First Insights on Organic Cosolvent Effects on FhuA Wildtype and FhuA 忖1-159

作者：Stefanie Joana Tenne; Ulrich Schwaneberg

来源：International Journal of Molecular Sciences, 2012.

DOI：10.3390/ijms13022459

• secondary structure
• circular dichroism
• membrane protein
• organic cosolvent
• &beta
• -barrel
• FhuA
• precipitation
• structural integrity

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 汕-sheets and an internal globular cork domain which acts as an iron transporter. FhuA and the deletion variant FhuA 忖1-159 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 忖1-159 ≒1 vol%). Deconvolution of CD-spectra for FhuA and FhuA 忖1-159 yielded 汕-sheet contents of 61 % (FhuA) and 58% (FhuA 忖1-159). Interestingly, FhuA and FhuA 忖1-159 had comparable 汕-sheet contents in the presence and absence of all three organic cosolvents. Additionally, precipitated FhuA and FhuA 忖1-159 (in 40 vol% C/M or 65 vol% THF) redissolved by supplementing the detergent n-octyl-oligo-oxyethylene (oPOE).