Reference : Crystal structure of recombinant triosephosphate isomerase from Bacillus stearothermo...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
Crystal structure of recombinant triosephosphate isomerase from Bacillus stearothermophilus. An analysis of potential thermostability factors in six isomerases with known three-dimensional structures points to the importance of hydrophobic interactions
Delboni, Luis F [University of Washington > > > >]
Mande, Shekhar C [University of Washington - UW > > > >]
Rentier-Delrue, Françoise mailto [Université de Liège - ULiège > Département des sciences de la vie > Biologie et génétique moléculaire - GIGA-R : Coordination scientifique >]
Mainfroid, Véronique [Université de Liège - ULiège > > > >]
Turley, Stewart [University of Washington - UW > > > >]
Vellieux, Frederique M D [Centre National de la Recherche Scientifique - CNRS > > > >]
Martial, Joseph mailto [Université de Liège - ULiège > Département des sciences de la vie > GIGA-R : Biologie et génétique moléculaire >]
Hol, WIM G [University of Washington - UW > > > >]
Protein Science : A Publication of the Protein Society
Cold Spring Harbor Laboratory Press
Yes (verified by ORBi)
[en] Amino Acid Sequence ; Bacillus stearothermophilus/*enzymology ; Binding Sites ; Binding, Competitive ; Chemistry, Physical ; Crystallization ; Crystallography, X-Ray ; Enzyme Inhibitors/metabolism ; Enzyme Stability ; Glycolates/metabolism ; *Hot Temperature ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Molecular Structure ; Physicochemical Phenomena ; Proline/chemistry ; Recombinant Proteins/chemistry ; Structure-Activity Relationship ; Triose-Phosphate Isomerase/antagonists & inhibitors/*chemistry/metabolism
[en] The structure of the thermostable triosephosphate isomerase (TIM) from Bacillus stearothermophilus complexed with the competitive inhibitor 2-phosphoglycolate was determined by X-ray crystallography to a resolution of 2.8 A. The structure was solved by molecular replacement using XPLOR. Twofold averaging and solvent flattening was applied to improve the quality of the map. Active sites in both the subunits are occupied by the inhibitor and the flexible loop adopts the "closed" conformation in either subunit. The crystallographic R-factor is 17.6% with good geometry. The two subunits have an RMS deviation of 0.29 A for 248 C alpha atoms and have average temperature factors of 18.9 and 15.9 A2, respectively. In both subunits, the active site Lys 10 adopts an unusual phi, psi combination. A comparison between the six known thermophilic and mesophilic TIM structures was conducted in order to understand the higher stability of B. stearothermophilus TIM. Although the ratio Arg/(Arg+Lys) is higher in B. stearothermophilus TIM, the structure comparisons do not directly correlate this higher ratio to the better stability of the B. stearothermophilus enzyme. A higher number of prolines contributes to the higher stability of B. stearothermophilus TIM. Analysis of the known TIM sequences points out that the replacement of a structurally crucial asparagine by a histidine at the interface of monomers, thus avoiding the risk of deamidation and thereby introducing a negative charge at the interface, may be one of the factors for adaptability at higher temperatures in the TIM family. Analysis of buried cavities and the areas lining these cavities also contributes to the greater thermal stability of the B. stearothermophilus enzyme. However, the most outstanding result of the structure comparisons appears to point to the hydrophobic stabilization of dimer formation by burying the largest amount of hydrophobic surface area in B. stearothermophilus TIM compared to all five other known TIM structures.

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