Details

Autor(en) / Beteiligte

• Bao, Xiaofeng
• Nickels, Bryce E.
• Fan, Huizhou

Titel

Chlamydia trachomatis protein GrgA activates transcription by contacting the nonconserved region of σ

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2012-10, Vol.109 (42), p.16870-16875

Ort / Verlag

National Academy of Sciences

Erscheinungsjahr

2012

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• The bacterial RNA polymerase holoenzyme consists of a catalytic core enzyme in complex with a σ factor that is required for promoter-specific transcription initiation. Primary, or housekeeping, σ factors are responsible for most of the gene expression that occurs during the exponential phase of growth. Primary σ factors share four regions of conserved sequence, regions 1-4, which have been further subdivided. Many primary σ factors also contain a nonconserved region (NCR) located between subregions 1.2 and 2.1, which can vary widely in length. Interactions between the NCR of the primary σ factor of Escherichia coli, σ⁷⁰, and the β' subunit of the E. coli core enzyme have been shown to influence gene expression, suggesting that the NCR of primary σ factors represents a potential target for transcription regulation. Here, we report the identification and characterization of a previously undocumented Chlamydia trachomatis transcription factor, designated GrgA (g̱eneral ṟegulator of g̱enes A̲). We demonstrate in vitro that GrgA is a DNA-binding protein that can stimulate transcription from a range of σ⁶⁶-dependent promoters. We further show that GrgA activates transcription by contacting the NCR of the primary σ factor of C. trachomatis, σ⁶⁶. Our findings suggest GrgA serves as an important regulator of σ⁶⁶-dependent transcription in C. trachomatis. Furthermore, because GrgA is present only in chlamydiae, our findings highlight how non-conserved regions of the bacterial RNA polymerase can be targets of regulatory factors that are unique to particular organisms.