Differential binding of BvgA to two classes of virulence genes of Bordetella pertussis directs promoter selectivity by RNA polymerase

Abstract

Transcription of virulence genes of Bordetella pertussis is co-ordinately regulated by the BvgA and BvgS proteins, which are members of the two-component family of bacterial signal-transduction proteins. BvgS is the transmembrane sensor and BvgA the transcriptional regulator. By gel mobility shift assays we demonstrate that phosphorylated BvgA (BvgA approximately P) forms distinct complexes with the filamentous haemagglutinin (PFHA) promoter DNA at different BvgA approximately P: DNA ratios. DNase I protection analyses show that phosphorylation of BvgA not only enhances affinity of the protein for the binding sites of the PFHA and bvgP1 promoters, but it extends significantly the bound region towards position -35 of these promoters. Conversely, a 10-fold higher amount of BvgA approximately P is required for binding to a large DNA region, from -168 to -60, of the pertussis toxin (Ptox) promoter sequence. These findings suggest that the molecular interaction of BvgA approximately P with the Ptox promoter is different from its interaction with the PFHA and bvgP1 promoters. The sigma 70 Escherichia coli RNA polymerase (RNP) does not bind to the bvg-regulated promoters. However, following the formation of a BvgA approximately P-promoter complex, the E. coli RNP specifically recognizes and binds to the bvg-regulated promoters. Thus, BvgA approximately P exerts its action at the level of promoter recognition by directing promoter selectivity by RNP.

The ChrA Response Regulator in Corynebacterium diphtheriae Controls Hemin-Regulated Gene Expression through Binding to the hmuO and hrtAB Promoter Regions

“…Previous studies established that RNA polymerase has an effect on the binding pattern of the B. pertussis response regulator BvgA at the fhA and ptx promoters (9,48). BvgA and ChrA are both members of the NarL family of response regulators.…”

The Bordetella pertussis model of exquisite gene control by the global transcription factor BvgA

“…For most of the B. pertussis virulence gene promoters, the binding site for the downstream-most BvgA~P dimer is located near the -35 region of the promoter, in a position to interact with s and/or aCTD, as in class II activation, while the upstream binding sites could interact with the other aCTD, as in class I (Boucher & Stibitz, 1995;Boucher et al, 1997Boucher et al, , 2001Karimova et al, 1996;Karimova & Ullmann, 1997;Kinnear et al, 1999;Merkel et al, 2003;Zu et al, 1996). Consistent with a combination class I/II (Fig.…”

“…For example, NarL does not detectably bind DNA unless it is phosphorylated (Proulx et al, 2002). In contrast, unphosphorylated BvgA has been shown to bind DNA (Boucher et al, 1994(Boucher et al, , 1997Karimova et al, 1996;Zu et al, 1996; K. B. Decker, unpublished data). In addition, BvgA~P binds to virulence gene promoters with greater affinity and in at least one case, in a different binding pattern than does BvgA (Boucher et al, 1994(Boucher et al, , 1997Boucher & Stibitz, 1995;Karimova et al, 1996;Steffen et al, 1996;Zu et al, 1996; K. B. Decker, unpublished data).…”

Backbone Dynamics of an Atypical Orphan Response Regulator Protein, Helicobacter pylori 1043

“…Other RRs, such as PhoP or BvgV, could bind to DNA without unphosphorylation events (Boucher et al, 1997;Liu and Hulett, 1997;Zu et al, 1996); however, the affinity of DNA binding was increased by phosphorylation. The signature "switch" residues involved in rearrangements associated with phosphorylation are Ser 75 and Tyr 94 in HP-RR, located in the β4-α4 loop and β5 region, respectively.…”

“…Recent studies have already proposed that the HP-RR is capable of specific binding to its target genes without phosporylation (Müller et al, 2007;Schär et al, 2005). Other RRs, such as PhoP or BvgV, are able to bind to DNA without phosphorylation (Boucher et al, 1997;Liu and Hulett, 1997;Zu et al, 1996); however, the affinity of DNA binding is increased by phosphorylation. Surprisingly, HP-RR lacks the conserved phosphrylation site which corresponds to Asp 57 in Escherichia coli CheY and, instead, avidly binds its own promoter sequence without phosphorylation.…”