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Annular lipids linked to flippase activity of a transporter

February 2015. Defining the lipid composition that exists around membrane protein complexes in natural bilayers is a challenging task. Now, key lipids important for the structure and function of an ABC transporter have been revealed by systematically removing layers of lipids, and using mass spectrometry to monitor those that remained closely associated with the membrane protein. 

A team of scientists from Frankfurt and Oxford showed for the heterodimeric ABC transporter TmrAB that the extent of delipidation can be controlled by timed exposure to detergent. The scientists subsequently characterized the cohort of endogenous lipids that were extracted in contact with the membrane protein complex. With prolonged delipidation the number of neutral lipids is reduced in favour of their negatively charged counterparts. Lipid A is retained by the transporter and the extent of its binding decreases during the catalytic cycle, suggesting that lipid A release is linked to adenosine tri-phosphate hydrolysis. The scientists propose that a subset of annular lipids is invariant in composition, with negatively charged lipids binding tightly to TmrAB, implying a role for this exporter in glycolipid translocation. The work has been published in the recent issue of the scientific journal Nature Chemistry. More ...


Commentary in Nature Chemistry's News and Views: Link

Robert Tampé 
Institute of Biochemistry
Goethe-University Frankfurt

Full reference:
Chérine Bechara, Anne Nöll, Nina Morgner, Matteo T. Degiacomi, Robert Tampé & Carol V. Robinson. 2015. A subset of annular lipids is linked to the flippase activity of an ABC transporter. Nature Chemistry, published online 2 February 2015, doi:10.1038/nchem.2172. More ...