Research in the Garrett Lab
The biosynthesis of lipids, even low abundance lipids such as headgroup-acylated glycerophospholipids (GPLs), impacts essential cell functions such as cell division. The research in the Garrett lab is focused on determining the function and biosynthesis of this under-investigated class of GPLs. We are currently using an biochemical and molecular genetic approach to determine how headgroup-acylated lipids function in the cell. The two headgroup-acylated GPLs we are studying are acyl-phosphatidylglycerol and N-acyl phosphatidylethanolamine.
We are studying two enzymes that impact headgroup-acylted GPL levels in E. coli. The E. coli enzyme PldB catalyzes the formation of the headgroup-acylated GPL, acyl phosphatidylglycerol (acyl PG) by transferring an acyl chain from a monoacylated GPL (lyso GPL) to the headgroup of PG.
The Arabidopsis thaliana enzyme At1g78690p, which acylates lyso GPLs to form di-acylated GPLs in vitro, leads to the accumulation of the tri-acylated GPL, acyl PG, when over-expressed in E. coli.
We are currently working to understand the substrate specificities and kinetic mechanisms of these enzymes. This information will enable us to probe how lyso GPL metabolism and cellular levels impact headgroup-acylated GPL levels in vivo.
We are also investigating the role of headgroup-acylated GPLs in E. coli by altering the levels of these lipids in wild-type E. coli and in E. coli with mutations in enzymes of GPL biosynthesis. This work will provide the basis to understand the function of these lipids and help, in future work, explain the complexity of lipids found in all cells.
Every aspect of this research directly involves undergraduate student researchers. Students prepare lipid substrates and protein extracts, perform the in vitro enzyme assays, purify the enzymes to homogeneity, and construct the E. coli strains necessary to make significant contributions to the field of lipid biochemistry. They present their work at scientific conferences as poster and oral presentations and publish in peer-reviewed journals.