Investigating the Function of the Transcription Elongation Factor, GreA, in Chlamydia trachomatis Growth and Development

Author

Abigail R. Swoboda, University of Nebraska at OmahaFollow
Scot P. Ouellette, University of Nebraska Medical CenterFollow

Author ORCID Identifier

https://orcid.org/0009-0002-2799-6787

Month/Year of Graduation

5-2024

Degree Name

Bachelor of Science (B.S.)

Department

Biology

First Advisor

Scot Ouellette

Abstract

The obligate intracellular pathogen, Chlamydia trachomatis (Ctr), undergoes a complex developmental cycle where the bacterium differentiates between two functionally and morphologically distinct forms: the elementary body (EB) and the reticulate body (RB). The EB is the smaller, infectious, and non-dividing form that initiates infection of a host cell whereas the RB is the larger and non-infectious form that replicates within a membrane-bound vesicle termed an inclusion. The mechanism(s) underlying transcriptional changes in the developmental forms remains poorly understood but is important for understanding how Ctr transitions between EBs and RBs. GreA is a transcription elongation factor, which executes anti-arrest activity to restore RNA polymerase transcription elongation. Although chlamydial GreA is homologous to canonical GreAs, it possesses an unusually extended N-terminus region of unknown function. We hypothesize that the Ctr greA gene is expressed as two distinct products that may contribute to developmental progression. To test this, we investigated the impact on Ctr growth and development of (i) expressing different isoforms of the greA gene and (ii) altering GreA expression. By assessing bacterial morphology and infectious progeny production, we found that overexpression of the GreA N-terminus and CRISPRi-mediated knockdown of greA 5’ or greA 3’ elicited negative impacts on Ctr development. The growth defect during greA 5’ knockdown was partially complemented by expression of full-length GreA whereas greA 3’ knockdown was partially restored by GreA C-terminal domain complementation. We also observed evidence for an internal promoter that drives expression of the C-terminus alone, suggesting that the greA gene may be transcribed as two separate gene products. These data implicate the annotated GreA open reading frame as essential for Ctr growth and development.

Recommended Citation

Swoboda, Abigail R. and Ouellette, Scot P., "Investigating the Function of the Transcription Elongation Factor, GreA, in Chlamydia trachomatis Growth and Development" (2024). Theses/Capstones/Creative Projects. 324.
https://digitalcommons.unomaha.edu/university_honors_program/324