ABSTRACT
BACKGROUND: A variety of hereditary spinocerebellar ataxia (SCA) develops a broad spectrum of both ataxia and non-ataxia symptoms. Cognitive and affective changes are one such non-ataxia symptoms, but have been described only in hereditary SCAs with exonic CAG gene expansion. METHODS: We newly found intronic hexanucleotide GGCCTG gene expansion in NOP56 gene as the causative mutation (=SCA36) in nine unrelated Japanese familial SCA originating from Asida river area in the western part of Japan, thus nicknamed Asidan for this mutation. These patients show unique clinical balance of cerebellar ataxia and motor neuron disease (MND), locating on the crossroad of these two diseases. In the nine families, 14 patients were clinically examined and genetically confirmed to Asidan. In the present study, we examined cognitive and affective analyses on 12 patients (seven men and five women) who agreed to join the examination with average age at onset of 53.1 ± 3.2 years, average duration of 12.1 ± 5.2 years, and current average age at 65.1 ± 6.2 years. RESULTS: The 12 Asidan patients demonstrated a significant decrease in their frontal executive functions measured by frontal assessment battery (FAB) and Montreal cognitive assessment (MoCA) compared with age- and gender-matched controls, whilst mini-mental state examination (MMSE) and Hasegawa dementia score-revised (HDS-R) were within normal range. The decline of frontal executive function was related to their disease duration and scale for the assessment and rating of ataxias (SARA). They also demonstrated mild depression and apathy. Single-photon emission tomography (SPECT) analysis showed that these Asidan patients showed decline of regional cerebral blood flow (rCBF) in a particular areas of cerebral cortices such as Brodmann areas 24 and 44-46. CONCLUSION: These data suggest that the patients with Asidan mutation show unique cognitive and affective characteristics different from other hereditary SCAs with exonal CAG expansion or MND.
Subject(s)
Cognition Disorders/genetics , Motor Neuron Disease/complications , Motor Neuron Disease/genetics , Mutation , Nuclear Proteins/genetics , Spinocerebellar Ataxias/complications , Spinocerebellar Ataxias/genetics , Age of Onset , Aged , Female , Humans , Japan , Male , Middle Aged , Neuropsychological Tests , Tomography, Emission-Computed, Single-PhotonABSTRACT
The expressions of glutamate transporter proteins were immunocytochemically examined in the spinal cord of transgenic mice harboring a Gly93 --> Ala (G93A) mutant human SOD1 gene. Astroglial EAAT2 protein level was preserved in the ventral horn even after the beginning of paralysis, and finally decreased at terminal stage of the disease (35 weeks of age), when neuronal EAAT3 protein level was also decreased. In contrast, glial fibrillary acidic protein (GFAP) immunoreactivity progressively increased from 25 weeks of age in the ventral horn. The present results show interesting dissociative expressions of astroglial proteins EAAT2 and GFAP in the same ventral horn, but suggest not an early and primary role of EAAT2 in the motoneuronal death of this model.
Subject(s)
Amino Acid Transport System X-AG/metabolism , Astrocytes/metabolism , Spinal Cord/metabolism , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/metabolism , Amyotrophic Lateral Sclerosis/pathology , Animals , Excitatory Amino Acid Transporter 2/metabolism , Glial Fibrillary Acidic Protein/metabolism , Immunohistochemistry , Matched-Pair Analysis , Mice , Mice, Transgenic , Spinal Cord/cytology , Superoxide Dismutase/genetics , Superoxide Dismutase-1 , Time FactorsABSTRACT
Using UV-Vis, resonance Raman, and EPR spectroscopy we have studied the properties of the oxygenated ferrous cytochrome P450 from Sulfolobus solfataricus, (CYP119). The recently determined crystal structure of CYP119 is compared with other available structures of P450s, and detailed structural and spectroscopic analyses are reported. With several structural similarities to CYP102, such as in-plane iron position and a shorter iron-proximal ligand bond, CYP119 shows low-spin conformation preference in the ferric form and partially in the ferrous form at low temperatures. These structural features can explain the fast autoxidation of the oxyferrous complex of CYP119. Finally, we report the first UV-Vis and EPR spectra of the cryoradiolytically reduced oxygenated intermediate of CYP119. The primary reduced intermediate, a hydroperoxo-ferric complex of CYP119, undergoes a 'peroxide shunt' pathway during gradual annealing at 170-195 K and returns to the low-spin ferric form.
Subject(s)
Cytochrome P-450 Enzyme System/chemistry , Oxygenases/chemistry , Sulfolobus/enzymology , Archaeal Proteins , Electron Spin Resonance Spectroscopy , Models, Chemical , Models, Molecular , Oxygen/chemistry , Spectrophotometry , Spectrum Analysis, RamanABSTRACT
The mechanisms of motor neuronal death in amyotrophic lateral sclerosis (ALS) remain to be unclear. Phosphatidy-linositol 3-kinase (PI3-K) and its main downstream effector, Akt/protein kinase B (PKB) have been shown to play a central role in neuronal survival against apoptosis supported by neurotrophic factors. In order to investigate a possible impairment of survival signaling, we examined expressions of PI3-K and Akt in the spinal cord of the transgenic mice overexpressing a mutant Cu/Zn superoxide dismutase (SOD1) gene, a valuable model for human ALS. Immunoblotting and immunohistochemical analyses showed that the majority of spinal motor neurons lost the immunoreactivities for both PI3-K and Akt in the early and presymptomatic stage that preceded significant loss of the neurons. The present results suggest that an early decrease of survival signal proteins in the spinal motor neurons may account for the subsequent motor neuronal loss in this animal model of ALS.
Subject(s)
Amyotrophic Lateral Sclerosis/metabolism , Motor Neurons/cytology , Motor Neurons/metabolism , Protein Serine-Threonine Kinases , Signal Transduction , Spinal Cord/cytology , Superoxide Dismutase/genetics , Amyotrophic Lateral Sclerosis/diagnosis , Amyotrophic Lateral Sclerosis/pathology , Animals , Apoptosis , Cell Survival , Mice , Mice, Inbred C57BL , Mice, Transgenic , Motor Activity , Mutation , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins c-akt , Superoxide Dismutase-1ABSTRACT
The static stabilometry patterns associated with Parkinson's disease (PD, n = 15) and spinocerebellar ataxia (SCA, n = 15) were compared with those of normal control (n = 15) by measuring the fractal dimensions. Fractal dimensions were estimated using the modified pixel dilation (mPD) method. The fractal dimensions with closed eyes showed a significant correlation with Environmental area for SCA group (p < 0.05). The fractal dimension for SCA group was significantly higher with closed eyes than that with open eyes (p < 0.05). The fractal dimension with closed eyes was significantly higher in PD and SCA groups than that in normal group (p < 0.05). The fractal dimension with closed eyes was higher when the clinical stage was more severe with PD and SCA group while Environmental and Longitude/Environmental areas were not. These findings suggest that the fractal dimension is more sensitive than traditional stabilometric analysis in an evaluation of postural instability in PD and SCA.
Subject(s)
Fractals , Parkinson Disease/physiopathology , Posture , Spinocerebellar Ataxias/physiopathology , Aged , Female , Humans , Male , Middle Aged , Posture/physiology , Reference Values , Vision, Ocular/physiologyABSTRACT
Alkyl-isocyanides are able to bind to both ferric and ferrous iron of the heme in cytochrome P450, and the resulting complexes exhibit characteristic optical absorption spectra. While the ferric complex gives a single Soret band at 430 nm, the ferrous complex shows double Soret bands at 430 and 450 nm. The ratio of intensities of the double Soret bands in the ferrous isocyanide complex of P450 varies, as a function of pH, ionic strength, and the origin of the enzyme. To understand the structural origin of these characteristic spectral features, we examined the crystallographic and spectrophotometric properties of the isocyanide complexes of Pseudomonas putida cytochrome P450cam and Fusarium oxysporum cytochorme P450nor, since ferrous isocyanide complex of P450cam gives a single Soret band at 453 nm, while that of P450nor gives one at 427 nm. Corresponding to the optical spectra, we observed C-N stretching of a ferrous iron-bound isocyanide at 2145 and 2116 cm(-1) for P450nor and P450cam, respectively. The crystal structures of the ferric and ferrous n-butyl isocyanide complexes of P450cam and P450nor were determined. The coordination structure of the fifth Cys thiolate was indistinguishable for the two P450s, but the coordination geometry of the isocyanide was different for the case of P450cam [d(Fe-C) = 1.86 A, angleFe-C-N = 159 degrees ] versus P450nor [d(Fe-C) = 1.85 A, angleFe-C-N = 175 degrees ]. Another difference in the structures was the chemical environment of the heme pocket. In the case of P450cam, the iron-bound isocyanide is surrounded by some hydrophobic side chains, while, for P450nor, it is surrounded by polar groups including several water molecules. On the basis of these observations, we proposed that the steric factors and/or the polarity of the environment surrounding the iron-bound isocyanide significantly effect on the resonance structure of the heme(Fe)-isocyanide moiety and that differences in these two factors are responsible for the spectral characteristics for P450s.
Subject(s)
Camphor 5-Monooxygenase/chemistry , Cytochrome P-450 Enzyme System/chemistry , Nitriles/chemistry , Oxidoreductases/chemistry , Crystallization , Crystallography, X-Ray , Electron Spin Resonance Spectroscopy , Ferric Compounds/chemistry , Ferrous Compounds/chemistry , Fusarium/enzymology , Macromolecular Substances , Models, Molecular , Pseudomonas putida/enzymology , Spectrophotometry, Infrared , StereoisomerismABSTRACT
The role of glutamate in the mechanism of spinal motor neuron death is not fully understood. With addition of glutamate to primary culture of 11-day-old rat spinal cord, terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) positive nuclei were found in spinal large motor neurons from 24 h, and the number of TUNEL positive large motor neurons greatly increased at 48 h. In contrast, only a small number of large motor neurons became TUNEL positive at 48 h with addition of vehicle to the primary spinal cord culture. The present results show that excessive amount of glutamate enhances DNA fragmentation in developing large motor neuron of cultured spinal cord by involving in apoptotic process of the neurons.
Subject(s)
DNA Fragmentation/drug effects , Glutamic Acid/pharmacology , Motor Neuron Disease/chemically induced , Motor Neurons/drug effects , Neurotoxins/pharmacology , Spinal Cord Diseases/chemically induced , Spinal Cord/drug effects , Animals , Animals, Newborn , Cell Count/statistics & numerical data , Cells, Cultured/drug effects , Cells, Cultured/metabolism , Cells, Cultured/pathology , DNA Fragmentation/physiology , Disease Models, Animal , Glutamic Acid/metabolism , In Situ Nick-End Labeling , Motor Neuron Disease/pathology , Motor Neuron Disease/physiopathology , Motor Neurons/metabolism , Motor Neurons/pathology , Neurotoxins/metabolism , Rats , Rats, Sprague-Dawley , Spinal Cord/pathology , Spinal Cord/physiopathology , Spinal Cord Diseases/pathology , Spinal Cord Diseases/physiopathologyABSTRACT
Biliverdin reductase (BVR) is a soluble cytoplasmic enzyme that catalyzes the conversion of biliverdin to bilirubin using NADH or NADPH as electron donor. Bilirubin is a significant biological antioxidant, but it is also neurotoxic and the cause of kernicterus. In this study, we have determined the crystal structure of rat BVR at 1.4 A resolution. The structure contains two domains: an N-terminal domain characteristic of a dinucleotide binding fold (Rossmann fold) and a C-terminal domain that is predominantly an antiparallel six-stranded beta-sheet. Based on this structure, we propose modes of binding for NAD(P)H and biliverdin, and a possible mechanism for the enzyme.
Subject(s)
Oxidoreductases Acting on CH-CH Group Donors , Oxidoreductases/chemistry , Amino Acid Sequence , Animals , Biliverdine/metabolism , Binding Sites , Crystallography, X-Ray , Heme/metabolism , Kinetics , Models, Molecular , Molecular Sequence Data , NAD/metabolism , NADP/metabolism , Oxidoreductases/genetics , Oxidoreductases/metabolism , Protein Structure, Tertiary , Rats , Sequence Alignment , Zinc/analysisABSTRACT
Arg and Lys residues are concentrated on the distal side of cytochrome P450nor (P450nor) to form a positively charged cluster facing from the outside to the inside of the distal heme pocket. We constructed mutant proteins in which the Arg and Lys residues were replaced with Glu, Gln, or Ala. The results showed that this cluster plays crucial roles in NADH interaction. We also showed that some anions such as bromide (Br(-)) perturbed the heme environment along with the reduction step in P450nor-catalyzed reactions, which was similar to the effects caused by the mutations. We determined by x-ray crystallography that a Br(-), termed an anion hole, occupies a key region neighboring heme, which is the terminus of the positively charged cluster and the terminus of the hydrogen bond network that acts as a proton delivery system. A comparison of the predicted mechanisms between the perturbations caused by Br(-) and the mutations suggested that Arg(174) and Arg(64) play a crucial role in binding NADH to the protein. These results indicated that the positively charged cluster is the unique structure of P450nor that responds to direct interaction with NADH.
Subject(s)
Cytochrome P-450 Enzyme System/chemistry , Cytochrome P-450 Enzyme System/metabolism , Heme/chemistry , NAD/metabolism , Oxidoreductases/chemistry , Oxidoreductases/metabolism , Amino Acid Sequence , Arginine/physiology , Binding Sites , Bromides/metabolism , Camphor 5-Monooxygenase/chemistry , Crystallography, X-Ray , Cytochrome P-450 Enzyme System/genetics , Kinetics , Lysine/physiology , Molecular Sequence Data , Mutagenesis, Site-Directed , Nitric Oxide/metabolism , Oxidoreductases/genetics , Phosphates/metabolism , Protein Structure, Secondary , Sequence Homology, Amino Acid , SpectrophotometryABSTRACT
The CO-sensing transcriptional activator CooA contains a six-coordinate protoheme as a CO sensor. Cys(75) and His(77) are assigned to the fifth ligand of the ferric and ferrous hemes, respectively. In this study, we carried out alanine-scanning mutagenesis and EXAFS analyses to determine the coordination structure of the heme in CooA. Pro(2) is thought to be the sixth ligand of the ferric and ferrous hemes in CooA, which is consistent with the crystal structure of ferrous CooA (Lanzilotta, W. N., Schuller, D. J., Thorsteinsson, M. V., Kerby, R. L., Roberts, G. P., and Poulos, T. L. (2000) Nat. Struct. Biol. 7, 876-880). CooA exhibited anomalous redox chemistry, i.e. hysteresis was observed in electrochemical redox titrations in which the observed reduction and oxidation midpoint potentials were -320 mV and -260 mV, respectively. The redox-controlled ligand exchange of the heme between Cys(75) and His(77) is thought to cause the difference between the reduction and oxidation midpoint potentials.
Subject(s)
Bacterial Proteins/metabolism , Escherichia coli Proteins , Fimbriae Proteins , Heme/metabolism , Iron/metabolism , Oxidation-Reduction , Alanine/chemistry , Bacterial Proteins/chemistry , Cysteine/chemistry , Electrochemistry , Heme/chemistry , Histidine/chemistry , Ligands , Models, Chemical , Mutagenesis, Site-Directed , Oxygen/metabolism , Spectrum Analysis, Raman , Transcriptional ActivationABSTRACT
Although excitotoxic and oxidative stress play important roles in spinal neuron death, the exact mechanisms are not fully understood. We examined cell damage of primary culture of 11 day-old rat spinal cord by addition of glutamate, nitric oxice (NO) or peroxynitrite (PN) with detection of caspase-3, terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) or 72 kDa heat shock protein (HSP72). With addition of glutamate, NOC18 (a slow NO releaser) or PN, immunoreactivity for caspase-3 became stronger in the cytoplasm of large motor neurons in the ventral horn at 6 to 24 hr. TUNEL positive nuclei were found in spinal large motor neurons from 24 h and the positive cell proportion greatly increased at 48 h in contrast to the vehicle. On the other hand, the immunoreactivity of HSP72 in the ventral horn was already positive at 0 h, and gradually decreased in the course of time with glutamate, NOC18 or PN than vehicle treatment. In the dorsal horn, the proportion of caspase-3 positive small neurons greatly increased at 6 to 48 h after addition of glutamate. The present results suggest that both excitotoxic and oxidative stress play important roles in the apoptotic pathway in cultured spinal neurons.
ABSTRACT
The structure-function relationship in cytochrome P450cam monooxygenase was studied by employing its active site mutant Thr252Ile. X-ray crystallographic analyses of the ferric d-camphor-bound form of the mutant revealed that the mutation caused a structural change in the active site giving an enlarged oxygen-binding pocket that did not contain any hydrophilic group such as the OH group of Thr and H(2)O. The enzyme showed a low monooxygenase activity of ca. 1/10 of the activity of the wild-type enzyme. Kinetic analyses of each catalytic step revealed that the rate of proton-coupled reduction of the oxygenated intermediate of the enzyme, a ternary complex of dioxygen and d-camphor with the ferrous enzyme, decreased to about 1/30 of that of the wild-type enzyme, while the rates of other catalytic steps including the reduction of the ferric d-camphor-bound form by reduced putidaredoxin did not change significantly. These results indicated that a hydrophilic group(s) such as water and/or hydroxyl group in the active site is prerequisite to a proton supply for the reduction of the oxygenated intermediate, thereby giving support for the operation of a proton transfer network composed of Thr252, Asp251, and two other amino acids and water proposed by previous investigators.
Subject(s)
Camphor 5-Monooxygenase/metabolism , Isoleucine/metabolism , Threonine/metabolism , Water/metabolism , Binding Sites , Camphor/metabolism , Camphor 5-Monooxygenase/chemistry , Camphor 5-Monooxygenase/genetics , Catalysis , Crystallography, X-Ray , Electron Transport , Models, Molecular , Mutagenesis, Site-Directed , Oxygen/metabolism , Protein Conformation , Spectrophotometry, UltravioletABSTRACT
The crystal structure of cytochrome c(6) from the red alga Porphyra yezoensis has been determined at 1.57 A resolution. The crystal is tetragonal and belongs to space group P4(3)2(1)2, with unit-cell parameters a = b = 49.26 (3), c = 83.45 (4) A and one molecule per asymmetric unit. The structure was solved by the molecular-replacement method and refined with X-PLOR to an R factor of 19.9% and a free R factor of 25.4%. The overall structure of cytochrome c(6) follows the topology of class I c-type cytochromes in which the heme prosthetic group covalently binds to Cys14 and Cys17, and the iron has an octahedral coordination with His18 and Met58 as the axial ligands. The sequence and the structure of the eukaryotic red algal cytochrome c(6) are very similar to those of a prokaryotic cyanobacterial cytochrome c(6) rather than those of eukaryotic green algal c(6) cytochromes.
Subject(s)
Cytochromes/chemistry , Rhodophyta/chemistry , Amino Acid Sequence , Chlorophyta/chemistry , Crystallography, X-Ray , Cytochromes/isolation & purification , Cytochromes f , Heme/chemistry , Models, Molecular , Molecular Sequence Data , Protein Conformation , Sequence Homology, Amino AcidABSTRACT
FixL is a sensor histidine kinase having a heme-containing domain as an O(2) sensing site. In the study presented here, Ile209 and Ile210 located near the heme iron of the heme domain of Rhizobium meliloti FixL (RmFixL) were mutated, and the mutational effects on the regulation of the kinase activity and the heme pocket structure were examined by the autophosphorylation assay and UV-visible absorption and resonance Raman (RR) spectroscopies. The mutation of these residues disrupted the regulation of the kinase activity by the sensor (heme) domain, indicating that Ile209 and Ile210 play important roles in the signal transduction between the heme and the kinase domains. By measurement of the resonance Raman and optical absorption spectra of Ile209 and Ile210 mutants in several oxidation, spin, and ligation states, it was found that both residues are highly flexible, and their side chains sterically interact with the O(2) ligand, when it binds to the heme iron. On the basis of the results, we propose an O(2) sensing mechanism of RmFixL; the kinase activity is regulated via conformational changes of Ile209 and Ile210 induced by the O(2) binding to the sensory center.
Subject(s)
Bacterial Proteins/metabolism , Heme/chemistry , Hemeproteins/metabolism , Isoleucine/chemistry , Oxygen/metabolism , Protein Kinases/chemistry , Sinorhizobium meliloti/enzymology , Bacterial Proteins/genetics , Carbon Monoxide/chemistry , Enzyme Activation , Ferric Compounds/chemistry , Heme/metabolism , Hemeproteins/genetics , Histidine/genetics , Histidine Kinase , Isoleucine/genetics , Mutagenesis, Site-Directed , Phosphorylation , Protein Binding/genetics , Protein Conformation , Protein Kinases/metabolism , Sinorhizobium meliloti/genetics , Spectrometry, Fluorescence , Spectrophotometry, Ultraviolet , Spectrum Analysis, Raman , Tryptophan/geneticsABSTRACT
This study was designed to elucidate the mechanism to develop levodopa-induced dyskinesia in patients with Parkinson's disease. For this purpose, we administered methyl levodopa repeatedly to a rat model of Parkinson's disease with unilateral 6-hydroxydopamine (6-OHDA)-induced lesion of the nigrostriatal dopamine pathway. After a washout period, we measured apomorphine sensitivity of contralateral rotation and made parallel determination of Fos expression in the caudate-putamen and globus pallidus of the same animal. Once daily, i.p. injection of methyl levodopa plus benserazide for 10 days increased the number of rotations over time. A challenge dose of apomorphine showed enhanced rotational response in rats pretreated with methyl levodopa. Repeated administration of methyl levodopa resulted in diminished apomorphine sensitivity of Fos expression in the dopamine depleted caudate-putamen and in enhanced sensitivity in the globus pallidus of the same side. Present results may add evidence to the idea that repeated administration of levodopa develops dopaminergic sensitization mediated by augmented activation of pallidal neurons involved in D2-responsive pallidal output pathway.
Subject(s)
Antiparkinson Agents/pharmacology , Apomorphine/pharmacology , Behavior, Animal/drug effects , Corpus Striatum/metabolism , Levodopa/analogs & derivatives , Levodopa/pharmacology , Proto-Oncogene Proteins c-fos/metabolism , Stereotyped Behavior/drug effects , Animals , Caudate Nucleus/drug effects , Caudate Nucleus/metabolism , Corpus Striatum/drug effects , Corpus Striatum/pathology , Dopamine/deficiency , Drug Resistance , Globus Pallidus/drug effects , Male , Oxidopamine/pharmacology , Putamen/drug effects , Putamen/metabolism , Rats , Rats, Sprague-Dawley , Substantia Nigra/drug effects , Substantia Nigra/pathologyABSTRACT
This is the first report of a patient with venous insufficiency following compressive arachnoiditis ossificans (AO). Symptoms of fluctuating monoplegia and sensory disturbance appeared monthly, lasting several weeks each time. Spinal magnetic resonance imaging (MRI) showed high T2-weighted signal intensity in the posterior portion of the column from T11 to T12 and an intradural lesion with low T2-weighted signal intensity. Neurological function and MRI improved markedly following an operation on AO. The symptoms seen in the present case were due to posterior venous insufficiency following compressive AO.
Subject(s)
Arachnoiditis/diagnosis , Paralysis/etiology , Spinal Cord Diseases/diagnosis , Spinal Cord/blood supply , Venous Insufficiency/diagnosis , Aged , Arachnoiditis/complications , Arachnoiditis/pathology , Female , Humans , Magnetic Resonance Imaging , Spinal Cord/pathology , Spinal Cord Diseases/complications , Spinal Cord Diseases/pathology , Venous Insufficiency/complicationsABSTRACT
We report a sporadic case of spinocerebellar ataxia accompanied by later but severe involvement of the motor neuron system. A 72-year-old man began to show ataxia and dysarthria at age 66 years. Neurological examinations revealed saccadic eye movement, slurred speech, truncal ataxia, pyramidal sign, and urinary disturbance. Neither history of alcoholism nor hereditary factors were found. He developed muscular atrophy of the lower and upper extremities and limb ataxia within three years. Superficial and deep sensations were diminished in both feet four years after onset. Thus, he presented with cerebellar ataxia, bulbar sign, upper and lower motor neuron symptoms, sensory disturbance, and autonomic sign after six years at age 72. The level of serum, creatine phosphokinase (CPK) was increased, and muscle biopsy showed marked neurogenic change. Magnetic resonance imaging (MRI) revealed mild cerebellar and pontine atrophy. Although the combination of spinocerebellar ataxia and motor neuron disease is very rare, the present case suggests the inter-relation of the spinocerebellar and motor neuron systems, and presents peripheral neuropathy as a subtype of multisystem atrophy.
Subject(s)
Motor Neuron Disease/complications , Motor Neuron Disease/physiopathology , Spinocerebellar Ataxias/complications , Spinocerebellar Ataxias/physiopathology , Aged , Ataxia , Dysarthria , Humans , Male , Muscle, Skeletal/pathology , Neurologic Examination , Saccades , Urination DisordersABSTRACT
Cytochrome P450nor (P450nor) is a heme enzyme isolated from the denitrifying fungus Fusarium oxysporum and catalyzes the NO reduction to N2O. Crystal structures of the wild type and two Ser286 mutants (Ser286-->Val, Ser286-->Thr) of P450nor have been determined for the ferric resting forms at a 1.7 A resolution at cryogenic temperature (100 K). We carried out three comparative analyses: (1) between the structures of P450nor at room temperature and cryogenic temperature, (2) between the structures of P450nor and four monooxygenase P450s, and (3) between the structures of the WT and the Ser286 mutant enzymes of P450nor. Comparison of the charge distribution on the protein surface suggests that proton and electron flow to the heme site is quite different in P450nor than in monooxygenase P450s. On the basis of the mutant structures, it was found that a special hydrogen-bonding network, Wat99-Ser286-Wat39-Asp393-solvent, acts as a proton delivery pathway in NO reduction by P450nor. In addition, the positively charged cluster located beneath the B'-helix is suggested as possible NADH binding site in P450nor, from which the direct two-electron transfer to the heme site allows to generate the characteristic intermediate in the NO reduction. These structural characteristics were not observed in structures of monooxygenase P450s, implying that these are factors determining the unique NO reduction activity of P450nor.
Subject(s)
Cytochrome P-450 Enzyme System/chemistry , Mutation , Oxidoreductases/chemistry , Binding Sites , Crystallography, X-Ray , Electrons , Fusarium/enzymology , Heme/chemistry , Hydrogen Bonding , Kinetics , Ligands , Models, Molecular , Nitric Oxide/metabolism , Protein Conformation , Protein Structure, Secondary , Protons , Recombinant Proteins/chemistry , Serine/chemistry , Spectrophotometry , Temperature , Threonine/chemistry , Valine/chemistry , Water/chemistry , Water/metabolismABSTRACT
This is the first report of a patient with acute transverse myelopathy as the initial manifestation of primary Sjögren's syndrome (SS). The patient developed tetraparesis and sensory disturbance within 6 days of onset. Spinal MRI showed an extensive intraparenchymal lesion with high T2-weighted signal intensity, gadolinium enhancement, and cord swelling. Although the patient did not show clinical sicca symptoms, primary SS was diagnosed on the basis of clinical tests on lacrimal and salivary glands which showed high levels of autoantibodies. Treatment with prednisone improved motor and sensory symptoms and resulted in improvement of MRI findings. The present case suggests that acute transverse myelopathy can occur as an initial symptom of SS.