Different Requirements for σ Region 4 in BvgA Activation of the Bordetella pertussis Promoters Pfim3 and PfhaB

JOURNAL OF MOLECULAR BIOLOGY

卷:409

Article

Decker, Kimberly B.¹  Chen, Qing²  Hsieh, Meng-Lun¹  Boucher, Philip²  Stibitz, Scott²  Hinton, Deborah M.¹ 

[1] NIDDK, Gene Express & Regulat Sect, Mol & Cellular Biol Lab, NIH, Bethesda, MD 20892 USA

[2] US FDA, Div Bacterial Parasit & Allergen Prod, Ctr Biol Evaluat & Res, Bethesda, MD 20892 USA

关键词: BvgA;    fim;    sigma;    polymerase;    promoter;   

DOI  :  10.1016/j.jmb.2011.04.017

来源: Elsevier

【 摘 要 】

Bordetella pertussis BvgA is a global response regulator that activates virulence genes, including adhesin-encoding fim3 and fhaB. At the fhaB promoter, P-fhaB, a BvgA binding site lies immediately upstream of the -35 promoter element recognized by Region 4 of the sigma subunit of RNA polymerase (RNAP). We demonstrate that sigma Region 4 is required for BvgA activation of P-fhaB, a hallmark of Class II activation. In contrast, the promoter-proximal BvgA binding site at P-fim3 includes the -35 region, which is composed of a tract of cytosines that lacks specific sequence information. We demonstrate that sigma Region 4 is not required for BvgA activation at P-fim3. Nonetheless, Region 4 mutations that impair its typical interactions with core and with the -35 DNA affect P-fim3 transcription. Hydroxyl radical cleavage using RNAP with sigma D581C-FeBABE positions Region 4 near the -35 region of P-fim3; cleavage using RNAP with alpha 276C-FeBABE or alpha 302C-FeBABE also positions an alpha subunit C-terminal domain within the -35 region, on a different helical face from the promoter-proximal BvgA similar to P dimer. Our results suggest that the -35 region of P-fim3 accommodates a BvgA similar to P dimer, an alpha subunit C-terminal domain, and sigma Region 4. Molecular modeling suggests how BvgA, sigma Region 4, and alpha might coexist within this DNA in a conformation that suggests a novel mechanism of activation. Published by Elsevier Ltd.

【 授权许可】

Free