Skip to main content
NCBI home page
Protein & Cell logoLink to Protein & Cell
. 2011 Nov 6;2(10):827–836. doi: 10.1007/s13238-011-1105-3

Structural insight into substrate specificity of human intestinal maltase-glucoamylase

Limei Ren 1,2, Xiaohong Qin 1,3, Xiaofang Cao 1,2, Lele Wang 1,3, Fang Bai 2, Gang Bai 1,2,✉, Yuequan Shen 1,3,✉
PMCID: PMC4875297  PMID: 22058037

Abstract

Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alphaglucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s13238-011-1105-3 and is accessible for authorized users.

Keywords: MGAM C-terminal domain, inhibitor, crystal structure, acarbose, type 2 diabetes

Electronic supplementary material

13238_2011_1105_MOESM1_ESM.pdf (372.4KB, pdf)

Supplementary material, approximately 372 KB.

Footnotes

These authors contributed equally to the work.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s13238-011-1105-3 and is accessible for authorized users.

Contributor Information

Gang Bai, Email: gangbai@nankai.edu.cn.

Yuequan Shen, Email: yshen@nankai.edu.cn, Email: yuequan74@yahoo.com.

References

  1. Adams P.D., Afonine P.V., Bunkóczi G., Chen V.B., Davis I.W., Echols N., Headd J.J., Hung L.W., Kapral G.J., Grosse-Kunstleve R.W., et al. PHENIX: a comprehensive Python-based system for macromolecular structure solution. Acta Crystallogr D Biol Crystallogr. 2010;66:213–221. doi: 10.1107/S0907444909052925. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Brayer G.D., Luo Y., Withers S.G. The structure of human pancreatic alpha-amylase at 1. A resolution and comparisons with related enzymes. Protein Sci. 1995;4:1730–1742. doi: 10.1002/pro.5560040908. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Brayer G.D., Sidhu G., Maurus R., Rydberg E.H., Braun C., Wang Y., Nguyen N.T., Overall C.M., Withers S.G. Subsite mapping of the human pancreatic alpha-amylase active site through structural, kinetic, and mutagenesis techniques. Biochemistry. 2000;39:4778–4791. doi: 10.1021/bi9921182. [DOI] [PubMed] [Google Scholar]
  4. Brünger A.T., Adams P.D., Clore G.M., DeLano W.L., Gros P., Grosse-Kunstleve R.W., Jiang J.S., Kuszewski J., Nilges M., Pannu N.S., et al. Crystallography & NMR system: A new software suite for macromolecular structure determination. Acta Crystallogr D Biol Crystallogr. 1998;54:905–921. doi: 10.1107/S0907444998003254. [DOI] [PubMed] [Google Scholar]
  5. Cowell G.M., Tranum-Jensen J., Sjöström H., Norén O. Topology and quaternary structure of pro-sucrase/isomaltase and final-form sucrase/isomaltase. Biochem J. 1986;237:455–461. doi: 10.1042/bj2370455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Dahlqvist A., Telenius U. Column chromatography of human small-intestinal maltase, isomaltase and invertase activities. Biochem J. 1969;111:139–146. doi: 10.1042/bj1110139. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Danielsen E.M. Dimeric assembly of enterocyte brush border enzymes. Biochemistry. 1994;33:1599–1605. doi: 10.1021/bi00172a041. [DOI] [PubMed] [Google Scholar]
  8. Emsley P., Cowtan K. Coot: model-building tools for molecular graphics. Acta Crystallogr D Biol Crystallogr. 2004;60:2126–2132. doi: 10.1107/S0907444904019158. [DOI] [PubMed] [Google Scholar]
  9. Ernst H.A., Lo Leggio L., Willemoës M., Leonard G., Blum P., Larsen S. Structure of the Sulfolobus solfataricus alphaglucosidase: implications for domain conservation and substrate recognition in GH31. J Mol Biol. 2006;358:1106–1124. doi: 10.1016/j.jmb.2006.02.056. [DOI] [PubMed] [Google Scholar]
  10. Gray G.M., Lally B.C., Conklin K.A. Action of intestinal sucrase-isomaltase and its free monomers on an alpha-limit dextrin. J Biol Chem. 1979;254:6038–6043. [PubMed] [Google Scholar]
  11. Heymann H., Breitmeier D., Günther S. Human small intestinal sucrase-isomaltase: different binding patterns for maltoand isomaltooligosaccharides. Biol Chem Hoppe Seyler. 1995;376:249–253. [PubMed] [Google Scholar]
  12. Jenkins D.J., Taylor R.H., Goff D.V., Fielden H., Misiewicz J.J., Sarson D.L., Bloom S.R., Alberti K.G. Scope and specificity of acarbose in slowing carbohydrate absorption in man. Diabetes. 1981;30:951–954. doi: 10.2337/diab.30.11.951. [DOI] [PubMed] [Google Scholar]
  13. Lee B., Richards F.M. The interpretation of protein structures: estimation of static accessibility. J Mol Biol. 1971;55:379–400. doi: 10.1016/0022-2836(71)90324-X. [DOI] [PubMed] [Google Scholar]
  14. Low L.C. The epidemic of type 2 diabetes mellitus in the Asia-Pacific region. Pediatr Diabetes. 2010;11:212–215. doi: 10.1111/j.1399-5448.2010.00682.x. [DOI] [PubMed] [Google Scholar]
  15. McCoy A.J. Solving structures of protein complexes by molecular replacement with Phaser. Acta Crystallogr D Biol Crystallogr. 2007;63:32–41. doi: 10.1107/S0907444906045975. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Nichols B.L., Avery S., Sen P., Swallow D.M., Hahn D., Sterchi E. The maltase-glucoamylase gene: common ancestry to sucrase-isomaltase with complementary starch digestion activities. Proc Natl Acad Sci U S A. 2003;100:1432–1437. doi: 10.1073/pnas.0237170100. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Nichols B.L., Eldering J., Avery S., Hahn D., Quaroni A., Sterchi E. Human small intestinal maltase-glucoamylase cDNA cloning. Homology to sucrase-isomaltase. J Biol Chem. 1998;273:3076–3081. doi: 10.1074/jbc.273.5.3076. [DOI] [PubMed] [Google Scholar]
  18. Nichols B.L., Quezada-Calvillo R., Robayo-Torres C.C., Ao Z., Hamaker B.R., Butte N.F., Marini J., Jahoor F., Sterchi E.E. Mucosal maltase-glucoamylase plays a crucial role in starch digestion and prandial glucose homeostasis of mice. J Nutr. 2009;139:684–690. doi: 10.3945/jn.108.098434. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Otwinowski Z., Minor W. Processing of X-ray Diffraction Data Collected in Oscillation Mode. Methods Enzymol. 1997;276:307–326. doi: 10.1016/S0076-6879(97)76066-X. [DOI] [PubMed] [Google Scholar]
  20. Qin X., Ren L., Yang X., Bai F., Wang L., Geng P., Bai G., Shen Y. Structures of human pancreatic α-amylase in complex with acarviostatins: Implications for drug design against type II diabetes. J Struct Biol. 2011;174:196–202. doi: 10.1016/j.jsb.2010.11.020. [DOI] [PubMed] [Google Scholar]
  21. Quezada-Calvillo R., Robayo-Torres C.C., Opekun A.R., Sen P., Ao Z., Hamaker B.R., Quaroni A., Brayer G.D., Wattler S., Nehls M.C., et al. Contribution of mucosal maltaseglucoamylase activities to mouse small intestinal starch alphaglucogenesis. J Nutr. 2007;137:1725–1733. doi: 10.1093/jn/137.7.1725. [DOI] [PubMed] [Google Scholar]
  22. Quezada-Calvillo R., Sim L., Ao Z., Hamaker B.R., Quaroni A., Brayer G.D., Sterchi E.E., Robayo-Torres C.C., Rose D.R., Nichols B.L. Luminal starch substrate “brake” on maltaseglucoamylase activity is located within the glucoamylase subunit. J Nutr. 2008;138:685–692. doi: 10.1093/jn/138.4.685. [DOI] [PubMed] [Google Scholar]
  23. Rabasa-Lhoret R., Chiasson J.L. Potential of alphaglucosidase inhibitors in elderly patients with diabetes mellitus and impaired glucose tolerance. Drugs Aging. 1998;13:131–143. doi: 10.2165/00002512-199813020-00005. [DOI] [PubMed] [Google Scholar]
  24. Rossi E.J., Sim L., Kuntz D.A., Hahn D., Johnston B.D., Ghavami A., Szczepina M.G., Kumar N.S., Sterchi E.E., Nichols B.L., et al. Inhibition of recombinant human maltase glucoamylase by salacinol and derivatives. FEBS J. 2006;273:2673–2683. doi: 10.1111/j.1742-4658.2006.05283.x. [DOI] [PubMed] [Google Scholar]
  25. Semenza G. Anchoring and biosynthesis of stalked brush border membrane proteins: glycosidases and peptidases of enterocytes and renal tubuli. Annu Rev Cell Biol. 1986;2:255–313. doi: 10.1146/annurev.cb.02.110186.001351. [DOI] [PubMed] [Google Scholar]
  26. Sim L., Quezada-Calvillo R., Sterchi E.E., Nichols B.L., Rose D.R. Human intestinal maltase-glucoamylase: crystal structure of the N-terminal catalytic subunit and basis of inhibition and substrate specificity. J Mol Biol. 2008;375:782–792. doi: 10.1016/j.jmb.2007.10.069. [DOI] [PubMed] [Google Scholar]
  27. Sim L., Willemsma C., Mohan S., Naim H.Y., Pinto B.M., Rose D.R. Structural basis for substrate selectivity in human maltase-glucoamylase and sucrase-isomaltase N-terminal domains. J Biol Chem. 2010;285:17763–17770. doi: 10.1074/jbc.M109.078980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Van Beers E.H., Büller H.A., Grand R.J., Einerhand A.W., Dekker J. Intestinal brush border glycohydrolases: structure, function, and development. Crit Rev Biochem Mol Biol. 1995;30:197–262. doi: 10.3109/10409239509085143. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

13238_2011_1105_MOESM1_ESM.pdf (372.4KB, pdf)

Supplementary material, approximately 372 KB.

Articles from Protein & Cell are provided here courtesy of Oxford University Press

RESOURCES