LPG_synthase_TM is the N-terminal region of this family of bacterial phosphatidylglycerol lysyltransferases. The function of the family is to add lysyl groups to membrane lipids, and this region is the transmembrane domain of 7xTMs. In order to counteract attack by membrane-damaging external cationic antimicrobial molecules - from host immune systems, bacteriocins, defensins, etc - bacteria modify their anionic membrane phosphatidylglycerol with positively-charged L-lysine; this results in repulsion of the foreign cationic peptides.
Jiyao W et al.(2023). "The conserved domain database in 2023.",