Biomedical subjects

A Randolf

Publications and source records attributed to A Randolf.

6 recordsLinked to original sources

PubMed2001

Phosphorylation of Marburg virus VP30 at serines 40 and 42 is critical for its interaction with NP inclusions.

The Marburg virus (MBGV) nucleocapsid complex is composed of four viral proteins (NP, L, VP35, and VP30) and the negative-strand nonsegmented genomic RNA. NP, L, and VP35 are functionally conserved among the order Mononegavirales, whereas VP30, a phosphoprotein, represents a filovirus-specific nucleocapsid protein. In the present paper, we have characterized the localization and function of VP30 phosphorylation. The main phosphorylation sites are represented by seven serine residues in the region of amino acid 40 to 51 of VP30. Additionally, trace amounts of phosphothreonine were detected. Substitution of serine residues 40 and 42 by alanine abolished the interaction of VP30 with NP-induced inclusion bodies, which contain nucleocapsid-like structures formed by NP. Substitution of the other phosphoserine residues had little effect on this interaction. Replacement of the introduced alanine residues 40 and 42 by aspartate restored the interaction between VP30 and the NP inclusions pointing to the importance of negative charges at these particular positions.

Alkaline Phosphatase↗

PubMed2000

Intron-exon structure and gene copy number of a gene encoding for a membrane-intrinsic light-harvesting polypeptide of the red alga Galdieria sulphuraria.

Genes for light-harvesting proteins (lhc genes) of higher plants are well examined. However, little is known about the corresponding genes of algae, although this knowledge might give valuable information about the evolution of photosynthetic antennae. In the case of rhodophytes only two cDNA sequences from a single organism, Porphyridium cruentum, have been published. Here we describe an additional sequence from another species, the thermo-acidophilic red alga Galdieria sulphuraria. For the first time also a genomic sequence for a red algal lhc gene is presented. From a cDNA library of G. sulphuraria we isolated a clone containing an open reading frame for a protein of 302 amino acids with a deduced molecular mass of 33.86kDa. It shares major structural features with eukaryotic light-harvesting polypeptides. A proposed cleavage site between transit peptide and mature protein gives rise to a transit peptide of 119 amino acids and a mature protein of 183 residues. Hydropathy analysis suggests that the mature protein consists of three transmembrane helices. Several amino acid residues supposed to bind chlorophyll a and chlorophyll b in higher plants are conserved. The protein shows up to 69% identity and 81% similarity to the Porphyridium polypeptides in the transmembrane helices 1 and 3. Using oligonucleotides annealing in the regions of the start and stop codons of the gene as primers, a DNA sequence was amplified from nuclear G. sulphuraria DNA by PCR. Compared with the cDNA clone, this sequence contains five additional intervening DNA strings of 50-74bp length. Four of them show typical features of spliceosomal introns with GT-AG borders, and the fifth differs by starting with GC. Three of the supposed introns are located in similar positions as introns of higher plant light-harvesting proteins. Southern blotting and hybridization experiments indicate that G. sulphuraria contains at least three copies of this gene.

Algal Proteins↗

PubMed2000

Not all peripheral immune stimuli that activate the HPA axis induce proinflammatory cytokine gene expression in the hypothalamus.

Administration of low doses of lipopolysaccharide (LPS) that do not disrupt the blood-brain barrier (BBB) results in the expression of interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor-alpha (TNF alpha) in the hypothalamus in parallel to stimulation of the hypothalamus-pituitary-adrenal (HPA) axis. This endocrine response is triggered by peripheral cytokines, and we recently obtained evidence that brain-borne IL-1 contributes to its maintenance. LPS preferentially stimulates cells of the macrophage lineage and B lymphocytes. The possibility that primarily stimulation of other types of peripheral immune cells also results in the expression of proinflammatory cytokines in the brain and in the activation of the HPA axis was investigated. Our results showed that, in contrast to LPS, administration of the superantigen staphylococcal enterotoxin B (SEB), which stimulates T cells by binding to appropriate V beta domains of the T-cell receptor, did not result in induction of IL-1 beta, IL-6, and TNF alpha expression in the hypothalamus. Furthermore, although IL-2 transcripts in the spleen were highly increased, expression of this gene was not detected in the brain. However, as with LPS, SEB administration also results in elevated levels of glucocorticoids in blood. Therefore, our data suggest that increased expression of proinflammatory cytokines in the brain is not a necessary step in the stimulation of the HPA axis by SEB.

Animals↗

PubMed2000

Sympathetic innervation affects superantigen-induced decrease in CD4V beta 8 cells in the spleen.

The stimulation by superantigens of T cells expressing an appropriate V beta chain results in a strong proliferative response that is followed by a state of energy specific for the antigen used. This model was used to continue our studies on immunoregulatory host neuroendocrine responses. We have recently found that four days after administration of the superantigen staphylococcal enterotoxin B (SEB) into mice, that is, at an early stage of the anergic phase, the decrease in the percentage of splenic CD4V beta 8 was accompanied by a decrease in the splenic concentration of the sympathetic neurotransmitter noradrenaline (NA) as compared to vehicle-injected mice. No comparable changes were detected in the kidney. At this point, blood levels of NA, adrenaline, and corticosterone were comparable in SEB- and vehicle-injected mice. We have also found that the decrease in splenic CD4V beta 8 cells was not observed in animals that had been chemically sympathectomized prior to the administration of the superantigen. These results indicate that the sympathetic response induced by SEB may have immunoregulatory implications.

Animals↗

PubMed1992

The nucleotide sequence of the L gene of Marburg virus, a filovirus: homologies with paramyxoviruses and rhabdoviruses.

The nucleotide sequence of the L gene of Marburg virus, strain Musoke, has been determined. The L gene has a single long open reading frame encoding a polypeptide of 2330 amino acids (MW 267,175) that represents the viral RNA-dependent RNA polymerase. The putative transcription start signal (3'CUACCUAUAAUU 5') and the termination signal (3' UAAUUCUUUUU 5') of the gene could be identified. Computer-assisted comparison of the L protein with L proteins of other nonsegmented negative-stranded RNA viruses (Paramyxoviridae: Sendai virus, Newcastle disease virus, human parainfluenza 3 virus, measles virus, human respiratory syncytial virus; Rhabdoviridae: vesicular stomatitis virus, rabies virus) revealed significant homologies primarily in the N-terminal half of the proteins. We have identified three common conserved boxes (A, B, and C) among filo-, paramyxo-, and rhabdovirus L proteins, which are probably involved in the polymerase function. The L proteins can be divided into an N-terminal half, which seems to accommodate the common enzymatic sites, and a C-terminal half carrying virus specific peculiarities. The data presented here suggest a common evolutionary history for all nonsegmented negative-stranded RNA viruses and show that filoviruses are more closely related to paramyxo- than to rhabdoviruses.

Amino Acid Sequence↗

PubMed1992

Marburg virus, a filovirus: messenger RNAs, gene order, and regulatory elements of the replication cycle.

The genome of Marburg virus (MBG), a filovirus, is 19.1 kb in length and thus the largest one found with negative-strand RNA viruses. The gene order - 3' untranslated region-NP-VP35-VP40-GP-VP30-VP24-L-5' untranslated region-resembles that of other non-segmented negative-strand (NNS) RNA viruses. Six species of polyadenylated subgenomic RNAs, isolated from MBG-infected cells, are complementary to the negative-strand RNA genome. They can be translated in vitro into the known structural proteins NP, GP (non-glycosylated form), VP40, VP35, VP30 and VP24. At the gene boundaries conserved transcriptional start (3'-NNCUNCNUNUAAUU-5') and stop signals (3'-UAAUUCUUUUU-5') are located containing the highly conserved pentamer 3'-UAAUU-5'. Comparison with other NNS RNA viruses shows conservation primarily in the termination signals, whereas the start signals are more variable. The intergenic regions vary in length and nucleotide composition. All genes have relatively long 3' and 5' end non-coding regions. The putative 3' and 5' leader RNA sequences of the MBG genome resemble those of other NNS RNA viruses in length, conservation at the 3' and 5' ends, and in being complementary at their extremities. The data support the concept of a common taxonomic order Mononegavirales comprising the Filoviridae, Paramyxoviridae, and Rhabdoviridae families.

Base Sequence↗