Papers in the Biological Sciences
Date of this Version
1999
Citation
Journal of Bacteriology, July 1999, p. 3920–3927 Vol. 181, No. 13
Abstract
The existence of a global gene regulatory system in the hyperthermophilic archaeon Sulfolobus solfataricus is
described. The system is responsive to carbon source quality and acts at the level of transcription to coordinate
synthesis of three physically unlinked glycosyl hydrolases implicated in carbohydrate utilization. The specific
activities of three enzymes, an a-glucosidase (malA), a b-glycosidase (lacS), and an a-amylase, were reduced
4-, 20-, and 10-fold, respectively, in response to the addition of supplementary carbon sources to a minimal
sucrose medium. Western blot analysis using anti-a-glucosidase and anti-b-glycosidase antibodies indicated
that reduced enzyme activities resulted exclusively from decreased enzyme levels. Northern blot analysis of
malA and lacS mRNAs revealed that changes in enzyme abundance arose primarily from reductions in
transcript concentrations. Culture conditions precipitating rapid changes in lacS gene expression were established
to determine the response time of the regulatory system in vivo. Full induction occurred within a single
generation whereas full repression occurred more slowly, requiring nearly 38 generations. Since lacS mRNA
abundance changed much more rapidly in response to a nutrient down shift than to a nutrient up shift,
transcript synthesis rather than degradation likely plays a role in the regulatory response.
Comments
Copyright © 1999, American Society for Microbiology. All Rights Reserved.