Engineering prokaryotic transcriptional activator XylR as a xylose-inducible biosensor for transcription activation in yeast.

Biosensors regulated by specific substrates are needed to develop genetic tools to meet the needs of engineering microbial cell factories. Here, a xylose-inducible biosensor (Xylbiosensor), comprising the activation factor XylR, fusion activation domain (AD) VPRH, and a hybrid promoter with operator , was established in . Addition of xylose to an engineered strain harboring the Xylbiosensor could trigger significant transcriptional activation of target genes, such as and the xylose utilization gene. Furthermore, a novel promoter Pleu-Pxo-Ptef was developed to construct a bi-directional expression system. The Xylbiosensor showed good portability in , suggesting its potential value in other eukaryotic cells. This study is the first to construct a "turn-on" Xylbiosensor induced by xylose addition based on a prokaryotic activator XylR and eukaryotic universal AD. The Xylbiosensor exhibits potential in pathway engineering for xylose utilization and xylose-derived product biosynthesis in yeast.