Investigation of the POTRA Domains from Cyanobacterial Omp85 by PELDOR Spectroscopy

p { margin-bottom: 0.21cm; } Investigation of the POTRA Domains from Cyanobacterial Omp85 by PELDOR Spectroscopy

Eva-M. Brouwer¹, Maik S. Sommer¹ Reza Dastvan², Sevdalina Lyubenova², Oliver Mirus¹, Thomas F. Prisner²_, Enrico Schleiff¹

Cluster of Excellence Frankfurt, Center for Membrane Proteomics, ¹Department of Biosciences, Molecular Cell Biology of Plants, ²Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany.


Proteins of the Omp85 family are conserved in all kingdoms of life. They mediate protein transport across or protein insertion into membranes and reside in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Omp85 proteins contain a C-terminal transmembrane beta-barrel and a soluble N terminus with a varying number of polypeptide-transport-associated or POTRA domains. Here we investigate Omp85 from the cyanobacterium Anabaena sp. PCC 7120. The crystallographic three-dimensional structure of the N-terminal region shows three POTRA domains, named P1 to P3 from the N terminus. Molecular dynamics simulations revealed a hinge between P1 and P2 but in contrast show that P2 and P3 are fixed in orientation. The P2-P3 arrangement is identical as seen for the POTRA domains from proteobacterial FhaC, suggesting this orientation is a conserved feature. Using site-directed spin labeling we investigate the conformational flexibility between the POTRA domains by PELDOR spectroscopy.