The glucose effect and regulation of alpha-amylase synthesis in the hyperthermophilic archaeon Sulfolobus solfataricus

An alpha-amylase was purified from culture supernatants of Sulfolobus solfataricus 98/2 during growth on starch as the sole carbon and energy source. The enzyme is a homodimer with a subunit mass of 120 kDa. It catalyzes the hydrolysis of starch, dextrin, and alpha-cyclodextrin with similar efficiencies, Addition of exogenous glucose represses production of alpha-amylase, demonstrating that a classical glucose effect is operative in this organism, Synthesis of [S-35]-alpha-amylase protein is also subject to the glucose effect, alpha-Amylase is constitutively produced at low levels but can be induced further by starch addition, The absolute levels of alpha-amylase detected in culture supernatants varied greatly with the type of sole carbon source used to support growth. Aspartate was identified as the most repressing sole carbon source for alpha-amylase production, while glutamate was the most derepressing. The pattern of regulation of cw-amylase production seen in this organism indicates that a catabolite repression-like system is present in a member of the archaea.