Premium
Stereochemical characterization of acyl‐phosphatidylglycerol and bis ‐(monoacylglycerol)phosphate using nuclear magnetic resonance
Author(s) -
Peros Colin S,
Garrett Teresa A
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.629.17
Subject(s) - chemistry , phosphatidylglycerol , phosphatidic acid , glycerophospholipids , stereochemistry , acyltransferase , phosphatidylethanolamine , biosynthesis , escherichia coli , acyltransferases , biochemistry , enzyme , phospholipid , phosphatidylcholine , membrane , gene
Gram‐negative bacteria such as Escherichia coli contain mainly glycerophospholipids (GPLs), with phosphatidylethanolamine (PA), phosphatidic acid (PA) and phosphatidylglycerol (PG) comprising about 95% of the total lipids in the cell. Low level (~0.1% total GLPs) lipids are formed when an additional acyl chain is added to the headgroup of PG or lyso PG to form acyl PG and bis (monoacylglycero)phosphate (BMP), respectively. Two enzymes that affect headgroup‐acylated GPL levels are E. coli PldB and the Arabidopsis thaliana lysophospholipid acyltransferase At1g78690. It was previously assumed that the stereochemistry of the sn ‐2 and sn ‐2′ positions of the substrates involved in the lipids' biosynthesis set the configuration of the glycerols but given that there is precedence for inversion of the glycerol stereochemistry by the enzymes involved in BMP formation in eukaryotes, we wanted to directly investigate the stereochemistry of BMP and acyl PG formed in E. coli . Furthermore, other works suggest that during extraction the acyl chain can migrate from the sn ‐2′ position to the sn ‐3′ position. Understanding the exact structure, including the stereochemistry of the sn ‐2 and sn ‐2′ position, will allow us to fully understand the function and biosynthetic origin of the acyl‐PG and BMP isoforms. We are structurally characterizing acyl‐PG and BMP using nuclear magnetic resonance (NMR) following covalent modification of the glycerol hydroxyls of the polyglycerolphosphate backbone. The enantiomers of α‐methoxyphenylacetic acid (MPA) will be added to the hydroxyl of the base deacylated isolated acyl PG or BMP molecules, followed by 1 H‐NMR on the resulting conjugated lipid. The covalently‐bonded MPA leads to shielding and deshielding on the proton of the chiral glycerol carbons that allow discrimination of the stereochemical configuration by comparing the chemical shifts of the ( R )‐ and ( S )‐MPA modified molecules. Determination of the stereochemistry will give insight into the mechanism of biosynthesis, origin, and function of these low abundance lipids. Support or Funding Information National Science Foundation Research at Undergraduate Institutions Grant #1516805 and #1152463, and National Science Foundation Major Instrumentations Grant #1039659 and #1526982