Variable role of the long terminal repeat Sp1-binding sites in human immunodeficiency virus replication in T lymphocytes.
The long terminal repeat (LTR) of the human immunodeficiency virus (HIV) contains three binding sites for the transcriptional factor Sp1. In order to investigate the role that the Sp1-binding sites play in regulation of HIV replication, we have introduced a deletion of all three Sp1-binding sites into the LTR of an infectious molecular clone of HIV. Viral stocks have been prepared from this mutant virus, designated dl-Sp, and these stocks have been used to study its replicative ability in human T cells. The dl-Sp virus replicated efficiently in MT4 cells and in phytohemagglutinin-stimulated human peripheral blood lymphocytes, but it replicated poorly and with delayed kinetics in A3.01 (CEM) T cells unless those cells had been treated with the cytokine tumor necrosis factor alpha. Gel retardation assays to study the levels of DNA-binding proteins present in these cells showed that NF-kappa B activity could be detected in the nuclei of MT4 cells but not in A3.01 cells unless they had been treated with tumor necrosis factor alpha. Thus, the presence of NF-kappa B activity appeared to be required for efficient replication of an HIV whose LTR Sp1-binding sites had been deleted. This suggests that NF-kappa B can functionally compensate for Sp1 in activating HIV replication. The HIV LTR is therefore similar to the promoter-enhancer units of other viruses in that it is composed of multiple functional elements that may contribute differently to viral replication depending on the levels of DNA-binding proteins present in the target cells.
Parrott
C
C
Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
Seidner
T
T
Duh
E
E
Leonard
J
J
Theodore
T S
TS
Buckler-White
A
A
Martin
M A
MA
Rabson
A B
AB
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002872:Chromosome Deletion; D006678:HIV / Q000235:genetics / Q000502:physiology*; D016325:HIV Long Terminal Repeat; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D015183:Restriction Mapping; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013601:T-Lymphocytes; D014157:Transcription Factors / Q000378:metabolism*; D014779:Virus Replication
D016328:NF-kappa B; D016329:Sp1 Transcription Factor; D014157:Transcription Factors