PDBsum entry 4jfb

Membrane protein

PDB id: 4jfb

Contents

Protein chains

(+ 0 more) 340 a.a.

PDB id:

4jfb

Name:

Membrane protein

Title:

Crystal structure of ompf in c2 with tncs

Structure:

Outer membrane protein f. Chain: a, b, c, d, e, f. Synonym: outer membrane protein 1a, outer membrane protein b, outer membrane protein ia, porin ompf. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 83333. Strain: k12. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

3.80Å R-factor: 0.264 R-free: 0.314

Authors:

B.Wiseman,A.Kilburg,V.Chaptal,G.C.Reyes-Meija,J.Sarwan,P.Falson, J.M.Jault

Key ref:

B.Wiseman et al. (2014). Stubborn contaminants: influence of detergents on the purity of the multidrug ABC transporter BmrA. PLoS One, 9, e114864. PubMed id: 25517996

Date:

28-Feb-13 Release date: 05-Mar-14

Protein chains

P02931  (OMPF_ECOLI) -  Outer membrane porin F from Escherichia coli (strain K12)

Seq: 362 a.a.

Struc: 340 a.a.

PLoS One 9:e114864 (2014)

PubMed id: 25517996

Stubborn contaminants: influence of detergents on the purity of the multidrug ABC transporter BmrA.

B.Wiseman, A.Kilburg, V.Chaptal, G.C.Reyes-Mejia, J.Sarwan, P.Falson, J.M.Jault.

ABSTRACT

Despite the growing interest in membrane proteins, their crystallization remains a major challenge. In the course of a crystallographic study on the multidrug ATP-binding cassette transporter BmrA, mass spectral analyses on samples purified with six selected detergents revealed unexpected protein contamination visible for the most part on overloaded SDS-PAGE. A major contamination from the outer membrane protein OmpF was detected in purifications with Foscholine 12 (FC12) but not with Lauryldimethylamine-N-oxide (LDAO) or any of the maltose-based detergents. Consequently, in the FC12 purified BmrA, OmpF easily crystallized over BmrA in a new space group, and whose structure is reported here. We therefore devised an optimized protocol to eliminate OmpF during the FC12 purification of BmrA. On the other hand, an additional band visible at ∼110 kDa was detected in all samples purified with the maltose-based detergents. It contained AcrB that crystallized over BmrA despite its trace amounts. Highly pure BmrA preparations could be obtained using either a ΔacrAB E. coli strain and n-dodecyl-β-D-maltopyranoside, or a classical E. coli strain and lauryl maltose neopentyl glycol for the overexpression and purification, respectively. Overall our results urge to incorporate a proteomics-based purity analysis into quality control checks prior to commencing crystallization assays of membrane proteins that are notoriously arduous to crystallize. Moreover, the strategies developed here to selectively eliminate obstinate contaminants should be applicable to the purification of other membrane proteins overexpressed in E. coli.