Previous Article | Next Article ![]()
Molecular and Cellular Biology, September 1998, p. 5404-5413, Vol. 18, No. 9
Department of Microbiology, University of
Iowa, Iowa City, Iowa 52242
Received 10 February 1998/Returned for modification 24 March
1998/Accepted 8 June 1998
Inefficient splicing of human immunodeficiency virus type 1 (HIV-1)
RNA is necessary to preserve unspliced and singly spliced viral RNAs
for transport to the cytoplasm by the Rev-dependent pathway. Signals
within the HIV-1 genome that control the rate of splicing include weak
3' splice sites, exon splicing enhancers (ESE), and exon splicing
silencers (ESS). We have previously shown that an ESS present within
tat exon 2 (ESS2) and a suboptimal 3' splice site together
act to inhibit splicing at the 3' splice site flanking tat
exon 2. This occurs at an early step in spliceosome assembly. Splicing
at the 3' splice site flanking tat exon 3 is regulated by a
bipartite element composed of an ESE and an ESS (ESS3). Here we show
that ESS3 is composed of two smaller elements (AGAUCC and
UUAG) that can inhibit splicing independently. We also show that ESS3
is more active in the context of a heterologous suboptimal splice site
than of an optimal 3' splice site. ESS3 inhibits splicing by blocking
the formation of a functional spliceosome at an early step, since A
complexes are not detected in the presence of ESS3. Competitor RNAs
containing either ESS2 or ESS3 relieve inhibition of splicing of
substrates containing ESS3 or ESS2. This suggests that a common
cellular factor(s) may be required for the inhibition of
tat mRNA splicing mediated by ESS2 and ESS3.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
The Exon Splicing Silencer in Human
Immunodeficiency Virus Type 1 Tat Exon 3 Is Bipartite and Acts
Early in Spliceosome Assembly
*
Corresponding author. Mailing address: Department of
Microbiology, University of Iowa, 3770 Bowen Science Building, Iowa
City, IA 52242. Phone: (319) 335-7793. Fax: (319) 335-9006. E-mail: marty-stoltzfus{at}uiowa.edu.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|