The amino terminal end of different S. pneumoniae proteins ensures expression of the Citrine fluorescent signal when a conserved LE motif is present.

(Left panel) Sequence of the first aminoacids of proteins WchA, MurM, MurN, Wze and Wzd that were linked to Citrine (shown as a white rectangle) are shown. Highlighted (black) are the conserved aminoacids L (leucine) and E (glutamic acid). (Right panel) Median fluorescence, with 25% and 75% inter-quartile range (black lines) of the fluorescence signal detected in S. pneumoniae R36A unencapsulated bacteria, in arbitrary units (A. U.), emitted by Citrine (BCSMH033), WchA_(1-10)-Citrine (BCSMH063), MurM_(1-10)-Citrine (BCSJC012), MurN_(1-10)-Citrine (BCSJC013), Wze_(1-10)-Citrine (BCSJC001) and Wzd_(1-10)-Citrine (BCSJC011). At least 100 cells of each strain were quantified. Representative images of each strain are shown. Scale bar: 1 µm.