Expression of the cop operon which effects copper homeostasis in Enterococcus hirae is controlled by the copper responsive repressor CopY. Purified Zn(II)CopY binds to a synthetic cop promoter fragment in vitro. Here we show that the 8 kDa protein CopZ acts as a copper chaperone by specifically delivering copper(I) to Zn(II)CopY and releasing CopY from the DNA. As shown by gel filtration and luminescence spectroscopy, two copper(I) are thereby quantitatively transferred from Cu(I)CopZ to Zn(II)CopY, with displacement of the zinc(II) and transfer of copper from a non-luminescent, exposed, binding site in CopZ to a luminescent, solvent shielded, binding site in CopY. 相似文献
Automatic Selection of clinical Trial based on Eligibility Criteria (ASTEC) project is to automate, so as to make it systematic, the search of cancer clinical trials, by reusing the patient data contained into an oncologic electronic health record. ASTEC project tackles two major scientific challenges for medical informatics: 1) the syntactic and semantic interoperability between information systems. The oncologic electronic medical records and the recruitment decision system must be interoperable. The ASTEC project proposes a framework of syntactico-semantic interoperability based on international standards. Generic methods of mediation and reasoning based on ontologies are developed to match data from the electronic medical records to the inclusion/exclusion criteria of clinical trials; 2) a decision support system for recruitment. We have developed inference methods on the electronic medical records adapted to the data structure as well as the eligibility criteria. this paper, we present and justify our choices, concerning the medical process in oncology and the scientific and technical aspects. Furthermore the system will be evaluated in real time. The aim is to demonstrate a significative improvement of the prescreening rate of patient. 相似文献
Hepatitis E virus (HEV) causes acute hepatitis in many parts of the world including Asia, Africa and Latin America. Though self-limiting in normal individuals, it results in ~30% mortality in infected pregnant women. It has also been reported to cause acute and chronic hepatitis in organ transplant patients. Of the seven viral genotypes, genotype-1 virus infects humans and is a major public health concern in South Asian countries. Sporadic cases of genotype-3 and 4 infection in human and animals such as pigs, deer, mongeese have been reported primarily from industrialized countries. Genotype-5, 6 and 7 viruses are known to infect animals such as wild boar and camel, respectively. Genotype-3 and 4 viruses have been successfully propagated in the laboratory in mammalian cell culture. However, genotype-1 virus replicates poorly in mammalian cell culture and no other efficient model exists to study its life cycle. Here, we report that endoplasmic reticulum (ER) stress promotes genotype-1 HEV replication by inducing cap-independent, internal initiation mediated translation of a novel viral protein (named ORF4). Importantly, ORF4 expression and stimulatory effect of ER stress inducers on viral replication is specific to genotype-1. ORF4 protein sequence is mostly conserved among genotype-1 HEV isolates and ORF4 specific antibodies were detected in genotype-1 HEV patient serum. ORF4 interacted with multiple viral and host proteins and assembled a protein complex consisting of viral helicase, RNA dependent RNA polymerase (RdRp), X, host eEF1α1 (eukaryotic elongation factor 1 isoform-1) and tubulinβ. In association with eEF1α1, ORF4 stimulated viral RdRp activity. Furthermore, human hepatoma cells that stably express ORF4 or engineered proteasome resistant ORF4 mutant genome permitted enhanced viral replication. These findings reveal a positive role of ER stress in promoting genotype-1 HEV replication and pave the way towards development of an efficient model of the virus. 相似文献
Soluble fractions from chick liver and aorta were examined for copper-binding proteins. In liver a zinc-binding thionein appeared to be the major binding protein for copper. Aortic tissue contained only traces of this thionein protein. Unlike liver, moderate amounts of soluble copper in aorta showed no association with macromolecules. Chicks fed on copper-deficient diets for 8 days had one-third the liver copper concentrations of controls. Aortic copper concentration was decreased only slightly, but the activity of lysyl oxidase, a copper-dependent enzyme in aorta, was decreased significantly. Treating the deficient chicks with CuSO4 (1 mg/kg) restored liver copper rapidly. The increase correlated with the binding of copper to a 10 000-mol.wt. component in the soluble fraction. Aortic copper concentrations responded much less to the CuSO4 treatment, but lysyl oxidase activity was again measurable in the tissue. Radioactive isotopes of copper bound almost exclusively to the 10 000-mol.wt. component in liver and to components of mol.wt. 30 000 or above in aorta. Hardly any of the administered radioactivity appeared with the 10 000-mol.wt. components in aorta, and none was found with unbound copper. The 30 000-mol.wt. components in aorta showed superoxide dismutase activity that was sensitive to NaCN. They also showed the highest specific activity of copper of any other aorta component. A clear distinction was seen between the metabolism of copper in liver and aortic tissues. Whereas a copper thionein, metallothionein, was a major component in the liver pathway, it is doubtful that this protein plays a major role in the intracellular metabolism of copper in aortic tissue. 相似文献
Low-lying coral reef islands are considered highly vulnerable to climate change, necessitating an improved understanding of when and why they form, and how the timing of formation varies within and among regions. Several testable models have been proposed that explain inter-regional variability as a function of sea-level history and, more recently, a reef platform size model has been proposed from the Maldives (central Indian Ocean) to explain intra-regional (intra-atoll) variability. Here we present chronostratigraphic data from Pipon Island, northern Great Barrier Reef (GBR), enabling us to test the applicability of existing regional island evolution models, and the platform size control hypothesis in a Pacific context. We show that reef platform infilling occurred rapidly (~4–5 mm yr−1) under a “bucket-fill” type scenario. Unusually, this infilling was dominated by terrigenous sedimentation, with platform filling and subsequent reef flat formation complete by ~5000 calibrated years BP (cal BP). Reef flat exposure as sea levels slowly fell post highstand facilitated a shift towards intertidal and subaerial-dominated sedimentation. Our data suggest, however, a lag of ~1500 yr before island initiation (at ~3200 cal BP), i.e. later than that reported from smaller and more evolutionarily mature reef platforms in the region. Our data thus support: (1) the hypothesis that platform size acts to influence the timing of platform filling and subsequent island development at intra-regional scales; and (2) the hypothesis that the low wooded islands of the northern GBR conform to a model of island formation above an elevated reef flat under falling sea levels.
Immunoglobulins are encoded by a large multigene system that undergoessomatic rearrangement and additional genetic change during the developmentof immunoglobulin-producing cells. Inducible antibody and antibody-likeresponses are found in all vertebrates. However, immunoglobulin possessingdisulfide-bonded heavy and light chains and domain-type organization hasbeen described only in representatives of the jawed vertebrates. Highdegrees of nucleotide and predicted amino acid sequence identity areevident when the segmental elements that constitute the immunoglobulin geneloci in phylogenetically divergent vertebrates are compared. However, theorganization of gene loci and the manner in which the independent elementsrecombine (and diversify) vary markedly among different taxa. One strikingpattern of gene organization is the \"cluster type\" that appears to berestricted to the chondrichthyes (cartilaginous fishes) and limitssegmental rearrangement to closely linked elements. This type of geneorganization is associated with both heavy- and light-chain gene loci. Insome cases, the clusters are \"joined\" or \"partially joined\" in the germline, in effect predetermining or partially predetermining, respectively,the encoded specificities (the assumption being that these are expressed)of the individual loci. By relating the sequences of transcribed geneproducts to their respective germ-line genes, it is evident that, in somecases, joined-type genes are expressed. This raises a question about theexistence and/or nature of allelic exclusion in these species. Theextensive variation in gene organization found throughout the vertebratespecies may relate directly to the role of intersegmental(V<==>D<==>J) distances in the commitment of the individualantibody-producing cell to a particular genetic specificity. Thus, theevolution of this locus, perhaps more so than that of others, may reflectthe interrelationships between genetic organization and function. 相似文献
Cadmium-sulfide crystallites form in the yeast Candida glabrata cultured in the presence of cadmium salts. The particles function to sequester and detoxify intracellular cadmium ions. The crystallites are peptide-coated, but the coating peptide varies with the nutrient conditions of the growth medium. When cultured in rich nutrient broth the yeast forms intracellular CdS particles coated with a mixture of glutathione and the gamma-glutamylcysteine dipeptide. In contrast, cultures in synthetic minimal medium yield particles coated with polymerized gamma EC peptides of general structure (gamma-Glu-Cys)n-Gly. Glutathione/gamma-glutamylcysteine particles exhibit properties analogous to quantum, semiconductor-type crystallites. The optical properties are dependent on particle size, and irradiation results in photoluminescence and photoreduction not observed in bulk CdS mineral. Aerobic irradiation leads to particle decomposition presumably via oxidation of the sulfide ions within the crystallite. 相似文献
Despite intense studies, questions still remain regarding the molecular mechanisms leading to the development of hereditary breast and ovarian cancers. Research focused on elucidating the role of the breast cancer susceptibility gene 1 (BRCA1) in the DNA damage response may be of the most critical importance to understanding these processes. The BRCA1 protein has an N-terminal RING domain possessing E3 ubiquitin-ligase activity and a C-terminal BRCT domain involved in binding specific phosphoproteins. These domains are involved directly or indirectly in DNA double-strand break (DSB) repair. As the two terminal domains of BRCA1 represent two separate entities, understanding how these domains communicate and are functionally altered in regards to DSB repair is critical for understanding the development of BRCA1-related breast and ovarian cancers and for developing novel therapeutics. Herein, we review recent findings of how altered functions of these domains might lead to cancer through a mechanism of increased aberrant homologous recombination and possible implications for the development of BRCA1 inhibitors.Key words: BRCT, DNA repair, peptide, radiation, RING, ubiquitylation相似文献
MOTIVATION: At the core of most protein gene-finding algorithms are the
coding measures used to make a decision on coding/non-coding. Of the
protein coding measures, the Fourier measure is one of the most important.
However, due to the limited length of the windows usually used, the
accuracy of the measure is not satisfactory. This paper is devoted to
improving the accuracy by lengthening the sequence to amplify the
periodicity of 3 in the coding regions. RESULTS: A new algorithm is
presented called the lengthen-shuffle Fourier transform algorithm. For the
same window length, the percentage accuracy of the new algorithm is 6-7%
higher than that of the ordinary Fourier transform algorithm. The resulting
percentage accuracy (average of specificity and sensitivity) of the new
measure is 84.9% for the window length 162 bp. AVAILABILITY: The program is
available on request fromC.- T. Zhang. Contact: ctzhang@tju.edu.cn
相似文献
The oncogenic E7 proteins of human papilloma virus (HPV 16) and of cottontail rabbit papilloma virus (CRPV) have been purified from an expression system in Escherichia coli. The proteins as purified from E. coli contain one tightly bound Zn(II) ion per molecule. The metal site shows facile exchange with either Cd(II) or Cu(I). The HPV 16 E7 maximally bound one Cd(II) or two Cu(I) ions, while the CRPV E7 bound two Cd(II) or three Cu(I) ions. The Cd(II) and Cu(I) E7 molecules exhibited optical transitions in the ultraviolet suggestive of metal:thiolate coordination. E7 proteins from HPV 16 and CRPV contain 7 and 8 cysteines/molecule, respectively. Reaction of the E7 proteins with the sulfhydryl reagent, dithiodipyridine, revealed that all the cysteinyl sulfurs are present in the reduced thiol state. Cu(I)-E7 molecules are luminescent with maximal emission at 570 nm. The observed emission at room temperature is indicative of metal coordination within a compact protein environment shielded from solvent interactions. The emission maxima occurs at the same wavelength (570 nm) as Cu(I)-cysteinyl sulfur clusters in Cu(I)-metallothioneins. The single Zn(II) atom in each protein can be removed from E7 in the presence of EDTA. The resulting apoE7 molecules remain soluble and can be partially reconstituted with Cd(II) to regain the ultraviolet charge transfer transitions. 相似文献