The linker pivot in Ci-VSP: the key to unlock catalysis.
In the voltage-sensitive phosphatase Ci-VSP, conformational changes in the transmembrane voltage sensor domain (VSD) are transduced to the intracellular catalytic domain (CD) leading to its dephosphorylation activity against membrane-embedded phosphoinositides. The linker between both domains is proposed to be crucial for the VSD-CD coupling. With a combined approach of electrophysiological measurements on Xenopus oocytes and molecular dynamics simulations of a Ci-VSP model embedded in a lipid bilayer, we analyzed how conformational changes in the linker mediate the interaction between the CD and the activated VSD. In this way, we identified specific residues in the linker that interact with well-defined amino acids in one of the three loops forming the active site of the protein, named TI loop. With our results, we shed light into the early steps of the coupling process between the VSD and the CD, which are based on fine-tuned electrostatic and hydrophobic interactions between the linker, the membrane and the CD.
Institute of Chemistry, Max-Volmer-Laboratory of Biophysical Chemistry, Technische Universität Berlin, Berlin, Germany. kirstin.hobiger@tu-berlin.de
Kirstin
K
Hobiger
Tillmann
T
Utesch
Maria Andrea
MA
Mroginski
Guiscard
G
Seebohm
Thomas
T
Friedrich
D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D007700:Kinetics; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D016415:Sequence Alignment; D014981:Xenopus
C509671:voltage-sensor-containing phosphatase, Ciona intestinalis; D010744:Phosphoric Monoester Hydrolases