Necessary for the succinyl substitution of periplasmic glucans. Could catalyze the transfer of succinyl residues from the cytoplasmic side of the membrane to the nascent glucan backbones on the periplasmic side of the membrane. Glycan metabolism; osmoregulated periplasmic glucan (OPG) biosynthesis. Belongs to the acyltransferase 3 family. OpgC subfamily.