First insights on organic cosolvent effects on FhuA wildtype and FhuA ?1-159.

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

SUBMITTER: Tenne SJ 

PROVIDER: S-EPMC3292033 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature