FIG. 5.

N-Acetylglucosaminyltransferase activity is mediated by the ica locus. Crude membrane extracts were incubated with radiolabeled UDP-N-acetylglucosamine, and synthesized oligomers were separated on an NH₂-HPTLC plate. Lane S contains the standard, N-acetylglucosamine, alone. The remaining lanes contain products synthesized by crude membrane extracts from S. carnosus carrying pTXicaADBC, an inducible expression plasmid containing S. epidermidis icaA, icaD, icaB, and icaC (lane 1), S. carnosus harboring the vector, pTX16, alone (lane 2), S. epidermidis ATCC 35984 (RP62A), which produces PIA (lane 3), S. epidermidis 5179, a strain that does not produce PIA and does not form biofilms (lane 4), S. aureus wild-type strain ATCC 35556 (lane 5), and S. aureus ica knockout strain ATCC 35556Δica::tet (lane 6). An arrow indicates the monomer. Oligomers of increasing size are seen as a ladder-like series of spots that descend on the plate toward the origin (arrowhead) at the bottom. The smear just above the origin is unreacted UDP-N-acetylglucosamine.