The first 50 amino acids of MucA are necessary and sufficient for
viability. (a) Schematic of MucA encoded by the ectopic mucA
alleles in PAO1 ∆algD strains tested for
mucA essentiality in (b). MucA aa 1–143 lacks the
MucB binding domain and is the product of the common mucA22
allele. MucA 1–110 lacks the entire periplasmic domain. MucA aa
1–75 contains most of the AlgU binding domain, while shorter truncations
contain only parts of the AlgU binding domain (MucA aa 1–62, 1–50,
1–40, and 1–24). Green, AlgU binding domain (AlgU BD); blue, the
transmembrane domain (TM); and purple, the MucB binding domain (MucB BD). (b)
Frequency of observed isolates resolving to the endogenous mucA
allele (WT, black) or the deletion allele (∆mucA, white)
in the allelic exchange assay. Super-imposed on the bars are the number of
isolates that were tested in each category. Asterisk, p
< .0001; Fisher’s exact test. Caret, slower growing isolates