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A hyperthermophilic protein acquires function at the cost of stability.
Biochemistry. 2006 Oct 24; 45(42):12673-9.B

Abstract

Active-site residues are not often optimized for conformational stability (activity-stability trade-offs) in proteins from organisms that grow at moderate temperature. It is unknown if the activity-stability trade-offs can be applied to proteins from hyperthermophiles. Because enzymatic activity usually increases at higher temperature and hyperthermophilic proteins need high conformational stability, they might not sacrifice the stability for their activity. This study attempts to clarify the contribution of active-site residues to the conformational stability of a hyperthermophilic protein. We therefore examined the thermodynamic stability and enzymatic activity of wild-type and active-site mutant proteins (D7N, E8A, E8Q, D105A, and D135A) of ribonuclease HII from Thermococcus kodakaraensis (Tk-RNase HII). Guanidine hydrochloride (GdnHCl)-induced denaturation was measured with circular dichroism at 220 nm, and heat-induced denaturation was studied with differential scanning calorimetry. Both GdnHCl- and heat-induced denaturation were highly reversible in these proteins. All the mutations of these active-site residues, except that of Glu8 to Gln, reduced the enzymatic activity dramatically but increased the protein stability by 7.0 to 11.1 kJ mol(-1) at 50 degrees C. The mutation of Glu8 to Gln did not seriously affect the enzymatic activity and increased the stability only by 2.5 kJ mol(-1) at 50 degrees C. These results indicate that hyperthermophilic proteins also exhibit the activity-stability trade-offs. Therefore, the architectural mechanism for hyperthermophilic proteins is equivalent to that for proteins at normal temperature.

Authors+Show Affiliations

Department of Material and Life Science, Osaka University, Yamadaoka, Suita 565-0871, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17042484

Citation

Mukaiyama, Atsushi, et al. "A Hyperthermophilic Protein Acquires Function at the Cost of Stability." Biochemistry, vol. 45, no. 42, 2006, pp. 12673-9.
Mukaiyama A, Haruki M, Ota M, et al. A hyperthermophilic protein acquires function at the cost of stability. Biochemistry. 2006;45(42):12673-9.
Mukaiyama, A., Haruki, M., Ota, M., Koga, Y., Takano, K., & Kanaya, S. (2006). A hyperthermophilic protein acquires function at the cost of stability. Biochemistry, 45(42), 12673-9.
Mukaiyama A, et al. A Hyperthermophilic Protein Acquires Function at the Cost of Stability. Biochemistry. 2006 Oct 24;45(42):12673-9. PubMed PMID: 17042484.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A hyperthermophilic protein acquires function at the cost of stability. AU - Mukaiyama,Atsushi, AU - Haruki,Mitsuru, AU - Ota,Motonori, AU - Koga,Yuichi, AU - Takano,Kazufumi, AU - Kanaya,Shigenori, PY - 2006/10/18/pubmed PY - 2006/12/9/medline PY - 2006/10/18/entrez SP - 12673 EP - 9 JF - Biochemistry JO - Biochemistry VL - 45 IS - 42 N2 - Active-site residues are not often optimized for conformational stability (activity-stability trade-offs) in proteins from organisms that grow at moderate temperature. It is unknown if the activity-stability trade-offs can be applied to proteins from hyperthermophiles. Because enzymatic activity usually increases at higher temperature and hyperthermophilic proteins need high conformational stability, they might not sacrifice the stability for their activity. This study attempts to clarify the contribution of active-site residues to the conformational stability of a hyperthermophilic protein. We therefore examined the thermodynamic stability and enzymatic activity of wild-type and active-site mutant proteins (D7N, E8A, E8Q, D105A, and D135A) of ribonuclease HII from Thermococcus kodakaraensis (Tk-RNase HII). Guanidine hydrochloride (GdnHCl)-induced denaturation was measured with circular dichroism at 220 nm, and heat-induced denaturation was studied with differential scanning calorimetry. Both GdnHCl- and heat-induced denaturation were highly reversible in these proteins. All the mutations of these active-site residues, except that of Glu8 to Gln, reduced the enzymatic activity dramatically but increased the protein stability by 7.0 to 11.1 kJ mol(-1) at 50 degrees C. The mutation of Glu8 to Gln did not seriously affect the enzymatic activity and increased the stability only by 2.5 kJ mol(-1) at 50 degrees C. These results indicate that hyperthermophilic proteins also exhibit the activity-stability trade-offs. Therefore, the architectural mechanism for hyperthermophilic proteins is equivalent to that for proteins at normal temperature. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/17042484/A_hyperthermophilic_protein_acquires_function_at_the_cost_of_stability_ L2 - https://doi.org/10.1021/bi060907v DB - PRIME DP - Unbound Medicine ER -