Table 2

Nucleotide changes at the third position of codon triplets that do not alter the protein sequence of the secretion signal were introduced into YopN1–15-Npt. Secretion was measured by immunoblotting of culture supernatants and cell sediment. The relative amount of synthesized fusion protein [X] was measured by pulse labeling and is reported as the ratio to another type III secreted protein [YopH]. [x]/[yopH] indicates relative levels of mRNA that were observed by RNA blot hybridization.

YopN1−15-NptCodons 2 to 4Secretion (%)[X]/[YopH][x]/[yopH]
Wild typeACG ACG CUU500.10.7
Codon 2ACC ACG CUU520.10.2
Codon 3ACG ACC CUU390.10.3
Codon 4ACG ACG CUG640.10.3
Codons 2 and 3ACC ACC CUU460.10.4
Codons 3 and 4ACG ACC CUG480.10.3
Codons 2 and 4ACC ACG CUG400.040.1
Codons 2 to 4ACC ACC CUG450.10.5