Chromatin structure of recombinant Moloney murine leukemia virus proviral DNAs that contain tax-responsive sequences from human T-cell lymphotropic virus type II in the presence and absence of tax.
AUTOR(ES)
Kitado, H
RESUMO
Human T-cell lymphotropic virus types I and II (HTLV-I and HTLV-II) are replication-competent retroviruses which contain two additional regulatory proteins, tax and rex. tax is a transcriptional transactivator of the HTLV-I or HTLV-II long terminal repeat (LTR) and also of some heterologous promoters. To investigate the mechanism of tax transactivation, we used chimeric Moloney murine leukemia viruses (M-MuLVs) with LTRs containing tax-responsive sequences from the HTLV-II LTR (nucleotides -273 to -32). Mo+HTLV-II+ M-MuLV contained the HTLV II sequences inserted into the wild-type M-MuLV LTR at nucleotide -150, whereas delta Mo+HTLV-II+ M-MuLV contained the same sequences inserted into an M-MuLV LTR lacking its own enhancer region. HTLV-II tax (tax II)-positive mouse cells (15S-5a) infected with Mo+HTLV-II+ M-MuLV or delta Mo+HTLV-II+ M-MuLV showed higher rates of viral transcription in nuclear run-on assays than did infected tax-negative NIH 3T3 cells. The chromatin structure of these viruses was investigated by high-resolution mapping of DNase I-hypersensitive (HS) sites. Three prominent HS sites were associated with HTLV-II sequences in proviral chromatin both in tax-positive and in tax-negative cells. The spacing resembled that of the 21-base-pair (bp) repeats, but the HS sites were displaced approximately 50 bp upstream of the 21-bp repeats. This suggested that cellular proteins bound to the HTLV-II sequences in the presence or absence of tax. No direct effect of tax on chromatin structure was found. These in vivo results were consistent with results of in vitro DNase footprinting studies performed by other investigators.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=250863Documentos Relacionados
- Acetylation of Nucleosomal Histones by p300 Facilitates Transcriptionfrom Tax-Responsive Human T-Cell Leukemia Virus Type 1Chromatin Template
- Acetylation of Nucleosomal Histones by p300 Facilitates Transcription from Tax-Responsive Human T-Cell Leukemia Virus Type 1 Chromatin Template
- Isolation of cDNAs for DNA-binding proteins which specifically bind to a tax-responsive enhancer element in the long terminal repeat of human T-cell leukemia virus type I.
- Mutational analysis of human T-cell leukemia virus type 2 Tax.
- Construction of recombinant murine retroviruses that express the human T-cell leukemia virus type II and human T-cell lymphotropic virus type III trans activator genes.