title: First insights on organic cosolvent effects on FhuA wildtype and FhuA Δ1-159.
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).
authors.affiliation: Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringer Weg 1, Aachen, D-52074, Germany.
authors.forename: Stefanie-Joana
authors.initials: SJ
authors.lastname: Tenne
authors.affiliation: Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringer Weg 1, Aachen, D-52074, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schwaneberg
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics; D002725:Chloroform / Q000494:pharmacology; D002942:Circular Dichroism; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics; D000431:Ethanol / Q000494:pharmacology; D005663:Furans / Q000494:pharmacology; D017353:Gene Deletion; D000432:Methanol / Q000494:pharmacology; D050505:Mutant Proteins / Q000737:chemistry / Q000187:drug effects; D009930:Organic Chemicals / Q000494:pharmacology*; D017433:Protein Structure, Secondary / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D012997:Solvents / Q000494:pharmacology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; C050900:FhuA protein, E coli; D005663:Furans; D050505:Mutant Proteins; D009930:Organic Chemicals; D012997:Solvents; D000431:Ethanol; C018674:tetrahydrofuran; D002725:Chloroform; D000432:Methanol