Table 1A.

C. trachomatis transcription factors and their function.

Transcription Factor	Activation in Developmental Cycle	Function	References
Euo	Early – immediately post-entry of EB	Repressor of late gene expression for differentiation into EB during early stages.	(Li et al., 1998; Wurihan et al., 2021)
GrgA	Early	Activates transcription for euo and hcrA through interaction with σ66 and σ28 promoters.	(Bao et al., 2012; Wurihan et al., 2021)
HrcA	Late	Conserved regulator of late gene expression of molecular chaperone proteins (e.g. dnaK and groE operons).	(Wilson and Tan, 2002; Nicholson et al., 2003; Wurihan et al., 2021)
TrpR	Throughout	Negative regulator of tryptophan synthetase (trpBA) gene expression.	(Akers and Tan, 2006; Carlson et al., 2006)
ChxR	Mid-cycle	Conserved regulator of signal transduction responses.	(Koo et al., 2006; Barta et al., 2014; Yang et al., 2017)
ArgR (Arginine-dependent gene regulator R)	Mid- to late-cycle	Regulates bacterial arginine biosynthesis and transport.	(Schaumburg and Tan, 2006)
NrdR	Mid- to late-cycle	Regulates ribonuclease reductase transcription, dependent on intracellular nucleotide levels.	(Kolberg et al., 2004; Case et al., 2011)
CtcC (AtoC)	Late (transition from RB to EB)	Predicted σ54 RNA polymerase holoenzyme activator to regulate phenotype differentiation and hrcA.	(Koo and Stephens, 2003; Soules et al., 2020; Huang et al., 2022)
YtgR	Throughout	Iron-dependent transcriptional repressor regulator (ytg operon) and tryptophan salvage pathway.	(Akers et al., 2011; Thompson et al., 2012; Pokorzynski et al., 2019)
DksA	Late (transition from RB to EB)	Transcription “late” gene regulator responding to environmental “stress” stimuli.	(Mandel et al., 2022)