-Techniques in Glycobiology -
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Transcript of -Techniques in Glycobiology -
-Techniques in Glycobiology-NHLBI CardioPEG – Gerald W.Hart, September 17, 2013
Funded by NHLBI P01HL107153
Analysis ofGPI-Anchors
VSG’s Critical Role in History of GPI-Anchor Analysis:
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T. Brucei 107 VSG per Cell!
In Blood Stream Trypansomes Defeat the Immune System by Switching Their VSG
Coats!
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6Ferguson, M..A.J. Journal of Cell Science 112, 2799-2809 (1999)
Tightly Packed VSG Shields the Parasite From the Immune System:
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Relationship of GPI-Anchors to Phosphatidylinositol Ram VishwakarmaCSIR-Indian Institute of Integrative Medicine, JammuNational Institute of Immunology, New Delhi Piramal Life Sciences Ltd, Mumbai
Amide Linkage toCOOH Terminus ofProtein.
Non-Acetylated GlcN
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Structure of Triton-X114
10n=7 or 8
Triton-X114 Partitioning is a Simple & Powerful Method for Isolation of GPI-Anchor Proteins.
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Example of the Use of TX-114 Partitioning for GPI-Anchored Proteins:
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TX-114 is a Powerful Tool:
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Tot P insol. Aq pellet final Det phase
Isolation in SDS conserves Anchor, but short incubation endogenous GPI-PLC Releases sVSG
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Coomassie
SDS Hepes Hepes Hepes +NP40 5mM Zn
3H-myr
T T TS S SP PP
Purification of mfVSG and sVSG:
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Wcells CM Ifacial Aq ph Wcells TCA ppt CM:MetTCA of Supnt of 3
1. TCA PPt Cells
2. Extract pellet with Chloroform:Methanol
3. Add NaCl soln. to form 2 phases
4. mfVSG in Aqueous
1. Incubate tyrps in buffer with organic to lyse cells
MfVSG has ONLY Myristic Acid:
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sVSG
mfVSG
Separation of mfVSG and sVSG on 7.5% SDS-PAGE
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mfVSG Mix sVSG
Studying GPI Biosynthesis in vitro
cell membranessalts,buffersradiolabeled Sugar donor
30 °C
add solventsspin
evaporate
F
O
thin layerchromatography
O F
GPI-Anchor Biosynthetic Pathway Was Mostly Elucidated byThin-Layer Chromatography and Pulse-Chase Labelling:
From Varki
Radiolabeling & TLC Were Used to Elucidate the GPI-Anchor Biosynthetic Pathway:
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Incorporation of 3H-Glucosamine
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Cell, Vol. 56, 793400, March 10, 1989,
UDP-[3H]GlcNAc UDP-[3H]GlcNAc In Vivo
Pulse-Chase Labeling Reveals Intermediates in Pathway:
21Cell, Vol. 56, 793400, March 10, 1989,
Pulse with UDP-3H-GlcNAcChase UDP-GlcNAc & GDP-Mannose
No
GD
P-M
an
3H -Myrstate
No
UD
P-G
lcN
Ac
MPD Trea
ted
with
GP
I-PLC
In Vivo- +PI-PLC
Early Studies SuggestedLipid Remodeling of GPI-AnchorIn
vitr
o U
DP
-Glc
NA
c +
GD
P-M
an
Lyso-Lipid RemodelingIntermediate
Inositol Acylated
A=dimyrisoyl GPI
A’=other F.A. GPI
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Characterization of GPI-Anchor Intermediates:
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Glycolipids A and A’ Have The Same Glycan Structure:
Cell, Vol. 56, 793400, March 10, 1989,
Gel Filtration – P4
Dionex HIPC-ASG
IntermediatesAfter HONO Treatment
Leaves Glycan with AHMAt Reducing Terminus.
Biosynthetic Pathway of VSG GPI
24FEBS Letters 584 (2010) 1670–1677
Insect Form of Parasite
Blood Stream Form
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Schematic Structure & Cleavage Sites of GPI-Anchors:
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Flow Chart For GPI-Anchor Protein Analysis:
Chemical and enzymatic reactions of GPI anchors
Chapter 11, Figure 3Essentials of Glycobiology
Second Edition
Ferguson et al. Partial Structure Elucidation of GPI-
Anchor:
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JBC Vol. 260, pp. 14547-14555 1985
1. Treatment with HONO releases intact PI.
2. Treatment of sVSG (released by PI-PLC) with Pronase yields glycopeptide.
3. GP insensitive to alkaline phos. & yields myo-inositol 1-P on HONO treatment.
4. Mild acid renders sensitive to alk phos.
5. Subsequent HONO yields myoinositol
6. HONO yields AHM.
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3,4
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Linkages Were Determined by Methylation Analysis: Glycan Methylate all Free Hydroxyl Groups (Ether Linkages, Acid Stable)Acid HydrolyzeReduce and Per-Acetylate (Alditol Acetates) GC Analysis
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Size of the Glycan Moiety And Structure Was Estimated by Gel Filtration in Combination With Specific Degradation (Easily Resolve a Hexose Difference):
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NMR Was Used to Determine the Glycan Structure of the GPI:
Proteomics/Glycomics of GPI-Proteins
32Molecular & Cellular Proteomics 2: 1261–1270, 2003.
Isolation of GPI-anchored Proteins:
33Molecular & Cellular Proteomics 2: 1261–1270, 2003.
>CRD Ab Released to Sol by PLC
Example of MS Data:
34Molecular & Cellular Proteomics 2: 1261–1270, 2003.
Band 1
MS/MS Identification:
35Molecular & Cellular Proteomics 2: 1261–1270, 2003.
Algorithms for Predicting GPI-Anchor Attachment:
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Conclusions: GPI-Anchor’s Unique Structures Require
Unique Approaches. PI-PLC release from membranes is diagnostic
for GPI-Anchors Triton-X114 Partitioning is a Great Method to
Start Purification of GPI-Anchored Proteins Reductive Labeling of Anhydromannose after
nitrous acid treatment is a powerful tool. Aqueous HF releases GPI from protein. Sizing and sequential use of glycosidases use
same methods as other oligosaccharides. Consensus sequence for predicting GPIs.
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