Transcriptional regulation in the hyperthermophilic Pyrococcus furiosus: Coordinated expression of divergently oriented genes in response to beta-linked glucose polymers

The genetic organization, expression, and regulation of the celB locus of t he hyperthermophilic archaeon Pyrococcus furiosus were analyzed. This locus includes the celB gene, which codes for an intracellular beta-glucosidase, and a divergently orientated gene cluster, adhA-adhB-lamA, which codes for two alcohol dehydrogenases and an extracellular beta-1,3-endoglucanase tha t is transcribed as a polycistronic messenger (the lamA operon), During gro wth of P. furiosus on either the beta-1,4-linked glucose dimer cellobiose o r the beta-1,3-linked glucose polymer laminarin, the activities of both bet a-glucosidase and endoglucanase were increased at least fivefold compared w ith levels during growth on maltose or pyruvate, Northern blot analysis rev ealed an enhanced transcription of both the celB gene and the lamA operon i n the presence of these glucose-containing substrates. The in vivo and in v itro transcription initiation sites of both the celB gene and the lamA oper on were identified 25 nucleotides downstream of conserved TATA box motifs, A number of repeating sequences have been recognized in the celB-adhA inter genic region, some of which might he part of a transcriptional regulator-bi nding site.