A novel domain arrangement in a monomeric cyclodextrin-hydrolyzing enzyme from the hyperthermophile Pyrococcus furiosus

► PFTA is a unique hyperthermophilic amylase with cyclodextrin hydrolysis activity. ► The crystal structure of PFTA shows that the enzyme is a self-sufficient monomer. ► The extended N-terminal region folded into its own active site. ► Mutant at the domain interface produced higher purity of maltoheptaose. ► Result supports functional substitution of the N′‐domain in hyperthermophilic archaea.