2e09

File:2e09.jpg

spinqualitylabelsall models 2e09, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structure of mutant tryptophan synthase alpha-subunit (E74A) from a hyperthermophile, Pyrococcus furiosus

OverviewOverview

The structure of the tryptophan synthase alpha-subunit from Pyrococcus, furiosus was determined by x-ray analysis at 2.0-A resolution, and its, stability was examined by differential scanning calorimetry. Although the, structure of the tryptophan synthase alpha(2)beta(2) complex from, Salmonella typhimurium has been already determined, this is the first, report of the structure of the alpha-subunit alone. The alpha-subunit from, P. furiosus (Pf-alpha-subunit) lacked 12 and 6 residues at the N and C, termini, respectively, and one residue each in two loop regions as, compared with that from S. typhimurium (St-alpha-subunit), resulting in, the absence of an N-terminal helix and the shortening of a C-terminal, helix. The structure of the Pf-alpha-subunit was essentially similar to, that of the St-alpha-subunit in the alpha(2)beta(2) complex. The, differences between both structures were discussed in connection with the, higher stability of the Pf-alpha-subunit and the complex formation of the, alpha- and beta-subunits. Calorimetric results indicated that the, Pf-alpha-subunit has extremely high thermostability and that its higher, stability is caused by an entropic effect. On the basis of structural, information of both proteins, we analyzed the contributions of each, stabilization factor and could conclude that hydrophobic interactions in, the protein interior do not contribute to the higher stability of the, Pf-alpha-subunit. Rather, the increase in ion pairs, decrease in cavity, volume, and entropic effects due to shortening of the polypeptide chain, play important roles in extremely high stability in Pf-alpha-subunit.

About this StructureAbout this Structure

2E09 is a Single protein structure of sequence from Pyrococcus furiosus. Active as Tryptophan synthase, with EC number 4.2.1.20 Full crystallographic information is available from OCA.

ReferenceReference

Entropic stabilization of the tryptophan synthase alpha-subunit from a hyperthermophile, Pyrococcus furiosus. X-ray analysis and calorimetry., Yamagata Y, Ogasahara K, Hioki Y, Lee SJ, Nakagawa A, Nakamura H, Ishida M, Kuramitsu S, Yutani K, J Biol Chem. 2001 Apr 6;276(14):11062-71. Epub 2000 Dec 15. PMID:11118452

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