Biotechnologically Relevant Enzymes and Proteins

Applied Microbiology and Biotechnology

, Volume 84, Issue 1, pp 119-133

Open Access This content is freely available online to anyone, anywhere at any time.

The evolution of cyclodextrin glucanotransferase product specificity

  • Ronan M. KellyAffiliated withMicrobial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Carbohydrate Bioprocessing, University of Groningen
  • , Lubbert DijkhuizenAffiliated withMicrobial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Carbohydrate Bioprocessing, University of Groningen Email author 
  • , Hans LeemhuisAffiliated withMicrobial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Carbohydrate Bioprocessing, University of Groningen

Abstract

Cyclodextrin glucanotransferases (CGTases) have attracted major interest from industry due to their unique capacity of forming large quantities of cyclic α-(1,4)-linked oligosaccharides (cyclodextrins) from starch. CGTases produce a mixture of cyclodextrins from starch consisting of 6 (α), 7 (β) and 8 (γ) glucose units. In an effort to identify the structural factors contributing to the evolutionary diversification of product specificity amongst this group of enzymes, we selected nine CGTases from both mesophilic, thermophilic and hyperthermophilic organisms for comparative product analysis. These enzymes displayed considerable variation regarding thermostability, initial rates, percentage of substrate conversion and ratio of α-, β- and γ-cyclodextrins formed from starch. Sequence comparison of these CGTases revealed that specific incorporation and/or substitution of amino acids at the substrate binding sites, during the evolutionary progression of these enzymes, resulted in diversification of cyclodextrin product specificity.

Keywords

Protein evolution CGTase α-Amylase Reaction specificity Protein stability