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Molecular cloning and characterization of a cellulase gene from a symbiotic protist of the lower termite, Coptotermes formosanus.

The endo-beta-1,4-glucanase gene was cloned from a cDNA library constructed from the mixed population of symbiotic protists in the hindgut of the lower termite, Coptotermes formosanus, using the lambda ZAP II vector. The recombinant phage library was screened for cellulolytic activity by the Congo red staining procedure. The nucleotide sequence comprised 941 nucleotides including a polyA tail sequence and showed high sequence similarity with endoglucanase genes belonging to glycosyl hydrolase family 5. Determination of the 5' end of the cellulase gene using the 5'RACE method showed that the full-length cDNA comprised a 921-bp ORF, encoding a putative 33,620 Da protein. The organismal source of this cellulase gene was identified using PCR with gene-specific primers and whole-cell in situ hybridization as the smallest symbiotic hypermastigote protist, Spirotrichonympha leidyi. The optimal pH and temperature of the cellulase heterologously expressed in Escherichia coli were 5.8-6.0 and 70 degrees C, respectively. The Km and Vmax values on carboxymethyl cellulose (CMC) substrate were 1.90 mg/ml and 148.2 units/mg protein, respectively.

Amino Acid Sequence↗

AA-type amyloidosis associated with non-Hodgkin's lymphoma: a case report.

Amyloid-associated protein (AA)-type systemic amyloidosis has been referred to as secondary amyloidosis because it is secondary to an associated inflammatory condition. It is extremely rare in patients with non-Hodgkin's lymphoma (NHL). Here we report an autopsy case of follicular small cleaved cell lymphoma with focal large B-cell lymphoma transformation in association with systemic AA-type amyloidosis. Formalin-fixed, paraffin-embedded tissues from autopsy and the patient's previous surgical specimen were studied by Congo red stain; electron microscopy; and immunostaining with antibodies against AA protein, P component, and kappa and lambda light chains. There was a marked AA amyloid deposition in the glomeruli of both kidneys, the retroperitoneal lymphoma mass, the blood vessels, the adrenal glands, and the adipose tissues. The patient's previous surgical specimens were negative for amyloid. We propose that this patient's systemic AA-type amyloidosis developed along the course of his NHL.

Amyloidosis↗

Detection of icaA and icaD loci by polymerase chain reaction and biofilm formation by Staphylococcus epidermidis isolated from dialysate and needles in a dialysis unit.

Staphylococcus epidermidis, a coagulase-negative staphylococcus, is a major cause of infections associated with indwelling medical devices. Certain strains produce slime and form biofilm on polymer surfaces, where their pathogenicity is associated with biofilm formation. In this report, we investigated the presence or absence of the intercellular adhesion icaA and icaD genes by polymerase chain reaction, and phenotypic biofilm production was examined by qualitative Congo red agar (CRA) assay. A total of 32 strains of S. epidermidis were identified from dialysates and needles 4h after the initiation of dialysis. Qualitative biofilm production revealed that 16 (50%) strains produced slime on CRA plates. Among the 23 strains positive for the ica operon, 15 were biofilm positive on CRA, eight were biofilm negative, and one was icaA and icaD negative but produced slime. These results show that the ability of S. epidermidis to produce slime is not associated with the presence of icaA and icaD genes.

Bacterial Adhesion↗

Retention of misfolded mutant transthyretin by the chaperone BiP/GRP78 mitigates amyloidogenesis.

Carriers of the D18G transthyretin (TTR) mutation display an unusual central nervous system (CNS) phenotype with late onset of disease. D18G TTR is monomeric and highly prone to misfold and aggregate even at physiological conditions. Extremely low levels of mutant protein circulate both in human serum and cerebrospinal fluid, indicating impaired secretion of D18G TTR. Recent data show efficient selective ER-associated degradation (ERAD) of D18G TTR. One essential component of the ER-assisted folding machinery is the molecular chaperone BiP. Co-expression of BiP and D18G TTR, or BiP and wild-type (wt) TTR, or mutants A25T TTR and L55P TTR in Escherichia coli showed that only D18G TTR was significantly captured by BiP. Negligible capture of wt TTR and L55P TTR was seen and a sixfold smaller amount of A25T TTR bound to BiP compared to D18G TTR. These data correlate very well with thermodynamic and kinetic stability of the TTR variants, indicating that folding efficiency is inversely correlated to BiP capture. The complexes between BiP and D18G TTR were stable and could be isolated through affinity chromatography. Analytical ultracentrifugation and size-exclusion chromatography revealed that D18G TTR and BiP formed a mixture of 1:1 complexes and large soluble oligomers. The stoichiometry of captured D18G TTR versus BiP increased with increasing size of the oligomers. This indicates that BiP either worked as a molecular shepherd collecting the aggregation-prone mutant into stable oligomers or that BiP could bind to oligomers formed from misfolded mutant protein. Sequence analysis of bound TTR peptides to BiP revealed a bound sequence corresponding to residues 88-103 of TTR, comprising beta-strand F in the folded TTR monomer constituting part of the hydrogen bonding tetramer interface in native TTR. The F-strand has also been suggested as a possible elongation region of amyloid fibrils, implicating how substoichiomeric amounts of BiP could sequester prefibrillar amyloidogenic oligomers through binding to this part of TTR. BiP binding to D18G TTR was abolished by addition of ATP. The released D18G TTR completely misfolded into amyloid aggregates as shown by ThT fluorescence and Congo red binding.

Amino Acid Sequence↗

Amyloid formation by recombinant full-length prion proteins in phospholipid bicelle solutions.

A soluble, oligomeric beta-sheet-rich conformational variant of recombinant full-length prion protein, PrP beta, was generated that aggregates into amyloid fibrils, PrP betaf. These fibrils have physico-chemical and structural properties closely similar to those of pathogenic PrP Sc in scrapie-associated fibrils and prion rods, including a closely similar proteinase K digestion pattern and Congo red birefringence. The conformational transition from PrP C to PrP beta occurs at pH 5.0 in bicellar solutions containing equimolar mixtures of dihexanoyl-phosphocholine and dimyristoyl-phospholipids, and a small percentage of negatively charged dimyristoyl-phosphoserine. The same protocol was applicable to human, cow, elk, pig, dog and mouse PrP. Comparison of full-length hPrP 23-230 with the N-terminally truncated human PrP fragments hPrP 90-230, hPrP 96-230, hPrP 105-230 and hPrP 121-230 showed that the flexible peptide segment 105-120 must be present for the generation of PrP beta. Dimerization of PrP C represents the rate-limiting step of the PrP C-to-PrP beta conformational transition, which is dependent on the amino acid sequence. The activation enthalpy of dimerization is about 130 kJ/mol for the recombinant full-length human and bovine prion proteins, and between 260 and 320 kJ/mol for the other species investigated. The in vitro conversion assay described here permits direct molecular characterization of processes that might be closely related to conformational transitions of the prion protein in transmissible spongiform encephalopathies.

Amyloid↗

Linker histone H1 binds to disease associated amyloid-like fibrils.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most prevalent neurodegenerative diseases of the central nervous system. These two diseases share a common feature in that a normally soluble peptide (amyloid-beta) or protein (alpha-synuclein) aggregates into an ordered fibrillar structure. As well as structural similarities observed between fibrillar aggregates related to these diseases, common pathological processes of increased oxidative injury, excitotoxicity and altered cell cycle are also evident. It was the aim of this study to identify novel interacting proteins to the amyloid-like motif and therefore identify common potential pathways between neurodegenerative diseases that share biophysical properties common to classical amyloid fibrils. Optimal ageing of recombinant proteins to form amyloid-like fibrils was determined by electron microscopy, Congo red birefringement and photo-induced cross-linking. Using pull-down assays the strongest detected interacting protein to the amyloid-like motifs of amyloid-beta, alpha-synuclein and lysozyme was identified as histone H1. The interaction with the amyloid-like motif was confirmed by techniques including surface plasmon resonance and immunohistochemistry. Histone H1 is known to be an integral part of chromatin within the nucleus, with a primary role of binding DNA that enters and exits from the nucleosome, and facilitating the shift in equilibrium of chromatin towards a more condensed form. However, phosphorylated histone H1 is predominantly present in the cytoplasm and as yet the functional significance of this translocation is unknown. This study also found that histone H1 is localised within the cytoplasm of neurons and astrocytes from areas affected by disease as well as amyloid plaques, supporting the hypothesis that histone H1 favoured binding to an ordered fibrillar motif. We conclude that the binding of histone H1 to a general amyloid-like motif indicates that histone H1 may play an important common role in diseases associated with amyloid-like fibrils.

Alzheimer Disease↗

Amyloid in neurosurgical and neurological practice.

The amyloidoses are a diverse group of diseases characterized by the deposition of specific proteins with distinct affinity to the dye Congo red, collectively called amyloid. The amyloidogenic proteins have acquired an abnormal, highly ordered, beta-pleated sheet configuration with a propensity to self-aggregate. The amyloid may be distributed in different organs with a remarkable diversity. Two broad categories of amyloidoses are recognised: The systemic (consisting of the primary or light chain form, the secondary or reactive form and the familial or hereditary form) and the localised that target specific organs. A tropism of amyloid proteins to the neural tissue produces certain patterns of central nervous system diseases: cerebral amyloid angiopathy, a substrate of spontaneous intracerebral haemorrhage; mature neuritic plaques found in Alzheimer disease and a subset of prion diseases; a topographically restricted accumulation of extracellular proteins giving rise to tumour-mimicking masses, the amyloidomas; and finally, spinal extradural amyloid collections that occasionally are found in the context of rheumatoid arthritis. In this review article we present original illustrative cases of amyloid diseases of the central nervous system that may be encountered in neurosurgical and neurological practice. Molecular aspects and clinical management problems are discussed.

Amyloid↗

The binding of thioflavin-T to amyloid fibrils: localisation and implications.

Amyloid fibrils are a polymeric form of protein, involving a continuous beta-sheet with the strands perpendicular to the long axis of the fibril. Although typically implicated in diseases such as Alzheimer's disease and the transmissible spongiform encephalopathies, non disease-associated protein can also be converted into amyloid fibrils. Traditionally, amyloid fibrils are identified via the use of specific dyes such as Congo red and thioflavin-T, although their specificity is ill understood. Recently, solutions of bovine insulin and bovine beta-lactoglobulin have been found to form spherulites, micron-sized spherical structures containing radially arranged amyloid fibrils. When studied by confocal microscopy using polarised laser light and thioflavin-T, a consistent pattern of emission, rather than a uniform disc, was observed. This suggests the dye binds in a specific, regular fashion to amyloid fibrils. Confocal microscopy studies of thioflavin-T aligned in stretched poly-vinyl alcohol films showed that the dye dipole excitation axis lies parallel to the long molecular axis. Therefore, thioflavin-T binds to amyloid fibrils such that their long axes are parallel. We propose binding occurs in 'channels' that run along the length of the beta-sheet. Steric interactions between dye molecules and side chains indicate why thioflavin-T fluoresces more intensely when bound to amyloid fibrils and can explain why this interaction with amyloid fibrils is specific, but with varying efficiency.

Amyloid↗

Filaments of the Ure2p prion protein have a cross-beta core structure.

Formation of filaments by the Ure2 protein constitutes the molecular mechanism of the [URE3] prion in yeast. According to the "amyloid backbone" model, the N-terminal asparagine-rich domains of Ure2p polymerize to form an amyloid core fibril that is surrounded by C-terminal domains in their native conformation. Protease resistance and Congo Red binding as well as beta-sheet content detected by spectroscopy-all markers for amyloid-have supported this model, as has the close resemblance between 40 A N-domain fibrils and the fibrillar core of intact Ure2p filaments visualized by cryo-electron microscopy and scanning transmission electron microscopy. Here, we present electron diffraction and X-ray diffraction data from filaments of Ure2p, of N-domains alone, of fragments thereof, and of an N-domain-containing fusion protein that demonstrate in each case the 4.7A reflection that is typical for cross-beta structure and highly indicative of amyloid. This reflection was observed for specimens prepared by air-drying with and without sucrose embedding. To confirm that the corresponding structure is not an artifact of air-drying, the reflection was also demonstrated for specimens preserved in vitreous ice. Local area electron diffraction and X-ray diffraction from partially aligned specimens showed that the 4.7A reflection is meridional and therefore the underlying structure is cross-beta.

Glutathione Peroxidase↗

Plaques of Alzheimer's disease originate from cysts of Borrelia burgdorferi, the Lyme disease spirochete.

Here is hypothesized a truly revolutionary notion that rounded cystic forms of Borrelia burgdorferi are the root cause of the rounded structures called plaques in the Alzheimer brain. Rounded "plaques' in high density in brain tissue are emblematic of Alzheimer's disease (AD). Plaques may be conceptualized as rounded "pock mark-like" areas of brain tissue injury. In this century, in brain tissue of AD, plaques are Amyloid Plaques according to the most up to date textbooks. In the last century, however, Dr. Alois Alzheimer did not require amyloid as the pathogenesis for either the disease or for the origin of its plaques. Surely, amyloid is an event in AD, but it may not be the primal cause of AD. Indeed in plaques, amyloid is regularly represented by the "congophilic core" structure which is so named because the waxy amyloid material binds the congo red stain and is congophilic. However an accepted subset of plaques in AD is devoid of a congophilic amyloid core region (these plaques "cotton wool" type plaques, lack a central congophilic core structure). Furthermore, there is "plaque diversity" in Alzheimer's; small, medium and large plaques parallel variable cystic diameters for Borrelia burgdorferi. Perturbations of AD plaque structure (i.e. young plaques devoid of a central core and older plaques with or without a central core structure) offer room for an alternate pathway for explanation of ontogeny of the plaque structures. If amyloid is not required to initiate all of the possible plaques in Alzheimer's, is it possible that amyloid just a by product of a more fundamental primal path to dementia? If a byproduct status is assigned to amyloid in the realm of plaque formation, then is amyloid also an epiphenomenon rather than a primary pathogenesis for Alzheimer's disease. In the "anatomy is destiny" model, cysts of borrelia are always round. Why then not accept roundness as a fundamental "structure determines function" argument for the answer to the mystery of why Alzheimer plaques are always round? Parataxis causality, a concept borrowed from philosophy, is the error that comes from linking two events, which occur contemporaneously or in close proximity to one another with a cause and effect relationship. Parataxis tells us that what appears to be cause and effect in the couplet "amyloid plaque" merely by a proximity relationship may be "spurious causality" which is a cognitive dead end.

Alzheimer Disease↗

Capillary isoelectric focusing--useful tool for detection of the biofilm formation in Staphylococcus epidermidis.

The biofilm formation is an important factor of S. epidermidis virulence. Biofilm-positive strains might be clinically more important than biofilm-negative ones. Unlike biofilm-negative staphylococci, biofilm-positive staphylococci are surrounded with an extracellular polysaccharide substance. The presence of this substance on the surface can affect physico-chemical properties of the bacterial cell, including surface charge. 73 S. epidermidis strains were examined for the presence of ica operon, for the ability to form biofilm by Christensen test tube method and for the production of slime by Congo red agar method. Isoelectric points (pI) of these strains were determined by means of Capillary Isoelectric Focusing. The biofilm negative strains focused near pI value 2.3, while the pI values of the biofilm positive strains were near 2.6. Isoelectric point is a useful criterion for the differentiation between biofilm-positive and biofilm-negative S. epidermidis strains.

Amidohydrolases↗

Human monoclonal antibodies against amyloid-beta from healthy adults.

Two anti-amyloid-beta human antibody-producing cell lines were established from amyloid-beta (Abeta)-selected lymphocytes from peripheral blood of healthy adults. ELISA and Western blot analysis showed that the monoclonal antibodies bound with high affinity to the 43 amino acid-long amyloid-beta peptide. The antigen epitope of these antibodies encountered within amino acids 1-16 of the amyloid-beta peptide. The antibodies did not bind to several immunoglobulin light chain amyloids (AL) and amylin. One of the monoclonals was tested by immunohistochemistry for the binding to frozen sections of brains derived from patients with Alzheimer's disease. It specifically and intensively stained diffuse and core amyloid-beta plaques; whereas, sections from normal brains were not stained. Concomitant staining with a commercial mouse anti-amyloid-beta monoclonal antibody co-localized with that of the human antibody. Simultaneous staining with the human antibody and Congo red implied that the antibody binds primarily to an early immature form of beta-amyloid. Human monoclonal antibodies, which resemble physiologically normal non-pathogenic and possibly protective antibodies in healthy adults, might be attractive candidates for immune therapy of Alzheimer's disease.

Adult↗

Clinicopathological and immunohistochemical study of 39 cases of Adenomatoid Odontogenic Tumour: a multicentric study.

Adenomatoid Odontogenic Tumour (AOT) is a relatively uncommon odontogenic lesion and few studies describing its cytokeratin profile have been reported in the English-language literature. Thirty-nine cases of AOT from three Oral Diagnosis services (Brazil, Mexico and Guatemala) were studied, considering their clinical, radiographic, and histological features and immunohistochemical expression of cytokeratins (AE1/AE3, 34betaE12, CK1, CK5, CK6, CK7, CK8, CK10, CK13, CK14, CK16, CK18, and CK19), vimentin and Ki-67. Sixty five percent of cases affected women, anterior maxilla was the preferred site and radiographically most cases showed unilocular radiolucency with well defined sclerotic borders. Calcifying epithelial odontogenic tumour (CEOT)-like areas were found in 36 out of 39 cases, and 10 cases showed positivity for Congo red in polarized light. All cases were positive for AE1/AE3, 34betaE12, CK5, CK14 and CK19. CEOT-like areas were negative for CK 19. Vimentin was also expressed in 27 cases and this profile may indicate the existence of a variable phenotype in certain areas of the tumour. There were no recurrences after surgical treatment, and this can be related to the low proliferative activity observed in all cases with Ki-67 marker.

Adolescent↗

PEGylated phospholipid nanomicelles interact with beta-amyloid((1-42)) and mitigate its beta-sheet formation, aggregation and neurotoxicity in vitro.

beta-Amyloid (Abeta) is a hydrophobic peptide that drives the pathogenesis of Alzheimer's disease (AD) due to its aberrant aggregation. Inhibition of Abeta aggregation process is one of the most promising strategies for therapeutic intervention in AD. Here, we demonstrate that sterically stabilized (PEGylated) phospholipid nanomicelles (SSM) are effective in mitigating Abeta-42 aggregation using several deterministic techniques such as (1) Turbidimetry (2) Congo red binding (3) Thioflavine-T binding (4) Laser light scattering and (5) Electron Microscopy. alpha-Helicity of Abeta-42 is significantly augmented in the presence of SSM as demonstrated by circular dichroism (p<0.05). Cytotoxicity studies, employing human neuroblastoma SHSY-5Y cells, established that PEGylated phospholipid associated peptide demonstrated significantly lower neurotoxicity compared to lipid untreated Abeta-42 (p<0.05). Collectively, our results establish that PEGylated phospholipids abrogate transformation of Abeta-42 to amyloidogenic beta-sheeted form and impart neuroprotection in vitro. This study provides a foundation for designing nanoconstructs of PEGylated phospholipid nanomicelles in conjunction with a therapeutic agent for multitargeting the different pathophysiologies associated with AD.

Amyloid beta-Peptides↗

Elastolytic activity and alveolar epithelial type-1 cell damage after chronic LPS inhalation: effects of dexamethasone and rolipram.

This study investigated whether a correlation between leukocyte-derived elastolytic activity, alveolar epithelial type-1 cell damage, and leukocyte infiltration of the airways existed in guinea-pigs chronically exposed to inhaled lipopolysaccharide (LPS). The airway pathology of this model, notably the neutrophilia, resembles chronic obstructive pulmonary disease (COPD). The effect of the corticosteroid, dexamethasone, or the phosphodiesterase-4 (PDE4)-inhibitor, rolipram, on these features was studied. Conscious guinea-pigs were exposed for 1 h to single or repeated (nine) doses of LPS (30 microg ml(-1)). Dexamethasone (20 mg kg(-1), ip) or rolipram (1 mg kg(-1), ip) was administered 24 and 0.5 h before the first exposure and daily thereafter. Bronchoalveolar lavage fluid (BALF) was removed and elastolytic activity determined as the elastase-like release of Congo Red from impregnated elastin. The presence of the specific epithelial cell type-1 protein (40-42 kDa) RT1(40) in BALF was identified by Western blotting using a rat monoclonal antibody and semi-quantified by dot-blot analysis. The antibody was found to identify guinea-pig RT1(40). BALF inflammatory cells, particularly neutrophils and macrophages, and elastolytic activity were increased in chronic LPS-exposed guinea-pigs, the latter by 90%. Chronic LPS exposure also increased (10.5-fold) RT1(40) levels, indicating significant alveolar epithelial type-1 cell damage. Dexamethasone or rolipram treatment reduced the influx of inflammatory cells, the elastolytic activity (by 40% and 38%, respectively), and RT1(40) levels (by 50% and 57%, respectively). In conclusion, chronic LPS-exposed guinea-pigs, like COPD, exhibit elastolytic lung damage. This was prevented by a PDE4 inhibitor and supports their development for suppressing this leukocyte-mediated pathology.

Administration, Inhalation↗

Pseudomonas aeruginosa from canine otitis externa exhibit a quorum sensing deficiency.

Pseudomonas aeruginosa LasB elastase gene (lasB) transcription depends on cell density-dependent quorum-sensing mechanisms of gene activation. Previously, we collected several non-mucoid P. aeruginosa veterinary isolates and showed that the total matrix protease phenotype was similar for isolates regardless of host and site of isolation. In contrast, isolates from chronic canine ear infections (otitis externa) were significantly more likely to exhibit less elastase activity as measured by elastin Congo red than from any other site [Clin. Diag. Lab. Immun. 8 (2001) 632]. In this study, we found that the elastase deficiency phenotype is stable upon passage in broth culture. Transcript amplification analyses indicated that the elastase deficiency appears to be strain-specific, with each isolate exhibiting a unique expression profile relative to strain PAO1. Although a number of strain-specific transcriptional differences were observed, the overall pattern that emerges is a quorum sensing deficiency among canine ear P. aeruginosa isolates.

Animals↗

Formation of nucleoplasmic protein aggregates impairs nuclear function in response to SiO2 nanoparticles.

Despite of their exponentially growing use, little is known about cell biological effects of nanoparticles. Here, we report uptake of silica (SiO(2)) nanoparticles to the cell nucleus where they induce aberrant clusters of topoisomerase I (topo I) in the nucleoplasm that additionally contain signature proteins of nuclear domains, and protein aggregation such as ubiquitin, proteasomes, cellular glutamine repeat (polyQ) proteins, and huntingtin. Formation of intranuclear protein aggregates (1) inhibits replication, transcription, and cell proliferation; (2) does not significantly alter proteasomal activity or cell viability; and (3) is reversible by Congo red and trehalose. Since SiO(2) nanoparticles trigger a subnuclear pathology resembling the one occurring in expanded polyglutamine neurodegenerative disorders, we suggest that integrity of the functional architecture of the cell nucleus should be used as a read out for cytotoxicity and considered in the development of safe nanotechnology.

Cell Division↗

Aberrant protein aggregation is essential for a mutant desmin to impair the proteolytic function of the ubiquitin-proteasome system in cardiomyocytes.

Aberrant protein aggregates in cardiomyocytes are frequently observed in many forms of cardiomyopathies and are often associated with impairment of proteolytic function of the ubiquitin-proteasome system (UPS). However, a causal relationship between mutant desmin (MT-des) induced aberrant protein aggregation and UPS impairment has not been established. The present study has tested the causal relationship. In cultured neonatal rat ventricular myocytes, modest overexpression of a human (cardio)myopathy-linked MT-des protein led to formation of desmin-positive aggregates and inhibited UPS proteolytic function in cardiomyocytes in a dose-dependent manner. Prevention or reduction of aberrant protein aggregation by co-expression of a heat shock protein (Hsp), alphaB-crystallin or inducible Hsp70, or by treatment of Congo red prevented and/or significantly attenuated the induction of UPS malfunction by MT-des. These findings prove for the first time that aberrant protein aggregation is not only sufficient but also required for MT-des to impair UPS proteolytic function in cardiomyocytes.

Animals↗