Signaling States of a Short Blue-Light Photoreceptor Protein PpSB1-LOV Revealed from Crystal Structures and Solution NMR Spectroscopy.
Light-Oxygen-Voltage (LOV) domains represent the photo-responsive domains of various blue-light photoreceptor proteins and are widely distributed in plants, algae, fungi, and bacteria. Here, we report the dark-state crystal structure of PpSB1-LOV, a slow-reverting short LOV protein from Pseudomonas putida that is remarkably different from our previously published "fully light-adapted" structure [1]. A direct comparison of the two structures provides insight into the light-activated signaling mechanism. Major structural differences involve a~11Å movement of the C terminus in helix Jα, ~4Å movement of Hβ-Iβ loop, disruption of hydrogen bonds in the dimer interface, and a~29° rotation of chain-B relative to chain-A as compared to the light-state dimer. Both crystal structures and solution NMR data are suggestive of the key roles of a conserved glutamine Q116 and the N-cap region consisting of A'α-Aβ loop and the A'α helix in controlling the light-activated conformational changes. The activation mechanism proposed here for the PpSB1-LOV supports a rotary switch mechanism and provides insights into the signal propagation mechanism in naturally existing and artificial LOV-based, two-component systems and regulators.
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany.
Katrin
K
Röllen
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany.
Joachim
J
Granzin
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany.
Vineet
V
Panwalkar
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany.
Vladimir
V
Arinkin
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany.
Raj
R
Rani
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany.
Rudolf
R
Hartmann
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany.
Ulrich
U
Krauss
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany; Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52426, Jülich, Germany.
Karl-Erich
KE
Jaeger
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany; Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, D-40225, Düsseldorf, Germany.
Dieter
D
Willbold
Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany. Electronic address: r.batra-safferling@fz-juelich.de.
Renu
R
Batra-Safferling
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D055537:Light Signal Transduction; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008958:Models, Molecular; D011487:Protein Conformation; D016958:Pseudomonas putida / Q000201:enzymology*
D001426:Bacterial Proteins
Dimerization; LOV domain; PAS domain; Photocycle; Signaling