# STUDIES OF RETROVIRAL PROTEINS

> **NIH NIH R01** · CASE WESTERN RESERVE UNIVERSITY · 1988 · $163,909

## Abstract

The goal of this research is to define biochemical mechanisms of avian
retrovirus replication through the study of interactions of viral proteins
with nucleic acids.  The proposal outlines experiments 1) to elucidate the
mechanism of specific cleavage of cloned viral LTR DNA by the endonuclease
associated with reverse transcriptase (RT-endonuclease) and to evaluate its
potential role in viral DNA integration and 2) to study the interaction of
the viral pp12 nucleocapsid protein with viral RNA, evaluate its role in
virion assembly and its ability to act as an RNA unwinding protein during
reverse transcription of viral RNA.

RT-endonuclease:  Specific experiments are outlined 1) to define the
nucleotide sequence at the U5/U3 junction sequence of two tandem LTRs
required for specific cleavage.  This will be accomplished by mapping
endonuclease cleavage in single-stranded and RF I DNAs that contain
deletions of sequence about this primary LTR cleavage site and by
reconstruction of the site by direct synthesis (18).  2) An exonuclease
activity, which has been detected in all of our purified reverse
transcriptase preparations, will be characterized and its potential role in
integration evaluated.  3) The action of the RT-endonuclease on cell DNA
sequences known to contain sites for integration of retrovirus DNA will be
examined.  4) The knowledge gained from the above studies will be used to
attempt to reconstitute a non-homologous viral - cell DNA recombination
system using cloned DNAs.

pp12:  The role of phosphorylation of serine residues in pp12 and the
ability to alter the binding of this protein to viral RNA will be further
studied.  The specific residues that are phosphorylated in vitro and in
vivo will be identified and the action of protease activated kinase I to
phosphorylate pp12 will be studied.  Protein phosphatases, capable of
releasing phosphate from pp12, will be purified from extracts of virus free
of contaminating nuclease activities.  Then their ability, in conjuction
with pp12, to stimulate elongation synthesis by reverse transcriptase
primed with viral RNA in vitro will be investigated.

## Key facts

- **NIH application ID:** 3176062
- **Project number:** 5R01CA038046-05
- **Recipient organization:** CASE WESTERN RESERVE UNIVERSITY
- **SAM.gov UEI:** HJMKEF7EJW69
- **Principal Investigator:** JONATHAN P LEIS
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $163,909
- **Award type:** 5
- **Project period:** 1984-07-01 → 1989-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3176062

## Citation

> US National Institutes of Health, RePORTER application 3176062, STUDIES OF RETROVIRAL PROTEINS (5R01CA038046-05). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3176062. Licensed CC0.

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