title: A regulator from Chlamydia trachomatis modulates the activity of RNA polymerase through direct interaction with the beta subunit and the primary sigma subunit.
abstract: The obligate intracellular human pathogen Chlamydia trachomatis undergoes a complex developmental program involving transition between two forms: the infectious elementary body (EB), and the rapidly dividing reticulate body (RB). However, the regulators controlling this development have not been identified. To uncover potential regulators of transcription in C. trachomatis, we screened a C. trachomatis genomic library for sequences encoding proteins that interact with RNA polymerase (RNAP). We report the identification of one such protein, CT663, which interacts with the beta and sigma subunits of RNAP. Specifically, we show that CT663 interacts with the flap domain of the beta subunit (beta-flap) and conserved region 4 of the primary sigma subunit (sigma(66) in C. trachomatis). We find that CT663 inhibits sigma(66)-dependent (but not sigma(28)-dependent) transcription in vitro, and we present evidence that CT663 exerts this effect as a component of the RNAP holoenzyme. The analysis of C. trachomatis-infected cells reveals that CT663 begins to accumulate at the commencement of the RB-to-EB transition. Our findings suggest that CT663 functions as a negative regulator of sigma(66)-dependent transcription, facilitating a global change in gene expression. The strategy used here is generally applicable in cases where genetic tools are unavailable.
authors: Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
authors: Xiancai
authors: X
authors: Rao
authors: Padraig
authors: P
authors: Deighan
authors: Ziyu
authors: Z
authors: Hua
authors: Xiaomei
authors: X
authors: Hu
authors: Jin
authors: J
authors: Wang
authors: Miao
authors: M
authors: Luo
authors: Jie
authors: J
authors: Wang
authors: Yanmei
authors: Y
authors: Liang
authors: Guangming
authors: G
authors: Zhong
authors: Ann
authors: A
authors: Hochschild
authors: Li
authors: L
authors: Shen
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002692:Chlamydia trachomatis / Q000201:enzymology* / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D015964:Gene Expression Regulation, Bacterial; D012808:Sigma Factor / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit