# Molecular and cellular biology of the phage nucleus and spindle

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2020 · $489,819

## Abstract

We recently described the discovery of a nucleus like structure assembled by phage
201Φ2-1 after infection of Pseudomonas chlororaphis. The phage nucleus is composed
of a protein shell (GP105) that segregates phage and host bacterial proteins according
to function, with metabolic enzymes and ribosomes in the cytoplasm and proteins
related to DNA and RNA processing inside the phage nucleus. This compartment is
centered by a bipolar spindle composed of the phage-encoded tubulin PhuZ. Capsids
assemble on the bacterial membrane and then migrate to and dock on the surface of
the phage nucleus where phage DNA is packaged. Ultimately, capsids assemble with
tails to create mature particles and the cell lyses. The GP105 shell appears in our
preliminary cryoEM as an irregularly shaped 5 nm wide border that encloses phage
DNA. Remarkably, this shell allows selective entry or retention of specific proteins. This
work raises a number of questions such as: Is the GP105 shell essential for phage
replication? Are other proteins required for shell assembly? What is the structural
organization of GP105 within the shell and how does it assemble and incorporate new
subunits as it grows? Does it contain pores that allow diffusion of mRNA, proteins and
small molecules in and out of the structure? How is the PhuZ spindle organized over
time as it pushes the growing GP105 to midcell? Does the spindle participate in other
aspects of phage development such as capsid movement? Here, we propose to use a
combination of genetics, biochemistry, structural biology, and cell biology to study the
nucleus like structure assembled by GP105 and the spindle assembled by PhuZ and
determine how these two structures participate in viral lytic growth.

## Key facts

- **NIH application ID:** 9985116
- **Project number:** 5R01GM129245-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** JOSEPH A POGLIANO
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $489,819
- **Award type:** 5
- **Project period:** 2018-09-06 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9985116

## Citation

> US National Institutes of Health, RePORTER application 9985116, Molecular and cellular biology of the phage nucleus and spindle (5R01GM129245-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9985116. Licensed CC0.

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