4CTD

X-ray structure of an engineered OmpG loop6-deletion

Summary for 4CTD

• Entry DOI: 10.2210/pdb4ctd/pdb
• Descriptor: OUTER MEMBRANE PROTEIN G, CHLORIDE ION, (HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE (3 entities in total)
• Functional Keywords: transport protein, ion-channel-engineering, porin
• Biological source: ESCHERICHIA COLI K-12
• Cellular location: Cell outer membrane; Multi-pass membrane protein: P76045
• Total number of polymer chains: 2
• Total formula weight: 65538.22

Authors

Grosse, W.,Essen, L.-O. (deposition date: 2014-03-13, release date: 2014-08-13, Last modification date: 2023-12-20)

Primary citation

Grosse, W.,Psakis, G.,Mertins, B.,Reiss, P.,Windisch, D.,Brademann, F.,Burck, J.,Ulrich, A.,Koert, U.,Essen, L.
Structure-Based Engineering of a Minimal Porin Reveals Loop- Independent Channel Closure.
Biochemistry, 53:4826-, 2014

PubMed Abstract: Porins, like outer membrane protein G (OmpG) of Escherichia coli, are ideal templates among ion channels for protein and chemical engineering because of their robustness and simple architecture. OmpG shows fast transitions between open and closed states, which were attributed to loop 6 (L6). As flickering limits single-channel-based applications, we pruned L6 by either 8 or 12 amino acids. While the open probabilities of both L6 variants resemble that of native OmpG, their gating frequencies were reduced by 63 and 81%, respectively. Using the 3.2 Å structure of the shorter L6 variant in the open state, we engineered a minimal porin (220 amino acids), where all remaining extramembranous loops were truncated. Unexpectedly, this minimized porin still exhibited gating, but it was 5-fold less frequent than in OmpG. The residual gating of the minimal pore is hence independent of L6 rearrangements and involves narrowing of the ion conductance pathway most probably driven by global stretching-flexing deformations of the membrane-embedded β-barrel.

PubMed: 24988371
DOI: 10.1021/BI500660Q

Experimental method

X-RAY DIFFRACTION (3.2 Å)