WXG100 proteins form dimeric complexes, studied using FRET.

<p>(A) Schematic diagram of the FRET experiments. Fluorescence donor, Alexa 488 (green), and fluorescence acceptor, Alexa 647 (red), are represented as stars. The Alexa fluorescence dye-conjugated proteins are indicated after their names along with the type of the Alexa dye, e.g. D-ESAT-6 instead of Alexa 488-ESAT-6. (B) The fluorescence spectra of the labelled proteins in those combinations, which were indicated in the schematic diagram A. Control contains only donor labelled protein (black). The donor/acceptor labelled ESAT-6 shows no FRET signal, also after heat de- and renaturation, indicating no homo-dimer formation (dark green). The donor labelled ESAT-6 and acceptor labelled CFP-10 gives a FRET signal, showing that CFP-10 and ESAT-6 spontaneously form a heterodimer (green). <i>sag</i>EsxA exhibits after initial mixing no FRET, but upon heat de- and renaturation there is reconstitution of FRET pairs (blue). For the FRET measurements the respective samples are mixed equimolar prior the measurements.