title: Sensory domain contraction in histidine kinase CitA triggers transmembrane signaling in the membrane-bound sensor.
abstract: Bacteria use membrane-integral sensor histidine kinases (HK) to perceive stimuli and transduce signals from the environment to the cytosol. Information on how the signal is transmitted across the membrane by HKs is still scarce. Combining both liquid- and solid-state NMR, we demonstrate that structural rearrangements in the extracytoplasmic, citrate-sensing Per-Arnt-Sim (PAS) domain of HK CitA are identical for the isolated domain in solution and in a longer construct containing the membrane-embedded HK and lacking only the kinase core. We show that upon citrate binding, the PAS domain contracts, resulting in a shortening of the C-terminal β-strand. We demonstrate that this contraction of the PAS domain, which is well characterized for the isolated domain, is the signal transmitted to the transmembrane (TM) helices in a CitA construct in liposomes. Putting the extracytoplasmic PAS domain into context of the membrane-embedded CitA construct slows down citrate-binding kinetics by at least a factor of 60, confirming that TM helix motions are linked to the citrate-binding event. Our results are confirmation of a hallmark of the HK signal transduction mechanism with atomic resolution on a full-length construct lacking only the kinase core domain.
authors.affiliation: Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Gottingen, Germany.
authors.forename: Michele
authors.initials: M
authors.lastname: Salvi
authors.affiliation: Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Gottingen, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schomburg
authors.affiliation: Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Gottingen, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Giller
authors.affiliation: Institute for Microbiology and Wine Research, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Graf
authors.affiliation: Institute for Microbiology and Wine Research, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Unden
authors.affiliation: Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Gottingen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Becker
authors.affiliation: Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Gottingen, Germany; cigr@nmr.mpibpc.mpg.de alange@fmp-berlin.de.
authors.forename: Adam
authors.initials: A
authors.lastname: Lange
authors.affiliation: Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Gottingen, Germany; cigr@nmr.mpibpc.mpg.de alange@fmp-berlin.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Griesinger
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D019343:Citric Acid / Q000737:chemistry / Q000378:metabolism; D056506:Geobacillus; D000071677:Histidine Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D008958:Models, Molecular; D008968:Molecular Conformation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D019343:Citric Acid; D000071677:Histidine Kinase
keywords: histidine sensor kinase; integrated structural biology; solid-state NMR spectroscopy; transmembrane receptors; transmembrane signaling