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Structure of a high-resolution crystal form of human triosephosphate isomerase: improvement of crystals using the gel-tube method.

ABSTRACT: Crystals of human triosephosphate isomerase with two crystal morphologies were obtained using the normal vapour-diffusion technique with identical crystallization conditions. One had a disordered plate shape and the crystals were hollow (crystal form 1). As a result, this form was very fragile, diffracted to 2.8 A resolution and had similar crystallographic parameters to those of the structure 1hti in the Protein Data Bank. The other had a fine needle shape (crystal form 2) and was formed more abundantly than crystal form 1, but was unsuitable for structure analysis. Since the normal vapour-diffusion method could not control the crystal morphology, gel-tube methods, both on earth and under microgravity, were applied for crystallization in order to control and improve the crystal quality. Whereas crystal form 1 was only slightly improved using this method, crystal form 2 was greatly improved and diffracted to 2.2 A resolution. Crystal form 2 contained a homodimer in the asymmetric unit, which was biologically essential. Its overall structure was similar to that of 1hti except for the flexible loop, which was located at the active centre Lys13.

SUBMITTER: Kinoshita T

PROVIDER: S-EPMC1952429 | biostudies-literature | 2005 Apr

REPOSITORIES: biostudies-literature

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Structure of a high-resolution crystal form of human triosephosphate isomerase: improvement of crystals using the gel-tube method.

Kinoshita Takayoshi T Maruki Riyo R Warizaya Masaichi M Nakajima Hidenori H Nishimura Shintaro S

Acta crystallographica. Section F, Structural biology and crystallization communications 20050324 Pt 4

Crystals of human triosephosphate isomerase with two crystal morphologies were obtained using the normal vapour-diffusion technique with identical crystallization conditions. One had a disordered plate shape and the crystals were hollow (crystal form 1). As a result, this form was very fragile, diffracted to 2.8 A resolution and had similar crystallographic parameters to those of the structure 1hti in the Protein Data Bank. The other had a fine needle shape (crystal form 2) and was formed more a ...[more]

PMID: 16511037

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Project description:Background. Amyloid secondary structure relies on the intermolecular assembly of polypeptide chains through main-chain interaction. According to this, all proteins have the potential to form amyloid structure, nevertheless, in nature only few proteins aggregate into toxic or functional amyloids. Structural characteristics differ greatly among amyloid proteins reported, so it has been difficult to link the fibrillogenic propensity with structural topology. However, there are ubiquitous topologies not represented in the amyloidome that could be considered as amyloid-resistant attributable to structural features, such is the case of TIM barrel topology. Methods. This work was aimed to study the fibrillogenic propensity of human triosephosphate isomerase (HsTPI) as a model of TIM barrels. In order to do so, aggregation of HsTPI was evaluated under native-like and destabilizing conditions. Fibrillogenic regions were identified by bioinformatics approaches, protein fragmentation and peptide aggregation. Results. We identified four fibrillogenic regions in the HsTPI corresponding to the β3, β6, β7 y α8 of the TIM barrel. From these, the β3-strand region (residues 59-66) was highly fibrillogenic. In aggregation assays, HsTPI under native-like conditions led to amorphous assemblies while under partially denaturing conditions (urea 3.2 M) formed more structured aggregates. This slightly structured aggregates exhibited residual cross-β structure, as demonstrated by the recognition of the WO1 antibody and ATR-FTIR analysis. Discussion. Despite the fibrillogenic regions present in HsTPI, the enzyme maintained under native-favoring conditions displayed low fibrillogenic propensity. This amyloid-resistance can be attributed to the three-dimensional arrangement of the protein, where β-strands, susceptible to aggregation, are protected in the core of the molecule. Destabilization of the protein structure may expose inner regions promoting β-aggregation, as well as the formation of hydrophobic disordered aggregates. Being this last pathway kinetically favored over the thermodynamically more stable fibril aggregation pathway.

Dataset Information

Structure of a high-resolution crystal form of human triosephosphate isomerase: improvement of crystals using the gel-tube method.

Publications

Structure of a high-resolution crystal form of human triosephosphate isomerase: improvement of crystals using the gel-tube method.

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