Together, the results of the activity assays support the phenotypic data and muropeptide analysis showing that LdtD is highly active in producing 3-3 cross-links in PG sacculi, and it is able to cooperate with the GTase activity of PBP1B and DD-CPases to utilize nascent PG as the substrate, consistent with a role in protective remodeling of PG during OM defective assembly. This evidence concerns the gene RNGTT and ocular melanoma.