Distinct metal dependence for catalytic and structural functions in the l-arabinose isomerases from the mesophilic Bacillus halodurans and the thermophilic Geobacillus stearothermophilus

Lee, Dong Woo; Choe, Eun Ah; Kim, Seong Bo; Eom, Soo Hyun; Hong, Young Ho; Lee, Sang Jae; Lee, Han Seung; Lee, Dong Yun; Pyun, Yu‐Ryang

doi:10.1016/j.abb.2004.11.004

Cited by 87 publications

(94 citation statements)

References 31 publications

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“…As previously reported, it was found that the metal dependence of the AIs increased with the temperature at which they were assayed [20,21]. To further characterize this aspect, we analysed the decrease in enzyme activity of the apo and holo proteins at various GdnHCl concentrations (Fig.…”

Section: +mentioning

confidence: 98%

“…1B, probably because the active conformation of a thermophilic AI achieved at elevated temperature could not be detected in the GdnHCl-induced unfolding profiles at room temperature. We previously reported that thermophilic AIs have a metal-mediated active conformation at the elevated temperatures different from their inactive forms at 25°C, indicating the conformational flexibility of AIs although the protein is folded at both temperatures [21]. Nonetheless, Fig.…”

Section: +mentioning

confidence: 99%

“…Recombinant AIs were purified as described elsewhere [20,21]. The purified AIs were dialyzed against 10 mM Tris-HCl buffer [pH 7.0 except with B. halodurans (BHAI) at pH 8.0] and stored at 4°C.…”

Section: Expression and Purification Of Aismentioning

confidence: 99%

“…Although, these AIs are highly conserved with respect to primary amino acid sequence (similarity, >70%) and secondary structure [20], in contrast to mesophilic AIs such as E. coli AI, B. halodurans AI, and Lactobacillus gayonii AI, (hyper) thermophilic AIs from T. maritima [20], T. neapolitana [22], and G. stearothermophilus [21] showed an absolute metal dependence for their thermostability as well as active conformation. In addition, they also have metal-mediated isomerization activity not only for arabinose to ribulose in vivo but also for galactose to tagatose in vitro.…”

Section: Introductionmentioning

confidence: 99%

“…For these and related reasons, we have begun to study the unfolding of bacterial L L-arabinose isomerases (AI), specifically the three homo-tetrameric metalloenzymes (M r = 225 000) from mesophilic B. halodurans, thermophilic G. stearothermophilus, and hyperthermophilic T. maritima that contain 498 residues per monomer [20,21]. Although, these AIs are highly conserved with respect to primary amino acid sequence (similarity, >70%) and secondary structure [20], in contrast to mesophilic AIs such as E. coli AI, B. halodurans AI, and Lactobacillus gayonii AI, (hyper) thermophilic AIs from T. maritima [20], T. neapolitana [22], and G. stearothermophilus [21] showed an absolute metal dependence for their thermostability as well as active conformation.…”

Section: Introductionmentioning

confidence: 99%

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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

et al. 2005

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To gain insight into the structural stability of homologous homo-tetrameric L 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 (DG U ) 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 Mn 2+ , those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (T m ) due to decreased heat capacity (DC p ). Moreover, the extent of difference in DC 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 DC p , 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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Section: +mentioning

confidence: 98%

Section: +mentioning

confidence: 99%

Section: Expression and Purification Of Aismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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

et al. 2005

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Enzymes, Extremely Thermophilic

Harris

Adams

Kelly

2010

Encyclopedia of Industrial Biotechnology

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The availability of enzymes with optimal functional temperatures above 70°C has had considerable impact on basic and applied elements of biocatalysis. Not only have extremely thermophilic enzymes expanded the known thermal range of biological systems but they have also ushered in a new era in applied biocatalysis that is less restricted by limitations related to thermoactivity and thermostability. While much effort has been directed at understanding the intrinsic basis for enzyme stabilization at high temperatures, there is still much to be learned to appreciate this complex biomolecular trait. Nonetheless, strategic uses of extremely thermophilic enzymes continue to emerge and prospects for expanded use of biocatalysts in a variety of bioprocess settings are promising. As genome sequence information from extremely thermophilic microorganisms is mined for novel biocatalysts and molecular biological tools for improving enzyme function are refined, the future is bright for biologically based catalysis.

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Biological Aspects of Metal Enolates

Ming

2010

Patai's Chemistry of Functional Groups

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Distinct metal dependence for catalytic and structural functions in the l-arabinose isomerases from the mesophilic Bacillus halodurans and the thermophilic Geobacillus stearothermophilus

Cited by 87 publications

References 31 publications

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

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

Enzymes, Extremely Thermophilic

Biological Aspects of Metal Enolates

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