# GENETIC STUDIES OF PHAGE-PROPHAGE INTERACTIONS

> **NIH NIH R01** · UNIVERSITY OF IOWA · 1991 · $189,609

## Abstract

We propose to continue our studies of the P2-P4 system of E. coli
phages, in particular with regard to three topics:  (1) The control
of capsid (= head) size by P2 and P4 genes which leads proteins
encoded by P2 to assemble either as large (= P2 size) heads or, in
the presence of P4, as "small" (= P4 size) heads.  Plans include
continued studies of P2's sir mutations which let P2 assemble
large heads even in the presence of P4 (the three already mapped
sir mutations all occur in gene N which encodes the major head
protein); a search for P2 mutations causing P2 to assemble small
heads even in the absence of P4 (hence preventing production of
P2 itself but sitll allowing P2 to serve as helper for P4)  and the
analysis of such mutations, if found; study of P4 mutations,
especially in its head size direction gene sid, using P4 mutants
isolated by selection procedures based on the P2-P4 head size
control interactions; and further studies of these interactions.  (2)
The role of P4's ash (cI) gene in the negative control of P4 gene
expression.  Some of the results of our previous studies of ash
mutations are difficult to interpret in terms of the ash gene
encoding a repressor protein.  Proposed are tests to determine the
effects of already recognized ash-amber mutations on the control
of P4 gene expression; identification of P4 promoters that are 1pf
gene, which may be identical to rpoA; identification of the P4
genes requiring the Lpf+ controlled by ash; and a search  for a
possible countertranscript from the ash region.  (3) The nature of
E. coli mutatios (1pf) specifically interfering with P4's lytic
growth iP2 lysogens.  Plans include identification of the function
for their expression; and studies of P4 mutants, including certain
P4 ash mutants, able to grow in Lpf- hosts.

## Key facts

- **NIH application ID:** 3124172
- **Project number:** 5R01AI004043-30
- **Recipient organization:** UNIVERSITY OF IOWA
- **SAM.gov UEI:** Z1H9VJS8NG16
- **Principal Investigator:** ERICH W SIX
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1991
- **Award amount:** $189,609
- **Award type:** 5
- **Project period:** 1979-01-01 → 1991-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3124172

## Citation

> US National Institutes of Health, RePORTER application 3124172, GENETIC STUDIES OF PHAGE-PROPHAGE INTERACTIONS (5R01AI004043-30). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3124172. Licensed CC0.

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