Glycosylation of VSV glycoprotein is similar in cystic fibrosis,heterozygous carrier,and normal human fibroblasts

The single envelope glycoprotein of vesicular stomatitis virus was used as a specific probe of glycosyltransferase activities in fibroblasts from two cystic fibrosis patients, an obligate heterozygous carrier and a normal individual. Gel filtration of pronasedigested glycopeptides from both purified virions and infected cell-associated VSV glycoprotein which had been labeled with [³H] glucosamine did not reveal any significant differences in the glycosylation patterns between the different cell cultures. All 4 cell lines were apparently able to synthesize the mannose- and glucosamine-containing core structure and branch chains terminating in sialic acid which are characteristic of asparagine-linked carbohydrate side chains in cellular glycoproteins. Analysis of tryptic glycopeptides by anion-exchange chromotography indicated that the same 2 major sites on the virus polypeptide were recognized and glycosylated in all 4 VSV-infected cell cultures. These studies suggest that the basic biochemical defect(s) in cystic fibrosis is not an absence or deficiency in enzymes responsible for the biosynthesis of complex carbohydrate side chains.     

Specific changes in the oligosaccharide moieties of VSV grown in different lectin-resistnat CHO cells.

The carbohydrate moieties of the G glycoprotein of vesicular stomatitis virus (VSV) grown in three distinct lectin-resistant (LecR) Chinese hamster ovary (CHO) cell lines have been compared by fine structural analysis of radiolabeled glycopeptides. The mutant WgaRIII, selected for resistance to wheat germ agglutinin (WGA), produces VSV containing G glycoprotein specifically lacking in sialic acid. The mutant PhaRI, selected for resistance to phytohemagglutinin (PHA) and previously shown to lack a particular glycoprotein N-acetyl-glucosaminyl-transferase activity, produces VSV containing G glycoprotein specifically lacking terminal N-acetylglucosamine-galactose-sialic acid sequences and possessing an increased number of mannose residues in the "core" region of its carbohydrate moieties. The mutant PhaRIConARII, a "double" mutant selected from PhaRI cells for resistance to concanavalin A (ConA), produces VSV containing G glycoprotein with a further alteration in the mannose residues of the "core" oligosaccharide region. We discuss the relevance of these findings to the mechanisms of glycoprotein biosynthesis in mammalian cells and to the biochemical bases of lectin resistance in CHO cells.     

Three different frameshift mutations of the tyrosinase gene in type IA oculocutaneous albinism.

Mutations in the gene for the pigment-producing enzyme tyrosinase are responsible for type IA (tyrosinase-negative) oculocutaneous albinism (OCA). Most reported mutations have been single base substitutions. We now report three different frameshift mutations in three unrelated individuals with type IA OCA. The first individual has a single base deletion within a series of five guanidines, resulting in a premature stop codon in exon I on one allele and a missense mutation at codon 382 in exon III on the homologous allele. The second individual is a genetic compound of two separate frameshift mutations, including both the same exon I single base deletion found in the first individual and a deletion of a thymidine-guanidine pair, within the sequence GTGTG, forming a termination codon (TAG) in exon I on the homologous allele. The third individual has a single base insertion in exon I on one allele and a missense mutation at codon 373 in exon III on the homologous allele. The two missense mutations occur within the copper Bbinding region and may interfere with either copper binding to the enzyme or oxygen binding to the copper. These five different mutations disrupt tyrosinase function and are associated with a total lack of melanin biosynthesis.     

Zinc finger motif for single-stranded nucleic acids? investigations by nuclear magnetic resonance

Nuclear magnetic resonance (NMR) methods have been used to address issues regarding the relevance and feasibility of zinc binding to "zinc finger-like" sequences of the type C-X2-C-X4-H-X4-C [referred to as CCHC or retroviral-type (RT) zinc finger sequences]. One-dimensional (1D) NMR experiments with an 18-residue synthetic peptide containing the amino acid sequence of an HIV-1 RT-zinc finger domain (HIV1-F1) indicate that the sequences are capable of binding zinc tightly and stoichiometrically. 1H-113Cd spin echo difference NMR data confirm that the Cys and His amino acids are coordinated to metal in the 113Cd adduct. The 3D structure of the zinc adduct [Zn(HIV1-F1)] was determined to high atomic resolution by a new NMR-based approach that utilizes 2D-NOESY back-calculations as a measure of the consistency between the structures and the experimental data. Several interesting structural features were observed, including (1) the presence of extensive internal hydrogen bonding, and (2) the similarity of the folding of the first six residues to the folding observed by X-ray crystallography for related residues in the iron domain of rubredoxin. Structural constraints associated with conservatively substituted glycines provide further rationale for the physiological relevance of the zinc adduct. Similar NMR and structural results have been obtained for the second HIV-1 RT-zinc finger peptide, Zn(HIV1-F2). NMR studies of the zinc adduct with the NCP isolated directly from HIV-1 particles provide solid evidence that zinc finger domains are formed that are conformationally similar (if not identical) to the peptide structures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Physical Maps of Autographa californica and Rachiplusia ou Nuclear Polyhedrosis Virus Recombinants

TN-368 cells were infected simultaneously with the closely related Autographa california (AcMNPV) and Rachiplusia ou (RoMNPV) nuclear polyhedrosis viruses. Progeny viral isolates were plaque purified, and their DNAs were analyzed with restriction endonucleases. Of 100 randomly cloned plaques, 7 were AcMNPV and RoMNPV recombinants, 5 were RoMNPV, and 88 were AcMNPV. The recombinants contained DNA sequences derived from both parental genomes. By comparing the restriction cleavage patterns of parental and recombinant DNAs, the crossover sites were mapped. A single double crossover was detected in each of the seven recombinant genomes. In addition, six of the seven recombinants revealed a crossover site mapping between 78 and 89% of the genome. The structural polypeptides of the seven recombinants and two parental viruses were analyzed by polyacrylamide gel electrophoresis, and their polyhedrins were identified by tryptic peptide mapping. An analysis of the segregation of three enveloped nucleocapsid proteins and of the polyhedrins among the recombinants located the DNA sequences coding for AcMNPV structural polypeptides with molecular weights of 37,000 (a capsid polypeptide), 56,000, and 90,000 and the RoMNPV structural polypeptides with molecular weights of 36,000 (a capsid polypeptide), 56,000, and 91,000. The AcMNPV and RoMNPV polypeptides of molecular weights 37,000 and 36,000, respectively, mapped within 78 to 89% or 1 to 29%, the polypeptides of molecular weights 55,000 and 56,000 mapped within 78 to 29%, and the polypeptides of molecular weights 90,000 and 91,000 mapped within 19 to 56% of the genome. The region of the parental DNAs that codes for polyhedrin was located within 70 to 89% of the genome.     

Inhibition of Epstein-Barr virus DNA synthesis and late gene expression by phosphonoacetic acid.

Growth of lymphoblastoid cells (B95-8, Raji) is not inhibited by the presence of 0.4 mM phosphonoacetic acid. The synthesis of Epstein-Barr virus (EBV) in the producer line B95-8 is completely inhibited, as shown by the total inhibition of viral capsid antigen synthesis. Early viral antigens are made normally in the presence of phosphonoacetic acid, but EBV DNA synthesis is blocked in cells entering the productive cycle. Nonproducer cells in the population replicate the resident EBV DNA by a mechanism that is resistant to phosphonoacetic acid. These results are consistant with the hypotheses that EBV DNA is replicated by two mechanisms, one in the noninduced cell and a different mechanism in the producer cell, and that prior replication of EBV DNA, probably by the second mode, is a prerequisite for late gene expression.