Chen-Hsi Chu and Kun-Mou Li contributed equally to this work.
Crystal structures of starch binding domain from Rhizopus oryzae glucoamylase in complex with isomaltooligosaccharide: Insights into polysaccharide binding mechanism of CBM21 family
Article first published online: 22 NOV 2013
© 2013 Wiley Periodicals, Inc.
Proteins: Structure, Function, and Bioinformatics
Volume 82, Issue 6, pages 1079–1085, June 2014
How to Cite
Chu, C.-H., Li, K.-M., Lin, S.-W., Chang, M. D.-T., Jiang, T.-Y. and Sun, Y.-J. (2014), Crystal structures of starch binding domain from Rhizopus oryzae glucoamylase in complex with isomaltooligosaccharide: Insights into polysaccharide binding mechanism of CBM21 family. Proteins, 82: 1079–1085. doi: 10.1002/prot.24446
- Issue published online: 17 MAY 2014
- Article first published online: 22 NOV 2013
- Accepted manuscript online: 9 OCT 2013 12:37PM EST
- Manuscript Accepted: 26 SEP 2013
- Manuscript Revised: 10 SEP 2013
- Manuscript Received: 25 JUN 2013
- National Science Council of Taiwan, Republic of China . Grant Number: NSC 101-2311-B-007-009-MY3 (Y.-J. Sun) and NSC 100-2628-B-007-003-MY3 (M.D.-T. Chang)
- National Tsing Hua University Taiwan, Republic of China . Grant Number: 102N2787E1 to Y.-J. Sun
- Shen's Culture and Education Foundation (T.-Y. Jiang scholarship award)
- Rhizopus oryzae;
- starch binding domain;
Glucoamylases are responsible for hydrolysis of starch and polysaccharides to yield β-d-glucose. Rhizopus oryzae glucoamylase (RoGA) is composed of an N-terminal starch binding domain (SBD) and a C-terminal catalytic domain connected by an O-glycosylated linker. Two carbohydrate binding sites in RoSBD have been identified, site I is created by three highly conserved aromatic residues, Trp47, Tyr83, and Tyr94, and site II is built up by Tyr32 and Phe58. Here, the two crystal structures of RoSBD in complex with only α-(1,6)-linked isomaltotriose (RoSBD-isoG3) and isomaltotetraose (RoSBD-isoG4) have been determined at 1.2 and 1.3 Å, respectively. Interestingly, site II binding is observed in both complexes, while site I binding is only found in the RoSBD-isoG4 complex. Hence, site II acts as the recognition binding site for carbohydrate and site I accommodates site II to bind isoG4. Site I participates in sugar binding only when the number of glucosyl units of oligosaccharides is more than three. Taken together, two carbohydrate binding sites in RoSBD cooperate to reinforce binding mode of glucoamylase with polysaccharides as well as the starch. Proteins 2014; 82:1079–1085. © 2013 Wiley Periodicals, Inc.