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). 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. Monomer. Permanently associated with the membrane. The acceptor mannose ring localizes in a cavity at the end of a surface-exposed long groove where the active site is located, whereas the palmitate moiety accommodates into a hydrophobic pocket deeply buried in the alpha/beta core of the protein. Mutant exhibits severe growth defects and contains an increased amount of phosphatidylinositol mono- and dimannosides and a decreased amount of acylated phosphatidylinositol dimannosides compared with the wild-type parental strain. Belongs to the LpxL/LpxM/LpxP family.