1W0M

Triosephosphate isomerase from Thermoproteus tenax

Summary for 1W0M

• Entry DOI: 10.2210/pdb1w0m/pdb
• Related: 1W0L
• Descriptor: TRIOSEPHOSPHATE ISOMERASE, PHOSPHATE ION (3 entities in total)
• Functional Keywords: isomerase, triosephosphate isomerase, glycolysis, gluconeogenesis
• Biological source: THERMOPROTEUS TENAX
• Total number of polymer chains: 8
• Total formula weight: 187262.97

Authors

Walden, H.,Taylor, G.,Lorentzen, E.,Pohl, E.,Lilie, H.,Schramm, A.,Knura, T.,Stubbe, K.,Tjaden, B.,Hensel, R. (deposition date: 2004-06-08, release date: 2004-09-09, Last modification date: 2024-05-08)

Primary citation

Walden, H.,Taylor, G.,Lorentzen, E.,Pohl, E.,Lilie, H.,Schramm, A.,Knura, T.,Stubbe, K.,Tjaden, B.,Hensel, R.
Structure and Function of a Regulated Archaeal Triosephosphate Isomerase Adapted to High Temperature
J.Mol.Biol., 342:861-, 2004

PubMed Abstract: 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.

PubMed: 15342242
DOI: 10.1016/J.JMB.2004.07.067

Experimental method

X-RAY DIFFRACTION (2.5 Å)