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First Insights on Organic Cosolvent Effects on FhuA Wildtype and FhuA Δ1-159
Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringer Weg 1, Aachen, D-52074, Germany
* Author to whom correspondence should be addressed.
Received: 6 January 2012; in revised form: 9 February 2012 / Accepted: 13 February 2012 / Published: 22 February 2012
Abstract: Circular dichroism (CD) and deconvolution were used to study the structural integrity of a “plugged” and an “open” FhuA transmembrane channel protein in the presence of varied concentrations of tetrahydrofuran (THF), ethanol (EtOH) and chloroform/methanol (C/M). FhuA is an Escherichia coli outer membrane protein (78.9 kDa) consisting of 22 β-sheets and an internal globular cork domain which acts as an iron transporter. FhuA and the deletion variant FhuA Δ1-159 showed comparable and remarkable resistance in the presence of THF (≤40 vol%) and EtOH (≤10 vol%). In C/M, significant differences in structural resistance were observed (FhuA stable ≤10 vol%; FhuA Δ1-159 ≤1 vol%). Deconvolution of CD-spectra for FhuA and FhuA Δ1-159 yielded β-sheet contents of 61 % (FhuA) and 58% (FhuA Δ1-159). Interestingly, FhuA and FhuA Δ1-159 had comparable β-sheet contents in the presence and absence of all three organic cosolvents. Additionally, precipitated FhuA and FhuA Δ1-159 (in 40 vol% C/M or 65 vol% THF) redissolved by supplementing the detergent n-octyl-oligo-oxyethylene (oPOE).
Keywords: secondary structure; circular dichroism; membrane protein; organic cosolvent; β-barrel; FhuA; precipitation; structural integrity
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Tenne, S.-J.; Schwaneberg, U. First Insights on Organic Cosolvent Effects on FhuA Wildtype and FhuA Δ1-159. Int. J. Mol. Sci. 2012, 13, 2459-2471.
Tenne S-J, Schwaneberg U. First Insights on Organic Cosolvent Effects on FhuA Wildtype and FhuA Δ1-159. International Journal of Molecular Sciences. 2012; 13(2):2459-2471.
Tenne, Stefanie-Joana; Schwaneberg, Ulrich. 2012. "First Insights on Organic Cosolvent Effects on FhuA Wildtype and FhuA Δ1-159." Int. J. Mol. Sci. 13, no. 2: 2459-2471.