Superfolder mTurquoise2ox optimized for the bacterial periplasm allows high efficiency in vivo FRET of cell division antibiotic targets

What is it about?

The periplasmic space of Gram-negative bacteria contains many regulatory, transport and cell wall maintaining proteins. A preferred method to investigate these proteins in vivo is by the detection of fluorescent protein fusions. This is challenging since most fluorescent proteins do not fluoresce in the oxidative environment of the periplasm. We assayed popular fluorescent proteins for periplasmic functionality and describe key factors responsible for periplasmic fluorescence. Using this knowledge, we engineered superfolder mTurquoise2ox (sfTq2ox), a new cyan fluorescent protein capable of bright fluorescence from the periplasm. We show that our improvements come without a trade-off from its parent mTurquoise2. Employing sfTq2ox as FRET donor we show the direct in vivo interaction and disruption of unique periplasmic antibiotic targets FtsB and FtsL.

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