# Spore Assembly in Clostridioides difficile

> **NIH NIH R01** · TUFTS UNIVERSITY BOSTON · 2021 · $437,421

## Abstract

Clostridioides difficile is the leading cause of nosocomial infections in the United States and costs
the healthcare system an estimated $5 billion/yr. C. difficile infections are costly and difficult to treat
because they recur at high frequency (~20%). Disease recurrence depends on C. difficile’s ability to form
metabolically dormant spores because they are the transmissive form of this obligate anaerobe. Recent
studies in mice have shown that preventing spore formation can break the damaging cycle of recurrent
infection that characterizes C. difficile disease. While blocking spore formation with cephamycins can
prevent recurrence in mice when combined with vancomycin, the current standard-of-care, cephamycins
can sensitize humans to C. difficile infections by exacerbating gut dysbiosis. Thus, anti-sporulation
therapies that selectively target C. difficile are needed. Developing such therapies, however, will require
a deeper understanding of how C. difficile assembles a spore.
 Cephamycins block spore formation by inhibiting SpoVD, a sporulation-induced penicillin-binding
protein. In Bacillus subtilis, SpoVD works in concert with the SpoVE glycosyltransferase and SpoVB
flippase to synthesize a thick, protective layer of spore peptidoglycan (PG) known as the cortex. While
we confirmed that C. difficile cortex synthesis requires these three factors, we unexpectedly found that C.
difficile SpoVD and SpoVE regulate the earliest stage of spore formation, asymmetric division. We also
identified sporulation-induced, divisome-like proteins that regulate asymmetric division. These results
strongly suggest that C. difficile uses a unique sporulation-induced PG synthesis machine to synthesize
polar septa; this machinery could be selectively targeted to prevent spore formation.
 Our data further suggest that C. difficile uses a distinct PG synthesis machinery to synthesize
medial septa during vegetative cell division because the divisome components we have identified are
dispensable in C. difficile, despite being essential in all other bacteria studied to date. Interestingly,
sporulation-induced SpoVD may modulate vegetative cell division because loss of SpoVD sensitizes C.
difficile to cephamycin antibiotics during broth culture. Based on these findings, this proposal seeks to
determine how C. difficile regulates polar septum formation during sporulation and how it uses some of
these components to enhance C. difficile’s resistance to cell wall antibiotics during vegetative growth.
Completing these aims will define an important new mechanism by which C. difficile assembles
infectious spores, lay the foundation for developing C. difficile-specific anti-sporulation therapies, and
reveal novel mechanisms that contribute to C. difficile’s high level of resistance to cell wall antibiotics.

## Key facts

- **NIH application ID:** 10365431
- **Project number:** 2R01AI122232-07A1
- **Recipient organization:** TUFTS UNIVERSITY BOSTON
- **Principal Investigator:** Aimee Shen
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $437,421
- **Award type:** 2
- **Project period:** 2016-07-14 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10365431

## Citation

> US National Institutes of Health, RePORTER application 10365431, Spore Assembly in Clostridioides difficile (2R01AI122232-07A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10365431. Licensed CC0.

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