3d9b

Publication Abstract from PubMed

In the course of a crystallographic study of the Methanosarcina mazei CorA transporter, the membrane protein was obtained with at least 95% purity and was submitted to crystallization trials. Small crystals (<100 microm) were grown that diffracted to 3.42 A resolution and belonged to space group R32, with unit-cell parameters a = b = 145.74, c = 514.0 A. After molecular-replacement attempts using available CorA structures as search models failed to yield a solution, it was discovered that the crystals consisted of an Escherichia coli contaminating protein, acriflavine resistance protein B (AcrB), that was present at less than 5% in the protein preparations. AcrB contamination is a major problem when expressing membrane proteins in E. coli since it binds naturally to immobilized metal-ion affinity chromatography (IMAC) resins. Here, the structure is compared with previously deposited AcrB structures and strategies are proposed to avoid this contamination.

There is a baby in the bath water: AcrB contamination is a major problem in membrane-protein crystallization.,Veesler D, Blangy S, Cambillau C, Sciara G Acta Crystallogr Sect F Struct Biol Cryst Commun. 2008 Oct 1;64(Pt 10):880-5., Epub 2008 Sep 30. PMID:18931428^[4]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.