5oar
From Proteopedia
Crystal structure of native beta-N-acetylhexosaminidase isolated from Aspergillus oryzae
Structural highlights
FunctionHEXA_ASPOZ Selectively hydrolyzes GlcNAcbeta(1->4)GlcNAc (N,N'-diacetylchitobiose) and Gal-NAcbeta(1->4)GlcNAc, but not their C-2 epimers GlcNAcbeta(1->4)ManNAc or Gal-NAcbeta(1->4)ManNAc. However, hydrolyzes both GlcNAcbeta(1->6)GlcNAc and GlcNAcbeta(1->6)ManNAc (Ref.7). Part of the binary chitinolytic system. Involved in hydrolyzation of chitobiose and higher chito-oligomers (produced from cell wall chitin by endochitinases), thus contributing to the formation of germ tubes, fruit-bodies and septa during hyphenation (Probable). Hydrolyzes synthetic substrate p-nitrophenyl-beta-N-acetyl-D-glucosaminide (pNP-GlcNAc) (PubMed:17302431, PubMed:12723619, Ref.7). Hydrolyzes synthetic substrate p-nitrophenyl-beta-N-acetyl-D-galactosaminide (pNP-GalNAc) (PubMed:12723619). Hydrolyzes chromogenic substrate 4-nitrophenyl-2-acetamido-2-deoxyglucopyranoside (PubMed:21505251, PubMed:17509134, PubMed:29239122).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedbeta-N-acetylhexosaminidase from the fungus Aspergillus oryzae is a secreted extracellular enzyme that cleaves chitobiose into constituent monosaccharides. It belongs to the GH 20 glycoside hydrolase family and consists of two N-glycosylated catalytic cores noncovalently associated with two 10-kDa O-glycosylated propeptides. We used X-ray diffraction and mass spectrometry to determine the structure of Aspergillus oryzae beta-N-acetylhexosaminidase isolated from its natural source. The three-dimensional structure determined and refined to a resolution of 2.3 A revealed that this enzyme is active as a uniquely tight dimeric assembly further stabilized by N- and O-glycosylation. The propeptide from one subunit forms extensive noncovalent interactions with the catalytic core of the second subunit in the dimer, and this chain swap suggests the distinctive structural mechanism of the enzyme's activation. Unique structural features of beta-N-acetylhexosaminidase from Aspergillus oryzae define a very stable and robust framework suitable for biotechnological applications. The crystal structure reported here provides structural insights into the enzyme architecture as well as the detailed configuration of the active site. These insights can be applied to rational enzyme engineering. This article is protected by copyright. All rights reserved. Crystal structure of native beta-N-acetylhexosaminidase isolated from Aspergillus oryzae sheds light onto its substrate specificity, high stability, and regulation by propeptide.,Skerlova J, Blaha J, Pachl P, Hofbauerova K, Kukacka Z, Man P, Pompach P, Novak P, Otwinowski Z, Brynda J, Vanek O, Rezacova P FEBS J. 2017 Dec 14. doi: 10.1111/febs.14360. PMID:29239122[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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