Glycan Requirements of Glycosylphosphatidylinositol Phospholipase C from Trypanosoma brucei
| ISSN: | 0021-9258 |
|---|---|
| Přístupová URL adresa: | https://explore.openaire.eu/search/publication?articleId=doi_________::4507d3a3f39ec4b20b63ad6244a65f6d https://doi.org/10.1074/jbc.270.6.2517 |
| Rights: | OPEN |
| Přírůstkové číslo: | edsair.doi...........4507d3a3f39ec4b20b63ad6244a65f6d |
| Autor: | Kojo Mensa-Wilmot, Lei Ping-Sheng, James Morris, Tsung-Ying Shen |
| Rok vydání: | 1995 |
| Předmět: |
chemistry.chemical_classification
Glycan Phospholipase C biology Stereochemistry Phosphatidylinositol diacylglycerol-lyase Cell Biology Biochemistry carbohydrates (lipids) Enzyme activator chemistry.chemical_compound Enzyme chemistry Phosphoinositide phospholipase C Glycosylphosphatidylinositol diacylglycerol-lyase biology.protein lipids (amino acids peptides and proteins) Phosphatidylinositol Molecular Biology |
| Zdroj: | Journal of Biological Chemistry. 270:2517-2524 |
| ISSN: | 0021-9258 |
| Popis: | Glycosylphosphatidylinositol phospholipase C (GPI-PLC) from Trypanosoma brucei and phosphatidylinositol phospholipase C (PI-PLC) from Bacillus sp. both cleave glycosylphosphatidylinositols (GPIs). However, phosphatidylinositol, which is efficiently cleaved by PI-PLC, is a very poor substrate for GPI-PLC. We examined GPI-PLC substrate requirements using glycoinositol analogs of GPI components as potential inhibitors. Glucosaminyl (alpha 1-->6)-D-myo-inositol (GlcN(alpha 1-->6)Ins), GlcN(alpha 1-->6)Ins 1,2-cyclic phosphate, GlcN(alpha 1-->6)-2-deoxy-Ins, and GlcN(alpha 1-->6)Ins 1-dodecyl phosphonate inhibited GPI-PLC. GlcN(alpha 1-->6)Ins was as effective as Man-(alpha 1-->4)GlcN(alpha 1-->6)Ins; we surmise that GlcN(alpha 1-->6)Ins is the crucial glycan motif for GPI-PLC recognition. Inhibition by GlcN(alpha 1-->6)Ins 1,2-cyclic phosphate suggests product inhibition since GPIs cleaved by GPI-PLC possess a GlcN(alpha 1-->6)Ins 1,2-cyclic phosphate at the terminus of the residual glycan. The effectiveness of GlcN(alpha 1-->6)-2-deoxy-Ins indicates that the D-myo-inositol (Ins) 2-hydroxyl is not required for substrate recognition, although it is probably essential for catalysis. GlcN(alpha 1-->6)-2-deoxy-L-myo-inositol, unlike GlcN(alpha 1-->6)-2- deoxy-Ins, had no effect on GPI-PLC; hence, GPI-PLC can distinguish between the two enantiomers of Ins. Surprisingly, GlcN(alpha 1-->6)Ins 1,2-cyclic phosphate was not a potent inhibitor of Bacillus cereus PI-PLC, and GlcN(alpha 1-->6)Ins had no effect on the enzyme. However, both GlcN(alpha 1-->6)Ins 1-phosphate and GlcN(alpha 1-->6)Ins 1-dodecyl phosphonate were competitive inhibitors of PI-PLC. These observations suggest an important role for a phosphoryl group at the Ins 1-position in PI-PLC recognition of GPIs. Other studies indicate that abstraction of a proton from the Ins 2-hydroxyl is not an early event in PI-PLC cleavage of GPIs. Furthermore, both GlcN(alpha 1-->6)-2-deoxy-Ins 1-phosphate and GlcN(alpha 1-->6)-2-deoxy-L- myo-inositol inhibited PI-PLC without affecting GPI-PLC. Last, the aminoglycoside G418 stimulated PI-PLC, but had no effect on GPI-PLC. Thus, these enzymes represent mechanistic subclasses of GPI phospholipases C, distinguishable by their sensitivity to GlcN(alpha 1-->6)Ins derivatives and aminoglycosides. Possible allosteric regulation of PI-PLC by GlcN(alpha 1-->6)Ins analogs is discussed. |
| Databáze: | OpenAIRE |
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