Abstract
The thermophilic archaeon Sulfolobus acidocaldarius can use different carbon sources for growth, including the pentoses D-xylose and L-arabinose. In this study, we identified the activator XylR (saci_2116) responsible for the transcriptional regulation of the pentose transporter and pentose metabolizing genes in S. acidocaldarius. A xylR 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 S. acidocaldarius, 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 S. acidocaldarius to efficiently clone and express proteins in S. acidocaldarius.
Highlights
Metabolically less versatile than Saccharolobus solfataricus, the thermophilic archaeon S. acidocaldarius grows on different sugar substrates, including dextrin, sucrose, D-glucose, D-xylose, and L-arabinose (Grogan, 1989; Hatzinikolaou et al, 2001)
We identified a positive regulator responsible for controlling the expression of the genes involved in pentose import as well as pentose degradation in S. acidocaldarius: XylR
Based on the data presented in this paper, we propose that XylR is an activator that binds the Ara-box in the promotor region of genes involved in pentose uptake and degradation
Summary
Metabolically less versatile than Saccharolobus solfataricus, the thermophilic archaeon S. acidocaldarius grows on different sugar substrates, including dextrin, sucrose, D-glucose, D-xylose, and L-arabinose (Grogan, 1989; Hatzinikolaou et al, 2001). The transporter responsible for pentose uptake in S. acidocaldarius was identified: XylF (saci_2122), XylG (saci_2121), XylH (saci_2120) (Wagner et al, 2018). The pentose metabolizing genes involved in the aldolase independent Weimberg pathway were characterized. Our studies demonstrated that S. acidocaldarius strain MW001 utilizes only the Weimberg pathway and not the aldolase-dependent Dahms pathway (Wagner et al, 2018). Previous 13C labeling studies in S. acidocaldarius (DSM 639) grown on D-xylose revealed that both routes, the Weimberg and Dahms pathway, are operative in vivo at similar ratios (Nunn et al, 2010)
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