Search PubMed⌕ Search

Biomedical subjects

K Shimotohno

Publications and source records attributed to K Shimotohno.

At least 235 records · Page 13Linked to original sources
PubMed1984

Nucleotide sequence analysis of the long terminal repeat of human T-cell leukemia virus type II.

The nucleotide sequence of the human T-cell leukemia virus type II (HTLV-II) long terminal repeat (LTR) and its surrounding regions were determined. Our results show the following structural features: (i) the LTR is 763 base pairs (bp) in length and consists of 314 +/- 1 bp of region U3, 248 +/- 1 bp of region R, and 201 bp of region U5; (ii) the terminal nucleotides in the LTR form an inverted repeat of T-G.....C-A; (iii) 6-bp direct repeats of cellular sequences flanking the provirus were present; and (iv) the putative functional signals for initiation or termination of viral RNA synthesis were identified. Comparison of the HTLV-II LTR sequence with that previously published for adult T-cell leukemia virus (ATLV; HTLV-I) shows that the LTRs are distinct. Some small regions are conserved between HTLV-II and ATLV, involving sequences important for transcription and a sequence of 21 nucleotides repeated three times in U3. This 21-bp repeat may be important in regulating viral transcription in lymphoid cells.

Base Sequence↗
PubMed1984

Detection of pX proteins in human T-cell leukemia virus (HTLV)-infected cells by using antibody against peptide deduced from sequences of X-IV DNA of HTLV-I and Xc DNA of HTLV-II proviruses.

A 41-kilodalton protein was detected in four human T-cell leukemia virus type I (HTLV-I)-infected cell lines, a 68-kilodalton glycoprotein in MT-2 cells, and a 38-kilodalton protein in an HTLV-II-infected cell line by using antibody against a synthetic dodecapeptide, a portion of the polypeptide deduced from the nucleotide sequence of the X regions of HTLVs.

Animals↗
PubMed1984

Structural and antigenic characterization of the proteins of human T-cell leukemia viruses and their relationships to the gene products of other retroviruses.

The primary structure analysis of the gag gene products of human T-cell leukemia virus (HTLV)-ICR has been nearly completed. A comparison of the amino acid sequences with the published nucleotide sequence of HTLV-IATK established that i) p19 which is known to share antigenic determinants with a protein present in normal thymic epithelium, is nevertheless virally coded. ii) The gene order and complete primary structure of the gag precursor (Pr55) which has been shown to be myristylated (My) at its N-terminus is My-p19-p24-p15-OH; and iii) the Pr55gag amino acid sequences of HTLV-ICR and HTLV-IATK are nearly identical showing only a single residue difference in the C-terminal region of p15. Antibodies to synthetic peptides inferred from the nucleotide sequence of the env gene of HTLV-IATK were also raised and used to identify and purify env precursor gPr62-68, surface glycoprotein gp46-51 and transmembrane protein p21. While most of the peptide sera were shown to be subgroup specific some of them detected antigenic determinants shared between protein homologs of viruses of subgroups I and II. Partial or complete amino acid sequences of both the gag and env gene coded proteins of bovine leukemia virus (BLV) structural proteins have also been determined. These extensive protein data together with nucleotide sequences confirm and extend our initial finding that HTLV and BLV are structurally and antigenically related and may have originated from common ancestor. The structural and immunological studies revealed also relationships between HTLV and a number of type C and type D retroviruses studied. One of the highly conserved sequences is shared by the transmembrane proteins of these retroviruses which have been implicated in immunosuppression. It is conceivable that these common regions have common biological function. Two previously unidentified proteins of BLV have also been purified and structurally characterized. Nucleotide sequences capable of coding for related products are present in HTLV. The nature and possible biological functions of these new BLV proteins and the putative HTLV gene products will be discussed. The size and complexity of the genome of the replication competent retroviruses are similar but not identical. The 35S RNA of all replication competent helper viruses is divided into three genes encoding the viral structural proteins: the gag (group-specific antigen) gene codes for the internal structural proteins, the pol (polymerase) gene codes for the enzymes protease, reverse transcriptase and endonuclease and the env (envelope) gene codes for the proteins of the viral envelope.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1984

Nucleotide sequence analysis of human T-cell leukemia virus type II.

The total nucleotide sequence of an infectious clone of human T-cell leukemia virus type II (HTLV-II) provirus was determined. The provirus has 8,952 nucleotides with a long terminal repeat (LTR) at each end. The LTR consists of 341 +/- 1 bases of U3, 248 +/- 1 bases of R, and 201 bases of U5 regions. There are gag, pol, and env coding frames in this order from the 5' end of the provirus as in other avian or mammalian retroviruses. A coding frame that can code 178 amino acid residues found between gag and pol is supposed to be for a protease that hydrolyses a gag precursor protein to matured gag proteins. The gag and protease genes and the pol and env genes, respectively, partly overlap. In the region termed X between env and 3' LTR, there are three major open reading frames. Oligopeptides deduced from the sequence of one of the open reading frame in HTLV-I were synthesized chemically, and antibodies against these peptides were raised in rabbits. With these antibodies, 41 kdalton and 38 kdalton proteins were detected in cells infected with HTLV-I and HTLV-II, respectively.

Base Sequence↗
PubMed1984

The comparative molecular biology of HTLV-I and HTLV-II.

The human T-cell leukemia viruses (HTLV) I and II, have been implicated in naturally occurring T-cell malignancies in man. We are engaged in ongoing comparative studies of HTLV-I and HTLV-II in our laboratory. We have isolated a replication-competent clone of HTLV-II, as well as several defective HTLV-II proviruses from the Mo-T hairy-cell leukemia line. HTLV-II is able to transform normal T-lymphocytes, and can replicate in both T- and B-cell lines. We have devised a convenient system allowing direct transfection of the HTLV-II genome into a B-cell line, followed by selection of HTLV-infected cells. Transfection studies with HTLV-II indicate that the virus can replicate in lymphoid cells, but not in fibroblasts. Transfection of recombinant constructs demonstrates that the viral long terminal repeat (LTR) can function as a promoter in lymphoid cells, but not in fibroblasts, suggesting a role for the viral LTR in conferring target cell specificity. Structural similarities between the HTLV-I and HTLV-II LTRs, including the presence of similar repeated base sequences in the U3 region, may account for this LTR specificity. The X region of HTLV-II has been sequenced and compared to that of HTLV-I. We have identified an mRNA species encoded by the major open reading frames in the X region of HTLV-I and HTLV-II and have located the splice acceptor site. Using antisera generated to short peptide sequences encoded by X, we have identified specific X-encoded viral proteins in HTLV infected cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Transformation, Neoplastic↗
PubMed1982

Spontaneous variation and synthesis in the U3 region of the long terminal repeat of an avian retrovirus.

Recombinant DNA clones of a viral clone of spleen necrosis virus, an avian retrovirus, were found to have long terminal repeats of different sizes. The variation was in the U3 region of the long terminal repeats, and any one clone had U3 of the same size in both long terminal repeats. The U3 regions in the 5' and 3' long terminal repeat were shown both to be derived from the 3' long terminal repeat of parental virus DNA.

Alpharetrovirus↗
PubMed1981

Formation of infectious progeny virus after insertion of herpes simplex thymidine kinase gene into DNA of an avian retrovirus.

We have prepared several infectious stocks of an avian retrovirus, spleen necrosis virus, containing the herpes simplex virus type 1 thymidine kinase (tk) gene. The viruses were produced after cotransfection of chicken cells with DNA from recombinants between cloned spleen necrosis virus and tk DNAs and DNA of cloned reticuloendotheliosis virus strain A. removal of sequences in the tk gene for the end of tk mRNA increased a thousand fold the yield of infectious recombinant virus. Infection of chicken or rat tk- cells with the recombinant virus transformed them to a tk+ phenotype.

Animals↗
PubMed1980

Sequence of retrovirus provirus resembles that of bacterial transposable elements.

The nucleotide sequences of the terminal regions of an infectious integrated retrovirus cloned in the modified lambda phage cloning vector Charon 4A have been elucidated. There is a 569-base pair direct repeat at both ends of the viral DNA. The cell-virus junctions at each end consist of a 5-base pair direct repeat of cell DNA next to a 3-base pair inverted repeat of viral DNA. This structure resembles that of a transposable element and is consistent with the protovirus hypothesis that retroviruses evolved from the cell genome.

Base Sequence↗
PubMed1980

No apparent nucleotide sequence specificity in cellular DNA juxtaposed to retrovirus proviruses.

The sequences of the virus-cell junctions of seven DNA clones of spleen necrosis virus provirus were analyzed to determine the nucleotide sequence specificity of the cellular integration sites. As previously reported for one provirus, all clones contain a 5-base-pair direct repeat of cellular DNA at the cell-virus junctions and a 3-base-pair inverted repeat at both ends of the provirus DNA. The sequences of the 5-base-pair direct repeats are different in each clone and have no apparent homology to viral DNA. No apparent common features and no sequences significantly homologous to the ends of the provirus DNA were found in the cellular DNAs surrounding the viral integration sites.

Animals↗
PubMed1977

Importance of 5'-terminal blocking structure to stabilize mRNA in eukaryotic protein synthesis.

The 7-methylguanylic acid residue confronting the 5'-terminal nucleotide of mRNA through two pyrophosphate linkages was completely removed by tobacco pyrophosphatase from mRNAs of cytoplasmic polyhedrosis virus, tobacco mosaic virus (viral RNA), and globin without any scission in the inner part of the RNA chain. Protein synthesis ability in a wheat germ cell-free system was lost after this treatment of all three kinds of mRNA. The initiation complexes for protein synthesis of these three RNAs were not obtained after using tobacco phosphodiesterase-treated mRNA. On incubation of mRNA in a wheat germ extract, the mRNA lacking m7G was quickly degraded from the 5' terminus in an exonucleolytic way, whereas the intact mRNA remained stable. These results show that one of the confronting nucleotide structure's functions is to stabilize the mRNA, to prevent its degradation.

Animals↗
PubMed1977

Nucleoside triphosphate phosphohydrolase associated with cytoplasmic polyhedrosis virus.

Nucleoside triphosphate phosphohydrolase [EC 3.6.1.15] activity was found to be included in silkworm cytoplasmic polyhedrosis (CP) virus, which synthesizes mRNA carrying the 5'-terminal modification. This enzyme releases orthophosphate from the gamma-position in a nucleoside triphosphate, leaving nucleoside diphosphate. The rate of hydrolysis of ATP is faster than that of any other ribonucleoside triphosphate. Deoxy ATP is hydrolyzed rather faster than ATP. However, polynucleotides carrying triphosphate at the 5'-terminus, that is, 4S RNA which was synthesized by E. coli RNA polymerase [EC 2.7.7.6] using calf thymus DNA as a template, and the phage Q beta RNA (30S), are not effective substrates for this enzyme. Although the CP virion loses the viral genome and one kind of protein component on proteolytic treatment with pronase, the partially degraded virion still retains phosphohydrolase activity. The phosphohydrolase must therefore be associated firmly with the virion. This enzyme does not require the presence of nucleic acid for its function. Phosphohydrolysis of ATP by this enzyme activity represents a first step in the synthesis of the 5'-terminal modified mRNA of CP virus.

Adenosine Triphosphate↗