Bacterial aminoacyl phospholipids-Biosynthesis and role in basic cellular processes and pathogenicity.

The bacterial cell membrane accomplishes the controlled exchange of molecules with the extracellular space and mediates specific interactions with the environment. However, the cytoplasmic membrane also includes vulnerable targets for antimicrobial agents. A common feature of cationic antimicrobial peptides (CAMPs)produced by other bacteria or by the host immune system is to utilize the negative charge of bacterial phospholipids such as phosphatidylglycerol (PG)or cardiolipin (CL)for initial adherence and subsequent penetration into the membrane bilayer. To resist cationic antimicrobials many bacteria integrate positive charges into the membrane surface. This is accomplished by aminoacylation of negatively charged (PG)or (CL)with alanine, arginine, or lysine residues. The Multiple Peptide Resistance Factor (MprF)of Staphylococcus aureus is the prototype of a highly conserved protein family of aminoacyl phosphatidylglycerol synthases (aaPGSs)which modify PG or CL with amino acids. MprF is an oligomerizing membrane protein responsible for both, synthesis of lysyl phosphatidylglycerol (LysPG)in the inner leaflet of the cytoplasmic membrane and translocation of LysPG to the outer leaflet. This review focuses on occurrence, synthesis and function of bacterial aminoacyl phospholipids (aaPLs)and on the role of such lipids in basic cellular processes and pathogenicity. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.