cis-acting elements in the U3 region of a simian immunodeficiency virus.

A series of 5' deletions and a point mutation in the binding site for nuclear factor kappa B were introduced into the U3 region of a molecular clone of simian immunodeficiency virus from macaques (SIVmac142). The transcriptional activity of the mutated U3 regions was analyzed by transient chloramphenicol acetyltransferase assays. Two distinct regions in U3 appeared to contain important cis-acting sequences for transcriptional activity. Mutation of the single nuclear factor kappa B site in the SIVmac142 U3 region attenuated transcription in Rat-1 fibroblasts and Jurkat T cells. A second cis-acting element was localized to sequences between -162 and -114 in U3; deletion of long terminal repeat sequences up to -114 significantly attenuated transcriptional activity in Rat-1 cells. Furthermore, sequences between -162 and -114 contributed to inducibility of transcription by 1,3-phorbol myristate acetate in Jurkat T cells. Deletion of long terminal repeat sequences to -114, in addition to mutation of the nuclear factor kappa B site, was necessary to attenuate the response to 1,3-phorbol myristate acetate completely. A negative regulatory element analogous to that identified in the U3 region from the human immunodeficiency virus was not found in the U3 region from SIVmac142.