Identification of XylR, the Activator of Arabinose/Xylose Inducible Regulon in and Its Application for Homologous Protein Expression.

The thermophilic archaeon can use different carbon sources for growth, including the pentoses D-xylose and L-arabinose. In this study, we identified the activator XylR () responsible for the transcriptional regulation of the pentose transporter and pentose metabolizing genes in . A deletion mutant showed growth retardation on D-xylose/L-arabinose containing media and the lack of transcription of the respective ABC transporter. In contrast to so far used promoters for expression in , the xylR responsive promoters have a very low background activity. Finally, two XylR dependent promoters next to the long-established maltose inducible promotor were used to construct a high-throughput expression vector system for to efficiently clone and express proteins in .