title: Membrane-bound amylopullulanase is essential for starch metabolism of Sulfolobus acidocaldarius DSM639.
abstract: Sulfolobus acidocaldarius DSM639 produced an acid-resistant membrane-bound amylopullulanase (Apu) during growth on starch as a sole carbon and energy source. The physiological role of Apu in starch metabolism was investigated by the growth and starch degradation pattern of apu disruption mutant as well as biochemical properties of recombinant Apu. The Δapu mutant lost the ability to grow in minimal medium in the presence of starch, and the amylolytic activity observed in the membrane fraction of the wild-type strain was not detected in the Δapu mutant when the cells were grown in YT medium. The purified membrane-bound Apu initially hydrolyzed starch, amylopectin, and pullulan into various sizes of maltooligosaccharides, and then produced glucose, maltose, and maltotriose in the end, indicating Apu is a typical endo-acting glycoside hydrolase family 57 (GH57) amylopullulanase. The maltose and maltotriose observed in the culture medium during the exponential and stationary phase growth indicates that Apu is the essential enzyme to initially hydrolyze the starch into small maltooligosaccharides to be transported into the cell.
authors.affiliation: Department of Microbiology, College of Natural Sciences, Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, 609-735, Korea.
authors.forename: Kyoung-Hwa
authors.initials: KH
authors.lastname: Choi
authors.forename: Jaeho
authors.initials: J
authors.lastname: Cha
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D013213:Starch / Q000378:metabolism*; D016945:Sulfolobus acidocaldarius / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D013213:Starch; D006026:Glycoside Hydrolases; C082507:amylopullulanase