FIG 9.

Proposed model of MprF (A) or mutated MprF (* MprF) (B) affecting lipoprotein PrsA anchorage. Step 1, MprF uses cytosolic lysyl-tRNA to convert phosphatidylglycerol (PG) to lysyl phosphatidylglycerol (L-PG); step 1b, the enhanced transferase and/or flippase activity of mutated MprF increases the proportion of L-PG compared to that of phosphatidylglycerol in the outer membrane leaflet; step 2, prelipoprotein PrsA is secreted, which probably occurs through the Sec pathway; step 3, phosphatidylglycerol is used by the Lgt enzyme to lipid modify the PrsA lipobox cysteine; step 3b, inhibition of Lgt-mediated acyl transfer to PrsA occurs due to increased L-PG amounts/reduced phosphatidylglycerol amounts in the outer membrane leaflet; step 4, lipidated membrane-anchored PrsA helps with the posttranslational maturation of PBP 2a; step 4b, failure to produce lipidated membrane-anchored PrsA occurs.