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W Szer

Publications and source records attributed to W Szer.

At least 19 recordsLinked to original sources
PubMed1997

Identification of N(G)-methylarginine residues in human heterogeneous RNP protein A1: Phe/Gly-Gly-Gly-Arg-Gly-Gly-Gly/Phe is a preferred recognition motif.

Three sites of N(G),N(G)-arginine methylation have been located at residues 205, 217, and 224 in the glycine-rich, COOH-terminal one-third of the HeLa A1 heterogeneous ribonucleoprotein. Together with the previously determined dimethylated arginine at position 193 [Williams et al., (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5666-5670], it is evident that all four sites fall within a span of sequence between residues 190 and 233 that contains multiple Arg-Gly-(Gly) sequences interspersed with phenylalanine residues. These RGG boxes have been postulated to represent an RNA binding motif [Kiledjian and Dreyfuss (1992) EMBO J. 11, 2655-2664]. Dimethylation of HeLa A1 appears to be quantitative at each of the four positions. Arginines 205 and 224 have been methylated in vitro by a nuclear protein arginine methyltransferase using recombinant (unmethylated) A1 as substrate. This suggests A1 may be an in vivo substrate for this enzyme. Examination of sequences surrounding the sites of methylation in A1 along with a compilation from the literature of sites that have been identified in other nuclear RNA binding proteins suggests a methylase-preferred recognition sequence of Phe/Gly-Gly-Gly-Arg-Gly-Gly-Gly/Phe, with the COOH-terminal flanking glycine being obligatory. Taken together with data in the literature, identification of the sites of A1 arginine methylation strongly suggests a role for this modification in modulating the interaction of A1 with nucleic acids.

Amino Acid Sequence↗
PubMed1997

Antibodies to the 45 kDa DEK nuclear antigen in pauciarticular onset juvenile rheumatoid arthritis and iridocyclitis: selective association with MHC gene.

OBJECTIVE: To study the frequency of autoantibodies to the 45 kDa DEK nuclear antigen, a putative oncoprotein, in a sample of patients with juvenile rheumatoid arthritis (JRA), and to make correlations with disease subtype and complications such as iridocyclitis. Class I and Class II HLA associations with reactivity to the antigen were also sought. METHODS: Sera from 146 HLA typed patients with JRA representing all subtypes were analyzed for reactivity with the 45 kDa DEK protein by immunoblotting. The antigen was purified to near homogeneity from nuclei of HeLa cells. RESULTS: Antibodies to DEK were found in 57% of all patients with JRA compared to 3% of controls (p < 0.0001). Antibodies were detected more frequently in pauciarticular onset (78%) than in polyarticular onset patients (29%; p < 0.01) and controls (3%; p < 0.0001). 97% of patients with JRA (regardless of onset subtype) and iridocyclitis had anti-DEK antibodies compared to 47% of patients without eye disease (p < 0.0001). Anti-DEK antibodies were found more frequently in females compared to males in the pauciarticular onset disease group (84 vs 42%; p < 0.01). The occurrence of anti-DEK antibodies was closely associated with positive antinuclear antibody serology, and a strong association with the Class I gene HLA-A2 was also observed. CONCLUSION: Antibodies to the 45 kDa DEK protein are characteristic of the pauciarticular onset subtype of JRA, particularly in patients with a history of iridocyclitis. The occurrence of anti-DEK antibodies is significantly but paradoxically associated with the presence of the HLA-A2 allele in such patients.

Adolescent↗
PubMed1994

A novel autoantibody to the putative oncoprotein DEK in pauciarticular onset juvenile rheumatoid arthritis.

OBJECTIVE: To define the frequency of a novel autoantibody reactive with a 45 kDa protein in children with juvenile rheumatoid arthritis (JRA). This protein is expressed by the putative oncogene DEK associated with a subtype of acute myeloid leukemia. METHODS: The sera of 158 children with JRA were analyzed for the presence of anti-DEK by immunoblotting using purified DEK protein and compared with sera of 109 children with other rheumatic diseases and 25 healthy controls with no connective tissue disease. RESULTS: Antibodies to DEK were found significantly more frequently among children with JRA than among children with other rheumatic diseases or controls (p < 0.001). Among children with JRA, anti-DEK was significantly more often associated with pauciarticular onset than with poly-articular and systemic onset subtypes (77 vs 29 and 8%, respectively, p < 0.001). Anti-DEK was no more frequent among children with pauciarticular JRA complicated by iritis than among those without iritis (88 vs 71%, respectively). The frequency of anti-DEK in other rheumatic diseases varied from 0 in children with spondyloarthritis to 31% in scleroderma. CONCLUSION: Antibodies to DEK are highly associated with pauciarticular onset JRA.

Adolescent↗
PubMed1993

The putative oncoprotein DEK, part of a chimera protein associated with acute myeloid leukaemia, is an autoantigen in juvenile rheumatoid arthritis.

The 45-kD autoantigen associated with juvenile rheumatoid arthritis (JRA) has been isolated from HeLa cell nuclei and purified about 2500-fold to near homogeneity in a five-step chromatographic procedure. Purification of the antigen was monitored by immunoblot assays using a nearly monospecific anti-45-kD serum from a child with JRA. Tryptic peptide mapping and partial amino acid sequencing of the purified 45-kD antigen demonstrated its identity with the DEK protein. DEK is a 43-kD protein of unknown function expressed by the putative oncogene dek located on chromosome 6. As a result of a (6;9) translocation offociated with a rare subtype of acute myeloid leukaemia a chimeric protein containing most of DEK amino acids at the N-terminus is found in leukaemic cells (von Linden et al., Mol Cell Biol. 1992; 12: 1687-97). The 43-kD DEK was detected by immunoblotting with serum from a patient with JRA in a variety of rat tissues, and was most abundant in the spleen and in bone marrow.

Amino Acid Sequence↗
PubMed1991

Cloning and sequence analysis of a human type A/B hnRNP protein.

A cDNA encoding a 284 residue long type A/B hnRNP protein has been cloned. This protein, previously referred to as type C [(1987) J. Biol. Chem. 262, 17126-17137], is an RNA unwinding protein from HeLa 40S hnRNP with a high affinity for G- followed by U-rich sequences. The N-terminal part of the protein contains two consensus RNA binding domains present in a number of other RNA binding proteins. The C-terminal part is glycine-rich and contains a potential ATP/GTP binding loop. The distribution of charged amino acids is highly uneven and there are multiple potential phosphorylation sites.

Amino Acid Sequence↗
PubMed1991

Autoantibodies to DNA topoisomerase II in juvenile rheumatoid arthritis.

Sera from 58 children with juvenile rheumatoid arthritis were examined for the presence of antibodies to DNA topoisomerase II. Eight sera were reactive in immunoblotting with purified human topoisomerase II and a protein encoded by a cloned cDNA expressed in Escherichia coli which represents the carboxy-terminal domain of the human enzyme. In addition, the sera detect topoisomerase II in mitotic chromosomes and chromosome scaffolds. Five of the sera bind to the native enzyme in solution and deplete such solutions of the active enzyme. All eight sera also contain antibodies to nuclear antigens other than topoisomerase II.

Adolescent↗
PubMed1991

Antinuclear antibody profile in juvenile rheumatoid arthritis.

Immunoblot positive sera from children with juvenile rheumatoid arthritis detected from 1 to greater than or equal to 10 proteins in HeLa nuclear sonicates. Thirty percent of the sera reacted with histone H1. Antibodies to at least 1 of 6 most frequently detected nonhistone proteins were present in 85% of the sera. Using immunopurified antibodies to each of the 6 common antigens, we found that 4 of them were associated with mitotic chromosomes. Most sera detected at least 1 of these 4 nonhistone chromosomal proteins. Fifteen percent of the sera immunoprecipitated ribonucleoproteins; some exhibited a novel specificity, precipitating mature transcripts of RNA polymerase III. When present, antibodies to a 45 kDa protein occur only in sera from children without iritis and not in those with active iritis. Overall, the antibody profiles were highly individual and did not appear to correlate with disease subtype or activity.

Adolescent↗
PubMed1987

Purification and RNA binding properties of a C-type hnRNP protein from HeLa cells.

A protein of the C group, most likely C3 (Mr approximately 42,000, pI approximately 6, corresponding to IEF 48m,n of the HeLa protein catalogue (Celis, J. E., Bravo, R., Arenstorf, H. P., and LeStourgeon, W. M. (1986) FEBS Lett. 194, 101-109)), a minor hnRNP protein was purified to near homogeneity under nondenaturing conditions from 40 S heterogeneous nuclear ribonucleoprotein particles. Type C protein stoichiometrically disrupts the residual secondary structure of natural and synthetic RNAs, e.g. HeLa hnRNA, coliphage MS2 RNA, and poly(rU)-spermine, and decreases the Tm of duplex structures, e.g. poly[r(A + U)], by about 30 degrees C. Binding of the protein to polynucleotides is not highly cooperative and has a stoichiometry of one protein per about 10 nucleotides. Binding experiments with a variety of synthetic and natural poly- and oligonucleotides, including those containing consensus splice site sequences, indicate that the protein has a high affinity for G-rich and U-rich regions, G-rich regions being preferred. Base analogs I and T have affinities for the protein that are similar to G and U. There is little or no affinity for A- and C-rich regions. The presence of A residues in a G- or U-rich sequence does not interfere with binding while C-rich regions decrease or prevent the binding of the protein. The nucleotide specificity of type C protein, e.g. selective binding to an oligonucleotide from the 3' end of an intron, is discussed in relationship to the abundance of G and U and the relative scarcity of C residues in the processing signals in pre-mRNA.

Circular Dichroism↗
PubMed1986

Purification and domain structure of core hnRNP proteins A1 and A2 and their relationship to single-stranded DNA-binding proteins.

Protein A1 (Mr approximately 32,000), a major glycine-rich protein of heterogeneous nuclear ribonucleoproteins (hnRNP), was purified to near homogeneity under nondenaturing conditions from HeLa cells. Limited proteolysis of the native protein yields a trypsin-resistant N-terminal nucleic acid-binding domain about 195 amino acids long which has a primary structure nearly identical to that of the 195-amino acid-long single-stranded DNA (ssDNA)-binding protein UP1 (Mr 22,162) from calf thymus (Williams, K.R., Stone, K. L., LoPresti, M.B., Merrill, B. M., and Planck, S.R. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5666-5670). 45 of the 61 glycine residues of A1 are present in the trypsin-sensitive C-terminal domain of the protein which contains no sequences homologous to UP1. Protein A2, another major glycine-rich core hnRNP protein from HeLa, has a domain structure analogous to A1 and appears to be related to ssDNA-binding proteins UP1-B from calf liver and HDP-1 from mouse myeloma in a way similar to the A1/UP1 relationship. In contrast to ssDNA-binding proteins, A1 binds preferentially to RNA over ssDNA and exhibits no helix-destabilizing activity.

Amino Acid Sequence↗
PubMed1986

Antibodies to hnRNP core proteins inhibit in vitro splicing of human beta-globin pre-mRNA.

In vitro splicing of human beta-globin pre-mRNA can be fully inhibited by treatment of the splicing extract with polyclonal antibodies against hnRNP core proteins prior to the addition of pre-mRNA. Inhibition of the first step in the splicing pathway, cleavage at the 5' splice site and lariat formation, requires more antibodies than inhibition of the second step, cleavage at the 3' splice site and exon ligation. The anti-hnRNP antibodies can also inhibit the splicing reaction after the formation of the active nucleoprotein splicing complex which is known to occur during the initial lag period. Thus, hnRNP core proteins appear to be present in the complex that performs pre-mRNA splicing.

Antibody Specificity↗
PubMed1985

Cloning of cDNA sequences for an Artemia salina hnRNP protein: evidence for conservation through evolution.

A cDNA clone was isolated for Artemia salina protein HD40, a component of heterogenous nuclear ribonucleoproteins. Enriched Artemia 15S poly(A)+ RNA was used as a template and double-stranded cDNA sequences were inserted into the Pst I restriction endonuclease site of E. coli plasmid pBR322. Recombinant colonies were analyzed by positive hybrid selection of poly(A)+ RNA that directs the synthesis of protein HD40 in an in vitro assay. In vitro translation of the mRNA selected by recombinant clone 87HD yields a protein that is immunoprecipitated by anti-HD40 antibodies and that comigrates with authentic HD40 on gel electrophoresis. Partial proteolysis of protein HD40 and the in vitro translated product selected by clone 87HD produces the same peptide patterns. The size of the cloned insert is about 820 bp. The length of HD40 mRNA as determined by Northern blot analysis, is about 1500 nucleotides. Southern blot analysis performed with DNA of different species (plant, avian, mammal) shows cross-hybridizing bands when probed with clone 87HD DNA suggesting that the HD40 gene is evolutionarily conserved.

Animals↗
PubMed1984

Isolation of a minor species of actin from the nuclei of Acanthamoeba castellanii.

Actin was extracted from isolated nuclei of Acanthamoeba castellanii and purified to homogeneity under nondenaturing conditions by diethylaminoethylcellulose and Sephadex G-100 chromatography. The pure protein has the same molecular weight as cytoplasmic Acanthamoeba actin and a very similar amino acid composition. Isoelectrofocusing shows that nuclear actin is slightly more acidic than the major cytoplasmic species, and comparative analysis of peptides from tryptic and cyanogen bromide digests shows that both actins are very similar but not chemically identical. In an assay that is specific for most actins, the inhibition of DNase I through the formation of a 1:1 G-actin-DNase I complex, the nuclear and cytoplasmic actins are equally effective. By use of a similar procedure for the purification of both actins, it is estimated that the amount of nuclear actin is about 1.5% of the amount of cytoplasmic actin, a major protein of the amoeba. It is concluded that a minor isoelectric species of actin associates selectively with the nuclei of A. castellanii.

Actins↗
PubMed1984

Model investigations on the structure of heterogeneous nuclear ribonucleoproteins.

Protein HD40 , an RNA-helix destabilizing protein (Mr 40 000) is the major component of 30S heterogeneous nuclear ribonucleoprotein particles (hnRNP) from Artemia salina. The physical properties and the amino acid composition of HD40 are analogous to those of a group of well conserved core hnRNP proteins of higher eukaryotes. HD40 binds to and disrupts the secondary structure of single-stranded polynucleotides and forms extended nucleoprotein filaments at a stoichiometry of one protein per 12-15 nucleotides. The addition of a saturating amount of HD40 (one protein per 8 nucleotides) converts the filaments into bead-like complexes that are similar in properties and appearance to native hnRNP. To gain an understanding of the structure of hnRNP, we have used analytical ultracentrifugation and electron microscopy to investigate the structure of beaded complexes reconstituted from HD40 and poly(A)n of defined sizes. A complex containing 160 nucleotides forms a disc that is 3 nm high by 18 nm in diameter. At n less than 160 the complexes form sectors of the disc: 40 nucleotides give rise to a quarter of a disc, 80 nucleotides, half a disc, etc. At n greater than 160, the additional nucleoprotein elements may either initiate the formation of a second disc adjacent to the first or stack on top of the first disc to form a 6 nm high helix with a diameter of 18 nm. A single "bead" sediments at approximately 30S and contains an average of approximately 300 nucleotides and 1.8 turns of the helix. Native hnRNP particles from A. salina sediment at about 30S, have a diameter of 18-20 nm, and contain RNA fragments 180 to 400 nucleotides long.

Animals↗
PubMed1983

Structure of complexes between a major protein of heterogeneous nuclear ribonucleoprotein particles and polyribonucleotides.

We have investigated the structure of complexes formed between a series of poly(A)n (n = 30 to 480) and HD40 (helix-destabilizing protein, molecular weight of 40,000), the major protein component of 30 S heterogeneous nuclear ribonucleoprotein particles (hnRNP) from the brine shrimp Artemia salina. Protein HD40 is similar to corresponding hnRNP proteins from higher eukaryotes and the complexes it forms with single-stranded nucleic acids are strikingly similar to the native "beads-on-a-string" structure of hnRNP. Using analytical ultracentrifugation and electron microscopy we find: (1) complexes formed between HD40 and long ribohomopolymers also have a beads-on-a-string structure, showing that the ability to form this structure is an inherent property of HD40, and is not dependent on any structural features of natural RNA; (2) complexes between HD40 and poly(A)160 form disks that are about 3 nm high by 18 nm in diameter and contain 20 HD40 molecules; (3) complexes of HD40 with poly(A)n with fewer than 160 nucleotides form sectors of a disk: 40 nucleotides give rise to a quarter of a disk, 80 nucleotides, half a disk, etc. The molecular weights increase with the size of poly(A)n at the rate of 5300 per nucleotide, a stoichiometry of eight nucleotides per HD40; (4) as the size of the poly(A)n increases beyond 160 nucleotides, the additional nucleoprotein elements may either initiate the formation of a second disk adjacent to the first or stack on top of the first disk to form a 6 nm high helix with a diameter of 18 nm. Based on these results, we propose that the existence of lateral protein-protein interactions that produce the basic 3 nm X 18 nm disk, combined with the marginal stability of the helix result in (a) interruptions of the helix that give rise to the beads-on-a-string appearance of the complexes, and (b) inherent heterogeneity of individual "beads" which may contain one or more turns of the helix. From measurements of HD40 complexes with coliphage MS2 RNA, phi X174 viral DNA as well as with the homopolymers, a bead is estimated to contain an average of approximately 300 nucleotides; approximately 1 X 8 turns of the helix.

Animals↗
PubMed1983

The effects of bisulfite on growth and macromolecular synthesis in Escherichia coli.

Bisulfite reversibly inhibits the growth of a variety of microorganisms and has been used as a preservative in foods and beverages for that reason. We have now measured macromolecule synthesis in Escherichia coli K12 after bisulfite treatment. RNA synthesis, the synthesis of total protein, and of an inducible enzyme, beta-galactosidase, stopped almost immediately upon addition of 2 mM (or higher concentrations) of bisulfite. These functions resumed after a lag whose duration depended on the concentration of bisulfite added. The synthesis of DNA was slowed upon bisulfite addition, but did not stop entirely. The inhibition of RNA synthesis by bisulfite took place in both stringent and relaxed strains of E. coli and was not relieved upon addition of chloramphenicol. Stringent control was therefore not involved in this effect. No effect on protein synthesis was observed in the cell-free system of E. coli (using poly(U) or MS2 RNA as messenger) at bisulfite concentrations up to 10 mM. Protein synthesis inhibition in vivo was apparently not due to a reaction of bisulfite with a component of this system. In additional experiments, RNA polymerase was not impaired by bisulfite, and the growth inhibition effect was shown to proceed in the presence of inhibitors of free radical chain reactions.

Escherichia coli↗
PubMed1983

Reversal of growth inhibition in Escherichia coli by bisulfite.

Bisulfite inhibits growth, protein synthesis and RNA synthesis in micro-organisms. These inhibitory effects, in Escherichia coli K12, were diminished when certain amino acids were added to the minimal growth medium. The effects of individual amino acids were additive, synergistic and independent of their concentration. At 10 or 5 mM bisulfite, the presence of tyrosine had the greatest importance, while phenylalanine, glycine and methionine played a lesser role. E. coli cultures resume growth subsequent to bisulfite inhibition, after a lag whose duration is proportional to the initial concentration of added bisulfite. This resumption of growth was shown not to result from the depletion of bisulfite (by air oxidation or metabolism), but rather to adaptation to the presence of bisulfite concentrations that previously were inhibitory. The inhibitory effects of bisulfite were duplicated by lesser concentrations of cysteine. Both substances inhibited RNA synthesis by a mechanism that was independent of the stringent control system. A sulfite reductase deficient mutant was more resistant to inhibition by both bisulfite and cysteine. The various results indicate that growth inhibition by bisulfite is not due to covalent reactions with cellular target molecules, but to conversion of bisulfite to other substances, probably including cysteine, which in turn inhibit bacterial growth.

Amino Acids↗
PubMed1982

Nucleic acid binding properties of major proteins from the heterogeneous nuclear ribonucleoproteins of wheat.

Glycine-rich core hnRNP proteins purified from wheat bind tightly to single-stranded but not to double-stranded nucleic acids with a preference for natural RNA over single-stranded DNA. Binding results in i) a progressive disruption of the residual secondary structure of the polynucleotide and the formation of an extended nucleoprotein filament until a protein to polynucleotide weight ratio of about 5:1 is attained. As more protein is added, this is followed by ii) the formation of globular structures along the polynucleotide chain with a concomitant reduction in the contour length of the nucleoprotein complex. These two features of the interaction--unwinding and condensation into beads--are analogous to the previously described behavior of the major glycine-rich core hnRNP protein from Artemia salina (Thomas et al. (1981) Proc. Natl. Acad. Sci. USA 78, 2888) and may represent the basic functional properties of this relatively well conserved group of nuclear proteins.

Circular Dichroism↗