Catalyzes the transfer of a palmitoyl moiety from palmitoyl-CoA to the 6-position of the mannose ring linked to the 2-position of myo-inositol in phosphatidyl-myo-inositol monomannoside (PIM1) or dimannoside (PIM2) (PubMed:12851411). Essential for growth and survival in axenic cultures and during macrophage infection and in a mouse model of infection (PubMed:33468587). a 2,6-O-bis(alpha-D-mannopyranosyl)-1-phosphatidyl-1D-myo-inositol + an acyl-CoA = 2-O-(alpha-D-mannosyl)-6-O-(6-O-acyl-alpha-D-mannosyl)-1-phosphatidyl-1D-myo-inositol + CoA a 1,2-diacyl-sn-glycero-3-phospho-[alpha-D-mannopyranosyl-(1<->6)-D-myo-inositol] + an acyl-CoA = a 1,2-diacyl-sn-glycero-3-phospho-[alpha-D-6-acyl-mannopyranosyl-(1<->6)-D-myo-inositol] + CoA Phospholipid metabolism; phosphatidylinositol metabolism. Permanently associated with the membrane. Essential, gene silencing is bactericidal (PubMed:33468587). Depletion of PatA causes a block in the biosynthesis of PIMs, resulting in severe changes in the composition of the mycobacterial cell wall membrane, which correlates with the loss of viability (PubMed:33468587). Belongs to the LpxL/LpxM/LpxP family.