# MOLECULAR MECHANISM OF DNA TRANSPOSITION

> **NIH NIH R01** · UNIVERSITY OF SOUTHERN CALIFORNIA · 1988 · $192,199

## Abstract

The focus of the proposed program is the continuing styd of the molecular
mechanisms for transposition of the transposable elements IS1 and IS50 (and
other recombination events mediated by the elements).  These elements
participate in the formation of compund transposons like Tn9 (IS1) and Tn5
(IS50).  A model system has been developed and used to study transposition,
cointegrate formation (plasmid fusion) and other recombination events
mediated by the elements.  This system uses an F-derived plasmid containing
no resident transposable elements as one component, and various
non-conjugative, pBR322-derived plasmids as the other element.  The system
is highly manipulable, easily portable into different genetic backgrounds,
and permits precise analysis of the recombination products.  The studies
carried out so far in this program have established that cointegrates are
not intermediates in the transposition of Tn9 or Tn5, in contrast to the
major pathway for transposition of the Tn3-like elements.  The precise
nature of the molecular pathways are not yet clear, however.  The goals of
the proposed program will be:  1) to understand the molecular basis of the
strong modulation of transposition activity by external transcription that
we have discovered, 2) to understand the quantitative effects of differing
activities for the flanking elements of the compound transposons on the
spectrum of recombination products (we have developed a simple quantitative
model that can be tested using our system), 3) to understand the source of
the strong target specificity and orientation effect that we have observed
for IS1, 4) to understand the roles of the structural components of IS1 in
the transposition process (the cloned end sequences, and the six largest,
overlapping open reading frames within the element) by cloning and
site-directed mutagenesis methods, 5) to analyze the properties (in vivo
and in vitro) of the proteins, and/or RNA's coded for by the element (one
IS1 protein has been identified in minicells, and a model-building study
initiated).

Another, recently-observed effect by which IS1 can activate the expression
of a gene by providing the -35 region of a "hybrid" promoter will be
investigated.  This effect may have important implications for the
understanding of the formation and stability of compound transposons.

## Key facts

- **NIH application ID:** 3128461
- **Project number:** 5R01AI019036-07
- **Recipient organization:** UNIVERSITY OF SOUTHERN CALIFORNIA
- **SAM.gov UEI:** G88KLJR3KYT5
- **Principal Investigator:** DAVID J. GALAS
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $192,199
- **Award type:** 5
- **Project period:** 1982-04-01 → 1990-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3128461

## Citation

> US National Institutes of Health, RePORTER application 3128461, MOLECULAR MECHANISM OF DNA TRANSPOSITION (5R01AI019036-07). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3128461. Licensed CC0.

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