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R Patarca

Publications and source records attributed to R Patarca.

At least 37 records · Page 2Linked to original sources
PubMed1987

Transcription directed by the HIV long terminal repeat in vitro.

The long terminal repeat (LTR) of the AIDS virus (HIV) has been found to contain promoter sequences that are active in uninfected HeLa whole cell and nuclear extracts. Here we report that elements upstream of position -104 (start site +1) do not affect transcriptional activity in vitro whereas sequences between -104 and -57 are required for such activity. Using a reconstituted RNA polymerase II system, we demonstrate that a partially purified fraction containing Spl not only stimulates, as was previously reported, but is required for accurate initiation of transcription directed by the HIV LTR. In addition, based on a computerized analysis, we report the presence of a region in the HIV LTR (positions -151 to -80) that is similar to the 72 base pair enhancer element of SV40 and that includes a highly conserved segment also present in the cytomegalovirus enhancer. Moreover, the HIV and HTLV-I LTRs are shown to share a region of similarity that includes the 21 base pair motif found in the enhancers of the human and bovine T-lymphotropic viruses. The R region of the HIV LTR is found to have two extensive regions of dyad symmetry rather than one as was previously reported. The significance of these observations for HIV pathogenesis is discussed.

DNA Restriction Enzymes↗
PubMed1985

Location of the trans-activating region on the genome of human T-cell lymphotropic virus type III.

The retrovirus involved in acquired immune deficiency syndrome (HTLV-III/LAV) contains a region that is necessary for stimulation of gene expression directed by the viral long terminal repeat. This region is located between nucleotides 5365 and 5607, immediately 5' to the envelope gene. A doubly-spliced message containing this region could encode an 86-amino acid protein with structural features similar to those of nucleic acid-binding proteins.

Base Sequence↗
PubMed1984

Sequence of the envelope glycoprotein gene of type II human T lymphotropic virus.

The sequence of the envelope glycoprotein gene of type II human T lymphotropic virus (HTLV) is presented. The predicted amino acid sequence is similar to that of the corresponding protein of HTLV type I, in that the proteins share the same amino acids at 336 of 488 residues, and 68 of the 152 differences are of a conservative nature. The overall structural similarity of these proteins provides an explanation for the antigenic cross-reactivity observed among diverse members of the HTLV retrovirus family by procedures that assay for the viral envelope glycoprotein, for example, membrane immunofluorescence.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Structure of 3' terminal region of type II human T lymphotropic virus: evidence for new coding region.

The sequence of the 3' terminus of the human T lymphotropic virus type II (HTLV-II) was determined and compared to the corresponding sequence of HTLV-I. The 1557-nucleotide-long sequence can be divided into a 5' region that is not conserved between the two viruses, and a 3', 1011-nucleotide-long region that is highly conserved and that corresponds precisely with a long open reading frame for both HTLV-I and -II. The proteins that could be encoded by these open reading frames have a molecular weight of about 38,000 and are closely related in primary amino acid sequence. The genomic structure in the 3' region of HTLV was found to be similar to that of bovine leukemia virus.

Base Sequence↗
PubMed1984

Long terminal repeat structure of an American isolate of type I human T-cell leukemia virus.

Variation in the structure of the long terminal repeat (LTR) element of human T-cell leukemia virus (HTLV) types has been noted (M. Seiki, S. Hattori, Y. Hirayama, and M. Yoshida (1983), Proc. Natl. Acad. Sci. USA 80, 3618-3622; K. Shimotohno, D. W. Golde, M. Miwa, T. Sugimura, and I. S. Y. Chen (1984), Proc. Natl. Acad. Sci. USA 81, 1079-1083; J. Sodroski, M. Trus, D. Perkins, R. Patarca, F. Wong-Staal, E. Gelmann, R. Gallo, and W. Haseltine (1984), Proc. Natl. Acad. Sci. USA 81, 4617-4621). To determine whether HTLV isolates with similar disease associations, but from different geographic locations, exhibit a conserved LTR structure, the nucleotide sequence of the LTR of an American HTLV isolate from a patient with adult T-cell leukemia/lymphoma was obtained. Comparison of this LTR sequence to that of two Japanese HTLV isolates associated with a similar disease reveals a highly conserved organization of the U3, R, and U5 regions. The U. S. isolate differs from the Japanese viruses by only 15-16 bases out of 754 bases in the LTR region. These results show that Japanese HTLV isolates from patients with adult T-cell leukemia/lymphoma are members of the HTLV-I family and that LTRs of HTLV-I isolates are highly conserved. A 50-nucleotide imperfect direct repeat element is also identified in the U3 of the HTLV LTR distant from the cap site. The position and conserved nature of this sequence make it a likely candidate for a transcriptional enhancer.

Base Sequence↗
PubMed1984

Repetitive structure in the long-terminal-repeat element of a type II human T-cell leukemia virus.

The majority of human T-cell leukemia virus isolates (HTLV-I) are associated with clinically aggressive adult T-cell leukemia/lymphomas. By contrast, HTLV-II has been isolated from a patient with a relatively benign hairy T-cell leukemia. To characterize differences in the viral genomes that might contribute to these different pathologies, we determined the nucleotide sequence of the long terminal repeat (LTR) of a HTLV-II provirus. Comparison with the type I HTLV LTR reveals that, whereas the overall structural features are similar, the two sequences differ markedly throughout most of the length of the LTR. Despite the overall differences, the sequences of several functional regions of the two LTRs are conserved. These include the 5' boundary of U3, the RNA cap site, and the tRNAPro-binding site immediately 3' to the LTR. Another point of similarity is a 21-base sequence that is repeated four times in the U3 region of HTLV-II and three times in the U3 region of HTLV-I. This sequence has a formal analogy to, but no common sequence with, viral transcriptional enhancers. The U3 region of HTLV-II possesses a series of imperfect tandem direct repeats, 42 bases long, 21 bases long, 19 bases long, and 7 bases long. These structures differ from those of HTLV-I except for the 21-base repeat sequence. Thus, the structure of HTLV-II differs substantially from that of HTLV-I in the region that governs transcriptional initiation and tissue specificity. Such differences may account for some of the differences in clinical presentation of HTLV-associated adult T-cell leukemia/lymphomas and hairy T-cell leukemia.

Base Sequence↗
PubMed1983

Mode of inhibition of active chloride transport in the frog cornea by furosemide.

The mechanism of inhibition of active Cl- secretion by 1 mM furosemide and 0.1 mM bumetanide was characterized in the isolated frog corneal epithelium. Transepithelial and transmembrane cell electrical parameters as well as transmembrane Cl- electrochemical potential difference were measured with conventional glass microelectrodes and Cl- selective microelectrodes. Furosemide caused the potential difference across the apical membrane to hyperpolarize by 20 mV while the transepithelial potential difference declined by 13 mV. The apical-to-basolateral membrane resistance ratio increased 3-4 times after furosemide or bumetanide addition. Preincubation with furosemide prevented a 30-mV depolarization of the apical membrane potential difference normally observed when Cl- was removed from the tear side bathing solution. In control conditions, intracellular Cl- activity was above equilibrium. Bumetanide further increased the Cl- electrochemical gradient between the cell compartment and the bathing solutions even though intracellular Cl- activity fell from 18 to 12 mM. In contrast, perfusion with Cl- -free Ringer in the stromal side bathing solution decreased the Cl- electrochemical gradient across the apical membrane to zero, indicating an equilibrium distribution. Adenosine, which selectively increases Cl- permeability of the apical membrane, also decreased the Cl- electrochemical gradient across the apical membrane. These results suggest that the diuretics inhibit active Cl- transport primarily by decreasing the Cl- permeability of the apical membrane.

Animals↗
PubMed1982

Creation of a data base for sequences of ribosomal nucleic acids and detection of conserved restriction endonucleases sites through computerized processing.

As part of a project pertaining the organization of ribosomal genes in Kinetoplastidae, we have created a data base for published sequences of ribosomal nucleic acids, with information in Spanish. As a first step in their processing, we have written a computer program which introduces the new feature of determining the length of the fragments produced after single or multiple digestion with any of the known restriction enzymes. With this information we have detected conserved SAU 3A sites: (i) at the 5' end of the 5.8S rRNA and at the 3' end of the small subunit rRNA, both included in similar larger sequences; (ii) in the 5.8S rRNA of vertebrates (a second one), which is not present in lower eukaryotes, showing a clear evolutive divergence; and, (iii) at the 5' terminal of the small subunit rRNA, included in a larger conserved sequence. The possible biological importance of these sequences is discussed.

Animals↗
PubMedDate not supplied

Determination of the leukaemogenicity of a murine retrovirus by sequences within the long terminal repeat.

Although the murine retrovirus SL3-3 is highly leukaemogenic, in both the structure of its genome and in its properties of replication in tissue culture it closely resembles the nonleukaemogenic retrovirus Akv (refs 3, 4). An earlier investigation of the properties of recombinant SL3-3-Akv viruses localized the major determinant of leukaemogenicity outside the env gene, in a region of the viral genome that includes the gag gene and the noncoding long terminal repeat (LTR). To localize the determinant of SL3-3's leukaemogenicity more precisely we have now construced a recombinant provirus containing the LTR of SL3-3 and the coding region of Akv. The leukaemogenicity of these recombinants demonstrates that the determinant of leukaemogenicity lies within the SL3-3 LTR. Nucleotide sequencing of the LTRs of SL3-3 and Akv shows that they differ by a set of changes in the region thought to contain a transcriptional enhancer element. We suggest that enhancer region sequences are the major determinants of leukaemogenicity in these viruses.

Animals↗
PubMedDate not supplied

Complete nucleotide sequence of the AIDS virus, HTLV-III.

The complete nucleotide sequence of two human T-cell leukaemia type III (HTLV-III) proviral DNAs each have four long open reading frames, the first two corresponding to the gag and pol genes. The fourth open reading frame encodes two functional polypeptides, a large precursor of the major envelope glycoprotein and a smaller protein derived from the 3'-terminus long open reading frame analogous to the long open reading frame (lor) product of HTLV-I and -II.

Acquired Immunodeficiency Syndrome↗