期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 287, 期 11, 页码 7979-7989出版社
ELSEVIER
DOI: 10.1074/jbc.M111.304774
关键词
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资金
- Marine and Extreme Genome Research Center from the Ministry of Land, Transport, and Maritime Affairs, Republic of Korea
- National Research Foundation of Korea (NRF)
- Ministry of Education, Science, and Technology [2009-0083290/2011-0017040]
- National Natural Science Foundation of China [31000760]
- Slovak Grant Agency VEGA [2/0148/11]
Staphylothermus marinus maltogenic amylase (SMMA) is a novel extreme thermophile maltogenic amylase with an optimal temperature of 100 degrees C, which hydrolyzes alpha-(1-4)-glycosyl linkages in cyclodextrins and in linear malto-oligosaccharides. This enzyme has along N-terminal extension that is conserved among archaic hyperthermophilic amylases but is not found in other hydrolyzing enzymes from the glycoside hydrolase 13 family. The SMMA crystal structure revealed that the N-terminal extension forms an N' domain that is similar to carbohydrate-binding module 48, with the strand-loop-strand region forming a part of the substrate binding pocket with several aromatic residues, including Phe-95, Phe-96, andTyr-99. A structural comparison with conventional cyclodextrin-hydrolyzing enzymes revealed a striking resemblance between the SMMA N' domain position and the dimeric N domain position in bacterial enzymes. This result suggests that extremophilic archaea that live at high temperatures may have adopted a novel domain arrangement that combines all of the substrate binding components within a monomeric subunit. The SMMA structure provides a molecular basis for the functional properties that are unique to hyperthermophile malto-genic amylases from archaea and that distinguish SMMA from moderate thermophilic or mesophilic bacterial enzymes.
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