Table 1

Scanning mutagenesis of the secretion signal of YopE1–15-Npt (pDA46) and YopN1–15-Npt (pDA85). Individual codons of the wild-type sequence were replaced with those encoding either alanine or glutamic acid. The secretion data were collected by separating culture medium from sedimented cells and immunoblotting with anti-Npt. 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]. ND, not determined.

ResidueYopEYopN
Ala (GCA)Glu (GAG)Ala (GCU)
Secretion (%)[X]/[YopH]Secretion (%)[X]/[YopH]Secretion (%)[X]/[YopH]
 2500.3750.3490.1
 3290.7440.2630.1
 4ND0330.2510.2
 5421.0530.4440.2
 6470.5530.4620.2
 7560.6500.5460.2
 8380.8530.4550.2
 9620.4510.4540.1
10630.4460.3470.2
11430.4390.4610.2
12680.5510.3630.2
13570.5380.7550.1
14480.6550.4630.2
15470.3570.4580.2
WT530.7500.1