A03: Functional state modulation of membrane proteins by dynamic association and dissociation

The central question we intend to investigate is how dynamic association and dissociation modulates the functional state of membrane proteins under the condition of conserving their molecular identity. We will address this question on two systems, I) molecular components central for ethylene perception in plants, which are located at the ER and Golgi membranes, and II) PlbF, a novel phospholipase A from P. aeruginosa suggested to be a virulence factor, which is anchored in the inner bacterial membrane and exposed to the periplasm. In both cases, (multi)membrane systems play a crucial role for spatial coordination of dynamic association and dissociation. By molecular simulation and modeling studies at an atomic level in close connection with experimental validation studies, we intend to provide insights on I) the role and transport of the copper cofactor for ethylene receptor biogenesis and ethylene perception in plants and II) the molecular mechanism of monomerization/dimerization-dependent PlbF activation. As for both systems either almost none or only static atomic-level information is available, it is mandatory to develop a conceptual framework of adequate computational approaches and high-content experimental platforms in the course of the investigations. The two systems are paradigmatic for addressing the central question that way, also with respect to other systems investigated within the CRC.

Figure 1: (A) Genetically defined pathway for eth-ylene signal transduction (adapted from ref. 1). (B) Model of the ETR1 dimer (center), with a schematic representation of the N-terminal half (blue: TM region; yellow: GAF do-main) and a composite structural model in the C-terminal half (green: dimerization histidine phosphotransfer domain from ERS1 (PDB code 4MTX); blue: catalytic ATP-binding domain from ETR1 (4PL9); orange: receiver domain from ETR1 (1DCF); adapted from ref. 5); the proposed ethylene bind-ing site is marked in magenta. Components suggested to be involved in copper transport to ETR1 are sche-matically represented. Red dotted lines to the faint ETR1 dimer on the right indicate putative protein-protein interactions upon receptor clustering.
Figure 2: (A) Crystal structure of the PlbF dimer with the TM domain col-ored blue, the catalytic phospholipase domain green, and the all-?-helical domain grey. Carbon at-oms of fatty acids are colored orange and those of OG dark blue.(B) Overlay of chains A and B from the dimer structure based on the membrane position suggested by OPM. (C) Orientation of a monomer as suggested by OPM. Grey dots depict the membrane position suggested by OPM; magenta boxes depict the active site tunnel.

Project leader:
Prof. Dr. Holger Gohlke, undefined email,
                        undefinedInstitute of Pharmaceutical and Medicinal Chemistry

Researchers: Sabahuddin Ahmad , undefined Email
                        Stephan Schott-Verdugo, undefined email

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