FIG 8.

Bacterial lipoprotein N-acylation. In Gram-negative bacteria, Lnt transfers the sn-1 acyl chain (orange) of a membrane phospholipid to form triacylated lipoprotein. In low-GC, Gram-positive firmicute species that make lyso-form lipoproteins, it is proposed that Lit transfers the sn-2 acyl chain (blue) internally from the diacylglycerol moiety to the α-amino group of cysteine. When heterologously expressed in E. coli (Fig. 6), the N-terminal dehydroalanyl fragment ion of Lpp shifts from an Lnt-catalyzed intermolecular sn-1 C_16:0 acyl chain transfer (m/z 813, orange acyl chain) to a WMC_RS08810-catalyzed intramolecular sn-2 C_16:1 acyl chain transfer (m/z 811, blue acyl chain).