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

Abstract

The thermophilic archaeon <i>Sulfolobus acidocaldarius</i> can use different carbon sources for growth, including the pentoses D-xylose and L-arabinose. In this study, we identified the activator XylR (<i>saci_2116</i>) responsible for the transcriptional regulation of the pentose transporter and pentose metabolizing genes in <i>S. acidocaldarius</i>. A <i>xylR</i> 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 <i>S. acidocaldarius</i>, 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 <i>S. acidocaldarius</i> to efficiently clone and express proteins in <i>S. acidocaldarius</i>.