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D M Knipe

Publications and source records attributed to D M Knipe.

89 records · Page 5Linked to original sources
PubMed1983

Mutations in the major DNA-binding protein gene of herpes simplex virus type 1 result in increased levels of viral gene expression.

We have examined the effect of temperature-sensitive mutations in the herpes simplex virus 1 DNA-binding protein gene on viral gene expression. We have found that at the nonpermissive temperature, the synthesis of certain immediate early, early, and late viral polypeptides was greater in cells infected with the temperature-sensitive mutants than in cells infected with the wild-type virus. This effect was independent of the requirement for this viral protein for viral DNA replication. The altered rate of synthesis of viral proteins was due to a thermolabile gene product. Cells infected with these mutants at the permissive temperature and then shifted to the nonpermissive temperature exhibited enhanced levels of viral gene expression. The addition of actinomycin D at the time of the temperature shift prevented the alteration in viral protein synthesis. Therefore, continuing transcription is required for this change in gene expression. Northern blot analysis of cytoplasmic RNA showed that the steady-state level of specific viral transcripts expressed from parental virus genomes was greater in cells infected by these mutants at the nonpermissive temperature. These results indicate that the major DNA-binding protein of herpes simplex virus type 1 acts as a negative regulator of viral gene expression by affecting the abundance of cytoplasmic viral mRNAs.

Animals↗
PubMed1983

Nuclear localization of herpesvirus proteins: potential role for the cellular framework.

Two herpes simplex virus proteins, the major capsid protein and the major DNA binding protein, are specifically localized to the nucleus of infected cells. We have found that the major proportion of these proteins is associated with the detergent-insoluble matrix or cytoskeletal framework of the infected cell from the time of their synthesis until they have matured to their final binding site in the cell nucleus. These results suggest that these two proteins may interact with or bind to the cellular cytoskeleton during or soon after their synthesis and throughout transport into the cell nucleus. In addition, the DNA binding protein remains associated with the nuclear skeleton at times when it is bound to viral DNA. Thus, viral DNA may also be attached to the nuclear framework. We have demonstrated that the DNA binding protein and the capsid protein exchange from the cytoplasmic framework to the nuclear framework, suggesting the direct movement of the proteins from one structure to the other. Inhibition of viral DNA replication enhanced the binding of the DNA binding protein to the cytoskeleton and increased the rate of exchange from the cytoplasmic framework to the nuclear framework, suggesting a functional relationship between these events. Inhibition of viral DNA replication resulted in decreased synthesis and transport of the capsid protein. We have been unable to detect any artificial binding of these proteins to the cytoskeleton when solubilized viral proteins were mixed with a cytoskeletal fraction or a cell monolayer. This suggested that the attachment of these proteins to the cytoskeleton represents the actual state of these proteins within the cell.

Animals↗
PubMed1982

Definition of a series of stages in the association of two herpesviral proteins with the cell nucleus.

We examined the kinetics and the nature of the association of two herpes simplex virus proteins, the major DNA-binding protein (ICP8) and the major capsid protein (ICP5), with the nuclei of infected cells. We defined a series of stages in the association of the ICP8 protein with the cell nucleus. (i) Immediately after synthesis, the protein was found in the cytoplasmic fraction but associated rapidly with the crude nuclear fraction. (ii) The initial association of ICP8 with the crude nuclear fraction was detergent sensitive but DNase resistant, and, thus, the protein was either bound to structures attached to the outside of the nucleus and had not penetrated the nuclear envelope or was loosely bound in the nucleus, (iii) At intermediate times, a low level of an intermediate form was observed in which the association of ICP8 with the nuclear fraction was resistant to both detergent and DNase treatment. The protein may be bound to the nuclear matrix at this stage. Inhibition of viral DNA synthesis caused the DNA-binding protein to accumulate in this form. (iv) At late times during the chase period, the association of ICP8 with the cell nucleus was resistant to detergent treatment but sensitive to DNase treatment. our results argue that at this stage ICP8 was bound to viral DNA. Thus, nuclear association of the DNA-binding protein did not require viral DNA replication. More important is the observation that there is a series of stages in the nuclear association of this protein, and, thus, there may be a succession of binding sites for this protein in the cell during its movement to its final site of action in the nucleus. The major capsid protein showed some similar stages of association with the cell nucleus but the initial association with the nucleus followed a lag period. Its early association with the crude nuclear fraction was also detergent sensitive but was resistant to detergent treatment at later times. Its association with the cell nucleus was almost completely resistant to DNase treatment at all times. Inhibition of viral DNA replication blocked the nuclear transport of this protein. Thus, these two viral proteins share some stages in nuclear transport, although their requirements for nuclear association are different.

Animals↗
PubMed1982

Characterization of two conformational forms of the major DNA-binding protein encoded by herpes simplex virus 1.

We have resolved two electrophoretic species of the major DNA-binding protein, infected cell polypeptide 8 (ICP8), encoded by herpes simplex virus 1. In pulse-chase experiments, we observed the conversion of the ICP8a form, the slower migrating species, to the faster migrating form, ICP8b. Thus, the two species appear to be related as precursor-product. The conversion was not due to proteolytic cleavage, because higher concentrations of reducing agents in the sample buffer shifted the faster moving form to the slower moving species. Also, the two forms have identical peptide patterns as analyzed by partial proteolysis in sodium dodecyl sulfate. Thus, the faster moving species appears to be a conformational isomer containing intramolecular disulfide bonds. The functional significance of the two forms of the protein is discussed.

Amino Acid Sequence↗
PubMed1981

Molecular genetics of herpes simplex virus. VII. Characterization of a temperature-sensitive mutant produced by in vitro mutagenesis and defective in DNA synthesis and accumulation of gamma polypeptides.

We report on the properties of a temperature-sensitive mutant produced by transfection of cells with intact DNA and a specific DNA fragment mutagenized with low levels of hydroxylamine. The plating efficiency of the mutant at 39 degrees C relative to that at 33.5 degrees C was 5 X 10(-6). The pattern of polypeptides produced at the nonpermissive temperature was similar to that seen with wild-type virus in infected cells treated with inhibitory concentrations of phosphonoacetic acid in that alpha and beta polypeptides were produced, whereas most gamma polypeptides were either reduced or absent. Consistently, the mutant did not make viral DNA, although temperature sensitivity of the viral DNA polymerase could not be demonstrated. Marker rescue studies with herpes simplex virus type 2 (HSV-2) DNA mapped the mutant in the L component within map positions 0.385 and 0.402 in the prototype (P) arrangement of the HSV-1 genome. Analysis of the recombinants permitted the mapping of the genes specifying infected cell polypeptides 36, 35, 37, 19.5, 11, 8, 2, 43, and 44, but only the infected cell polypeptide 8 of HSV-2 was consistently made by all recombinants containing demonstrable HSV-2 sequences. Marker rescue studies with cloned HSV-1 DNA fragments mapped the temperature-sensitive lesion within less than 10(3) base pairs between 0.383 and 0.388 map units. Translation of the RNA hybridizing to cloned HSV-1 DNA, encompassing the smallest region containing the mutation, revealed polypeptide 8 (128,000 molecular weight), which was previously identified as a beta polypeptide with high affinity for viral DNA, and a polypeptide (25,000 molecular weight) not previously identified in lysates of labeled cells.

Chromosome Mapping↗
PubMed1981

Molecular genetics of herpes simplex virus. VI. Characterization of a temperature-sensitive mutant defective in the expression of all early viral gene products.

The herpes simplex virus 1 (HFEM) mutant tsB7 failed to express any detectable viral polypeptides and did not significantly inhibit host cell protein synthesis in infected cells maintained at the nonpermissive temperature. The mutant could complement the growth of a coinfecting temperature-sensitive mutant virus differing in plaque phenotype and thus appeared capable of penetrating doubly infected cells. The yield of tsB7 was enhanced by the coinfecting virus but not to the extent that the coinfecting virus was enhanced. Coinfection studies suggested that the tsB7 defect was complemented in trans, but poorly, by the wild-type parent and other viruses. Marker rescue of tsB7 by transfection with herpes simplex virus 2 XbaI DNA fragments mapped the mutation between 0.45 and 0.70 map units. Analysis of the DNA structure of the ts(+) intertypic recombinants generated by this rescue showed that the herpes simplex virus 2 DNA substitutions all contained the region between 0.46 and 0.52 map units, thus further defining the map position of the mutation. Analyses of the polypeptides expressed by these intertypic recombinants defined the genome location of the genes specifying polypeptides 2, 6, 10, 32, 43, and 44 and indicated that the mutation maps in or near genes coding for virion structural polypeptides. This region of the genome is represented as stable transcripts and cytoplasmic mRNA only after viral DNA replication (P. C. Jones and B. Roizman, J. Virol. 31:299-314, 1979), and thus this gene appears to be a late function. These results are consistent with the ts mutation in tsB7 being in a gene coding for a virion component which functions before expression of the alpha genes early in infection. The most likely explanation is that the mutant is blocked at a stage of uncoating and the defect is complemented, although poorly, by a coinfecting virus gene product.

Animals↗
PubMed1979

Molecular genetics of herpes simplex virus: the terminal a sequences of the L and S components are obligatorily identical and constitute a part of a structural gene mapping predominantly in the S component.

In herpes simplex virus 1 (HSV-1) DNA, a small sequence, designated the a sequence, flanks the reiterated sequences at the ends of both the L and S components. The a sequence is the only sequence shared by the termini of all isomeric arrangements of HSV-1 DNA that arise from inversions of the covalently linked L and S components. We report that the a sequence, although present in both components, is a part of a structural gene mapping predominantly in the reiterated sequences of the S component. This conclusion is based on the observations that the mutant HSV-1(13)tsC75 is rescued by transfection of cells with the mutant DNA and any one of the four terminal or four L-S junction fragments of wild-type DNA. Furthermore, in doubly infected cells, this mutant shows little or no recombination or complementation with other ts mutants previously mapped within the reiterated sequences of the S component. Because it is otherwise difficult to explain the isolation of a mutant with several independent, equivalent mutations, the data argue for a mechanism that maintains the identity of the multiple copies of the a sequence.The paradox arising from the two observations that all termini rescue the ts mutant but that in coinfection tests the ts lesion is closely linked to the reiterated sequences of the S component could be accounted for by postulating that either recombination occurs while the DNA is in a circular form-in which case all a sequences would be adjacent to the reiterated sequence of the S component-or recombination can occur while the DNA is in a linear form. In this case the only effective substitution of the a sequence that is perpetuated is the one occurring at the L-S junction or in the S component. In light of the observations that tsC75 and the other mutants tested in this study map in the reiterated sequences and fail to yield appreciable recombinational frequencies, it is unlikely that isomerization of the DNA occurs by intramolecular recombination between reiterated sequences.

Base Sequence↗
PubMed1979

Molecular genetics of herpes simplex virus. II. Mapping of the major viral glycoproteins and of the genetic loci specifying the social behavior of infected cells.

We have mapped the location in herpes simplex virus (HSV) DNA of (i) three mutations at different loci (syn loci) which alter the social behavior of infected cells from clumping of rounded cells to polykaryocytosis, (ii) a mutation which determines the accumulation of one major glycoprotein [VP8.0(C(2))], and (iii) the sequences encoding four major virus glycoproteins [VP8.0(C(2)), VP7(B(2)), VP8.5(A), and VP19E(D(2))]. The experimental design and results were as follows. (i) Analysis of HSV-1 x HSV-2 recombinants showed that the sequences encoding the VP19E(D(2)) glycoprotein map in the S component, whereas the sequences encoding the other three major glycoproteins are in two locations in the L component of HSV DNA. The templates specifying the HSV-1 and HSV-2 glycoprotein VP8.0(C(2)) appear not to be colinear; we isolated recombinants specifying glycoproteins comigrating in sodium dodecyl sulfate-polyacrylamide gels with VP8.0(C(2)) of both HSV-1 and HSV-2. (ii) Marker rescue of a ts mutant defective in accumulation of glycoprotein VP7(B(2)) showed that the mutation maps within a region containing the sequences encoding that glycoprotein. (iii) Marker transfer experiments involving transfection of rabbit skin cells with donor HSV-1(F) DNA and fragments from several donor strains causing fusion of Vero or both Vero and HEp-2 cells revealed the existence of three syn loci specifying the social behavior of cells and one locus (Cr) determining the accumulation of glycoprotein VP8.0(C(2)). The Cr locus maps to the right of the template specifying VP8.0(C(2)) glycoprotein. Loci syn 1 and syn 2 map at or near the Cr locus but can be segregated from it. Locus syn 3 maps at or near the template specifying glycoproteins VP7(B(2)) and VP8.5(A). The expression of mutations in the syn 1 and syn 3 loci appear to be cell type dependent, in that recombinants with these mutations fuse Vero cells but not HEp-2 cells. Recipients of the syn 2 locus or of both syn 2 and syn 1 loci fuse both Vero and HEp-2 cells.

Animals↗
PubMed1979

Molecular genetics of herpes simplex virus. III. Fine mapping of a genetic locus determining resistance to phosphonoacetate by two methods of marker transfer.

We have transferred a genetic locus determining resistance to phosphonoacetic acid (PAAr) from one herpes simplex viral genome to another by two methods of marker transfer. One method requires recombination between an intact DNA molecule and a restriction endonuclease DNA fragment, whereas the other requires repair of a partial heteroduplex formed between the two DNA molecules. These two methods mapped the PAAr locus between positions 0.45 and 0.53 map units on the physical map of the viral DNA. Fine mapping of the PAAr locus showed that it maps at or near an EcoRI restriction endonuclease site at either 0.46 or 0.49 map units. We also describe and compare the two methods of marker transfer.

DNA Restriction Enzymes↗
PubMed1978

Molecular genetics of herpes simplex virus: demonstration of regions of obligatory and nonobligatory identity within diploid regions of the genome by sequence replacement and insertion.

The DNAs of herpes simplex virus (HSV) 1 and 2 consist of two components, L and S, each composed of unique sequences bracketed by inverted repeats. In this study we have probed the structure of the reiterated regions of the S component in marker rescue experiments involving transfection of cells with mixtures of intact HSV-1 mutant viral DNA and individual DNA fragments generated by restriction endonuclease digestion of wild-type HSV-1 or HSV-2 DNAs. The results were as follows: (i) HSV is diploid for the wild-type sequences that rescue two temperature-sensitive (ts) mutants. DNA fragments from both reiterated regions of the S component of HSV-1(F) DNA can rescue tsLB2 and tsD mutants. (ii) Identity of the entire reiterated sequence at both ends of S is not obligatory because only one end of the S component of wild phenotype virus HSV-1(1061) rescues tsD even though both ends rescue tsLB2. (iii) Genes in both reiterated sequences can be expressed. We produced, by marker rescue experiments, recombinants with heterotypic ends of the S component, and these specified corresponding polypeptides characteristic of both HSV-1 and HSV-2. (iv) The reiterated sequences of the S component may contain a region of obligatory identity. Thus, several recombinant clones produced by rescue with HSV-2 DNA contained identical HSV-2 DNA insertions within both reiterated regions of the HSV-1 S component. Consistent with this conclusion, the termini of the S component in the heterodiploids described in iii were identical by restriction enzyme analysis. (v) The observation that HSV DNA can be expanded by at least 5 x 10(6) by means of insertion in the S component suggests that it can be a vehicle for exogenous DNA.

Base Sequence↗
PubMed1977

Membrane assembly: synthesis and intracellular processing of the vesicular stomatitis viral glycoprotein.

The glycoprotein (G) of vesicular stomatitis virus (VSV) is synthesized on membrane-bound polyribosomes. Approximately 30 min after its synthesis, it reaches the surface plasma membrane where it is incorporated into budding virus. The first part of this paper focuses on the 2 intracellular, membrane-bound, glycosylated forms of the glycoprotein which are intermediates in its biogenesis. All glycosylation and processing is completed in the smooth microsome fraction before the protein reaches the surface. Next, we turn to the mechanism by which G is synthesized on membrane-bound polyribosomes. All of the G mRNA is bound to membranes, and studies with puromycin suggest that this attachment of G mRNA is mediated by the nascent glycoprotein chain. After its synthesis G is a transmembrane protein with about 30 amino acids at the carboxyl terminus remaining on the cytoplasmic side of the endoplasmic reticulum. Since 95% of the glycoprotein, containing the carbohydrate residues, is resistant to attack by external proteases, it appears to be within the lumen of the endoplasmic reticulum or embedded within the lipid bilayer. Finally, we show that synthesis, glycosylation, and proper asymmetric insertion of G into the ER can be achieved in cell-free extracts. Both glycosylation of G and proper insertion into the ER membrane in this cell-free system require concomitant protein synthesis.

Cell Line↗
PubMed1977

Localization of two cellular forms of the vesicular stomatitis viral glycoprotein.

Two cell-associated forms of the glycoprotein (G) of vesicular stomatitis virus, termed G1 and G2, have been resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. G1 has the higher electrophoretic mobility, but both forms migrate more slowly than G protein synthesized in a wheat germ cell-free system (G0), which presumably is the unglycosylated form. G1 is a kinetic precursor of the G2 form, and the apparent cause of the electrophoretic difference between the two species is the presence of N-acetylneuraminic acid on the G2 form. Conversion of G1 to G2 occurs 10 to 20 min prior to the appearance of the G2 form of the protein on the cell surface. This suggests that the G protein may be completely glycosylated several minutes prior to its migration to the cell surface and that glycosylation is not the limiting step in its maturation. No glycoprotein comigrating with G0 can be detected in the infected cells, even after 5-min labeling periods; this suggests that partial clycosylation of G occurs concomitantly with or immediately after its synthesis.

Cell Line↗
PubMed1977

Separate pathways of maturation of the major structural proteins of vesicular stomatitis virus.

Cell fractionation and protein electrophoresis were used to study the intracellular sites of synthesis and intermediate structures in the assembly of the virion proteins of vesicular stomatitis virus. Each of the three major virion proteins assembled into virions through a separable pathway. The nucleocapsid (N) protein was first a soluble protein and later incorporated into free, cytoplasmic nucleocapsids. A small amount of N protein was bound to membranes at later times, presumably representing either nucleocapsids in the process of budding or completed virions attached to the cell surface. The matrix (M) protein also appeared to be synthesized as a soluble protein, but was then directly incorporated into membranous structures with the same density as whole virus. Very little M protein was ever found in membranes banding at the density of plasma membranes. The M protein entered extracellular virus very quickly, as though it moved directly from a soluble state into budding virus. In contrast, the glycoprotein (G) was always membrane bound; it appeared to be directly inserted into membranes during its synthesis. Glycosylation of the G protein was completed only in smooth membrane fractions, possibly in the Golgi apparatus. After a minimum time of 15 min following its synthesis, G protein was incorporated into the surface plasma membrane, from which it was slowly shed into virions. These multiple processing steps probably account for its delayed appearance in virus. From this work it appears that the three major structural proteins come into the surface budding structure through independent pathways and together they coalesce at the plasma membrane to form the mature virion.

Cell Fractionation↗
PubMed1977

Maturation of viral proteins in cells infected with temperature-sensitive mutants of vesicular stomatitis virus.

Maturation of viral proteins in cells infected with mutants of vesicular stomatitis virus was studied by surface iodination and cell fractionation. The movement of G, M, and N proteins to the virion bud appeared to be interdependent. Mutations thought to be in G protein prevented its migration to the cell surface, allowed neither M nor N protein to become membrane bound, and blocked formation of viral particles. Mutant G protein appeared not to leave the endoplasmic reticulum at the nonpermissive temperature, but this defect was partially reversible. In cells infected with mutants that caused N protein to be degraded rapidly or prevented its assembly into nucleocapsids, M protein did not bind to membranes and G protein matured to the cell surface, but never entered structures with the density of virions. Mutations causing M protein to be degraded prevented virion formation, and G protein behaved as in cells infected by mutants in N protein. These results are consistent with a model of virion formation involving coalescence of soluble nucleocapsid and soluble M protein with G protein already in the plasma membrane.

Cell Fractionation↗