The fission yeast Schizosaccharomyces pombe has been utilized as a model system to study transcription factors. Yeast replicating vectors containing HIV-1 LTR-CAT (chloramphenicol acetyl transferase gene) and deletions of the HIV-LTR promoters were transfected in S. pombe cells. In a separate experiment, an SV40 promoter transcribing the TAT gene was used in a cotransfection assay. Our results show that HIV-LTR promoter is functional in yeast and RNA synthesis initiates from two sites, One of the 5' ends of the RNA corresponds to the 5' end of the HIV-mRNA observed in viral cells. Deletion analysis of the promoter suggests NF-kB binding sequences are required for promoter activity. However, the TAT gene product failed to transactivate transcription. A number of yeast replicating vectors have been developed. Enhancers which are generally present on viral promoters, such as SP1, NF-kB, CRE, and AP1, have been shown to be functional in fission yeast. A number of viral promoters have been introduced into the yeast such as the human cytomegalovirus (CMV), human low density lipoprotein receptor (LDL), human chorionic gonadotrophin- alpha (HCG-alpha), alpha-crystallin and albumin. The level of activity of these promoters is dependent on the type of enhancer present upstream. In our attempts to identify what causes the instability of HIV-gag mRNA, we observed that transcription of the HIV gag gene from the SV40 promoter in S. pombe results in a series of mRNAs that are less than full-length. These may result from poly-A signals within the coding region and are candidate crs sequences. Cis regulating sequences are responsible for dependence of HIV mRNAs on rev protein.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01CP005643-02
Application #
3853540
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
2
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Division of Cancer Epidemiology and Genetics
Department
Type
DUNS #
City
State
Country
United States
Zip Code