Mannosyl-oligosaccharide glucosidase explained

Mannosyl-oligosaccharide glucosidase
Ec Number:3.2.1.106
Cas Number:78413-07-7

Mannosyl-oligosaccharide glucosidase (MOGS) (processing α-glucosidase I, Glc3Man9NAc2 oligosaccharide glucosidase, trimming glucosidase I, GCS1) is an enzyme with systematic name mannosyl-oligosaccharide glucohydrolase.[1] [2] [3] [4] [5] MOGS is a transmembrane protein found in the membrane of the endoplasmic reticulum of eukaryotic cells. Biologically, it functions within the N-glycosylation pathway.

Enzyme mechanism

MOGS is a glycoside hydrolase enzyme, belonging to Family 63 as classified within the Carbohydrate-Active Enzyme database.[6]

It catalyses exohydrolysis of the non-reducing terminal glucose residue in the mannosyl-oligosaccharide glycan Glc3Man9GlcNAc2.

This reaction is the first trimming step in the N-glycosylation pathway. Prior to this, the glycan was co-translationally attached to a nascent protein by the oligosaccharyltransferase complex. MOGS removes the terminal glucose residue, leaving the glycoprotein linked to Glc2Man9GlcNAc2, which can then serve as a substrate for glucosidase II.

Substrate Specificity

MOGS is highly specific to the oligosaccharide in its biological substrate in the N-glycosylation pathway. Eukaryotic MOGS does not cleave simple substrates such as p-nitrophenyl glucose, and it also shows no activity to the α(1→3) linkage present at the terminus of Glc1-2Man9GlcNAc2.[7] [8] [9] Furthermore, the minimum substrate is the glucotriose molecule (Glc-α(1→2)-Glc-α(1→3)-Glc), linked as in its native Glc3Man9GlcNAc2 substrate. Kojibiose, the disaccharide Glc-α(1→2)-Glc, acts as a weak inhibitor on plant, animal, and yeast MOGS.[10] [11] [12]

MOGS also acts to lesser extent on the corresponding glycolipids and glycopeptides.

Notes and References

  1. Elting JJ, Chen WW, Lennarz WJ . Characterization of a glucosidase involved in an initial step in the processing of oligosaccharide chains . The Journal of Biological Chemistry . 255 . 6 . 2325–31 . March 1980 . 7358674 .
  2. Grinna LS, Robbins PW . Glycoprotein biosynthesis. Rat liver microsomal glucosidases which process oligosaccharides . The Journal of Biological Chemistry . 254 . 18 . 8814–8 . September 1979 . 479161 .
  3. Kilker RD, Saunier B, Tkacz JS, Herscovics A . Partial purification from Saccharomyces cerevisiae of a soluble glucosidase which removes the terminal glucose from the oligosaccharide Glc3Man9GlcNAc2 . The Journal of Biological Chemistry . 256 . 10 . 5299–603 . May 1981 . 7014569 .
  4. Grinna LS, Robbins PW . Substrate specificities of rat liver microsomal glucosidases which process glycoproteins . The Journal of Biological Chemistry . 255 . 6 . 2255–8 . March 1980 . 7358666 .
  5. Michael JM, Kornfeld S . Partial purification and characterization of the glucosidases involved in the processing of asparagine-linked oligosaccharides . Archives of Biochemistry and Biophysics . 199 . 1 . 249–58 . January 1980 . 7356331 . 10.1016/0003-9861(80)90278-7 .
  6. Web site: CAZy - GH63. www.cazy.org. 2016-04-05.
  7. Vijay IK, Shailubhai K, Dong-Yu B, Pratta MA, Saxena S . Studies on the biosynthesis and regulation of asparagine-linked glycoproteins in the lactating mammary gland . Indian Journal of Biochemistry & Biophysics . 25 . 1-2 . 127–32 . 1988-04-01 . 2846425 .
  8. Dhanawansa R, Faridmoayer A, van der Merwe G, Li YX, Scaman CH . Overexpression, purification, and partial characterization of Saccharomyces cerevisiae processing α glucosidase I . Glycobiology . 12 . 3 . 229–34 . March 2002 . 11971867 . 10.1016/0014-5793(86)80982-6 .
  9. Shailubhai K, Saxena ES, Balapure AK, Vijay IK . Developmental regulation of glucosidase I, an enzyme involved in the processing of asparagine-linked glycoproteins in rat mammary gland . The Journal of Biological Chemistry . 265 . 17 . 9701–6 . June 1990 . 2190984 .
  10. Zeng YC, Elbein AD . Purification to homogeneity and properties of plant glucosidase I . Archives of Biochemistry and Biophysics . 355 . 1 . 26–34 . July 1998 . 9647663 . 10.1006/abbi.1998.0717 .
  11. Schweden J, Borgmann C, Legler G, Bause E . Characterization of calf liver glucosidase I and its inhibition by basic sugar analogs . Archives of Biochemistry and Biophysics . 248 . 1 . 335–40 . July 1986 . 2942110 . 10.1016/0003-9861(86)90429-7 .
  12. Ugalde RA, Staneloni RJ, Leloir LF . Microsomal glucosidases of rat liver. Partial purification and inhibition by disaccharides . European Journal of Biochemistry . 113 . 1 . 97–103 . December 1980 . 7460954 . 10.1111/j.1432-1033.1980.tb06144.x. free . 11336/143170 . free .

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