A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic L-arabinose isomerases: The effects of divalent metal ions on protein stability at elevated temperatures

Dong Woo Lee, Young Ho Hong, Eun Ah Choe, Sang Jae Lee, Seong Bo Kim, Han Seung Lee, Jong-Won Oh, Hae Hun Shin, Yu Ryang Pyun

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

To gain insight into the structural stability of homologous homo-tetrameric l-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (ΔGU) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn2+, those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (Tm) due to decreased heat capacity (ΔCp). Moreover, the extent of difference in ΔC p between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced ΔCp, may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.

Original languageEnglish
Pages (from-to)1261-1266
Number of pages6
JournalFEBS Letters
Volume579
Issue number5
DOIs
Publication statusPublished - 2005 Feb 14

Fingerprint

L-arabinose isomerase
Protein Stability
Thermodynamics
Thermotoga maritima
Metal ions
Geobacillus stearothermophilus
Isomerases
Arabinose
Metals
Guanidine
Ions
Temperature
Proteins
Circular Dichroism
Circular dichroism spectroscopy
Oligomerization
Bacillus
Helmholtz equation
Freezing
Spectrum Analysis

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this

Lee, Dong Woo ; Hong, Young Ho ; Choe, Eun Ah ; Lee, Sang Jae ; Kim, Seong Bo ; Lee, Han Seung ; Oh, Jong-Won ; Shin, Hae Hun ; Pyun, Yu Ryang. / A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic L-arabinose isomerases : The effects of divalent metal ions on protein stability at elevated temperatures. In: FEBS Letters. 2005 ; Vol. 579, No. 5. pp. 1261-1266.
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abstract = "To gain insight into the structural stability of homologous homo-tetrameric l-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (ΔGU) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn2+, those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (Tm) due to decreased heat capacity (ΔCp). Moreover, the extent of difference in ΔC p between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced ΔCp, may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.",
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A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic L-arabinose isomerases : The effects of divalent metal ions on protein stability at elevated temperatures. / Lee, Dong Woo; Hong, Young Ho; Choe, Eun Ah; Lee, Sang Jae; Kim, Seong Bo; Lee, Han Seung; Oh, Jong-Won; Shin, Hae Hun; Pyun, Yu Ryang.

In: FEBS Letters, Vol. 579, No. 5, 14.02.2005, p. 1261-1266.

Research output: Contribution to journalArticle

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T1 - A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic L-arabinose isomerases

T2 - The effects of divalent metal ions on protein stability at elevated temperatures

AU - Lee, Dong Woo

AU - Hong, Young Ho

AU - Choe, Eun Ah

AU - Lee, Sang Jae

AU - Kim, Seong Bo

AU - Lee, Han Seung

AU - Oh, Jong-Won

AU - Shin, Hae Hun

AU - Pyun, Yu Ryang

PY - 2005/2/14

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N2 - To gain insight into the structural stability of homologous homo-tetrameric l-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (ΔGU) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn2+, those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (Tm) due to decreased heat capacity (ΔCp). Moreover, the extent of difference in ΔC p between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced ΔCp, may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.

AB - To gain insight into the structural stability of homologous homo-tetrameric l-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (ΔGU) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn2+, those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (Tm) due to decreased heat capacity (ΔCp). Moreover, the extent of difference in ΔC p between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced ΔCp, may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.

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