The Tat protein of equine infectious anemia virus is encoded by at least three types of transcripts.
Abstract: Nucleotide sequence analysis of a cDNA library of EIAV-infected canine cells established a complex pattern of gene expression, characterized by alternatively spliced polycistronic transcripts. The EIAV tat gene product was shown to be encoded by at least three species of mRNA which differed in their ability to trans-activate the EIAV LTR upon expression in canine cells. The most active cDNA was monocistronic, consisting of three exons. The most abundant cDNA in the library contained four exons and was identical to a polycistronic transcript previously described (Noiman et al., 1990b) which contains open frames for Tat, putative Rev, and truncated transmembrane proteins. Products consistent in size with those predicted for these last two proteins could be detected in in vitro translation experiments. The third Tat message, another four-exon form, also potentially encodes an amino terminally truncated transmembrane protein. In vitro mutagenesis experiments and analysis of subgenomic and partial cDNA clones confirmed and extended previous findings that S1 sequences are essential for trans-activation and that Tat translation initiates at a non-AUG codon either in the full-length Tat message or in the genomic S1 open reading frame. The Tat protein (8 kDa) was detected in cells transfected with a Tat cDNA construct and in canine cells persistently infected with EIAV. The Tat activity of polycistronic mRNAs was lower than that of the monocistronic form, suggesting that the expression of the EIAV trans-activator may be subject to several levels of posttranscriptional control.
Publication Date: 1991-10-01 PubMed ID: 1653485DOI: 10.1016/0042-6822(91)90422-8Google Scholar: Lookup
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Summary
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This research article explores how the Tat protein of equine infectious anemia virus (EIAV) is encoded by at least three different kinds of transcripts, demonstrating varying abilities for trans-activation in canine cells. These findings point towards the complexity of gene expression and the potential for different levels of posttranscriptional control in the EIAV pathogen.
Nature of the EIAV Tat Protein
- The EIAV Tat protein is a critical part of the perceived gene expression pattern. It is encoded through three different types of messenger RNAs (mRNAs).
- These mRNAs show differing abilities to trans-activate the EIAV Long Terminal Repeat (LTR) in infected canine cells.
Complex Pattern of Gene Expression
- A complicated pattern of gene expression was found from the analysis of a complementary DNA (cDNA) library produced from EIAV-infected canine cells.
- This gene expression pattern is marked by alternatively spliced polycistronic transcripts, i.e., mRNAs that can encode multiple proteins.
Type and Function of Various cDNAs
- Three types of cDNAs varied in activity. The most active among them was monocistronic, meaning it consists of three exons and can encode a single protein.
- The most abundant cDNA in the library, containing four exons, was found to correspond with a previously known polycistronic transcript and has open frames for Tat, a putative Rev, and truncated transmembrane proteins.
- The third cDNA is another four-exon form, which potentially encodes for an amino truncated transmembrane protein.
In Vitro Translations and Mutagenesis Experiments
- In vitro translation experiments revealed products of sizes corresponding to predicted sizes of the last two protein types.
- Mutagenesis experiments showed that S1 sequences are essential for trans-activation, and the initiation of Tat translation begins at a non-AUG codon either in the full-length Tat message or within the S1 open reading frame on the genome.
Detection of Tat Protein and Its Activity Analysis
- The Tat protein, with a size of 8 kDa, was detected in cells transfected with a Tat cDNA construct and in persistently EIAV-infected canine cells.
- The Tat activity of polycistronic mRNAs was identified to be lower than that of the monocistronic form, which implies that there may be multiple levels of post-transcriptional control influencing the expression of the EIAV trans-activator.
Cite This Article
APA
Noiman S, Yaniv A, Tsach T, Miki T, Tronick SR, Gazit A.
(1991).
The Tat protein of equine infectious anemia virus is encoded by at least three types of transcripts.
Virology, 184(2), 521-530.
https://doi.org/10.1016/0042-6822(91)90422-8 Publication
Researcher Affiliations
- Department of Human Microbiology, Sackler School of Medicine, Tel Aviv University, Israel.
MeSH Terms
- Amino Acid Sequence
- Base Sequence
- Cloning, Molecular
- DNA / genetics
- Gene Expression Regulation, Viral
- Gene Products, tat / genetics
- Genes, tat
- Infectious Anemia Virus, Equine / genetics
- Molecular Sequence Data
- Molecular Weight
- Peptide Chain Initiation, Translational
- RNA, Messenger / genetics
- Restriction Mapping
Citations
This article has been cited 9 times.- Quy VC, Pantano S, Rossetti G, Giacca M, Carloni P. HIV-1 Tat Binding to PCAF Bromodomain: Structural Determinants from Computational Methods.. Biology (Basel) 2012 Aug 13;1(2):277-96.
- Harris ME, Gontarek RR, Derse D, Hope TJ. Differential requirements for alternative splicing and nuclear export functions of equine infectious anemia virus Rev protein.. Mol Cell Biol 1998 Jul;18(7):3889-99.
- Tan W, Schalling M, Zhao C, Luukkonen M, Nilsson M, Fenyö EM, Pavlakis GN, Schwartz S. Inhibitory activity of the equine infectious anemia virus major 5' splice site in the absence of Rev.. J Virol 1996 Jun;70(6):3645-58.
- Beisel CE, Edwards JF, Dunn LL, Rice NR. Analysis of multiple mRNAs from pathogenic equine infectious anemia virus (EIAV) in an acutely infected horse reveals a novel protein, Ttm, derived from the carboxy terminus of the EIAV transmembrane protein.. J Virol 1993 Feb;67(2):832-42.
- Rosin-Arbesfeld R, Rivlin M, Noiman S, Mashiah P, Yaniv A, Miki T, Tronick SR, Gazit A. Structural and functional characterization of rev-like transcripts of equine infectious anemia virus.. J Virol 1993 Sep;67(9):5640-6.
- Carroll R, Derse D. Translation of equine infectious anemia virus bicistronic tat-rev mRNA requires leaky ribosome scanning of the tat CTG initiation codon.. J Virol 1993 Mar;67(3):1433-40.
- Martarano L, Stephens R, Rice N, Derse D. Equine infectious anemia virus trans-regulatory protein Rev controls viral mRNA stability, accumulation, and alternative splicing.. J Virol 1994 May;68(5):3102-11.
- Perry ST, Flaherty MT, Kelley MJ, Clabough DL, Tronick SR, Coggins L, Whetter L, Lengel CR, Fuller F. The surface envelope protein gene region of equine infectious anemia virus is not an important determinant of tropism in vitro.. J Virol 1992 Jul;66(7):4085-97.
- Schiltz RL, Shih DS, Rasty S, Montelaro RC, Rushlow KE. Equine infectious anemia virus gene expression: characterization of the RNA splicing pattern and the protein products encoded by open reading frames S1 and S2.. J Virol 1992 Jun;66(6):3455-65.
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