Nature Communications 5: Article number: 5803 (2015); Published 17 Dec 2014; Updated 3 Feb 2015.

The authors Robert C. Penner and Ebbe S. Andersen were incorrectly omitted from the list of corresponding authors in this Article. The correct information for correspondence is: 'Correspondence and requests for materials should be addressed to R.C.P. (email: rpenner@qgm.au.dk) or to E.S.A. (email: esa@inano.au.dk) or to J.E.A. (email: andersen@qgm.au.dk)'. The Article also contains errors in the labelling of Figs 1 and 2. In Fig. 1a, the labels should read , respectively. In Fig. 2, labels should read , respectively. The correct versions of these figures follow.

figure 1
figure 2