Abstract
Phosphatidylglycerol (PG) makes up 5-20% of the phospholipids of Escherichia coli and is essential for growth in wild-type cells. PG is synthesized from the dephosphorylation of its immediate precursor, phosphatidylglycerol phosphate (PGP) whose synthase in E. coli is PgsA. Using genetic, biochemical, and highly sensitive mass spectrometric approaches, we identified an alternative mechanism for PG synthesis in E. coli that is PgsA independent. The reaction of synthesis involves the conversion of phosphatidylethanolamine and glycerol into PG and is catalyzed by ClsB, a phospholipase D-type cardiolipin synthase. This enzymatic reaction is demonstrated herein both in vivo and in vitro as well as by using the purified ClsB protein. When the growth medium was supplemented with glycerol, the expression of E. coli ClsB significantly increased PG and cardiolipin levels, with the growth deficiency of pgsA null strain also being complemented under such conditions. Identification of this alternative mechanism for PG synthesis not only expands our knowledge of bacterial anionic phospholipid biosynthesis, but also sheds light on the biochemical functions of the cls gene redundancy in E. coli and other bacteria. Finally, the PGP-independent PG synthesis in E. coli may also have important implications for the understanding of PG biosynthesis in eukaryotes that remains incomplete.
Highlights
In Escherichia coli, depending on growth phase and conditions, phosphatidylglycerol (PG)2 can account for 5–20% of the total phospholipid content, with the remainder mainly comprising phosphatidylethanolamine (PE) and cardiolipin (CL) [1, 2]
We purified the ClsB protein and demonstrated its PG synthesis activity using PE and glycerol as substrates. Elucidation of this phosphatidylglycerol phosphate (PGP)-independent PG synthesis expands our knowledge of anionic phospholipid biosynthesis and metabolism and sheds light on the biochemical functions of the multiple cls genes found in E. coli and many other bacteria
liquid chromatography/mass spectrometry (LC/MS) Reveals pgsA-independent and cls-dependent PG Formation in E. coli—Under the normal phase LC conditions used in this study, the major E. coli glycerophospholipids elute in the following order: PG (ϳ11–12 min), CL (ϳ12–14 min), PE (ϳ16 –17 min), and phosphatidic acid (PA) (ϳ20 –21 min)
Summary
Phosphatidylglycerol (PG) makes up 5–20% of the phospholipids of Escherichia coli and is essential for growth in wild-type cells. When the growth medium was supplemented with glycerol, the expression of E. coli ClsB significantly increased PG and cardiolipin levels, with the growth deficiency of pgsA null strain being complemented under such conditions Identification of this alternative mechanism for PG synthesis expands our knowledge of bacterial anionic phospholipid biosynthesis, and sheds light on the biochemical functions of the cls gene redundancy in E. coli and other bacteria. We purified the ClsB protein and demonstrated its PG synthesis activity using PE and glycerol as substrates Elucidation of this PGP-independent PG synthesis expands our knowledge of anionic phospholipid biosynthesis and metabolism and sheds light on the biochemical functions of the multiple cls genes found in E. coli and many other bacteria
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
