geneity with an increase in the number of residues bearing PG. They further report that inactivation of pptB and substitution of pilin serine residue 93 (a conserved and likely site of PG occupancy in strain 8013) led to an approximately two-fold increase in the number of bacteria found in aggregates. Likewise, overexpression of pptB resulted in a decrease in bacterial aggregation. As type IV pili are the predominant effectors of such bacterial aggregates, these results provided a connection between altered pilin modification with PG and a pilus – associated phenotype. In an effort to understand this association, molecular models of the threedimensional structure of pilin and pilus fibers were generated. Here, the data were