title: Structural plasticity of the Salmonella FliS flagellar export chaperone.
abstract: The Salmonella FliS flagellar export chaperone is a highly α-helical protein. Proteolytic experiments suggest that FliS has a compact core. However, the calorimetric melting profile of FliS does not show any melting transition in the 25-110 °C temperature range. Circular dichroism measurements reveal that FliS is losing its helical structure over a broad temperature range upon heating. These observations indicate that FliS unfolds in a noncooperative way and its native state shows features reminiscent of the molten globule state of proteins possessing substantial structural plasticity. As FliS has several binding partners within the cell, conformational adaptability seems to be an essential requirement to fulfill its multiple roles.
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Ráchel
authors.initials: R
authors.lastname: Sajó
authors.affiliation: Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Tőke
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Hajdú
authors.affiliation: Bio-Nanosystems Laboratory, Research Institute for Chemical and Process Engineering, University of Pannonia, Veszprém, Hungary.
authors.forename: Hajnalka
authors.initials: H
authors.lastname: Jankovics
authors.affiliation: MTA-ELTE NAP B Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Micsonai
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Dobó
authors.affiliation: MTA-ELTE NAP B Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Kardos
authors.affiliation: Bio-Nanosystems Laboratory, Research Institute for Chemical and Process Engineering, University of Pannonia, Veszprém, Hungary.|Institute of Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Vonderviszt
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001692:Biological Transport; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D005407:Flagella / Q000378:metabolism*; D008024:Ligands; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D059748:Proteolysis; D012475:Salmonella / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D020860:Subtilisin / Q000378:metabolism; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D018832:Molecular Chaperones; C076734:FliS protein, Bacteria; D014357:Trypsin; D020860:Subtilisin
keywords: FliS; atypical molten globule; flagellar export chaperone; flagellar export system; noncooperative unfolding