Cell-free synthesis and folding of transmembrane OmpA reveals higher order structures and premature truncations

TY - JOUR

T1 - Cell-free synthesis and folding of transmembrane OmpA reveals higher order structures and premature truncations

AU - Debnath, Dilip K

AU - Otzen, Daniel E

N1 - Copyright © 2010 Elsevier B.V. All rights reserved.

PY - 2010/11/1

Y1 - 2010/11/1

N2 - We use a cell-free transcription-translation system to monitor the effect of different lipids on the synthesis and folding of the transmembrane domain of the outer membrane protein OmpA from E. coli under physiological conditions. Folding is consistent with previous observations made in vitro at high pH. Synthesis and folding yields are optimal in phosphocholine lipids, particularly in short chain lipids and small vesicles, while lipid rafts do not promote folding compared to the folding in the absence of lipids. Truncated species are observed during translation in the presence of the periplasmic chaperone Skp, which likely binds to the newly synthesized polypeptide chain during cell-free translation and thus prematurely terminate polypeptide chain synthesis. In contrast, folded and unfolded dimers of OmpA correlate negatively with folding yields. This suggests that dimer formation competes with folding and insertion of monomeric OmpA, though folded dimers slowly appear to convert to folded monomers.

AB - We use a cell-free transcription-translation system to monitor the effect of different lipids on the synthesis and folding of the transmembrane domain of the outer membrane protein OmpA from E. coli under physiological conditions. Folding is consistent with previous observations made in vitro at high pH. Synthesis and folding yields are optimal in phosphocholine lipids, particularly in short chain lipids and small vesicles, while lipid rafts do not promote folding compared to the folding in the absence of lipids. Truncated species are observed during translation in the presence of the periplasmic chaperone Skp, which likely binds to the newly synthesized polypeptide chain during cell-free translation and thus prematurely terminate polypeptide chain synthesis. In contrast, folded and unfolded dimers of OmpA correlate negatively with folding yields. This suggests that dimer formation competes with folding and insertion of monomeric OmpA, though folded dimers slowly appear to convert to folded monomers.

KW - Bacterial Outer Membrane Proteins

KW - Carrier Proteins

KW - Cell Membrane

KW - Cell-Free System

KW - DNA-Binding Proteins

KW - Escherichia coli

KW - Escherichia coli Proteins

KW - Hydrogen-Ion Concentration

KW - Molecular Chaperones

KW - Peptidylprolyl Isomerase

KW - Phosphatidylcholines

KW - Protein Folding

KW - Unilamellar Liposomes

U2 - 10.1016/j.bpc.2010.08.003

DO - 10.1016/j.bpc.2010.08.003

M3 - Journal article

C2 - 20813447

SN - 1057-8943

VL - 152

SP - 80

EP - 88

JO - Advances in Biophysical Chemistry

JF - Advances in Biophysical Chemistry

IS - 1-3

ER -