PMID- 10089216
OWN - NLM
STAT- MEDLINE
DCOM- 19990503
LR  - 20190513
IS  - 0959-6658 (Print)
IS  - 0959-6658 (Linking)
VI  - 9
IP  - 4
DP  - 1999 Apr
TI  - Differences between the trypanosomal and human GlcNAc-PI de-N-acetylases of
      glycosylphosphatidylinositol membrane anchor biosynthesis.
PG  - 415-22
AB  - De-N-acetylation of N-acetylglucosaminyl-phosphatidylino-sitol (GlcNAc-PI) is the
      second step of glycosylphosphatidylino-sitol (GPI) membrane anchor biosynthesis
      in eukaryotes. This step is a prerequisite for the subsequent processing of
      glucosaminyl-phosphatidylinositol (GlcN-PI) that leads to mature GPI membrane
      anchor precursors, which are transferred to certain proteins in the endoplasmic
      reticulum. In this article, we used a direct de-N-acetylase assay, based on the
      release of [14C]acetate from synthetic GlcN[14C]Ac-PI and analogues thereof, and 
      an indirect assay, based on the mannosylation of GlcNAc-PI analogues, to study
      the substrate specificities of the GlcNAc-PI de-N-acetylase activities of African
      trypanosomes and human (HeLa) cells. The HeLa enzyme was found to be more
      fastidious than the trypanosomal enzyme such that, unlike the trypanosomal
      enzyme, it was unable to act on a GlcNAc-PI analogue containing 2-O-octyl-d- myo 
      -inositol or on the GlcNAc-PI diastereoisomer containing l- myo -inositol
      (GlcNAc-P(l)I). These results suggest thatselective inhibition of the
      trypanosomal de-N-acetylase may be possible and that this enzyme should be
      considered as a possible therapeutic target. The lack of strict stereospecificity
      of the trypanosomal de-N-acetylase for the d- myo -inositol component was also
      seen for the trypanosomal GPI alpha-manno-syltransferases when GlcNAc-P(l)I was
      added to the trypanosome cell-free system, but not when GlcN-P(l)I was used. In
      an attempt to rationalize these data, we modeled the structure and dynamics of
      d-GlcNAcalpha1-6d- myo -inositol-1-HPO4-( sn )-3-glycerol and its diastereoisomer
      d-GlcNAcalpha1-6l- myo -inositol-1-HPO4-( sn )-3-glycerol. These studies indicate
      that the latter compound visits two energy minima, one of which resembles the
      low-energy conformer of former compound. Thus, it is conceivable that the
      trypanosomal de-N-acetylase acts on GlcNAc-P(l)I when it occupies a
      GlcNAc-PI-likeconformation and that GlcN-P(l)I emerging from the de-N-acetylase
      may be channeled to the alpha-mannosyltransferases in this conformation.
FAU - Sharma, D K
AU  - Sharma DK
AD  - Division of Molecular Parasitology & Biological Chemistry, Department of
      Biochemistry, University of Dundee, Dundee DD1 4HN, Scotland.
FAU - Smith, T K
AU  - Smith TK
FAU - Weller, C T
AU  - Weller CT
FAU - Crossman, A
AU  - Crossman A
FAU - Brimacombe, J S
AU  - Brimacombe JS
FAU - Ferguson, M A
AU  - Ferguson MA
LA  - eng
GR  - Wellcome Trust/United Kingdom
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Glycobiology
JT  - Glycobiology
JID - 9104124
RN  - 0 (Glycosylphosphatidylinositols)
RN  - 0 (Membrane Lipids)
RN  - EC 2.4.1.- (Mannosyltransferases)
RN  - EC 3.5.- (Amidohydrolases)
RN  - EC 3.5.1.89 (N-acetylglucosaminyl-phosphatidylinositol de-N-acetylase)
SB  - IM
MH  - Amidohydrolases/antagonists & inhibitors/*metabolism
MH  - Animals
MH  - Glycosylphosphatidylinositols/*biosynthesis/chemistry
MH  - HeLa Cells
MH  - Humans
MH  - Mannosyltransferases/metabolism
MH  - Membrane Lipids/*biosynthesis/chemistry
MH  - Molecular Conformation
MH  - Species Specificity
MH  - Substrate Specificity
MH  - Trypanosoma brucei brucei/*enzymology
EDAT- 1999/03/25 00:00
MHDA- 1999/03/25 00:01
CRDT- 1999/03/25 00:00
PHST- 1999/03/25 00:00 [pubmed]
PHST- 1999/03/25 00:01 [medline]
PHST- 1999/03/25 00:00 [entrez]
AID - cwc036 [pii]
AID - 10.1093/glycob/9.4.415 [doi]
PST - ppublish
SO  - Glycobiology. 1999 Apr;9(4):415-22. doi: 10.1093/glycob/9.4.415.