1w0m
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| , resolution 2.5Å | |||||||
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| Sites: | |||||||
| Ligands: | |||||||
| Activity: | Triose-phosphate isomerase, with EC number 5.3.1.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
TRIOSEPHOSPHATE ISOMERASE FROM THERMOPROTEUS TENAX
OverviewOverview
Triosephophate isomerase (TIM) is a dimeric enzyme in eucarya, bacteria and mesophilic archaea. In hyperthermophilic archaea, however, TIM exists as a tetramer composed of monomers that are about 10% shorter than other eucaryal and bacterial TIM monomers. We report here the crystal structure of TIM from Thermoproteus tenax, a hyperthermophilic archaeon that has an optimum growth temperature of 86 degrees C. The structure was determined from both a hexagonal and an orthorhombic crystal form to resolutions of 2.5A and 2.3A, and refined to R-factors of 19.7% and 21.5%, respectively. In both crystal forms, T.tenax TIM exists as a tetramer of the familiar (betaalpha)(8)-barrel. In solution, however, and unlike other hyperthermophilic TIMs, the T.tenax enzyme exhibits an equilibrium between inactive dimers and active tetramers, which is shifted to the tetramer state through a specific interaction with glycerol-1-phosphate dehydrogenase of T.tenax. This observation is interpreted in physiological terms as a need to reduce the build-up of thermolabile metabolic intermediates that would be susceptible to destruction by heat. A detailed structural comparison with TIMs from organisms with growth optima ranging from 15 degrees C to 100 degrees C emphasizes the importance in hyperthermophilic proteins of the specific location of ionic interactions for thermal stability rather than their numbers, and shows a clear correlation between the reduction of heat-labile, surface-exposed Asn and Gln residues with thermoadaptation. The comparison confirms the increase in charged surface-exposed residues at the expense of polar residues.
About this StructureAbout this Structure
1W0M is a Single protein structure of sequence from Thermoproteus tenax. Full crystallographic information is available from OCA.
ReferenceReference
Structure and function of a regulated archaeal triosephosphate isomerase adapted to high temperature., Walden H, Taylor GL, Lorentzen E, Pohl E, Lilie H, Schramm A, Knura T, Stubbe K, Tjaden B, Hensel R, J Mol Biol. 2004 Sep 17;342(3):861-75. PMID:15342242
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