Coiled-Coil Antagonism Regulates Activity of Venus Flytrap-Domain-Containing Sensor Kinases of the BvgS Family

Abstract

Bordetella pertussis controls the expression of its virulence regulon through the two-component system BvgAS. BvgS is a prototype for a family of multidomain sensor kinases. In BvgS, helical linkers connect periplasmic Venus flytrap (VFT) perception domains to a cytoplasmic Per-Arnt-Sim (PAS) domain and the PAS domain to the dimerization/histidine phosphotransfer (DHp) domain of the kinase. The two linkers can adopt coiled-coil structures but cannot do so simultaneously. The first linker forms a coiled coil in the kinase mode and the second in the phosphatase mode, with the other linker in both cases showing an increase in dynamic behavior. The intervening PAS domain changes its quaternary structure between the two modes. In BvgS homologues without a PAS domain, a helical “X” linker directly connects the VFT and DHp domains. Here, we used BvgS as a platform to characterize regulation in members of the PAS-less subfamily. BvgS chimeras of homologues with natural X linkers displayed various regulation phenotypes. We identified two distinct coiled-coil registers in the N- and C-terminal portions of the X linkers. Stable coil formation in the C-terminal moiety determines the phosphatase mode, similarly to BvgS; in contrast, coil formation in the N-terminal moiety along the other register leads to the kinase mode. Thus, antagonism between two registers in the VFT-DHp linker forms the basis for activity regulation in the absence of the PAS domain. The N and C moieties of the X linker play roles similar to those played by the two independent linkers in sensor kinases with a PAS domain, providing a unified mechanism of regulation for the entire family.

Insights into histidine kinase activation mechanisms from the monomeric blue light sensor EL346

“…The HDX-MS data presented here are completely consistent with this model, with DHpL helices α1 and α2 both showing increased exchange and presumably detachment from the LOV surface in enzymatically active states generated by illumination or point mutation. These data complement previous findings of changes in stability of helical domains N-terminal to signaling kinases-from destabilization of helices leading into DHp domains correlated with higher kinase activity in the dimeric transmembrane HKs DesK and BvgS (41)(42)(43) to increased stability in the helical domains of cytosolic fragments of EnvZ (44) and the Asp receptor (45). The implication of this structural rearrangement in activation across HKs with different sensor domains and oligomeric states strongly argues for a conserved universal role of changes in DHp helix stability in activation.…”

A Novel Bvg-Repressed Promoter Causes vrg -Like Transcription of fim3 but Does Not Result in the Production of Serotype 3 Fimbriae in Bvg − Mode Bordetella pertussis

“…Transcription of bvgR is activated directly by BvgA~P binding to the promoter PbvgR (18). Somewhat atypically compared to other twocomponent sensor kinases, BvgS appears to be turned on, i.e., actively phosphorylating BvgA, in the absence of specific signals, with recent elegant biochemical, structural, and genetic studies supporting this view (19)(20)(21)(22)(23)(24)(25). However, BvgS can be turned off by addition of compounds such as MgSO 4 or nicotinic acid to the growth medium or by culture at lower temperatures (25°C), resulting in the Bvg Ϫ mode, a phenomenon known as modulation (26).…”

Distinct virulence ranges for infection of mice by Bordetella pertussis revealed by engineering of the sensor-kinase BvgS

“…However, a sizeable proportion of BvgS homologs are devoid of a PAS domain and flanking linkers. Instead, a two-helix linker called the linker X directly connects the transmembrane segment to the DHp domain [ 20 ]. The two-helix linkers form coiled coils that regulate the BvgS enzymatic activity [ 18 , 19 ].…”

“…The two-helix linkers form coiled coils that regulate the BvgS enzymatic activity [ 18 , 19 ]. We have built several chimeras by replacing the region between the TM and DHp domains of BvgS with those from homologs devoid of PAS domain [ 18 , 20 ]. Among the various regulation phenotypes of those chimeras, that of the so-called BvgS Δ65 is inverted relative to that of BvgS [ 20 ].…”

“…We have built several chimeras by replacing the region between the TM and DHp domains of BvgS with those from homologs devoid of PAS domain [ 18 , 20 ]. Among the various regulation phenotypes of those chimeras, that of the so-called BvgS Δ65 is inverted relative to that of BvgS [ 20 ]. Thus, BvgS Δ65 shows low kinase activity at the basal state, most likely corresponding to the Bvg i phase, while chemical modulation or closure of the VFT1 domains triggers a large increase of kinase activity, shifting the bacteria to the Bvg + phase [ 20 ].…”