[A case of autoimmune glial fibrillary acidic protein astrocytopathy with various symptoms such as optic disc edema and cerebellar ataxia].

A 59-year-old man had developed visual abnormality, nausea, headache, and weight loss since three months before. The ophthalmologist found severe optic disc edema in both eyes, and referred him to our hospital. The patient had mild cerebellar ataxia.

Site-specific relaxation of peptide bond planarity induced by electrically attracted proton/deuteron observed by neutron crystallography.

In structural biology, peptide bonds, fundamental linkages between hundreds of amino acids, of which a protein molecule is composed, have been commonly treated as a plane structure just as Linus Pauling et al. proposed. In this paper, a site-specific peptide bond relaxation mechanism by deuterons whose localization has been suggested by neutron crystallography is proposed.

Confirmation of the formation of salt bridges in the denatured state of CutA1 protein using molecular dynamics simulations.

It remains unclear how the abundant charged residues in proteins from hyperthermophiles contribute to the stabilization of proteins. Previously, based on molecular dynamics (MD) simulations, we proposed that these charged residues decrease the entropic effect by forming salt bridges in the denatured state under physiological conditions (Yutani ., .

Evaluating the strengths of salt bridges in the CutA1 protein using molecular dynamic simulations: a comparison of different force fields.

Ion-ion interactions (salt bridges) between favorable pairs of charged residues are important for the conformational stability of proteins. Molecular dynamic (MD) simulations are useful for elucidating the interactions among charged residues fluctuating in solution. However, the quality of MD results depends strongly on the force fields used.

Ion-ion interactions in the denatured state contribute to the stabilization of CutA1 proteins.

In order to elucidate features of the denatured state ensembles that exist in equilibrium with the native state under physiological conditions, we performed 1.4-μs molecular dynamics (MD) simulations at 400 K and 450 K using the monomer subunits of three CutA1 mutants from Escherichia coli: an SH-free mutant (Ec0SH) with denaturation temperature (T) = 85.6 °C, a hydrophobic mutant (Ec0VV) with T = 113.

Strategy for Stabilization of CutA1 Proteins Due to Ion-Ion Interactions at Temperatures of over 100 °C.

In order to elucidate the contribution of charged residues to protein stabilization at temperatures of over 100 °C, we constructed many mutants of the CutA1 protein ( EcCutA1) from Escherichia coli. The goal was to see if one can achieve the same stability as for a CutA1 from hyperthermophile Pyrococcus horikoshii that has the denaturation temperature near 150 °C. The hydrophobic mutant of EcCutA1 ( Ec0VV) with denaturation temperature ( T) of 113.

Human ER Oxidoreductin-1α (Ero1α) Undergoes Dual Regulation through Complementary Redox Interactions with Protein-Disulfide Isomerase.

In the mammalian endoplasmic reticulum, oxidoreductin-1α (Ero1α) generates protein disulfide bonds and transfers them specifically to canonical protein-disulfide isomerase (PDI) to sustain oxidative protein folding. This oxidative process is coupled to the reduction of O to HO on the bound flavin adenine dinucleotide cofactor. Because excessive thiol oxidation and HO generation cause cell death, Ero1α activity must be properly regulated.

Thermodynamics of protein denaturation at temperatures over 100 °C: CutA1 mutant proteins substituted with hydrophobic and charged residues.

Although the thermodynamics of protein denaturation at temperatures over 100 °C is essential for the rational design of highly stable proteins, it is not understood well because of the associated technical difficulties. We designed certain hydrophobic mutant proteins of CutA1 from Escherichia coli, which have denaturation temperatures (Td) ranging from 101 to 113 °C and show a reversible heat denaturation. Using a hydrophobic mutant as a template, we successfully designed a hyperthermostable mutant protein (Td = 137 °C) by substituting six residues with charged ones.

Thermodynamic analysis of unusually thermostable CutA1 protein from human brain and its protease susceptibility.

Unusually stable proteins are a disadvantage for the metabolic turnover of proteins in cells. The CutA1 proteins from Pyrococcus horikoshii and from Oryza sativa (OsCutA1) have unusually high denaturation temperatures (Td) of nearly 150 and 100 °C, respectively, at pH 7.0.

Inhibition of the functional interplay between endoplasmic reticulum (ER) oxidoreduclin-1α (Ero1α) and protein-disulfide isomerase (PDI) by the endocrine disruptor bisphenol A.

Bisphenol A (BPA) is an endocrine disruptor that may have adverse effects on human health. We recently isolated protein-disulfide isomerase (PDI) as a BPA-binding protein from rat brain homogenates and found that BPA markedly inhibited PDI activity. To elucidate mechanisms of this inhibition, detailed structural, biophysical, and functional analyses of PDI were performed in the presence of BPA.

Strategy for cold adaptation of the tryptophan synthase α subunit from the psychrophile Shewanella frigidimarina K14-2: crystal structure and physicochemical properties.

To investigate the molecular basis of cold adaptation of enzymes, we determined the crystal structure of the tryptophan synthase α subunit (SfTSA) from the psychrophile Shewanella frigidimarina K14-2 by X-ray analysis at 2.6-Å resolution and also examined its physicochemical properties. SfTSA was found to have the following characteristics: (i) The stabilities against heat and denaturant of SfTSA were lower than those of an α subunit (EcTSA) from Escherichia coli.

Effect of heavy atoms on the thermal stability of α-amylase from Aspergillus oryzae.

Currently, there are no versatile and established methods for improving stability of proteins. In an entirely different approach from conventional techniques such as mutagenesis, we attempted to enhance enzyme stability of α-amylase from Aspergillus oryzae using a heavy-atom derivatization technique. We evaluated changes in stability using differential scanning calorimetry (DSC).

Structure and function of a TetR family transcriptional regulator, SbtR, from thermus thermophilus HB8.

SbtR is one of the four TetR family transcriptional regulators present in the extremely thermophilic bacterium, Thermus thermophilus HB8. We identified 10 genes controlled by four promoters with negative regulation by SbtR in vitro. The SbtR-regulated gene products include probable transporters, probable enzymes for sugar or amino acid metabolism, and nucleic acid-related enzymes.

Structural characterization of a trapped folding intermediate of pyrrolidone carboxyl peptidase from a hyperthermophile.

The refolding of cysteine-free pyrrolidone carboxyl peptidase (PCP-0SH) from a hyperthermophile is unusually slow. PCP-0SH is trapped in the denatured (D1) state at 4 °C and pH 2.3, which is different from the highly denatured state in the presence of concentrated denaturant.

Structure of indole-3-glycerol phosphate synthase from Thermus thermophilus HB8: implications for thermal stability.

The three-dimensional structure of indole-3-glycerol phosphate synthase (IGPS) from the thermophilic bacterium Thermus thermophilus HB8 (TtIGPS) has been determined at 1.8 Å resolution. The structure adopts a typical (β/α)(8)-barrel fold with an additional N-terminal extension of 46 residues.

Role of charged residues in stabilization of Pyrococcus horikoshii CutA1, which has a denaturation temperature of nearly 150 °C.

The CutA1 protein from Pyrococcus horikoshii (PhCutA1), a hyperthermophile, has an unusually high content of charged residues and an unusually high denaturation temperature. To elucidate the role of ion-ion interactions in protein stability, mutant proteins of PhCutA1 in which charged residues were substituted by noncharged residues were comprehensively examined. The denaturation temperatures (T(d)) for 13 of 53 examined mutant proteins were higher than that of the wild-type (148.

Crystal structure of TTHA0061, an uncharacterized protein from Thermus thermophilus HB8, reveals a novel fold.

The crystal structure of an uncharacterized protein TTHA0061 from Thermus thermophilus HB8, was determined and refined to 1.8 A by a single wavelength anomalous dispersion (SAD) method. The structural analysis and comparison of TTHA0061 with other existing structures in the Protein Data Bank (PDB) revealed a novel fold, suggesting that this protein may belong to a translation initiation factor or ribosomal protein family.

Remarkable improvement in the heat stability of CutA1 from Escherichia coli by rational protein design.

To enhance the heat stability of the CutA1 protein from Escherichia coli (EcCutA1) so that it has comparable stability to CutA1 from Pyrococcus horikoshii with a denaturation temperature (T(d)) of 150°C, we used the Stability Profile of Mutant Protein (SPMP) to examine the structure-sequence (3D-1D) compatibility between the conformation of EcCutA1 and its native sequence [J. Mol. Biol.

Large conformational changes in the Escherichia coli tryptophan synthase beta(2) subunit upon pyridoxal 5'-phosphate binding.

To understand the basis for the lower activity of the tryptophan synthase beta(2) subunit in comparison to the alpha(2)beta(2) complex, we determined the crystal structures of apo-beta(2) and holo-beta(2) from Escherichia coli at 3.0 and 2.9 A resolutions, respectively.

Crystal Structural and Functional Analysis of the Putative Dipeptidase from Pyrococcus horikoshii OT3.

The crystal structure of a putative dipeptidase (Phdpd) from Pyrococcus horikoshii OT3 was solved using X-ray data at 2.4 A resolution. The protein is folded into two distinct entities.

The catalytic efficiency (kcat/Km) of the class A beta-lactamase Toho-1 correlates with the thermal stability of its catalytic intermediate analog.

The extended-spectrum beta-lactamases are associated with antibiotic resistance. Toho-1 R274N/R276N, a Class A beta-lactamase of CTX-M-type, efficiently hydrolyzes first generationcephalosporins (for example, cephalothin), in addition to cefotaxime, a third generation cephalosporin. However, this enzyme only marginally hydrolyzes the third generation cephalosporin ceftazidime, and the monobactam aztreonam.

Follow-up magnetic resonance imaging findings in patients with progressive multifocal leukoencephalopathy: evaluation of long-term survivors under highly active antiretroviral therapy.

Purpose: The aim of this study was to clarify the early magnetic resonance imaging (MRI) findings of progressive multifocal leukoencephalopathy (PML) and to evaluate the relations of the clinical course and serial MRI findings in patients with acquired immunodeficiency syndrome (AIDS)-related PML treated with highly active antiretroviral therapy (HAART).

Materials And Methods: The clinical course and serial MRI findings in five patients with AIDS-related PML who were treated with HAART are described.

Results: Although all five patients were serologically naive to the therapy and alive at the end of the observation period, the lesions showed rapid extension on MRI for up to 3 months after the start of the therapy, and clinical symptoms progressed rapidly for a month after the start of the therapy.

Evaluation of suspicious nipple discharge by magnetic resonance mammography based on breast imaging reporting and data system magnetic resonance imaging descriptors.

Purpose: To evaluate the findings of magnetic resonance mammography for suspicious nipple discharge based on breast imaging-reporting and data system magnetic resonance imaging (MRI) descriptors and establish any correlations with the histopathologic diagnoses.

Methods: Forty-seven patients with suspicious nipple discharge underwent MRI using a 1.5-T system.