HIV-1 Tat protein trans-activates transcription in vitro.
Tat protein of human immunodeficiency virus 1 is a potent trans-activator of viral gene expression. We show that purified Tat protein stimulates transcription from viral promoters greater than 10-fold in vitro. A Tat protein mutant that does not trans-activate in vivo did not stimulate transcription in vitro. Tat trans-activation required a functional TAR RNA sequence; trans-activation was competed by the addition of in vitro synthesized wild-type TAR RNA but not by mutant TAR RNAs. That Tat protein directly interacts with the TAR RNA during trans-activation in vitro was suggested by competition with Tat peptides. Preliminary evidence suggests the involvement of a cellular factor in recognition of TAR RNA during Tat trans-activation. Analysis of Tat trans-activation in vitro will provide new mechanistic insights into this process and allow a more detailed study of the relationship between Tat protein structure and function.
Marciniak
R A
RA
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Calnan
B J
BJ
Frankel
A D
AD
Sharp
P A
PA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D015696:Gene Products, tat / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012367:RNA, Viral / Q000235:genetics; D013698:Templates, Genetic; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D012367:RNA, Viral; D054322:tat Gene Products, Human Immunodeficiency Virus