Mannosyl-oligosaccharide glucosidase

Mannosyl-oligosaccharide glucosidase (MOGS) (EC 3.2.1.106, processing alpha-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.

Mannosyl-oligosaccharide glucosidase
Identifiers
EC number3.2.1.106
CAS number78413-07-7
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum

Enzyme mechanism

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

This enzyme catalyses the following chemical reaction:

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.

The oligosaccharide substrate for MOGS

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.[8][10][11][12]

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

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