# Decoding the role of the C.trachomatis Inclusion membrane protein CT224 and the host ubiquitinligase TRAF7 during infection.

> **NIH NIH F31** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2021 · $41,498

## Abstract

PROJECT SUMMARY
Chlamydia trachomatis is an obligate intracellular pathogen for which no effective vaccine exists. It is the leading
cause of bacterial sexually transmitted infections, non-congenital infertility, and preventable blindness. After
entering host cells, Chlamydia species replicate within a protective membrane-bound compartment, termed the
inclusion. To establish a replicative niche, Chlamydia species employ a specialized protein export system, the
type III secretion system, to deliver up to ~100 secreted effectors into either the host cell cytoplasm or the
inclusion membrane. The inclusion membrane proteins (Incs) encode two or more transmembrane regions with
their cytoplasmic N and C terminal domains exposed to the host cytosol, where they may function as scaffolds
to mediate interactions with host proteins. While effectors comprise up to ~10% of the bacteria's coding capacity,
the function of only some of the effectors is known, partly because genetic manipulation of Chlamydia has only
recently become feasible. An extensive affinity purification-mass spectrometry (AP-MS) screen conducted by
the Engel lab identified potential host binding partners for approximately two-thirds of the C. trachomatis Incs.
This screen predicts a high confidence interaction between an early-expressed Inc, CT224, and human tumor
necrosis factor receptor associated factor 7 (TRAF7), which is part of a family of proteins (TRAFs) that stimulates
diverse cellular pathways with different outcomes including proliferation, apoptosis, and cytokine production. I
provide strong preliminary data that CT224 interacts with TRAF7 in the context of infection and propose to
investigate the role of this interaction in the C. trachomatis life cycle. In Aim 1, I will structurally and functionally
characterize the CT224-TRAF7 interaction. I will use biochemical methods to (A) determine if CT224 alters
TRAF7 protein-protein interactions; (B) Investigate whether CT224 modulates TRAF7 ubiquitin ligase activity;
and (C) Determine if CT224 and TRAF7 interact directly and map the binding interface. In Aim 2A, I will determine
the roles of CT224 and TRAF7 in the C. trachomatis intracellular life cycle and in TRAF7-depdendent signaling.
I propose to use (i) TRAF7-depleted or overexpressing cells and (ii) use recently developed genetic tools to
generate a CT224 null mutant or transfect cells with CT224 to independently test the roles of TRAF7 and CT224
during infection. In Aim 2B, I will determine whether CT224 alters NF-κB, AP-1, and apoptotic signaling in a
TRAF7-dependent manner. Overall, these experiments will allow us to uncover the molecular mechanisms by
which CT224 modulates TRAF7 to promote infection. Elucidating the molecular mechanisms that contribute to
C. trachomatis pathogenesis would allow us to develop more targeted forms of diagnosis and treatment for the
disease and could lead to a vaccine.

## Key facts

- **NIH application ID:** 10141657
- **Project number:** 1F31AI152286-01A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** Clara Herrera
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $41,498
- **Award type:** 1
- **Project period:** 2021-09-01 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10141657

## Citation

> US National Institutes of Health, RePORTER application 10141657, Decoding the role of the C.trachomatis Inclusion membrane protein CT224 and the host ubiquitinligase TRAF7 during infection. (1F31AI152286-01A1). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/10141657. Licensed CC0.

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