FIG 4.
Manipulation of the indels of Wzz2 modulates chain length determination. The mutants were expressed in the O13Δwzz1 Δwzz2 double mutant in the absence (−) or presence (+) of L-arabinose. (A) Deletion of insIL in Wzz2 [z2(ΔinsIL)] results in a shorter, broader chain length pattern. Insertion of insIL into Wzz1 (z1::insIL) reduces chain length. Replacement of the entire Wzz1 internal loop with that of Wzz2 (z1::wzz2-IL) similarly reduces chain length. (B) Deletion of insα6/7 in Wzz2 (z2Δinsα6/7) results in severely reduced chain length determining activity (bracket). (C) Deletion of residues 271 to 279 of insL4 in Wzz2 (Δ271-9) significantly reduces the OSA chain length. Replacing this region with flexible (FLEX) or rigid (RIGID) peptide sequences has a similar effect. Deletion of L4 (ΔL4) results in the greatest reduction in chain length-determining activity. (D) L4 R281A and E283A variants result in a very short chain length phenotype similar to that observed when insL4 is deleted. (E) Schematic representation of the periplasmic domain of Wzz2. The location of each region investigated is in dark gray. EV, empty vector.