): a large middle (LM) domain (residues 293–469), a small middle (SM) domain (residues 470–547), and the C-terminal (C) domain (residues 548–732). The structure of the LM domain starts with a 310-helix, which is followed by a three-layer architecture of α-β-α sandwich and a helical coil. It encompasses two disordered loops comprising residues 351–358 and 396–404. The SM domain is also folded into an α-β-α sandwich architecture, and contains a sulfate-binding site. The sulfate was hydrogen bonded to the side chains of R510, K513 and H514 within helix α7, which is close to the C domain (Figure 2A). The C domain begins with an amphipathic loop, which shows high B-values (Figure 3A), and contains a curved α-helix, a three-stranded β-sheet, a three-helix coil and an extended disordered arm between helix α10 and strand β11 (residues 617–629). Beyond residue 697, the structure is disordered.


The hexameric structures of human heat shock protein 90.

Lee CC, Lin TW, Ko TP, Wang AH - PLoS ONE (2011)

Comparison of HSP90 structures.(A) Disordered regions of MC-HSP90. The protomers A and B in the C2221 crystal are superimposed with RMSD of 0.637 Å between 367 Cα atom pairs. The residue number of N- and C-termini and the terminal ends of disordered loops in protomer A are indicated. The protein models are presented with ramped colors according to the B values. The start of the curved α-helix (α9) and the extended arm (α10) at C domain show high temperature factors. (B) The monomer structure of human MC-HSP90 (orange) is superimposed on the MC domains of closed-form yeast HSP82 (green) and open-form canine GRP94 (blue). (C) The dimer structure of human MC-HSP90 (orange) is superimposed on the MC domains of close-form yeast HSP82 (green). (D) Stereo view of superposed hexameric structures. The human MC-HSP90 hexamer and the N-terminal truncated yeast HSP82 (PDB: 2CGE) hexamer are superimposed. The protomers of Human MC-HSP90 dimer are colored in blue and orange, respectively, and six protomers of yeast HSP82 are colored in green. See Video S1 for more comprehensive aspects.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3102065&req=5

pone-0019961-g003: Comparison of HSP90 structures.(A) Disordered regions of MC-HSP90. The protomers A and B in the C2221 crystal are superimposed with RMSD of 0.637 Å between 367 Cα atom pairs. The residue number of N- and C-termini and the terminal ends of disordered loops in protomer A are indicated. The protein models are presented with ramped colors according to the B values. The start of the curved α-helix (α9) and the extended arm (α10) at C domain show high temperature factors. (B) The monomer structure of human MC-HSP90 (orange) is superimposed on the MC domains of closed-form yeast HSP82 (green) and open-form canine GRP94 (blue). (C) The dimer structure of human MC-HSP90 (orange) is superimposed on the MC domains of close-form yeast HSP82 (green). (D) Stereo view of superposed hexameric structures. The human MC-HSP90 hexamer and the N-terminal truncated yeast HSP82 (PDB: 2CGE) hexamer are superimposed. The protomers of Human MC-HSP90 dimer are colored in blue and orange, respectively, and six protomers of yeast HSP82 are colored in green. See Video S1 for more comprehensive aspects.
Mentions: In the current structure, each molecule folds into three major domains (Figure 2A): a large middle (LM) domain (residues 293–469), a small middle (SM) domain (residues 470–547), and the C-terminal (C) domain (residues 548–732). The structure of the LM domain starts with a 310-helix, which is followed by a three-layer architecture of α-β-α sandwich and a helical coil. It encompasses two disordered loops comprising residues 351–358 and 396–404. The SM domain is also folded into an α-β-α sandwich architecture, and contains a sulfate-binding site. The sulfate was hydrogen bonded to the side chains of R510, K513 and H514 within helix α7, which is close to the C domain (Figure 2A). The C domain begins with an amphipathic loop, which shows high B-values (Figure 3A), and contains a curved α-helix, a three-stranded β-sheet, a three-helix coil and an extended disordered arm between helix α10 and strand β11 (residues 617–629). Beyond residue 697, the structure is disordered.

Bottom Line: HSP90 identified on the cell surface has been found to play a crucial role in cancer invasion and metastasis, and has become a validated anti-cancer target for drug development.The crystal structure of MC-HSP90 reveals that, in addition to the C-terminal dimerization domain, the residue W320 in the M domain plays a critical role in its oligomerization.This study not only demonstrates how the human MC-HSP90 forms a hexamer, but also justifies the similar formation of HSP90N by using 3D modeling analysis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.

ABSTRACT

Background: The human 90-kDa heat shock protein (HSP90) functions as a dimeric molecular chaperone. HSP90 identified on the cell surface has been found to play a crucial role in cancer invasion and metastasis, and has become a validated anti-cancer target for drug development. It has been shown to self-assemble into oligomers upon heat shock or divalent cations treatment, but the functional role of the oligomeric states in the chaperone cycle is not fully understood.

Principal findings: Here we report the crystal structure of a truncated HSP90 that contains the middle segment and the carboxy-terminal domain, termed MC-HSP90. The structure reveals an architecture with triangular bipyramid geometry, in which the building block of the hexameric assembly is a dimer. In solution, MC-HSP90 exists in three major oligomer states, namely dimer, tetramer and hexamer, which were elucidated by size exclusion chromatography and analytical ultracentrifugation. The newly discovered HSP90 isoform HSP90N that lacks the N-terminal ATPase domain also exhibited similar oligomerization states as did MC-HSP90.

Conclusions: While lacking the ATPase domain, both MC-HSP90 and HSP90N can self-assemble into a hexameric structure, spontaneously. The crystal structure of MC-HSP90 reveals that, in addition to the C-terminal dimerization domain, the residue W320 in the M domain plays a critical role in its oligomerization. This study not only demonstrates how the human MC-HSP90 forms a hexamer, but also justifies the similar formation of HSP90N by using 3D modeling analysis.

Show MeSH
Related in: MedlinePlus