Transcriptional Regulation in the Hyperthermophilic Archaeon Pyrococcus furiosus : Coordinated Expression of Divergently Oriented Genes in Response to β-Linked Glucose Polymers

Abstract

ABSTRACT The genetic organization, expression, and regulation of the celB locus of the hyperthermophilic archaeon Pyrococcus furiosus were analyzed. This locus includes the celB gene, which codes for an intracellular β-glucosidase, and a divergently orientated gene cluster, adhA-adhB-lamA , which codes for two alcohol dehydrogenases and an extracellular β-1,3-endoglucanase that is transcribed as a polycistronic messenger (the lamA operon). During growth of P. furiosus on either the β-1,4-linked glucose dimer cellobiose or the β-1,3-linked glucose polymer laminarin, the activities of both β-glucosidase and endoglucanase were increased at least fivefold compared with levels during growth on maltose or pyruvate. Northern blot analysis revealed an enhanced transcription of both the celB gene and the lamA operon in the presence of these glucose-containing substrates. The in vivo and in vitro transcription initiation sites of both the celB gene and the lamA operon were identified 25 nucleotides downstream of conserved TATA box motifs. A number of repeating sequences have been recognized in the celB-adhA intergenic region, some of which might be part of a transcriptional regulator-binding site.