Weak pulling forces exerted on Nin-orientated transmembrane segments during co-translational insertion into the inner membrane of Escherichia coli.
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Cymer F, Ismail N, von Heijne G
FEBS Lett. 588 (10) 1930-1934 [2014-05-21; online 2014-04-12]
Transmembrane helices (TMHs) in membrane proteins can be orientated with their N-terminus towards the cytoplasm (Nin), or facing the non-cytoplasmic side (Nout). Most membrane proteins are inserted co-translationally into membranes, aided by Sec-type translocons. Since the final orientation of Nin- and Nout-orientated TMHs differs, they could also interact differently with the translocon and the surrounding membrane during insertion. We measured pulling forces exerted on Nin-orientated TMHs during co-translational insertion into the inner membrane of Escherichia coli. Our results demonstrate that Nin-orientated TMHs experience a weaker pulling force but retain the overall biphasic force profile seen previously for Nout-orientated TMHs (Ismail et al., 2012 [1]).
PubMed 24726730
DOI 10.1016/j.febslet.2014.03.050
Crossref 10.1016/j.febslet.2014.03.050
pii: S0014-5793(14)00269-5